Torque vs. Horsepower

Posted on January 25, 2012 by melwin23

If you’ve been around motorized vehicles for any length of time, you have probably been exposed to the great torque vs. power debate at some point. If not, it goes like this:

“Torque is what makes a bike accelerate, not power.”

“Wrong.”

Torque and power are inescapably linked by the fact that horsepower equals torque (in ft-pounds) times RPM divided by 5250, so people who talk as if they are independent are full of it. If you have a given torque curve for an engine, you have the horsepower curve also. Knowing how these two numbers work with each other lets you can poke through some of the BS you might read.

First, as usual, a few definitions.

Torque is a twisting force applied to an object, like a wheel or a crankshaft. Note that motion is not required for torque to exist! If you stand on a lug wrench that is on a frozen lug bolt, you are applying a torque to that bolt even though there may be no movement. For our purposes, we will consider that torque is measured in pounds-force feet (lbf-ft) meaning the equivalent of a given force, in pounds, acting on the end of a lever of length in feet. For example, standing with 180 pounds body weight on a lug wrench one foot long yields 180 lbf-ft of torque. A child of 90 pounds standing on a two-foot lug wrench applies the same torque.

Work is the application of force over a distance. Unfortunately, the units used are the same (pounds times feet) but we write this as ft-lb just to distinguish it. The real difference is that in this case, the “feet” part means feet of movement. If you push on a car with 100 pounds of force and maintain that for 30 feet, you have done 3000 ft-lb of work. An easier example is lifting a weight (in pounds) a given distance (in feet). If you use some sort of mechanical advantage, like a winch, you will do the same amount of work because by halving the effort required, you will have to double the distance through which you apply the force to achive the same objective.

Power is the application of work within a finite time. 550 ft-lb of work in one second is one horsepower.

So, let’s first go through the numbers to get from torque to horsepower. Pushing with 87.5 pounds (force) on the end of our 1-foot lug wrench applies a torque of 87.5 lbf-ft. No motion yet, so no work and no power. But now let’s say the lug bolt loosens slightly and starts to turn, but that same 87.5 pounds of force is needed to keep the wrench turning. For every revolution of the wrench, you are applying 87.5 pounds of force over a distance of (2 * pi * 1 foot) or 6.28 feet, the circumference of the circle that your hand is making, for a total of 550 ft-lb of work. It’s only when this system is actually moving that work is being performed. From here, it’s a quick step to say that if you work fast enough to turn that wrench once per second, then you are doing 550 ft-lb of work per second, which means you are applying one horsepower.

By the definitions we can see that HP is directly proportional to torque and RPM. “Directly proportional” means there may be a multiplyer involved, so let’s find it using our example numbers, remembering that 1 revolution per second is 60 RPM:

    torque * RPM * constant = hp

    87.5 lbf-ft * 60 rev/min * X = 1 hp

    X = 1 / (60 * 87.5) = 1/5250

    torque * RPM * 1/5250 = hp

    hp = (torque * RPM) / 5250

For internal combustion engines, torque is always given at a certain RPM because they can’t generate any torque when they aren’t moving. Once they are running fast enough to sustain their own operation, the force that they are exerting against a load can be measured, and the speed at which they are turning can be measured, so the torque (and therefore power) numbers become known.

So, if there is such a fixed relationship between torque and power, why do some people say that a certain engine has lots of power, but no torque? Remember that the connection between torque and power is rotational speed. A sportbike motor might generate 150hp at 14,000 RPM but the torque at that RPM is very small; about 53 ft-lbs. In comparison, a large-displacement twin might peak at 100 hp at 7000 RPM. The torque applied at the twin’s 7000 rpm, 75 ft-lbs, is greater than the torque applied at the sport bike’s 14,000 rpm but the sport bike makes up for it with a lot more engine speed and ends up with more horsepower.

The street, though, complicates things because the sport bike will probably not be ridden at 14,000 RPM. At 5000 RPM, the twin would likely have more power. This is an artificial handicap; the sport bike wasn’t meant to be ridden at that speed since it generates its power by sending the RPM part of the equation sky-high. For street riding, the twin is easier to ride, less prone to stalling as you pull away from a light, and you get that satisfying “oomph” when you twist the throttle. But as the RPM increases, the twin runs out of breath and the race bike, although the torque is low and probably getting lower, continues to make more and more power until it hits its peak at 14000.

[Insert dyno charts for comparison showing less torque but more power for sportbikes at high RPM]

Engines are designed for their intended use. Our twins are designed to yield fairly high torque values at low RPM, because this makes them easy to ride in day-to-day life, and Harley-Davidsons have their torque concentrated even lower in the RPM range than BMWs do. Low-end torque is accomplished by several design traits, one being small valves and intake tubes which create high air velocity into the cylinder for good fuel mix at low speed.

Those effects tend to become a restriction at high RPM, which means that engines intended for high RPM end up with larger valves, larger air intakes, smaller cylinders and other things that let them continue to breathe when other engines start to gasp. Race bike engines have fairly small displacement, which limits the torque that can be produced at the crank. They apply that torque at much higher speeds to get high horsepower (and who can argue that those bikes don’t accelerate quickly?).

To a lesser extent, BMW varies these techniques for different bikes. The GS series has narrower intake tubes to give a faster intake charge, giving better fuel/air mixing and better torque at low RPM. Since this becomes a bottleneck at higher RPM, the “power” engine in the RS and RT bikes have larger intake tubes. Swapping the GS tubes into an RS or RT is a common retrofit, as it makes the bike torquier at low RPM where most of us ride. Newer technology in cars, like variable valve timing and variable intake tract length, can give motors the best of both worlds by increasing torque at higher RPM without giving it up at low RPM. Incidentally, Honda has variable valve timing on a motorcycle now.

But to get back to the main point, it is power that moves our bikes down the road. Yes, torque provides the pushing force through the drivetrain, but it needs to happen at some given speed, and those two factors define “power.”

Why does torque drop after a certain RPM?

Torque starts to decrease because the engine cannot breathe as well. Due to the speed, the cylinder does not fill with air as well. A designer can get around this problem with “tuned intake” which sets up a resonance to pack the cylinder with air, but it only happens at a certain RPM. The next evolution of design is to make a variable system which packs the cylinders with air at all RPM; this is usually called “variable tuned intake runners” or something like that and involves valves which open and close to create a different size for the airbox and manifold.

Why does power continue to increase after torque decreases?

Remember that the power is essentially the product of the RPM and the torque. When the torque peaks at a certain RPM and starts to drop off, the decrease is small and is not enough to offset the increasing RPM, so the overall product still increases. Eventually the decrease in torque becomes large enough that it outweighs the increase in RPM and we see the power start to drop. Because of this, the power peak will always be after the torque peak.

A few other well-writen articles illustrate these concepts, although many can be found by entering “torque horsepower” into Google:

Learn From A Pro How To Install Piston Rings For Maximum Power Production Some Invaluable Advice From the Guys Who Do It Best

Posted on January 21, 2012 by melwin23

From the February, 2009 issue of Circle Track

By Joel Goodman

Photography by Will Handzel

There are so many details in putting together a race engine that it’s hard to cover the entire process and expect you to totally understand. Instead, we’re going to focus on one very specific step in engine building, installing piston rings, so I can be completely thorough, and you will understand.

The installation of piston rings is a critical step that really takes both artwork and science to end up with a combination that seals the combustion pressure above the piston, scrapes the oil off the cylinders so it doesn’t contaminate the combustion process, and transfers heat from the piston into the cylinder wall.

Besides fit, we use different rings for different applications, use some coatings, and try anything that will get more power to the rear wheels. But the basics to obtaining the optimum ring endgap, oil rails/expander fit, and reading rings when they come out of the engine, will get you in the horsepower game.

Piston ring fitment is very important and therefore warrants this discussion.

1. Installing piston rings sounds like it should be a box-to-piston process, but there is more to it than that. Learn what it takes to install rings for minimum cylinder leakage and maximum durability.

2. Piston rings come as a set wrapped in plastic and shipped in boxes. No matter what kind of rings you buy–moly filled, chrome, steel, and so on–inspect them for chips, cracks, rust, or any other inclusions that might cause a failure or combustion pressure leakage once installed. If a ring is damaged in any way, I won’t use it.

3. I like to wipe the rings down with lacquer thinner while inspecting them. Then, I sand all the edges of the rings with 400-grit sandpaper to knock off any rough edges. Use very light pressure and make only one or two passes over the edge. Red Scotch-Brite is then used to remove excessive coating or manufacturers film from the outer edge of the ring.

4. The next step is to install the ring in the appropriate bore, using a piston-ring squaring tool. Often, the piston rings won’t fit in the bore out of the box because they are oversize. If this is the case, don’t force or twist the ring, simply file a little material off the endgap and start the slow process of getting the ring sized right.

5. Many companies, like Powerhouse and ABS, offer piston-ring squaring tools. I had squaring tools made specifically for the pistons in our engines. They locate the ring where it will be around TDC of the stroke. Since combustion happens in this area. I like to set my end gap at this point. Also, due to cylinder distortion when the head is torqued down and the excessive heat generated at combustion, this is the area to establish the proper end-gap dimension.

6. Properly fitting piston rings into the block is a complex process that requires consistent measuring between all cylinders. It is a measured gap, but a certain feel is needed to get that gap right. I use a MAC FG013 feeler gauge with three sizes out (in this case, 0.020-, 0.021- and 0.022-inch sizes) and with the ring square in the bore. I try to slide the appropriate feeler gauge into the gap starting at the inside of the ring. If it doesn’t fit, I go down in size until one does. I consider a gap size true when the appropriate feeler gauge drags slightly going in and out of the gap and when the gap is tight enough that once the gauge is in the gap, the tension will just barely hold the entire feeler gauge in place.

7. In case you don’t know, cutting the ring gap should be done in very small amounts. This is a process that requires time because you need to sneak up on the perfect size. Take your time to avoid oversizing the end gap. If you need to remove 0.020 inch, take 0.010 inch from each side of the ring gap to prevent a poor mating of the two ends of the ring.

8. Before I attempt to cut the ring for the proper endgap, I always cut a couple of thousandths off each end of the ring and check how the ends mate. I pinch the ends together as the ring would be in the cylinder while looking into a light. If the rings does not mate perfectly flat across the end, I adjust the anchor point for the ring file and go through the process again until the two ends mate perfectly. This way, all the other rings for this engine will have good endgaps. This is to minimize combustion-pressure leakage and oil passing through this area.

9. This photo barely shows a sliver of pie-shaped light through the inside edge of the ring endgap. This is why it is important to adjust the ring file for end gap squareness in the beginning.

10. After all the iterations of checking the top and second ring in the bore, grinding on them, and rechecking them for size (measure and keep the rings organized for each specific bore), the next step is to size the oil rails and tensioners. These are truly a feel install. I start with the tensioner, installing it square in the bore and dragging it slowly down and up the bore. I like just enough tension so that the roughness of the bore is felt, but not so much that the tensioner is catching on the surface.

11.To adjust the expander size, I slightly, and I mean slightly, bend the endtabs back on each side of the expander. The tabs need to mate together after you bend the tabs, so don’t bend one a bunch and not touch the other.

12. Once the rings are sized for the bores, I check them all in the pistons. Before that happens, I use 400-grit sandpaper and an undersize feeler gauge to lightly sand the top ring land to knock down any burrs caused during the drilling of the gas ports. I’m not trying to remove material, just prevent the ring from hanging up on a burr.

13. Installing the top and second rings on a piston should be done with care. I like to spread the ring evenly using both hands (as shown). My experience has shown that if you twist a ring on and off the piston, it puts a set twist in the ring, which can prevent it from seating properly in the ring land during engine operation.

14. I then check the vertical clearance with respect to the ring and ring land. This will be different for various engines. For our situation, I want 0.0005- to 0.0008-inch vertical clearance on a restrictor-plate engine and 0.0008- to 0.0012-inch vertical clearance on our open engines. I use 0.001- (ENCO PN 615-5001) and 0.0005-(ENCO PN 615-5000) inch feeler gauges to determine these. Don’t hold these gauges in your hand for long; they will change thickness due to temperature very easily.

3 stroke engine – cross over between 2stroke and 4stroke engine

Posted on January 18, 2012 by melwin23

This is a pre-test of the world´s first three-stroke engine. At Miduniversíty in Östersund, Sweden. This principle is patended by Nils-Johan Nilsson.

