100cc Naraku Racing Big Bore 52mm Cylinder Kit for 50cc 4-Stroke 139QMB ScootersINCLUDES: Cylinder Bore: 52.4mmCylinder Sleeve Outer Diameter: 54.4mm Wrist Pin Diameter: 13mmTotal Piston Height: 36.3mmCompression Height (from center of wrist pin hole to top edge of piston): 20mmNon-emissions style headIntake Valve: 23mmExhaust Valve: 20mmIntake Port Diameter: 20.8mmExhaust Port Diameter: 18.7mmUses Short 64mm Valve Stems COMPATIBILITY: Amigo – 50cc 4-Stroke ScootersApollo – 50cc 4-Stroke ScootersBaotian – 50cc 4-Stroke ScootersBaron – 50cc 4-Stroke ScootersBintelli – 50cc 4-Stroke ScootersBMS – 50cc 4-Stroke ScootersCoolster – 50cc 4-Stroke ScootersCSC – 50cc 4-Stroke ScootersDiamo – 50cc 4-Stroke ScootersFlyscooter – 50cc 4-Stroke ScootersIce Bear – 50cc 4-Stroke ScootersItalica – 50cc 4-Stroke ScootersJCL – 50cc 4-Stroke ScootersJonway – 50cc 4-Stroke ScootersKandi – 50cc 4-Stroke ScootersKinroad – 50cc 4-Stroke ScootersKMD – 50cc 4-Stroke ScootersKymco – 50cc 4-Stroke ScootersLance