Airsal 50mm Big Bore Cylinder Kit for QMB139 50cc Engines. Kit includes cylinder, piston, rings, piston pin, cir clips, and gaskets. Aluminum cylinder construction for better heat dissipation.
When used in conjunction with a stock crankshaft the total displacement comes out to 81.3cc! Your stock head can be reused. High compression piston included! .5mm taller than most standard 50mm big bore kits.