3 Stroke engine working principle animation

http://www.youtube.com/get_player

Claims

1. An internal combustion engine comprising:

at least one cylinder;

a piston reciprocably mounted within the cylinder;

a combustion chamber defined by a space formed by the piston and the cylinder;

an intake operatively positioned in the cylinder for supplying a mixture of air and fuel to the combustion chamber;

an exhaust operatively positioned in the cylinder for releasing exhaust gases from the combustion chamber;

an intake valve operatively positioned in connection with the intake;

an exhaust valve operatively positioned in connection with the exhaust;

a compressor for pressurizing air supplied to said cylinder; and

a fuel means for supplying fuel comprising:

a pressure-regulating means operatively connected to the exhaust; and

a dosing means operatively connected to the intake and adapted to determine, in coaction with the pressure-regulating means, the amount of fresh mixture of fuel and air in relation to the amount of retained exhaust gases in the combustion chamber.

2. The internal combustion chamber according to claim 1, wherein the dosing means is a piston and cylinder assembly comprising a dosing piston and a dosing cylinder enclosing the same, that the dosing piston includes a first pressure side and together with the dosing cylinder defines a first chamber and a second opposite pressure side together with the cylinder defines a second chamber, said pressure-regulating means being connected to the first chamber and said compressor and said fuel means being connected to the second chamber with the second chamber being connected to the intake.
3. The internal combustion engine according to claim 2, wherein the dosing means comprises a returning means connected to the dosing piston for operatively imparting motion thereto.
4. The internal combustion engine according to claim 3, wherein the pressure-regulating means comprises an expansion vessel connected to the exhaust.
5. The internal combustion engine according to claim 3, wherein the pressure-regulating means comprises a throttle valve for controlling the pressure in the exhaust.
6. The internal combustion engine according to claim 2, wherein the pressure-regulating means comprises an expansion vessel connected to the exhaust.
7. The internal combustion engine according to claim 2, wherein the pressure-regulating means comprises a throttle valve for controlling the pressure in the exhaust.
8. The internal combustion engine according to claim 1, wherein the pressure-regulating means comprises an expansion vessel connected to the exhaust.
9. The internal combustion engine according to claim 8, wherein the pressure-regulating means comprises a throttle valve for controlling the pressure in the exhaust.
10. The internal combustion engine according to claim 1, wherein the pressure-regulating means comprises a throttle valve for controlling the pressure in the exhaust

3 stroke engine pre-test

http://www.youtube.com/get_player

CARBERRY ENFIELD-V-TWIN

Posted on December 31, 2011 by melwin23

The concept of the V-Twin was conceived by Paul Carberry and brought to fruition by Paul and Ian Drysdale (Of the Drysdale 750-V8 and 1000-V8 fame).

The basic premise was to create a “classic” style 1000cc British V-Twin utilising as many standard Royal Enfield parts as possible. All this to attain a well mannered torquey cruiser with the look, feel and sound expected from a bike with traditional British bloodlines but with enough technology to make it a practical every day work horse – at a reasonable price. The design premise included keeping production and maintenance costs down with a worldwide availability of spare parts.

The 55 degree vee angle was chosen for the combination of style, balance and mechanical simplicity. One consideration was to allow the hydraulic lifters to be accommodated above the standard Royal Enfield cams without modification to the barrels. Any vee angle tighter than 55 deg also requires heavy modification of the Royal Enfield heads for carburettor clearance. The standard Enfield primary drive cover has also been retained. The Enfield clutch is “beefed up” and a bigger engine sprocket is fitted to utilise the extra performance of the V-twin.

ENGINE
Engine type: Air-cooled, OHV, pushrod,four valve, 55 degrees V-Twin.
Bore & stroke: 87x90mm
Displacement: 1070 cc
Compression Ratio: 6.5:1
Ignition: Electronic CDI Bosch trigger
Fuel System: 2x28mm MIK-Indian CV carburettors
Fuel Type: 91 RON
Power: 45bhp @ 4800rpm

TRANSMISSION
Type:- 5 speed
Primary Drive: Duplex chain
Clutch: Wet, multiplate
Final Drive: Chain

CHASSIS AND RUNNING GEAR
Frame Type: Tubular- steel duplex
Rake: 27.5 degrees
Wheelbase: 1475 mm
Suspension: Royal Enfield
Front : Leading-axle teescopic forks. 150mm travel
Rear: Twin shocks adjustable preload,130mm travel
Wheels: Wire -spoked, steel rim
Front 3.25 x19 Rear:3.5 x 18
Tyres: Dunlop Roadmaster TT100
Front: 100/90R19 (57H)
Rear: 100/90R18 (61H)
Brakes:
Front 300mm disc, two piston Brembo caliper
Rear: 153mm single leading shoe-drum.

ADIMENSIONS AND CAPACITIES
Weight: 198 kg( Oil, no fuel)
Fuel capacity: 14 litres

How to Clean Motorcycle Brakes

Posted on December 29, 2011 by melwin23

Motorcycle brakes,
just like other parts on motorcycles, can become dirty and covered with oil, grease and other residue. However, for any kind of decent performance, motorcycle brakes must be very clean. So, it is important to quickly and effectively clean these pieces of equipment without damaging them.

Pull the motorcycle to an open, accessible area (preferably a lawn), and place the motorcycle on a jack stand or center stand. If you do not own one of these stands, try placing the bike on a large block or similar device.

Use a flat-head screwdriver to pry apart the brake pads in the brake assembly. Dip a rag in a bucket of hot, soapy water and use it to begin scrubbing the brake disc. The disc is easily accessible just to the side of the tire, and you can access the disc area within the brake pads by turning the wheel.

Slide the rag between the brake pads. Make sure to get them as clean as possible.

Use a sponge with a scrub side to scrub grime and grease off the surface of the brake disc. Again, spin the tire to access the portion of the disc that is between the brake pads and within the assembly.

Hose the entire braking assembly. It is important that no soapy residue is left on any surfaces of the brake, as it will cause slipping.

Leave the brake pads spread apart for several hours so they can dry.

How to Repair a Small-Engine part 2 -Ignition System

Posted on December 25, 2011 by melwin23

An ignition system in a small engine produces and delivers the high-voltage spark that ignites the fuel-air mixture to cause the combustion. Some small engines require a battery to supply electrical power and the ignition spark. Others develop the ignition spark using a magneto.

A small engine ignition includes the ignition controller (mechanical-breaker, capacitor-discharge, or transistor-controlled), spark plugs, flywheel, and wiring. Servicing the ignition system of your small engine depends on which types of components it has. Below are step-by-step instructions for servicing ignition systems found in modern small engines.

Servicing Nonbattery Ignition Systems

A magneto applies magnetism to supply electricity in ignitions where there is no battery. The magneto is turned by the crankshaft, which rotates when the manual recoil starter is pulled. Here’s how to service a non-battery ignition system:

Step 1: Service magneto.

Step 2: Service ignition controller.

Step 3: Service spark plug(s).

Step 4: Service flywheel.

If you need to service a magneto, use the following directions:

Step 1: Remove the magneto cap and clean surfaces with a small, clean paintbrush. Wipe any excess oil away.

Step 2: Service the ignition controller (mechanical-breaker, capacitor-discharge, or transistor-controlled) as described at the bottom of this page.

Servicing Battery Ignition Systems

A battery is a device containing electrical cells that produce and store direct current. Batteries used to start and operate small engines typically store 6 volts or 12 volts. Here’s how to service a battery ignition system:

Step 1: Service battery and charging system.

Step 2: Service ignition controller.

Step 3: Service spark plug(s).

Step 4: Service flywheel.

If you are interested in servicing a battery and charging system, here’s how:

Step 1: Use a voltage tester to verify that the battery is storing sufficient voltage. Each cell develops approximately 2 volts (1.9 to 2.1 volts). A 6-volt battery testing lower than 5.7 volts or a 12-volt battery lower than 11.4 volts should be recharged to rated voltage or higher.

Step 2: If the battery is conventional (has three or six caps on top), use a hydrometer to check the density of the liquid electrolyte in each cell. The density or specific gravity should be between 1.26 and 1.28 at room temperature.

If it’s below 1.25, recharge the battery. The difference in specific gravity between any two cells should be no more than 0.05. Note that a sealed maintenance-free battery cannot be tested in this way.

Step 3: Clean battery terminals using a small amount of baking soda and a stiff wire brush. Clean battery cables the same way.

Step 4: Inspect the cable insulation for corrosion and breaks; replace as needed.

Servicing Mechanical-Breaker Ignitions

For many years, mechanical-breaker ignition systems were the most popular of all ignition systems. The high voltage electricity from the coil is turned on and off using contact points and a condenser. The spark must be correctly timed to reach the spark plug at the exact moment when the piston is at the top of its travel and the fuel-air mixture is fully compressed. Here’s how to service a mechanical-breaker ignition:

Step 1: Remove the cover from the stator plate to expose the breaker points and condenser.

Step 2: Manually turn the crankshaft until the high point of the cam lobe opens the contact points. Inspect the points for uneven wear or damage. If necessary, replace the breaker points and condenser.

Step 3: Slightly loosen the points setscrew and place the appropriate thickness gauge between the two contacts. (Check your owner’s or service manual for the correct gap.) Move the points setscrew until the thickness gauge is touching both contacts but can be withdrawn without moving them.

Step 4: Tighten the points setscrew.

Step 5: Check the points gap with the thickness gauge again. Tightening the setscrew may have changed the gap.

Step 6: Clean the points with lint-free paper to remove any oil left by the thickness gauge.

Note: Some mechanical-breaker ignitions can be set using a dwell meter. If you have a dwell meter, refer to the unit’s operating instructions and the ignition specifications to determine what dwell angle setting is correct and how to set it.

Timing Mechanical-Breaker Ignitions

To work efficiently, the spark must be delivered to the combustion chamber at the exact moment that the piston is at or near TDC (top dead center). Here’s how to time the ignition spark:

Step 1: Loosen the adjustment nut(s) on the stator so it can be turned.

Step 2: Disconnect the coil lead wire from the points.

Step 3: Connect a lead of the continuity tester light or ohmmeter to the breaker point terminal and the other to the housing or a ground location.

Step 4: Rotate the stator until the light or ohmmeter indicates that the points have opened the circuit (light off or resistance high).

Step 5: Tighten the adjustment nut(s) on the stator without moving it.

Step 6: Reconnect the coil lead wire to the points.

Servicing Capacitor-Discharge Ignitions

Capacitor-discharge ignitions (CDIs) store and deliver voltage to the coil by way of magnets, diodes, and a capacitor. The mechanical points of a breaker point ignition are replaced with electronics. The only moving parts are the magnets on the flywheel. That’s why this system is sometimes called a breakerless ignition.

Because there are no breaker points on this system, there is no requirement for timing. However, the trigger module performs the same function as points. There must be a specific gap between the trigger module and the flywheel projection. Refer to your owner’s or service manual for specific steps to setting this gap. The typical steps to setting the trigger module gap on a CDI system are the following:

Step 1: Remove the lead from the spark plug to prevent starting. Ground the spark plug lead by attaching it to the shroud.

Step 2: Rotate the flywheel so the projection is aligned with the trigger module.

Step 3: Loosen the trigger module adjustment screw(s) and insert a thickness gauge of the correct thickness (typically 0.005 to 0.015 inch) in the gap.

Step 4: Move the trigger module until it touches the thickness gauge, making sure the projection and module surfaces are parallel.

Step 5: Tighten the trigger module adjustment screw(s) and replace the spark plug lead.

©2006 Publications International, Ltd. Capacitor-discharge ignitions and transistor-controlled ignitions look the same. Check the engine’s owner’s manual for specific information on servicing and repair.

Servicing Transistor-Controlled Ignitions

A transistor-controlled ignition (TCI) uses transistors, resistors, and diodes to control the timing of the spark to the engine. Because it has no moving parts, it too is called a breakerless or solid-state ignition. Most TCIs require no service. However, to ensure long-term performance, perform the following inspection on a regular basis.

The TCI controls a voltage of up to 30,000 volts for delivery to the spark plug. Be extremely careful when working around the TCI, as you can injure yourself or the ignition system with high voltage. Use the following steps to service a transistor-controlled ignition unit:

Step 1: Remove the lead from the spark plug to prevent starting. Ground the spark plug lead by attaching it to the shroud.

Step 2: Check the TCI unit to make sure it has not been damaged. Sensitive electronic components are mounted on a printed circuit board within the box and can be damaged by force or by excessive heat.

Step 3: Check all leads to and from the TCI unit to make sure they are tightly connected and that insulation is not cut or frayed.

Step 4: Visually inspect the magnet and ignition coil mounted next to the flywheel. Look for damage to the end of the magnet or the edge of the flywheel.

Servicing Spark Plugs

The spark plug in a small gas engine must withstand high voltage, high heat, and millions of ignitions during its life. A new spark plug requires about 5,000 volts of electricity to jump the gap. A used spark plug may require twice as much voltage to function. So servicing the spark plug is important to your engine’s operation. Here’s how to service a spark plug:

Step 1: Disconnect the lead wire from the top of the spark plug.

