Piston Kit - 39mm - 50cc Horizontal Engine Other sizes will not interchange

Other sizes will not interchange with drive sprockets

Measure your old chain to make sure correct chain is ordered

then you most likely need to replace the voltage regulator

669-18-30 [replaces 669-18

Piston Kit - 39mm - 50cc Horizontal Engine Other sizes will not interchangeChinese 39mm Piston Kit for 50cc ATVs, Dirt Bikes and Go Karts. This Chinese 39mm piston kit is the replacement part for many 4 stroke Chinese atvs, dirt bikes and go karts. Does not fit GY6 engines. Piston kits ship complete with piston, piston rings, piston pin and piston clips. Piston kit description: Piston Height: 36mm (1. 417 in) Piston Diameter: 39mm (1. 535 in) Piston Pin Length: 31mm (1. 22 in) Piston Pin Diameter: 13mm (0. 51 in) Set of 5