you asked yamaha experts answered

4-stroke logic
Q:What is the reasoning behind leaving the 2-stroke class empty? The Venoms are dying out and many ditch-diggers and mountain guys prefer lighter 2-strokes. - AmSnow.com member norwegian

Yamaha engineers answer: Currently some 2-stroke snowmobiles are lighter than 4-stroke snowmobiles. However, 2006 EPA regulations are approaching. This regulation will make 2 -strokes increase in weight and cost. Yamaha feels lightweight 4-stroke snowmobiles will be the best way to satisfy customers' needs.

Remember, we reduced the weight of the '05 RX-1 by 30 pounds. We've proven this in other markets such as outboard motors, personal watercraft, ATV's and Motocross bikes. When given a choice, the customers are picking 4-strokes.

Q:Why are the snowmobile 4-strokes geared down from the motorcycle versions? Can the clutches not handle spinning at the higher rpm? Why should we lose all that high-end, high-revving punch and power? - AmSnow.com member gerard143

Yamaha engineers answer: The CVT clutch system is most efficient at 9,000 rpm or less. The CVT clutch also reacts better to low-end torque than high rpm hp. So, the gear reduction does two things. First, it lowers the clutch rpm to a more efficient and reliable rpm of 8,500. When clutch rpm goes down, the torque goes up. So the gear reduction increases the torque delivered to the clutch. This provides the most efficient punch and power available using a CVT clutch system.