Step 2: Using the appropriate spark plug wrench, loosen the plug from the cylinder head. Before removing the plug, clean debris from around the spark plug base.

Step 3: Note the electrode’s appearance. Excessive buildup can mean incorrect fuel-air mixture, incorrect carburetor adjustment, weak spark voltage, or poor air cleaner maintenance, among other causes.

Step 4: Clean the spark plug surface with a soft cloth and the electrode with a wire brush or spark plug cleaning unit. If the electrode is worn or damaged, replace the spark plug with one of the same size and heat range to avoid any damage to the engine.

Step 5: Using a feeler gauge, set the gap on the spark plug electrode to the manufacturer’s recommendations.

Servicing Flywheels

The flywheel on a small gas engine is a simple part that requires little service. The most important part of servicing a flywheel is to inspect it for damage periodically. Here’s how to service a flywheel:

Step 1: Remove the lead from the spark plug (to ensure that the engine doesn’t start), then rotate the flywheel by hand and inspect it for wobble and obvious damage. Check edges and cooling fins, looking for cracks and missing pieces that can make the flywheel — and the engine — rotate out of balance.

Step 2: To inspect the inside of the flywheel, use a flywheel puller or a knock-off tool to remove the flywheel from the end of the crankshaft.

Step 3: Inspect the magnets on the inside of the flywheel, if so equipped. Wipe all surfaces clean, removing rust, oil, and debris.

Moving parts of a small engine can wear out prematurely if they aren’t lubricated. Learn tips about how to lubricate the engine, using oils and additives, in the next section.

How to Repair Small Engines part1-Small Engine Basics

Posted on December 25, 2011 by melwin23

Image via Wikipedia

Small gas engines serve us in many ways. They power lawn mowers, tillers, cultivators, trimmers, edgers, snowblowers, chain saws, pumps, generators, air compressors, and other useful home tools. They also power our fun: outboard boats, snowmobiles, motorcycles, all-terrain vehicles, ultralight aircraft, and other toys. To keep them operating efficiently, an owner of these tools and toys should know about small engines: how they work and what to do when they don’t.

Small gas engines are made up of individual systems that work together to produce power. Each system has many components. Internal combustion gasoline-powered engines require six systems: fuel, exhaust, ignition, combustion, cooling, and lubrication. In this article, we will discuss the systems and components that make small engines work.

Fuel and Exhaust

The fuel and exhaust systems are critical to operation. They furnish the fuel for combustion and remove exhaust gases. The following are components of a fuel and exhaust system.

Gasoline: Gasoline is a combustible liquid that burns relatively slowly. However, when sprayed as a mist and mixed with air, it is quite explosive. All it needs is a spark. Two-stroke engines require that oil be mixed with the gasoline to lubricate internal parts. Four-stroke engines use a fuel-air mixture.

Fuel Tank: The fuel tank stores fuel in preparation for mixing by the carburetor and use by the engine. Some fuel tanks are pressurized with air to help deliver fuel to the carburetor. Other tanks are non-pressurized and depend on a fuel pump to deliver fuel to the carburetor.

Fuel Line: Fuel is moved from the tank to the pump and/or carburetor through a fuel line. Pressurized fuel systems often have a squeeze bulb in the fuel line for building pressure.

Filter: A carburetor jet has a small opening that can easily become clogged. A fuel filter traps dirt and sediment from the gas before it is delivered to the carburetor.

Pump: A fuel pump produces a vacuum that pulls the fuel from an unpressurized tank, then delivers it to the carburetor.

Carburetor: The carburetor has one job: to mix the correct proportion of gasoline and air for the engine. Too much gasoline in the mixture makes it rich; too little gas makes it lean.

Throttle: The throttle controls the amount of fuel-air mixture that enters the engine from the carburetor. The throttle thus controls the speed of the engine.

Primer: A primer injects a small amount of gasoline into the carburetor throat to make the initial fuel-air mixture rich. A primer is used to help start a cold engine.

Choke: Some engines control the richness of the fuel-air mixture at startup by controlling the air rather than the fuel. A choke reduces the amount of air in the fuel-air mixture.

Governor: A governor is a device that automatically opens the engine’s throttle when more power is needed and closes it when the load is light.

Muffler: Small gas engines, especially two-stroke engines, are noisy when they operate. A muffler reduces the sound of the exhaust gases by passing them through baffles.

Spark Arrestor: A spark can exit the exhaust port of a small gas engine, potentially starting a fire on nearby combustibles. A spark arrestor on the exhaust port can reduce the chances of such a fire. Spark arrestors are especially important on chain saws, motorcycles, and all-terrain vehicles operated in dry woodlands.

Ignition

The ignition is a primary system within all small gas engines. It produces and delivers the high-voltage spark that ignites the fuel-air mixture to cause combustion. No spark means no combustion, which means your engine doesn’t run. Below are the components found in small engine ignition systems. Some systems will include breaker point ignitions while others depend on solid-state ignitions.

Magneto-Powered Ignition System: A magneto uses magnetism to supply electricity in ignitions where there is no battery. The magneto is turned by the crankshaft, which rotates when the manual recoil starter is pulled. The three types of magneto ignition systems are mechanical-breaker, capacitor-discharge, and transistor-controlled.

Battery-Powered Ignition System: If your small engine includes a battery for starting, the ignition coil will also use it to supply spark to the spark plugs. A battery stores electrical energy until needed. Battery ignition systems also use mechanical-breaker, capacitor-discharge, and transistor-controlled ignitions.

Mechanical-Breaker Ignitions: High-voltage electricity must be sent to the spark plug at the appropriate time. In mechanical-breaker ignitions, this job is performed through the contact points and a condenser.

Points: As the crankshaft rotates, a cam opens and closes a set of contact points. These points function as an on/off switch: Closed is on, and open is off.

Condenser: Because the spark moving across points can damage their surfaces, the condenser stores voltage to reduce arcing between points.

Capacitor-Discharge Ignitions (CDI): A capacitor is a large condenser. A CDI stores and delivers voltage to the coil using magnets, diodes, and a capacitor

Transistor-Controlled Ignitions (TCI): Transistors are electronic controllers. A TCI uses transistors, resistors, and diodes to control the timing of the spark.

Coil: An ignition coil is simply two coils of wire wrapped around an iron core. The coil changes low voltage (6 or 12 volts) into the high voltage (15,000 to 30,000 volts) needed by the spark plug.

Spark Plug: A spark plug is an insulated electrode that is screwed into the top of the engine cylinder. High-voltage timed electricity from the magneto travels by wire to the spark plug. The base of the plug has an air gap of about 0.030 inch (30 thousandths of an inch), which the current must jump.

Wires: The primary wire from the coil to the breaker point and secondary wire from the coil to the spark plug(s) deliver electricity to the ignition components.

Distributor: A distributor is an ignition system for engines with more than one cylinder and spark plug. It distributes the spark to the appropriate cylinder using a rotor, cap, and individual spark plug wires.

Combustion

The combustion system of a small gas engine is where the work gets done. Components of the combustion system include the cylinder block, cylinder head, camshaft, valves, piston, connecting rod, crankshaft, timing gears, and flywheel. To better understand small gas engines, let’s look at how this vital system works.

Cylinder Block: The largest single part in a small gas engine is the cylinder block. It is a piece of metal in which the cylinder hole is bored or placed.

Cylinder Head: The cylinder head is the top, or ceiling, of the cylinder and is attached to the block with bolts. Depending on the type of engine, the head may or may not include valves.

Piston: A piston is the movable floor in the combustion chamber. Its upward movement compresses the fuel-air mixture. After combustion, its downward movement rotates the crankshaft.

Crankshaft: An engine’s crankshaft is a metal shaft with an offset section onto which the connecting rod is attached. Rotation of the crankshaft moves the piston up in the cylinder. Movement of the piston down in the cylinder then rotates the crankshaft.

Connecting Rod: Between the piston and the crankshaft is a connecting rod. At the larger end of the connecting rod is a bearing that allows rotation around the moving crankshaft. The small end is attached to the piston pin.

Valves: Valves simply open and close passages. A reed valve in a two-stroke engine is activated by changes in air pressure.

Flywheel: At the end of the crankshaft is a circular weighted wheel called a flywheel. The flywheel delivers the engine’s power to devices (wheels, blades, etc.) and helps keep the crankshaft turning smoothly.

Small Engine Image Gallery

Cooling and Lubrication

Combustion and friction produce heat. Heat and friction — if not controlled — can quickly damage an engine’s components. Small gas engines are typically cooled by air. Friction is reduced using movable bearings and lubricants.

Air-Cooling Fins: For simplicity, most smaller gas engines are cooled by air. Metal fins around the outside of the combustion chamber help dissipate the internal heat.

Friction: Friction is resistance that occurs when one surface rubs against another. Friction causes wear. In an engine with many moving parts, friction is reduced with bearings and lubricants.

Bearings: A bearing is a replaceable part that takes the brunt of the friction. A friction bearing relies on lubricants to minimize friction. A nonfriction bearing uses hard steel rollers or balls to prevent wear, though it too requires some lubrication.

Lubricants: Lubricants such as oil and grease reduce surface friction by coating parts with a film. Lubricants in two-stroke engines are applied to surfaces by mixing oil with fuel.

Viscosity: An oil’s viscosity is its resistance to flow. The thicker a lubricating oil or grease is, the higher its viscosity number.

Filters: Friction happens. Moving parts wear, even with the best lubricants. The resulting metal as well as carbon from the combustion process must be cleaned from the oil to ensure long lubrication. Some small engines use oil filters to remove contaminants from the circulating oil.

Regularly servicing your small engine will ultimately save you money and time. In the next section, we’ll review how, where, and when to service this engine.

The Benefits of Regular Small-Engine Maintenance

Purchasing a small engine-driven implement can make a dent in your budget. Tools and toys powered by small engines can cost anywhere from $100 to $10,000. That’s why it’s a good idea to invest in periodic servicing of your small engine. Replacing an engine every couple of years is an annoying and needless expense. Below we will review detailed information on how to service two-stroke gas engines. Following these procedures could help you put more money in the bank and less into your mechanic’s pocket.

Benefits of Regular Service

Servicing your small engine tool or toy on a regular basis offers many advantages over the Wait-Until-It-Breaks Maintenance Program.

By establishing a service schedule, you will gain confidence that whenever you need the unit it will be ready for use.

By performing a number of service functions together, you will save time. You can pick up all needed parts and lubricants in one trip to the parts store. Then you need to disassemble a component only once to perform numerous service procedures rather than taking it apart many times.

Regular service gives you a chance to visually inspect the entire engine and related components for damage, wear, and other potential problems.

How, Where, and When to Service Knowing how to service is as important as knowing when. Some service procedures can be performed wherever you store your tool or toy: in a garage, storage shed, or tool shed. If the unit is heavy, you can build a ramp up to a sturdy table that is at a handy height for working. Or you can use a ratchet winch to lift the engine. Units weighing less than 40 pounds may be lifted to a workbench or table as long as you lift with your legs rather than with your back. Get help if you need it, and make sure that the unit will remain sturdily in place as you service it. Remember to always put safety first!Servicing a small engine is easy once you know what to do and when to do it. A service chart can help you determine common service requirements as well as track what service has been done. Your engine-powered unit may have a service chart in the owner’s manual or service manual. Typical recommendations include changing engine oil every 25 hours of use and tuning up the engine at least once a year.The purpose of ongoing service, also known as preventive maintenance, is to keep your engine-driven tool or toy in good operating condition. Ongoing service procedures include air cleaner service, crankcase breather service, cooling system service, muffler service, lubrication, and tune-up.Lubrication service means making sure that all moving parts have sufficient lubrication (oil and/or grease) to minimize wear. Lubrication service procedures include mixing oil with fuel in two-stroke engines, and lubricating other moving parts.A tune-up consists of the adjustment and/or replacement of parts critical to smooth and efficient engine operation. Those parts include components in all engine systems: fuel, exhaust, ignition, combustion, cooling, and lubrication. Ignition tune-ups are more important for mechanical-breaker ignitions than they are for self-contained solid-state ignitions. Regular tune-ups will keep your small engine running smoothly and reduce the need for repairs.In addition, you should check other systems and make adjustments as needed to keep them operating smoothly. This includes adjusting the throttle, choke, and governor linkage, and cleaning off debris.Engine-driven tools and toys usually come with an owner’s manual. While some manufacturers’ manuals are more complete and better written than others, most manuals include basic information on safe operation and service. Unfortunately, product manuals are often written to reduce the manufacturer’s liability for accidental misuse rather than to help the owner service the product. In addition, manuals for engine-driven products typically show how to service the nonengine components: the grass catcher, wheel adjustments, blades, chains, and other parts. Service information for the engine may be minimal or nonexistent in the owner’s manual.

