power valve benefits
Amsnow
Cleaner & Quieter
With the movement now performed by a computer-controlled servomotor, the tuning possibilities are expanded. Yamaha even included a "self-cleaning" feature where the valve is cycled through a program to prevent carbon build-up. As the snowmobile two stroke engine is made cleaner and quieter, the power valve will be an important part under continuous development. Arctic introduced a two stage slide valve to permit a more gradual opening.
The original Yamaha rotary valve allows gradual linear opening and has been resurrected in road racing. Kenny Roberts started using it again on his Proton road racers, claiming that it gave smoother performance at part throttle and that it was more tractable than a slide plate that was either there or suddenly gone.
Computer controlled valves with gradual opening that moves up the wall instead of back out of the way will most likely show up in future emissions controlled two strokes. This will not only enhance performance, but also secure the future of the light and powerful two stroke engines.