This 4 Pole Magneto Cylinder applies to (and is not limited to) 50cc 70cc 90cc 110cc and 125cc electric start automatic engines. Most commonly used for 125cc electric start ATVs, dirt bikes and buggies/go-karts. The outside diameter of this cylinder is 11cm and the inside diameter is 8.4cm Overall Height: 58.4mm Center Hole Mount (Tapered): 18.4/14mm