What can you do about this lack of information? Fortunately, there are numerous after-market publishers of service manuals for specific models of small engines. If you don’t have an owner’s manual, you can contact the manufacturer directly to purchase one; manufacturers also sell service manuals. Most manufacturers keep product manuals for up to 20 years. If they only have one original copy left, you can often request a photocopy for a small charge.

Knowing how to service the fuel system is an important part of caring for a small engine. Learn how to care for fuel filters, carburetors, and other major fuel system parts in the next section.

Understanding Carburetion – By: Canadian Dave

Posted on December 9, 2011 by melwin23

Carburetor Tuning

Understanding Carburetion

Motorcycle carburetion is fairly complex, but a basic understanding of the parts and theory involved will go a long way to simplify the processes and make fine-tuning your carburetor much less intimidating. Right off the bat I’m going to say this is only intended to be a very basic explanation. Motorcycle carburetion is quite complex with a number of circuits and conditions acting together to deliver a measured amount of gasoline and air to your engine. Most of which aren’t even mentioned here. To do it justice you would literally have to write a book and that’s not my goal here. Information from a 1988 to 2000 KDX200/220 Keihin PWK is illustrated here but the principals are the same for all KDXs.

Basic Motorcycle Carburetor Theory

Pressure can be your friend. Your KDX relays on differences in air pressure to deliver a charge of gasoline and air into the engine. If you measured the force applied by a column of air above the Earth you’d find that it exerts about 15 pounds of pressure per square inch at sea level. This pressure is referred to as atmospheric pressure and varies slightly with altitude, meteorological (weather) conditions etc. but we’ll talk about that later. Air, gasoline etc. will move from an area of higher pressure to an area of lower pressure until both are equal.

How does your engine produce a pressure differential? As the piston moves past bottom dead center ( its lowest point ) and back up towards top dead center ( its highest point ) the pressure above the cylinder increases and the pressure below the cylinder decreases. The reduced pressure inside the crankcase causes the reed valve to open and outside air, at a higher pressure, to flow through the carburetor delivering a charge for gasoline and air to the engine’s crankcase, which is at a lower pressure. Great so we know how air is drawn through the carburetor and into crankcase but what about the carburetor how is gasoline combined with the incoming charge of air?

Some times restrictions can be a good thing. If you place a restriction in the path of a flowing liquid or gas a drop in pressure is created. The pressure before the restriction will be greater than the pressure after the restriction. Yup we’re back to that pressure differential thing again. Since the charge of incoming air must pass through the horn shaped mouth of the carburetor and into the smaller venturi ( a restriction ), the pressure before the venturi is higher than after. Such a reduction in pressure will cause an increase in the airs velocity because the same amount of airflow must take place before the restriction as after it. Velocity will vary directly with the amount of flow, and as the flow increases a greater pressure differential will occur across the venturi.

Ok so we know that as air is drawn into the carburetor and meets the restriction imposed by the venturi a pressure differential is created. The atmospheric pressure outside the carburetor is greater than the pressure inside the carburetor. So why do you care? Because the carburetor’s float bowl is vented directly to the outside atmosphere (higher pressure) and connected to the venturi (lower pressure) via the pilot circuit and the needle jet/ spray bar ( through the main jet ) that’s why. If we remember that a liquid, gas etc. will move from an area of higher pressure to an area of lower pressure until both are equal we can see how gasoline is introduced into the incoming charge of air. In this case gasoline is forced from the float bowl up through the pilot and main jet into the carburetor’s bore where it is delivered to the crankcase.

Jetting

The Basics- When people talk about jetting a carburetor, tuning a carburetor or “breaking out the brass” they’re talking about manipulating the carburetor’s 4 main circuits to optimize gasoline delivery and therefore engine performance. They might adjust the air screw, adjust the jet needle’s clip position or exchanging the pilot (slow) jet, main jet, throttle valve (slide) or jet needle for one of an appropriate size. A perfectly tuned 2-stroke engine/carburetor delivers a 12.5 to 1 air to fuel ratio.

The Parts- No jet acts independently of the others but rather they work together to deliver gasoline to the engine. They do however target specific throttle openings and have the most effect is that area. See below.

The air screw is most effective between idle through 1/8 throttle.

The pilot (slow) jet is most effective between 1/8 through 1/4 throttle.

The slide valve is most effective between 1/8 through 1/2 throttle

The jet needle is most effective between 1/4 through 3/4 throttle.

The main jet is most effective between 3/4 through wide-open throttle.

Before we get into the different parts of the carburetor and how they effect gasoline delivery I want to stop for a second and define the terms RICHER and LEANER. I know these terms can cause some trouble for those who are new to the sport or new to carburetor tuning and they are often used incorrectly. The terms RICHER and LEANER refer to the amount of GASOLINE being delivered to the engine and not the amount of oil. If you’ve done a plug reading at wide open throttle and the plug indicates you are running rich ( dark brown to black ) this is an indication that too much gas is being delivered to the engine and not too much oil. I know there are people that will say “You’re running too rich, try to change your premix ration from 42 parts gas: 1 part oil ( 42:1 ) to 50 parts gas : 1 part oil, that should lean things out a little “. This is in fact increasing the amount of gasoline ( 8 more parts of gas for each part of oil ) and causing the engine to run RICHER rather than leaner. If you remember richer and leaner are referring to the amount of gasoline being delivered this will all make much more sense.

The pilot, or slow circuit, can be adjusted by manipulating two parts: the air screw and the pilot jet. The air screw controls the flow of air into the circuit. Turning the air screw clockwise reduces the air flow and richens the circuit. Turning it counter clockwise increases the airflow and leans the circuit. You can therefore use the air screw to fine tune the pilot circuit. The pilot jet restricts/regulates the flow of gasoline from the float bowl to the venturi. Pilot jets have a precisely machined orifice/hole running through their center which gasoline passes through. Increasing the size of the pilot jet ( size of the hole ) richens the circuit by supplying more gasoline; i.e. removing a 40 pilot jet and installing a 42 richens the circuit.

The slide/throttle valve has the most effect between 1/8 and 1/4 throttle with a declining effect up to 1/2 throttle. The throttle valve can be exchanged for one with a greater or smaller cutaway. The PWK equipped KDX200/220 comes equipped with a #5 or 5mm cutaway. The larger the cutaway the more air flows to the jet block/nozzle screen leaning the mixture. Exchanging the factory #5 ( 5mm cutaway ) throttle valve for a #6 (6mm cutaway) would lean the mixture.

The jet needle – Has the greatest effect between 1/4 and 3/4 throttle. It’s attached directly to the throttle valve. As the throttle is rolled open or closed the jet needle moves through the needle jet’s bore exposing different sections of the jet needle’s profile to the needle jet’s inner bore.

Six major elements determine the jet needle’s effect on fuel delivery – the diameter of the straight section, the length of the straight section, the jet needle’s taper, the clip position, the number of tapers and the length of each tapered section. The number of tapers is normally not changed from what was supplied from the factory.

I’ll talk about jet needles in greater detail in the Tuning section.

The Main Jet- regulates the flow of gasoline from ¾ to Wide Open Throttle. Like the pilot jet the main jet has a precisely sized hole drilled through its center. Increasing the size of the main jet ( size of the hole ) richens the circuit by supplying more gasoline; i.e. removing a 152 main jet and installing a 155 richens the circuit.

Tuning

Before you consider fine tuning your carburetor there are a few things that have to be done. First you need to install a clean air filter. Second you need to insure the float level is properly set. If the gasoline level is set too high or too low properly jetting your bike will be impossible. A high float level will cause it to run rich and a low level cause it to run lean. You can find instructions for setting you float level here.

Third you need to fill your tank with a fresh load of premixed gasoline. Don’t go out and try to jet your carburetor with the gasoline that’s been sitting around in your jerry can for the past month. Gasoline degrades over time so you’ll want to start with a fresh batch. While I’m talking about gasoline remember that different gasoline will change your jetting requirements. If you normally run race gas, straight or use it to cut pump gas, you’ll want to be sure you have it in your tank when you head out to tune the carburetor.

You also need to be aware of any potential mechanical problems that can imitate poor jetting. Eric Gorr has included a number of articles on his web site from his book “Motocross and Off- Road Motorcycle Performance Handbook”. An excellent article on carburetor tuning is included which covers this topic. Check it out here. If you don’t own a copy I’d definitely recommend picking one up. It’s chucked full of useful, easy to read information and make a great companion to your factory service manual.

When making jetting changes make one change at a time and test the result. It’s very helpful to keep a log book for your motorcycle where you can log changes to the jetting, the temperature, altitude etc and the result. Over time you’ll build a jetting history of your bike that you can go back to and determine what changes you have made. I also include routine maintenance and repairs in my log book.

Tuning From Idle to Wide Open Throttle, Plug Reading – Again this is a good method for beginners. Once you’ve gained more experience and are more comfortable with jetting you’ll start to relay more on power delivery and how the engine feels until then this is a good method.

If you go back and have a second look at the parts of a carb you’ll see that gasoline delivery is dependent on throttle position and not engine speed. You’ll also notice that the air screw, pilot jet, main jet, and jet needle target specific throttle setting. With this information in hand we can easily identify which circuit is likely the cause of a specific symptom.

Before you head out for a jetting session you’ll want to mark your throttle grip and housing so you can easily identify the four major target ranges. I like to use White Out but placing a piece of tape on the throttle grip and throttle housing and breaking out a marker will work just as well. With the throttle at idle and your materials in hand draw a straight line across the inner cuff of your throttle grip and onto the throttle housing. Now twist the grip to WOT and draw a second line on your grip straight across from the line on your throttle housing. Next find the half way point between the two and place a third line, this will indicate ½ throttle. Now divide the halves in half again and mark 1/4 and 3/4 throttle. Now with a quick glance you can easily determine the throttle position while jetting.

Now’s a good time to stop and talk about plug reading. The color and condition of the spark plug can tell you a lot about what’s happening in your engine. You’ll be doing some runs at known throttle settings and then observing your spark plug to determine the condition of the corresponding circuit i.e. is it lean, good or rich. Ideally a professional tuner would use a variety of instrumentation and how the engine feels to fine-tune jetting. For more information on instrumentation check out Eric Gorr’s comments on “How to use carburetor tuning gauges“. This method will insure you’re in the ballpark so you can start fine-tuning. When you have more experience and are more confident in your ability to determine jetting requirements by feel you’ll start to phase out this method for 1/4, 1/2 and 3/4 throttle setting and replace it with the jetting by feel method. You’ll continue to use this method for tuning the main jet at WOT. I’ll also say that my recommendation for the appearance of a good plug is going to be slightly different than someone who is jetting a motocross bike for an experienced rider. The conditions faced by enduro riders and moto-cross riders are quite different and therefore the jetting requirements are also slightly different.

Checking the Main Jet– Warm up the engine and go for a short ride letting the engine comes up to its normal operating temperature. Install a brand new plug that’s been properly gapped. With the new plug installed aggressively accelerate through the gears until you reach 4^th or 5^th gear. For best results you should accelerate up a slight up hill section to place additional load on the engine. Continue to run the engine at WOT for 20 to 30 seconds longer if there is not fear the engine is running lean. If you suspect the engine is running lean 15 to 20 seconds to give you an indication. At the end of your full throttle run simultaneously push the kill button, chop the throttle and pull in the clutch. This procedure is often refereed to as a ” plug chop”. It is important to perform a plug chop exactly as described. If you allow the engine to run or leave the throttle open for even a few seconds after the plug chop the plug reading will be invalid. Now remove the spark plug and carefully look at its color.

Plug Reading – What does a good plug look like? First you need to know where to look and what to look for. I’ve seen a lot of plug reading instruction that suggest you to look at the general appearance of the plug. That doesn’t work. The easily visible portion of the plug, the upper part of the porcelain and the electrodes, won’t give you an accurate reading. This area is mostly affected by additives in the gasoline and the oil you’re running. To get an accurate indication you want to look down inside the plug where the porcelain insulator emerges from the steal body of the spark plug. Ideally you should see a ring of light brown/tan at the lower 1/4 of the porcelain. White is lean and you’ll need to install the next richer main jet( larger number ) and do another plug reading. A dark brown to black ring is too rich and you’ll need to install the next leaner main jet ( smaller number ). A small flashlight and magnifying glass make this much easier to see and it’ll give your friends something to poke fun at. If you ride in a diverse area with fluctuations in temperature greater than 15 degrees F, and altitude changes dropping more that 3000 feet over the course of the day or you ride in high load conditions ( loose sand, mud, long steep hills ) adjust the size of your main jet until you reach the ideal condition then install the next richer main jet which should result in a dark brown plug reading. You’ll be loosing a small amount of top end power in trade for the added confidence that you can ride aggressively over the course of the day without fear of running lean at WOT.

