65.5mm Cylinder Piston Gasket Top End Rebuild Kit For Chinese ATV Quad Dirt Bike 250cc CG200 CG250. Most commonly used for (but not limited to) 200cc to 250cc engines. 65.5mm piston. 65.5mm Cylindre Piston Gasket Top End Rebuild Kit For Chinese ATV Quad Dirt Bike 250cc CG200 CG250.