50cc QMB139 4-stroke 50mm, Non Emissions Cylinder Head with 64mm Valves for use with 81.3cc Big Bore Kit! (See Related Items)*You may need to modify your engine case to accommodate the larger cylinder. For Use With 81.3cc Big Bore KitValve Length: 64mmOverall Height: 59.5mmIntake Port Diameter: 18mmExhaust Port Diameter: 17mmIntake Bolt Hole Spacing: 44.5mmExhaust Bolt Hole Spacing: 50mm