Checking the Jet Needle – Once you have the main jet properly sized you can turn your attention to the jet needle. Warm up the engine and go for a short ride until the engine comes up to its normal operating temperature. Install a brand new plug that has been properly gapped. With the new plug installed accelerate through the gears until you reach 4th gear. For best results you should find a location that allows you to run safely at half throttle with out having to ex or decelerate to avoid obstacles etc. A long straight away or well groomed oval track will work the best. Continue to run the engine at half throttle for more than 60 seconds if possible. Do a plug chop and inspect the plug. If the plug indicates a lean condition, lower the clip on the needle by one position. Lowering the clip by one position raises the needle further out of the needle jet allowing more gasoline to flow, richening the circuit. If the plug is dark brown to black raise the clip’s position by one notch to lean the circuit. As a general rule if you need to run the clip in the top position you should install a leaner jet needle. If you need to run the clip in the bottom position you should install a richer jet needle. Jet needle selection is something of an art. Watch for an article in the near future describing PWK jet needle profiles in more detail. This method will give you a good ball park indication if you jet needle is properly sized. However due to inefficient cylinder scavenging at lower throttle settings its often little more that a ball park indication and you’ll need to fine tune by feel.

Once you’re satisfied with the appearance of the plug turn to the jetting by feel method to fine-tune the circuit. Gradually roll the throttle open from 1/2 to 3/4 throttle paying particular attention to the sound and the type of power delivery. Having an experienced friend on the sidelines to listen and watch the silencer for excessive smoke is also helpful. A rich condition will result in excessive smoke from the silencer, the plug will often carbon foul and the engine will produce a sputtering/crackling sound. A lean condition will result in slow throttle response, you twist the throttle but the power delivery is lethargic and flat. A lean condition results in a tell tale booooooha sound as well. You can quickly verify a lean condition by pulling the choke half way out. Engaging the choke will deliver additional fuel to the system and the symptoms of a lean condition should clear up.

A Helping Hand

There’s a little tip that’ll make changing needle clip positions a breeze. If you’re like me you tire of wrestling the throttle valve spring and collar pretty quickly when it comes time to adjust your needle. Not to mention the first time you sent a spring loaded collar jettisoning into a dirty mound. Why is it those ” must stay clean” parts always find there way into the grim anyway? This little trick makes trail side needle adjustment anxiety a thing of the past.

Run to your local tool supply store, hobby shop or what have you and pick up a hemostat. I’m not talking about the bone crushing size here, a 4 to 5 inch pair will work just great and they’ll only set you back $4 to $5. The best thing about a hemostat is its small enough to carry in your fanny pack and they apply just enough pressure to prevent the spring and collar from slipping but not enough to damage the throttle cable. Nurse, hemostat please!

The Pilot Circuit, Tuning from Idle to ¼ Throttle –You can use the air screw to help determine if your pilot jet is appropriately sized. Take your bike for a short ride letting the engine come up to normal operating temperature. With the engine stopped, transmission in neutral and the bike on its stand turn the air screw clockwise until it just seats, gentle now it’s delicate and you don’t need to torque it down just gently seat it. Now turn the air screw a quarter of a turn out so the engine will fire and start it. Slowly turn the air screw counter clockwise ( out ) until the point where the engine just reaches the maximum obtainable rpm and continuing to turn the air screw beyond this point wont increase the engine speed (rpms) any further. I find it’s easier to hear the rpm increasing if you set the idle at its lowest possible position without the engine stalling. You’ll want to repeat this procedure a couple times until you’re confident that you’ve found the right spot and that the result is reproducible. When you’re comfortable count the number of turns ( 360° revolutions ) you’ve backed the air screw out to reach this point. The normal operating range is between 1 and 1.5 turns out so if you find the ideal setting is less that 0.75 turns out consider installing the next richer pilot jet (larger number ). If you find the ideal setting is more than 2 turns out consider installing the next leaner pilot jet ( smaller number ).

Once you’re comfortable you have an appropriate pilot jet installed you want to fine turn the circuit using the air screw. Starting with the air screw 0.5 turns out adjust the screw an 1/8 of a turn at a time until you’ve obtained the best possible throttle response between idle and 1/4 throttle. Continue to adjust the air screw until the engine’s throttle response off idle is clean with no hesitation or bogging. You can test the final results using the same method as you did for checking the jet needle this time riding in 2^nd or 3^rd gear at 1/4 throttle. Remember this is only a ball park indicator your goal here is to obtain the best possible throttle response not a perfect plug reading.

Because jets have a combined effect over a range of throttle setting its often useful to go back and recheck your jetting once you have followed this procedure. The second time through you can broaden the throttle settings to insure there’s a good transition between one circuit and another. So for example slowly roll the throttle open between 1/2 and WOT insuring the transition is progressive and that the engine doesn’t stumble etc. Do the same between 1/8 and 1/2 throttle, 1/4 and 3/4 throttle etc.

The Effect of Temperature, Altitude and Humidity on Jetting

Once your jetting is set it’s not necessarily set for life. Changes in air temperature, altitude and humidity can have an effect on how your engine runs.

If you captured a measured volume of air on a humid 90° F day at sea level or a cool dry 40° F day at 10,000 feet both would contain about 22% oxygen. The density and therefore the total number of oxygen molecules however would differ enough to effect the performance of your engine.

Temperature- For most of us changes in air temperature will have the greatest effect on our jetting. As the air temperature gets colder the air density increases. The air molecules become less active ( move around less ) and therefore take up less space. Because they take up less space more air, and therefore more oxygen, can fit into a measured volume of air as the temperature decreases. As the temperature drops the engine will begin to run leaner and more gasoline will need to be added to compensate. As the temperature increase the engine will begin to run richer and less gasoline will be needed.

Altitude- Again this is an issue of air density. At sea level atmospheric pressure is around 15 psi and as the altitude increased the atmospheric pressure decreases. Because less pressure is exerted on a measured volume of air as the altitude increases the air molecules are able to relax and they take up more space leaving less space for additional molecules. The higher the altitude the less air in a measured volume and therefore less oxygen present so jetting will have to be leaned to compensate.

Humidity– Humidity is a measure of how much water vapor is in the air. The higher the humidity the less space there is for additional molecules of air and therefore oxygen. As the humidity increases there is less oxygen and therefore the engine runs richer. Jetting that may have been spot on in the cool dry morning air may start to run rich as the temperature and humidity increase over the course of the day.

Correcting for Changes in Temperature, Altitude and Humidity

Correction Table-You can use a correction table to roughly determine the appropriate jetting changes to compensate for changes in temperature, altitude and humidity. I’ve included a typical correction factor chart that has been modified specifically for use with the KDX. To use the chart go back to your log book and record what jetting is presently installed in your carburetor then determine what altitude you’ll be riding at and the temperature. I’m assuming here that you’ve already optimized your jetting. I’ve used my present jetting as an example. You’ll need to slightly modify the table to fit the specific requirements of your bike but I’ll go over that in the example.

Example- I’m presently running a 45 pilot jet with the air screw 1.25 turns out, an 1173 jet needle in the second from the top clip position and a 152 main jet. This jetting was optimized at 20° C and 2240 ft above sea level. For this example lets assume I’m going riding in the mountains where the temperature is 20° C at 9600 ft. The first thing I do is adjust the bottom of the table so that it reflects the condition where my jetting was optimized. Using the illustration below as an example I draw a straight line from 20° C horizontally across the graph until I hit the line that represents 2240 ft., then draw a line vertically to the bottom axis on the graph. This point becomes 1.0. Adjust the work sheet by subtracting 0.02 for each increment to the left of this point and adding 0.02 for each increment to the right of this point. My graph now looks like this:

Now using my personalized graph I can calculate what jetting I should install before making the trip to the mountains. I draw a horizontal line from 20° C over to 10000 ft and then vertically down to determine the correction factor of 0.95. To find the correct pilot jet size I multiply 45 by 0.95 and the new jet size would be 42.75. The closest available size is a 42 and I’ll fine-tune the pilot circuit with the air screw once I get there. I then multiply my main jet size ,152, by 0.95 and the new jet size would be 145. Now remember this is intended to give you a rough indication.

You can print off your own correction factor table here.

Using a correction table should allow you to closely meet the requirements of changing conditions. It is however intended to be used as a guide. You should always carry an assortment of jetting in your toolbox and check any jetting suggestions you receive. At a minimum do a plug reading at WOT after changing your jetting to insure you aren’t running lean. Jetting recommendations that work well for one bike may not necessarily work for another even if it is being ridden in the same area with identical modifications.

Available Keihin Jets – Tle main and pilot jets for yhere’s a list of availabour reference. I’ve included jets sizes commonly used to fine tune PWK equipped KDXs. This includes 1988 to 2000 KDX200/220 as well as second generation KDX250s. There are larger and smaller sizes available that aren’t listed here. This list might seem rather long but it includes possible jet sizes for a number of temperatures, altitudes as well as modified cylinders.

“21 Series” Pilot Jets – 38,40,42,45,48,50,52

” 13 Series ” Main Jets – 140,142,145,148,150,152,155,158,160,162,165,168,170,172,175,178,180

Jetting Recommendations, a Starting Point

These are intended to be good jetting STARTING POINTS so use them as just that a starting point. In many instances jetting will be very close if not right on but you’ll need to insure you’re not running lean and optimize the jetting from here to meet your individual requirements. At the very least you’ll need to do a throttle reading at Wide Open Throttle and insure you’re not running lean.

These jetting recommendations are intended for use between sea level and 3000ft with an average temperature of 73 degrees plus or minus 7 degrees.

1995-2001 KDX200

Stock -Run the stock R1174K jet needle in the second from the top clip position, 45 pilot jet, 155 main jet and fine-tune the pilot circuit using the air screw.
With a performance pipe/expansion chamber, the air box lid removed and the stock or a performance silencer run a 42/45 pilot, R1174K jet needle in the mid clip position, a 152/155 main jet fine tune the pilot circuit using the air screw.

1997 to 2001 KDX220

Stock run a 42 pilot jet,the stock R1173L jet needle in the second from the top clip position, a 142/145 main jet and fine tune the pilot circuit using the air screw.
With a performance pipe/expansion chamber, air box mods , the factory or after-market silencer and the stock 33mm carburetor run a 42 pilot, the stock R1173L jet needle in the second from the top clip position, a 145/148 main jet and fine tune the pilot circuit using the air screw.
Same as above but with your carburetor bored between 35 and 36mm or running a 1988 to 2000 KDX200 35mm carb jet according to 95 to 2000 KDX200 requirements.
Addition of Boyesen reeds or a Boyesen RAD Valve will require you to lean the pilot and main jet one size and readjust your air screw.

1989 to 1994 KDX200

Stock -Run the stock R1172N jet needle in the second from the top clip position, 48 pilot jet, 155 main jet and fine-tune the pilot circuit using the air screw.
With a performance pipe/expansion chamber, the air box lid removed and the stock or a performance silencer run a 45/48 pilot, R1173N jet needle in the mid clip position, a 152/155 main jet fine tune the pilot circuit using the air screw.
Addition of Boyesen reeds or a Boyesen RAD Valve will require you to lean the pilot and main jet one size and readjust your air screw.

For jetting recommendations on remaining models ( 1982 to 1988 KDX200s ) check out Jeff Fredette’s engine performance recommendations

If you require addition jetting help fire your question off to the JustKDX Forum. You’ll need to include the following information; year, model, modifications ( things like after-market reeds, pipe, air box lid mods, silencer, ported cylinder etc etc. average riding conditions, air temperature ( don’t submit a range between 5 and 85 degrees F you need to beak it down into your present condition within 10 degrees C or about 15 degrees F. ) altitude and average humidity.

Source

2 Stroke Engine Troubleshooting And Tips – Basics

Posted on December 9, 2011 by melwin23

2 Stroke Engine 2 stroke engine animation running

So your 2 stroke engine won’t start. Maybe it’s a old machine your trying to bring back to life, or a dependable engine that never lets you down. Luckily for you 2 stroke engine troubleshooting is relatively simple.
Don’t worry, just follow these simple steps and we will have you back up and running in no time. If you are kicking or pulling your 2 stroke motor over repeatedly, please stop. This isn’t a hot 4 stroke we’re are talking about here, 2 stroke engines are very easy to start hot or cold, and hard starting is a sign that something is not right in your engine. All that kicking or pulling is just wearing out your starter and probably your leg or arm in the process.

This is all assuming that you have already checked the basics.

You have fuel in your fuel tank.
You remembered to “turn on the gas” (your fuel shutoff valve is “on”).
Your engine kill switch is in the “run” position.

