One of the nuances of the 4-stroke motors now found in some of the newer snowmobiles is the affect of engine compression braking when you let off the throttle. Owners of the 4-strokes, and those who have spent any amount of time riding one, can confirm this tendency, where the engine helps to slow the vehicle down through the clutching and compression braking that occurs as the clutches downshift the transmission to a lower ratio, much like using a lower gear to slow your car or truck instead of relying solely on the brakes. 4-stroke riders should also be familiar with how the sled coasts once the primary is completely disengaged.
A number of snowmobile clutch tuners have also commented on the conventional wisdom when it comes to using a CVT transmission on 4-stroke snowmobiles. With their broad powerbands, the need to maintain engine RPM within a relatively narrow bandwidth is no longer needed. Some have gone as far as to suggest the primary clutch spring isnâ€™t nearly as important as weâ€™ve always given it credit for.
Then we received an e-mail in regards to the Yamaha RX-1 that stated, â€œThe engine brake affect that pushes the rider forward as it decelerates can be over come by changing the front clutch spring. I put in a very light spring in the drive clutch that eliminates this, from Lennonâ€™s Power Equipment (518-773-7175). This did not in any way affect the ride in any other way. Hopefully this will help other riders.â€