Universal 50cc QMB139 50mm Big Bore Cylinder Kit- Upgrades to 81.3cc
Universal 50mm Big Bore Cylinder Kit for 50cc 4-stroke QMB139 engines.
Upgrades to 81.3cc based on a stock stroke of 41.4mm!
Kit includes cylinder, piston, rings, piston pin, cir clips, head gasket, and base gasket.
*You may need to modify your engine case to accommodate the larger cylinder.