The 3 Critical Things To Check While 2 Stroke Engine Troubleshooting
There are really only 3 things your 2 stroke engine needs to run:
Air
Spark
Fuel

Yep, it’s that simple. Now this is of course providing your engine isn’t blown up with a hole in the piston or something. Typically if you can “feel” resistance in the form of compression as you kick or pull your engine over, and it’s not making any horrible banging noises, it’s just a matter of checking air, fuel and spark to find the culprit and get you running again.

2 Stroke Engine Troubleshooting – Air

Checking to make sure your engine is getting air is the easiest part. Typically just a visual inspection of the air filter and carburetor area is all it takes. “Air” is usually never the problem. I have only once in my life experienced air being the problem with a 2 stroke engine not starting. It was an old snowmobile that had no air filter and it had sucked a piece of plastic sheeting material that came loose from under the hood into the carburetor. Somehow the plastic had jammed just right as to not cause the throttle to stick wide open but to block the air flow into the engine. (Just a side note, never run any kind of an engine without a good air filter. Your just asking to wear out your engine prematurely or worse.)
2 Stroke Engine Troubleshooting – Spark

You might be saying, “Jim why are we talking about spark before fuel?”. There are 2 reasons that we are going to check spark before we see if your engine is getting fuel:
To check spark, we are going to pull the spark plug, if the spark plug is wet, there is a good indication we ARE getting fuel.
If the plug is dry and we have spark, we are not getting fuel.

So to check the spark we need to pull the rubber cap off the spark plug and remove the plug from the engine. I am not going to get into plug reading as that will be a seperate article in itself. For the purpose of 2 stroke engine troubleshooting, we are going to keep the plug inspection simple.

Ok, so you have the spark plug out of the motor, if the business end of the spark plug is completely caked with black crud, do yourself a favor and get a new spark plug right away. With that said, if the plug looks wet, you are getting fuel. If it looks dry, well, don’t panic yet. Either way, put the spark plug wire back on the plug and lay the business end of the plug on the head (just set the plug on the metal part of the engine near the hole you took it out of). What you are doing here is grounding the plug to the engine, as if it were installed in the engine, but you want to be able to see if the plug sparks when you turn the engine over.

The engine will be very easy to spin over with the spark plug out of the cylinder, spin the engine over by quickly kicking or pulling it, you want it to spin over fairly quickly, don’t pull or kick it real slow. It may require a buddy so one of you can get your head down and look at the spark plug while the other spins the engine over. We are looking for a nice blue spark across the electrode of the spark plug. If you don’t get spark, try a new spark plug before you do anything else, even if the plug looks “good” try a new one.

If you have spark and the plug was dry, move on to “Fuel”

If you have spark and the plug was wet, replace the spark plug and try starting the engine again with the choke off. If this doesn’t work try with the throttle wide open as your engine may be flooded (too much fuel in the cylinder). When 2 stroke engine troubleshooting and the engine is flooded, you want to spin the engine over fast with the throttle wide open several times. You should start to hear it pop, just keep pulling or kicking and holding it wide open until it starts, then rev the engine a bit to clean it out and keep it running, then warm it up properly.

If you still don’t have spark with a new spark plug, you have problems with your electrical system. I won’t go into any more detail on that in this article but I plan to add these types of things to this website as I have time.

2 Stroke Engine Troubleshooting – Spark But No Fuel

As you read above this is assuming you have checked the basics, you know, gas is on, gas in the tank, choke is on. One quick check you can do is to pull the fuel line off your carburetor, turn the gas on for a second and see if fuel is flowing out the fuel line. If all that stuff is ok, then it’s likely at this point you have something blocking the fuel inside your carburetor. There can be several causes of this:
Water in the fuel.
Old fuel evaporated gumming up carb.
Debris in carb plugging up the jets.
Carburetor float stuck.

You have to use some common sense here. If this is a 30 year old motorcycle you pulled out of a barn somewhere, the carb will need to be pulled and comepletely disassembled and cleaned. If this is something that was running recently, and is clean with clean fuel, it may just have gotten moisture in the fuel or debris clogging up the carburetor jets. Most 2 stroke engine carburetors have an access plug or drain plug in the bowl on the bottom of them. Remove this plug (you may have to loosen the carb and tilt it to access this, or even remove the carb from the machine in some cases). Let the fuel drain out and then open the fuel valve ie. “turn on the gas” for a few seconds, it should run clean gas out the hole in the bottom of the carb at a pretty good rate. If not your float is stuck, you can sometimes “break” this loose by gently tapping on the side of the carb with the plastic handle of a screwdriver.

If you see anything remotely white colored in your fuel you have water in your gas. If you suspect you have water in your fuel, you should drain the fuel tank and start with fresh gas. Go to your nearest gas station and grab a bottle of isopropal heet, yes the stuff you put in your car gas tank in the winter. Add a bit of this to your new fuel to wick the remaining moisture out of your fuel system.

Again for the purpose of this 2 stroke engine troubleshooting article I am not going to go into any more detail, but I will be adding carburetor repair videos and ariticles on this brand new website very soon. Please check back often.Thank You Jim Marquardt

Motorcycle Engine Oil :The proper use of the correct grade engine oils in motorcycles;

Posted on November 17, 2011 by melwin23

Source: sportrider.com
This is a very good two part article related to the proper use of the correct grade engine oils in motorcycles;especially those with wet clutches.

Oils Well That Ends Well, Part 1
Part One: What is motor oil really made of?

Editor’s Note: This is Part One of a special Sport Rider comparison test, where we unlock the mysteries and debunk some of the myths of motor oil. We examine just what goes into motor oil, why those ingredients are there and what it means for your engine. In the next issue, Part Two will feature a scientific analysis of all major motorcycle-specific motor oils, plus a wear and dyno test of specific oils to determine whether there is a power difference.
When motorcyclists discuss engine oil, they quickly polarize into two groups. There are those who think all oils are basically the same, and that anyone spending more for premium oils is wasting his money, and there are those who feel there is a difference and are willing to spend the money to get the best product available. However, both groups share a lack of scientific information allowing them to make an informed decision. To offer some insight into this heated topic and help you determine which oil is right for you, we’ve decided to delve into this outwardly simple-but very complex-product. In Part One of this two-part series, we’ll dissect the real what, how and whys of motor oil.

The first thing you need to know about motor oil is what it does for your engine. Motor oil actually has several purposes, some of which may surprise you. Obviously, lubrication is the main purpose. The oil serves as a layer of protection between the moving parts, just like shaving gel does between your skin and a razor.

However, oil also acts as a dispersant, which means it holds damaging stuff like dirt and metal particles suspended in the oil (rather than letting them settle to the bottom of the oil pan where they can be recirculated through the engine) so they can be removed by the oil filter. Then there is the job of corrosion retardant. By reacting with the nasty acids created by combustion, oil actually prevents these byproducts from damaging the internals of the engine. For instance, when combustion takes place, sulfur molecules in gasoline occasionally combine with air and water molecules, forming a vile brew called sulfuric acid. Left unchecked, this acid will eat away at internal engine compounds. Good oils, however, contain enough of the right additives like calcium, boron or magnesium to neutralize these acids.

Cooling is another important factor. Oil serves to cool hot spots inside an engine that regular coolant passages cannot reach. Since coolant usually only deals with the hottest parts of the engine, like the cylinders and cylinder head, there are many internal engine components that depend on oil for cooling as well as lubrication. For example, the transmission and clutch rely heavily on oil to regulate temperatures, since excessive heat expansion can change tolerances and cause clearance-related problems. Another area that uses oil for cooling purposes is the undersides of the pistons; with pistons becoming thinner for less weight, yet dealing with ever-increasing compression ratios, keeping the piston assembly cool is vitally important. Parts such as these can expose oil to extreme temperatures, so this is one reason that thermal stability is so important for motorcycle engines. We will do a specific test in Part Two to predict the oils’ ability to survive in extreme heat.

These three oils have the proper JASO label, which shows they have tested and passed the JASO certification standards. The MA standard is for high friction motorcycle applications, so you’ll know the oil is specifically tailored for use in your sportbike-not some econobox car.
Who is the API?
The American Petroleum Institute (or API) was established in 1919 as an industry trade association with one of its goals stated as “promot(ing) the mutual improvement of its members and the study of the arts and science connected with the oil and gas industry.” Today, the API impacts the consumer market through the development and licensing of engine oil industry standards. On most oil containers, you will find a small circular label that says “API” along with letters like SG, SH, etc. Each of these letters represents a very complex set of specifications and tests that have to be met in order for an oil to carry the API designation. When you see an oil with the API symbol, this means the company has paid a license fee to the API, and in turn the API has tested its product to ensure it meets the applicable standard. If the API grades are simply listed on the bottle without the circular API symbol, this means the company claims to meet the API standards, but has decided not to obtain API licensing. This process is very expensive, and therefore many smaller producers choose not to be members, even though their products may be good enough to pass.

Every few years the API releases a new standard that is often specified by auto manufacturers, with the changes usually aimed at achieving lower levels of friction to obtain higher fuel economy, and to deal with other emissions-related issues. This is a never-ending battle in the automobile industry, as stricter federal emission and fuel economy standards are being imposed on automobiles. The API works with the auto industry to ensure that the oils are doing everything possible to reach these goals.
The motorcycle industry followed the ever-changing API service designations until a few years ago, when the SJ designation lowered maximum levels of certain additives used to reduce metal-to-metal friction. (The latest API designation is SL.) Specifically, the maximum allowable phosphorous content was lowered from 0.12 percent to 0.10 percent due to its negative effect on some catalytic converters. An engine burning oil will pass this phosphorous through the exhaust system, resulting in damage to oxygen sensors and catalytic converters. Since the EPA requires all emissions-related parts to be covered under warranty for seven years, this was a major motivator for manufacturers to meet the new standard.

Who is the JASO?
The motorcycle OEMs felt that lower levels of phosphorous and the introduction of more friction modifiers (aimed at higher fuel economy in cars) was not in the best interest of motorcycle engines. Since phosphorous is an important antiwear component, lower levels could reduce the ability of oil to protect transmission gears, since motorcycles share engine oil with the gearbox. Plus, added levels of friction modifiers could cause problems with slipping clutches, as well as less than optimal performance of back-torque limiting devices that lessens wheel lock-up on downshifts.

Note that these labels list only the API and JASO standards in text form without the proper labels. This means the manufacturers claim their product meets or exceeds both standards, but haven’t paid the fee for licensing (and testing). Note that the process to carry the official labels is very expensive, so smaller oil manufacturers may choose not to obtain licensing, even though their products may pass the tests.
Rather than continue to rely on specifications dedicated to automobiles, the Japanese Automotive Standards Organization (or JASO) developed its own set of tests specifically for motorcycles. JASO now publishes these standards, and any oil company can label its products under this designation after passing the proper tests. JASO offers two levels of certification, MA (high friction applications) and MB (low friction applications). JASO requires that the entire product label be approved before it can carry its label. If a label does not have a box with a registration number above the MA or MB lettering, it could be nonapproved oil whose manufacturer claims its products meet JASO standards when it may not have actually passed the tests.

These standards also include a test specifically designed to measure the oil’s effect on clutch lock-up, as well as heat stability and several other factors related to motorcycle engines. Our advice here is pretty simple: Read your manual, and if it calls for an API SG oil, use that. Don’t substitute a higher API designation oil like SL, because it will contain less of some additives like phosphorus, and it may contain other additives that will yield higher fuel economy in a car but could cause slippage in your clutch. (More on that later.)

While it may not be the perfect answer, you can also be safe by selecting JASO-labeled oil, because you will know that it has passed a bank of tests developed by the motorcycle industry. A quick look in several 2002-’03 owner’s manuals showed that an ’03 Kawasaki ZX-12R and most Hondas were the only sportbikes in our shop carrying a mention of JASO.

What Are Base Stocks?
Motor oils start with a base oil mixed with various additives. These base oils often account for approximately 80 to 90 percent of the volume, and are therefore the backbone of oil. Everyone knows that some oils are petroleum-based and some synthetic, while others are labeled semi-synthetic. What does all this mean? Well, not as much as it used to, because the lines are now blurred in the case of synthetic oils.
For our purposes, petroleum oils are the most basic and least expensive oils on the market. They are created from refined crude oil and offer good properties, though they are generally not as heat resistant as semi-synthetics or full synthetics. On the other end of the spectrum are synthetic oils. A synthetic oil has been chemically reacted to create the desired properties. Semi-synthetics are a blend of the two base stocks.
The API groups oils into five major categories, each with different properties and production methods:

Group I: Solvent frozen mineral oil. This is the least processed of all oils on the market today and is typically used in nonautomotive applications, though some of it may find its way into low-cost motor oils.

Group II: Hydro-processed and refined mineral oil. This is the most common of all petroleum oils and is the standard component of most petroleum-based automotive and motorcycle engine oils.

