This is the perfect kit for a rebuild or you can upgrade your 125cc to a 150cc. Chinese Scooter Parts Engine Rebuild Kit for The GY6 150cc Chinese Scooters Fits the 157QMJ Engines with the EGR Head, 76mm Bolt Pattern 2 1/2" Tall Head Kit comes with Complete EGR Cylinder Head with Valves already assembled Cylinder Kit 57mm Bore (stock 150cc) Piston Kit with Rings, Wrist Pin, & Cir Clips New Intake & Exhaust Studs, Roller Weights Engine Gasket Set as Pictured Noteļ¼This kit is the 76mm Bolt Pattern Cylinder & Head, Will not Fit the 80mm Bolt Pattern