Rovira Motorcycle Branded 63mm Big Bore COMBO Kit for the GY6 150cc 157QMJ engines. BORING OF THE ENGINE CASE IS REQUIRED.Also this kit will not fit any go kart, or ATV regardless if it has a GY6 in it. Cylinder, Piston, Piston Rings, Piston Clips, Rod and Gaskets. 63mm Taiwan Made Valve Head. Includes Gaskets, Studs, Bolts, Spark Plug. MADE IN TAIWAN BY SHENGEE.