Before jumping into how to do it, it's necessary to understand what the clutch does and why it was designed that way to begin with. The automatic CVT, or continuously variable transmission, is a cousin of your typical multi-speed, constant-mesh, gear-driven manual gearbox. Whereas the manual trans requires proper selection of the gear ratio to maintain power, the automatic trans does the thinking for the rider.

Of course, for novice riders the auto trans is a huge advantage in simplifying the riding experience. No worrying about stalling the engine, or keeping it in the right gear- it's all done magically by the CVT. However, unlike the CVT's other cousin, the automotive style automatic transmission, the CVT is designed very cleverly to continuously vary the transmission gear ratio to do one thing only- hold the engine speed constant.

This concept is key, and the crux to the whole tuning exercise. If you were to examine the power curve of a typical 2-cycle engine it would rise, and then fall very quickly near its power peak- hence the notorious reputation of the 2-stroke as a "pipey" variety compared to the more docile and predictable 4-stroke.

The question becomes- if you were limited to operating your engine at only one rpm, what would it be? The rpm at which peak power occurs, of course, and therein lies the beauty of the CVT transmission- it's ability to hold the engine there. The job of the clutch tuner is to identify that point and dial it in.

When modifying your engine you've more than likely shifted that peak power rpm. The original equipment manufacturer (OEM) has probably optimized his gearing to coincide with the stock machine’s peak power rpm. Without readjusting the clutching to realign the controlled rpm with the new power peak, full advantage of the engine mod may not be realized. In the example above, the stock clutch would be adjusted to hold the engine at 8000 rpm from the factory.

If the clutch wasn't readjusted to run at 9500 rpm, only a 50% improvement would be gained since there's only another 1.7 hp available at 8000 rpm. Not too shabby, but if the clutch was properly adjusted then max power available to the quad would be nearly 100% higher, or double!

Not to worry, most performance shops will sell you their products with either recommendations for a particular clutch setup, or provide the clutch hardware as part of their kit. They've no doubt ran their own hardware and through their own extensive testing have determined that a certain set of rollers and spring result in the best performance.

Realize though, that there are subtle (and not so subtle) differences between machines, and the recommended setup should only be considered a starting point. Move on to next part --> Understanding the Fundamentals