Hilliard Extreme-Duty clutches are ideal for the everyday demands of go-karts and youth-model snowmobiles. Thermodynamically designed clutch shoe increases the clutch's capacity to absorb heat without damaging the clutch springs, thereby providing a longer service life, even in the most demanding applications. For use with engines up to 8 HP. USA. Application: Sprocket, Chain Type: #35, Bore Diameter (in.): 3/4, Teeth (qty.): 12, Engine: Up to 8 HP, Engagement Speed (RPM): 2,300, Max. Operating Speed (RPM): 5,000, Keyway (in.): 3/16, Overload Protection: Yes