Group III (now called synthetic): The oils start as standard Group I oils and are processed to remove impurities, resulting in a more heat-stable compound than possible as a standard Group I or II oil. Some examples are Castrol Syntec automotive oil and Motorex Top Speed. These are the lowest cost synthetics to produce, and generally do not perform as well as Group IV or V oils.

Group IV: Polyalphaolefin, commonly called PAOs. These are the most common of the full synthetic oils, and usually offer big improvements in heat and overall stability when compared to Group III oils. They are produced in mass quantities and are reasonably inexpensive for full-synthetic oils. Since they are wax-free they offer high viscosity indexes (low temperature pour point) and often require little or no viscosity modifiers. Examples include Amsoil and Motorex Power Synt.

Group V: Esters. These oils start their life as plant or animal bases called fatty acids. They are then converted via a chemical reaction into esters or diesters which are then used as base stocks. Esters are polar, which means they act like a magnet and actually cling to metals. This supposedly offers much better protection on metal-to-metal surfaces than conventional PAOs, which do not have this polar effect. These base stock oils also act as a good solvent inside the engine, translating into cleaner operation. Esters are the most expensive to produce, and oils manufactured with them usually cost much more. Due to this higher cost, many companies only fortify their oils with esters. Some examples are Bel-Ray EXS, Torco MPZ Synthetic and Maxum 4 Extra. Motul 300V, however, uses 100 percent ester as its base oil, and is one of the more expensive oils.

The grouping of these oils is the source of much controversy. One topic that has been debated is what can be labeled a “full synthetic oil.” In 1999, Mobil brought a complaint against Castrol for changing the base oil in its Syntec product. They had used a Group IV PAO, but had changed to a Group III base oil. Mobil contended that Group III oils were not really “synthetic oil” and should not be labeled as such. After many expert opinions were heard, the National Advertising Division of the Better Business Bureau sided with Castrol and said that Group III oils could be labeled synthetic. Since that time there has been a lot of growth in this product type due to its low cost and similar performance to traditional synthetics. Many traditionalists still argue that Group III oils are not true synthetic oils.

Additives to the oil
Additives are the other 10 to 20 percent of the product that help the base oil do things that it otherwise could not. Additives fall into several basic categories:

Detergents/Dispersants: These ensure that foreign materials in the oil stay in suspension to allow the filtration system to remove dirt or debris.

Corrosion Inhibitors: These prevent oil from deteriorating from the attack of free radicals or oxidation.

Antiwear: These are perhaps the most- discussed additives, which serve to protect the engine from metal-to-metal wear. Common antiwear additives are phosphorous and zinc. Other antiwear additives include friction modifiers like molybdenum disulphide (or moly).

Acid Neutralizers: Additives like calcium, magnesium and boron act to absorb acids created during combustion to protect the engine. They are typically indicated by the TBN (Total Base Number). A higher number means the oil should last longer and provide increased protection against combustion-based acids.

Other additives such as foam inhibitors, viscosity modifiers and antirust components may also be present in motorcycle oils. In particular, antifoaming additives are important due to the high RPMs that can create cavitation and starve bearings from necessary lubrication in the process.

Viscosity
If you ask someone with years of riding under his belt what viscosity oil he uses, he may answer “20W-50.” All multiviscosity oils carry two numbers. In simple terms, the first number is the oil’s viscosity when cold (32Fahrenheit/0Celsius), and the other is the oil’s viscosity at operating temperature (212F/100C); the “W” stands for “weight” or viscosity, which is simply the liquid’s resistance to flow. In other words, when the oil is cold it will flow like a 20-weight, but when hot it will act like a 50-weight. In order to overcome the natural thinning that occurs as oil heats up, a component known as a viscosity modifier is added. This is a complex polymer that swells due to heat, the net result being that the oil thins less.

Typically, synthetic oil contains less of this additive, or in some cases none at all due to its naturally higher viscosity index. This is another reason why they are better suited for the wide range of temperatures and riding conditions associated with motor-cycle use. Viscosity modifiers are one of the first additives that wear out in oil, and a big reason that some synthetic oil manufacturers claim longer service life. Since they are naturally a multigrade product without the chemical modification mineral oils require, synthetic oils will hold their viscosity grade longer.

The reason the old-timer may suggest thicker oil is because in older engines with higher tolerances, thicker oils were necessary to keep oil pressure up. Others believe the use of higher viscosity oils results in better protection because high-performance engines are harder on oil. This isn’t true in modern engines, and using oil thicker than specified can actually harm an engine. Internal oil passages and galleys may not be large enough to allow thicker oils to penetrate and flow as well, which can possibly cause starvation. In fact, many race teams use the thinnest oil possible to gain extra horsepower by lowering the parasitic losses that occur when using thicker-than-necessary oil. The higher film strength offered by synthetic base stocks helps racing engines survive even endurance races when running ultra-lightweight oils. Of course, these engines are typically rebuilt after each race, so we do not suggest using a racing oil in your streetbike. Refer to your owner’s manual and use the viscosity of oil corresponding to your riding conditions as specified by the manufacturer. The manuals often have a table with various temperatures allowing you to select the right viscosity.

Can synthetic oils cause my clutch to slip?
To answer this in one word: No. Clutch slippage is caused by many things, but the use of synthetic oil alone is usually not the culprit. The truth is that some bikes seem to suffer clutch slippage no matter what oil goes in them, while others run fine with any oil. This is most likely caused by factors other than the oil, such as the spring pressure, age and clutch plate materials. If you have a bike known for clutch problems, you may have to be more selective in your oil choices.Moly is often blamed for clutch slippage, and it can have an effect-but moly alone is not the problem. We wish there was a hard and fast rule to follow, but it is just not that easy. Simply put, you will have to try an oil and evaluate it. If you experience slippage with the new oil, and have not had problems before, it may be the oil. The plates and/or springs could also be worn to the point that they have finally started to slip. Simply change back to the previous oil and see what happens. You can also check the test data in next issue’s article to see if that particular oil has a significant amount of moly. If so, try one that does not have as much moly next time.

We talked to Mark Junge, Vesrah’s Racing representative, who has won numerous WERA national championships using Vesrah’s clutches. He said that in his years of engine work he has yet to see a slipping clutch that could be pinned on synthetic motor oil. Junge felt that nearly every time the clutch was marginal or had worn springs, the new oil just revealed a problem that already existed.

Stay tuned for Part Two: Analysis, Wear and Dyno tests
This is the first part in a two stage article, so please stay tuned to the next issue where we will reveal the test data from an analytical oil laboratory as well as the results of our dyno horsepower shootout, where we will have a face-off of two different products to see if changing oils can yield horsepower gains as some manufacturers claim.

Oils Well That Ends Well, Part 2
Part Two: Laboratory and Dyno Analysis

In the first portion of Sport Rider’s oil test (“Oils Well That Ends Well?” August 2003), we covered the overall makeup and functions of motor oil to give you a basic understanding of its role in the performance of your engine. In this portion-the second and final part of the article-we go into a detailed analysis and testing of 22 oils to see what makes them different from one another, including comparing motorcycle-specific oils to automotive products. We also run a dyno test to see if the claims of increased horsepower made by some oil producers are really true.

Spectrographic Analysis
Presented first is the spectrographic analysis of each of the tested oils. Using units of parts per million (ppm) to show the amount of additives in each product, this test utilizes an atomic emission spectrometer to measure the wavelength of light emitted from each oil sample as it is “ionized;” in simplistic terms, this is similar to sticking the oil into a microwave oven, then using a prism to split the light emitted as the oil burns. Since each element has its own light wavelength, a computer compares each light measurement to a standard emission, and then calculates the amount of that particular element.

We called on Analysts Inc. in Norcross, Georgia (Analysts, Inc., 800/241-6315), to perform the spectrographic analysis testing. An ISO-9002-certified facility (meaning their lab meets strict worldwide quality-control specifications), Analysts Inc. has been in business since 1960, and is considered one of the top oil-testing labs in the country. They are able to identify extremely small amounts of metals and additives, and in some cases can detect as little as one ppm. If you send them used oil for analysis, they can generate a metal contents report that will help you discover internal engine problems before they occur. Most large diesel fleets use this to determine maintenance schedules.

This type of analysis also reports the absolute viscosity of the oil, and the total base number (TBN). The TBN is determined by measuring the milligrams of acid neutralizer (potassium hydroxide) required to nullify all the acids present in a one gram sample of oil. Viscosity retention and TBN are very important in deciding when to change your oil. A TBN of three or less typically denotes a failure of the oil to absorb acids. Oils with a higher initial TBN are therefore better suited for longer change intervals, assuming the base oil is of sufficient quality to maintain its specified viscosity over time. The subjects of base oil quality and viscosity retention are very complex, and are discussed later.

These elements are the most commonly discussed because they are one of motor oil’s most important components. Several additives fall into this group, including phosphorous. The maximum level of phosphorous allowed in some automotive oils has been reduced by the new API standards, due to its effect on catalytic converters. Zinc is another additive in this group, as is molybdenum, usually referred to as moly. These antiwear additives serve as a back-up to the oil film in protecting engine components. They are activated by heat and pressure, forming a thin layer between metal parts that would otherwise come in direct contact, preventing permanent engine wear.

Looking at the graphs, it’s interesting to note a wide variation in additive amounts. For instance, examining phosphorous levels in the antiwear additive graph (remembering the API limitations) shows that two automotive oils contain approximately 1000 ppm (Valvoline and Castrol Syntec), while the Mobil 1 product contains 1391 ppm. The average of the motorcycle-specific oils is 1322 ppm; the automotive oils average 1157 ppm. The Maxima Maxum products have the highest levels overall, with almost three times the amount found in the lowest product tested. The products with the lowest levels are Silkolene Comp 4, Yamalube and Honda HP4.

A similar correlation can be seen with zinc. The Maxima products again show the highest levels at almost 2000 ppm, while the Yamalube and Silkolene products again end up on the bottom of this list. The difference here between automotive oils and motorcycle-specific products is not as great, presumably because this additive is not regulated by the API. In fact, Valvoline is the only auto oil containing less than 1400 ppm. While the average motorcycle-specific product contains 1414 ppm, the automotive oils average 1328 ppm-not a huge difference.

Moly is often referred to as a friction modifier, but it is actually a solid metal dispersed in some oils. Because it has such a high melting temperature (4730 F versus 2795 F for iron), it works great as a high-temperature, high-pressure antiwear agent. Some claim that because moly is so slick, it can cause clutch slippage. In fact, some motorcycle manufacturers specify oil without moly due to this problem. The moly issue is such that Honda offers its HP4 both with and without it. Looking at the moly graph data, however, shows that even Honda’s “moly-free” product contains 71 ppm. Many of the products contain less than five ppm of moly, which is the threshold measurement on this test (meaning any amount less than five ppm will not be detected). Both Torco oils contain a significant dose of moly, while the Maxum Ultra and Motul 300V Factory contain far less. The Mobil 1 automotive oil contains 92 ppm, while the MX4T motorcycle-specific version has an undetectable amount. Only six of the 19 motorcycle oils we tested use moly at all. Those that do, however, average 298 ppm. Considering that many oils contain five ppm or less, 298 ppm is a significant dose.

One common claim is that motorcycle oils have specific additives that are more suited for motorcycle engines. Based on an average of the three automotive oils we tested, the bike oils do in fact contain more of everything except calcium and boron. Note that the average moly content, which is often the friction modifier of choice, is higher in the motorcycle oils than the car oils mainly due to the three bike oils that use an extremely high moly content.

Acid Neutralizers
We charted the three most common additives (boron, calcium and magnesium) used to neutralize acids produced inside an engine during combustion. In this category, we can see that the car and bike oils are different in some cases. Every company seems to agree that some dosage of calcium is required. The highest amount is Amsoil at 4843 ppm, which explains its very high TBN of 14.42. Amsoil does not use significant dosages of either magnesium or boron, though; many other oils use both of these to bolster their acid-fighting ability. Maxum Ultra contains only 986 ppm of calcium, but supplements that with the highest dose of magnesium in the test at 1275 ppm. The Mobil MX4T product uses 699 ppm of magnesium and 221 ppm of boron. Another difference between the auto and bike products offered by Mobil is the use of magnesium. Mobil 1 automobile oil contains only 33 ppm of magnesium.

Another common claim is that the higher price of motorcycle-specific synthetic oils allows oil manufacturers to use not only better and more heat-resistant base stocks (as shown in the heat aging data), but also more additives. Our averaged data shows that in general, the synthetic oils contain as much or more of each additive. Note, however, that we only tested two motorcycle-specific petroleum oils, and results could vary with more oils tested.

