Ill bet its the clutches or a worn belt. If was the fuel it probably wouldnt run good at all even up to 60mph but check that to anyways. Get a new belt and clean the clutches is a good starting point! After that a clutch rebuild would be my next step.
A forum community dedicated to snowmobile owners and enthusiasts. Come join the discussion about performance, racing, troubleshooting, trails, maintenance, riding tips, modifications, classifieds, gear, and more!