Universal Parts 117-12 Type-2 Clutch with Keyed Slot for 47cc Engines Clutch Shoes w/ Keyed Slot for 47/49cc Pocket bikes and Pocket ATVs. These clutch shoes are commonly found on 47/49cc reed valve engines. Outer Diameter: 75mm Inner Diameter (tapered): 12mm to 14mm Width: 16.75mm