Looking at overall averages, the bike oils have an average of 1986 ppm of calcium versus the car oils’ 2702 ppm. While the bike oils average 296 ppm of magnesium, the car oils muster only 54 ppm. Since many of the bike oils do not use any boron, their average is only 96 ppm compared to the car oils’ 116 ppm. However, looking only at bike oils that use boron as part of their additive package, the average is 253 ppm. The bike and car oils are clearly different in this category.

It’s pretty obvious which of these products should do the best job of keeping corrosive acids in check when looking at the TBN. Topping the list is Amsoil, both Motul products and the automotive oil Castrol Syntec. A lower TBN does not mean the oil is bad, it just means that the drain-interval potential is not as great. If you change your oil every 1000-2000 miles, then you shouldn’t be concerned with this value. Others should take at least a cursory look at this category, however.

It’s interesting to note a trend toward longer oil-change intervals in the automotive world. For example, BMWs now come with factory-proprietary synthetic oil, and the on-board computer usually suggests oil changes every 15,000 miles or so. However, BMW engines have oil sumps larger (their 2.5L six-cylinder holds seven quarts) than most similarly sized engines, as well as high-capacity oil filters. Mercedes-Benz follows a similar plan, using full synthetic oil with a change interval of 10,000-16,000 miles. Being the skeptical type, we tested oil from a BMW engine at 7500 miles, only to find the oil within viscosity and all other standard values-meaning it could have been left in longer.

Don’t let fancy colors influence your opinion of an oil’s quality or sophistication-some are just dyes that quickly burn off. Note how this sample of the Motorex PowerSyn synthetic oil quickly loses its green hue after just one hour in the heat test.

Although not the final word on an oil’s overall quality, some oils showed marked degradation in color during the heat test. Note the nasty coloration of the Torco T4R sample in the post-test tin.
The truth is that engine oils are better than ever with regard to base stocks, as well as viscosity improvers and acid neutralizers. If you don’t have a 12-month riding season, you should add an extra oil change before you winterize your bike to prevent that used oil (with corrosive acid buildup) from sitting and possibly damaging your engine internals. As long as your engine isn’t highly stressed, whether through competition or extreme mileage, our suggestion is to simply follow the change interval specified in your owner’s manual, and spend more time riding and less time worrying. Of course, this assumes that your engine is in good mechanical condition; problems like fuel or coolant diluting the oil could mean disaster a lot sooner than 1500 miles.

Evaporative Heat Stability Test
The oil inside your engine is subjected to an extreme environment. Sure, the coolant-temperature gauge may only show 200 F, but there are many internal engine parts that become far hotter. In order to determine each oil’s ability to survive in such a climate, we subjected samples to a test commonly known as the Noack method. This test takes an oil sample and cooks it at 250 C (the estimated temperature of the piston-ring area, which is the hottest an oil should get) for one hour. Before and after the exposure, the sample is carefully weighed on a precise laboratory scale. Because parts of some oils are unstable at these temperatures, they burn off during the test, and that loss can be accurately measured.

The higher the percentage of weight retained (meaning less oil has burned off), the better. As you can see in the charts, there is quite a difference between the best and worst oils. The top product on this test is the Mobil 1 car oil at 96.1 percent. What is not so clear is that Group III oils (synthetics processed from a mineral-base stock) like Castrol Syntec and Motorex Top Speed test about as well as Group IV (PAO synthetics) and V (ester synthetics) products such as Motul, Bel Ray, Maxum and Torco. This shows that Group III oils are getting better and more heat stable (i.e., using better base stocks) for these applications than they were a few years ago.

As expected, the petroleum-based oils such as BelRay EXL, both Valvoline oils and the Yamalube and Torco synthetic blends are on the low end of the scale. Proving how good some synthetic blends are, top blend performer Castrol GPS actually out-performs one of the full synthetic oils (BelRay EXS). In general, however, the full synthetic oils are the winners here, with an average value of 93 percent, compared to the synthetic blends at 89 percent and the dinosaur oils at 86 percent.

We suggest you look at this data carefully and determine your needs before picking an oil for your bike. While not the only important factor, heat stability is one of the top issues because most sportbikes are tuned to the highest levels of performance possible, usually generating intense heat in the process. Engine oil must be able to survive these temperatures and not evaporate when you need it most.

We were as surprised as anyone that just changing oil can produce a horsepower boost. Both the R1 and GSX-R1000 posted some significant gains in midrange and top-end, and were gaining power with every run until coolant temps got a little too hot. Before you go rushing to buy this stuff, however, check out the viscosity retention test.

Dyno Test
Some oil manufacturers and their representatives claim that using their product will result in more horsepower. These are special ultra-lightweight-viscosity racing synthetic oils that are said to reduce the parasitic drag that oil has on an engine’s internal reciprocating components. We decided to put these claims to the test-an actual dynamometer test. Two of the full synthetic oils in this test make these horsepower claims on their labels: Maxima Maxum Ultra (in 0W-30 and 5W-30) and Motul Factory Line 300V (in 5W-30). We took two open-class sportbikes-a Suzuki GSX-R1000 and a Yamaha YZF-R1-and ran them with common off-the-shelf Valvoline 10W-40 automobile mineral oil to set a baseline dyno run. That oil was drained and replaced with the 0W-30 Maxum Ultra in the Suzuki, and the 5W-30 Motul 300V in the Yamaha. After about 15 miles of running to get the oil fully circulated through the engine, the bikes were then dynoed again.

Lo and behold, both the Suzuki and Yamaha posted horsepower gains. While not an earth-shattering boost in power, the gains were far beyond common run variations, and weren’t restricted to the very top end. The GSX-R1000 posted an increase of 3.3 horsepower on top, with some noticeable midrange gains as well; even more interesting was that the power steadily increased for several dyno runs (as the coolant temp increased). The Yamaha responded nearly as well, with a 2.7 horsepower boost on top. It should also be noted that while riding both bikes, there was a noticeable ease in shifting with the synthetic oils compared to the automobile mineral oil. Pretty impressive for just changing oil, in our opinion.

But before you go rushing to buy these products, it should be noted that these are racing oils, and, despite manufacturer claims of viscosity retention performance identical to standard viscosity oils, are made to be changed on a much more frequent basis. You should take a close look at the Tapered Roller Shear Test that demonstrates an oil’s ability to maintain viscosity over time.

Four-Ball Wear Test
With an eye toward evaluating oil’s ability to lubricate under extreme pressure conditions, we picked a few candidates and ran them through the “Four-Ball Wear Test” (officially designated ASTM D-4172). To conduct this test, we enlisted the help of the Southwest Research Institute in San Antonio, Texas (www.swri.org; 210/684-5111). SwRI is a huge nonprofit independent testing and engineering firm with an entire group of people dedicated to motorcycle-related products.

This test is used to determine the wear properties of engine oil in sliding contact (such as a piston sliding against a cylinder wall). Three half-inch-diameter ball bearings are placed in a triangular fixture, with a fourth half-inch ball in the center (in contact with the other three) held in place with a clamp. The ***** are then immersed in the test lubricant while the top ball is spun at 1800 rpm for a period of one hour with a prescribed load of 40 kg (88 lbs.) and a constant temperature of 75 C (161 F). The “wear scar” on the three lower ball bearings is then carefully measured (in millimeters) using a microscope and averaged. The smaller the wear scar, the better the protection.

Because this test is expensive, we could not test every product listed in the spectrographic analysis, so we picked a few we thought would reveal the most information. We chose the Castrol GTX 10W-40 automotive oil because it is a simple Group II mineral-oil product that is widely used and inexpensive. As an example of motorcycle-specific oils, we picked the popular Mobil 1 MX4T motorcycle oil in 10W-40. It is a moderately priced full synthetic oil (approximately $8.99 per quart), and should represent all the technology and economy of scale that a large oil producer like Exxon/Mobil can offer. We also chose the Amsoil Group IV motorcycle oil. Amsoil makes product claims related to the performance of its oil on this test, so we decided to see if they could live up to their claims.

The four-ball wear testing did not show the huge variation expected. All of these oils basically perform the same. With any test there is some variation from sample to sample, and this data is so close we have to call it a tie, which means all these oils in their new, virgin state do a good job of protecting against sliding friction wear. Incidentally, Amsoil did perform up to the test claims stated on its label.

Tapered Roller Shear Test
We decided to conduct some additional testing aimed at evaluating an oil’s ability to withstand the shearing loads present in a motorcycle gearbox (but not in the typical automotive engine). One of the claims made by most motorcycle-specific oil producers is that motorcycles present a different set of conditions than typical cars do, and that therefore you should spend more money to get oil formulated specifically for this environment. The meshing of transmission gears is said to shear or tear oil polymers over time, resulting in the degradation of oil viscosity and severely reducing its performance. As we stated earlier, this may not be so critical if you frequently change your oil. However, if you run longer than standard intervals, this oil property is something to strongly consider.

The test we selected to measure this effect is officially called the “Tapered Roller Bearing Test” (CEC L-45-99), commonly called TB-20. Recent trials have shown that this test provides the best correlation to actual performance compared to other industry shear tests. For the TB-20 test, a tapered bearing fitted into a four-ball test machine spins submerged in 40 mL (1.3 fluid ounces) of lubricant at 60 C (140 F) at a constant speed for 20 hours. The viscosity of the used fluid is measured and compared to the new/original viscosity, and the percentage of change compared to the original viscosity is reported. The higher the number, the more viscosity loss the oil experienced during the test.

We picked Valvoline 10W-40 automotive, Motul 300V 5W-40 Factory line, Mobil MX4T 10W-40 and Motul 300V 10W-40 oils for this test. Part of the analysis also involves the testing of a reference oil with a known viscosity performance in order to measure the variation between tests. In our case the reference oil had a total variation of 2.5 percent. This means that differences of 2.5 percent or less should be judged as the same, and that these small differences are related to the test method rather than product differences.

The actual viscosity raw data test results are expressed in centistokes (cSt), the scientific unit of viscosity measurement. However, after the percentage of viscosity loss column, we have converted the centistokes to an approximation of SAE grade to give you an idea of how much viscosity breakdown has occurred.

The various oils show large differences in their ability to endure this difficult test. The one commonly available automotive mineral oil tested suffered a 41 percent loss. While this limited data does not conclude that all mineral-based automotive oils are bad, it is definitely not a good sign. Looking at the motorcycle-specific oils, it’s notable that the Motul 5W-40 version does not hold up nearly as well as the 10W-40 version (in fact, slightly worse than the auto oil). Motul and Maxima both claim that their ultra-lightweight-viscosity oils would last as long as normal 10W oils. Because we only tested the Motul version, we cannot say for sure that the Maxima Maxum Ultra would suffer the same loss. Yet our dyno test shows that both these oils post a horsepower gain. We consider ultra-lightweight racing oils such as 0W and 5W a special category of race products that should be changed on a strict regimen. Before you decide to run them, you need to weigh the risk of viscosity loss versus horsepower gains and make your own decision. Until more data convinces us otherwise, we would stick to something more practical for the street.

Conclusions
With all this testing data (and expense), you’d think making a clear-cut decision as to which oil is best would be easy. In the case of engine oils, however, there are too many products and variables that go into this equation. Due to the financial reasons stated earlier, not every test was run on every product, so crystal-clear conclusions aren’t in the picture. You must weigh all the data we have made available; for instance, the fact that some oils may absorb acids better, but may not handle high heat as well. Or that while the four-ball wear test shows that particular automobile and motorcycle-specific oils perform identically, the heat and viscosity shear tests show otherwise.

We did, however, unequivocally answer a few questions. For one, most name-brand motorcycle-specific oils are indeed different than common automotive oils, even within the same brand, debunking a common myth. Mobil One automotive oil is definitely different than its motorcycle-specific version. The same is true for the three oils provided by Castrol, showing that both companies have different goals when formulating their automotive and motorcycle products. Whether they perform better-despite the data we’ve gathered-is still a matter of opinion. Another manufacturer, on the other hand, appears to have selected the same additives in both of its offerings, which begs the question: Are they actually identical and simply relabeled?

Once again, the final decision is up to you. It’s your bike and your hard-earned money-so only you can make the decision whether to spend the extra bucks for full synthetic motorcycle oil or simple mineral-based car oil. Review the data we have presented, and select the product that is most suited to your bike and riding style.

This article originally appeared in the October, 2003 issue of Sport Rider.

Grease n Gasoline

http://hydro-carbons.blogspot.com/ Daily updates on cars / motorcycles : Custom designs , concepts , new launch , vintage , Motor racing

Category Archives: Internal combustion engine

Torque vs. Horsepower

If you’ve been around motorized vehicles for any length of time, you have probably been exposed to the great torque vs. power debate at some point. If not, it goes like this:

“Torque is what makes a bike accelerate, not power.”

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If you’ve been around motorized vehicles for any length of time, you have probably been exposed to the great torque vs. power debate at some point. If not, it goes like this:

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