SSP-G 50cc QMB139 4-stroke 50mm, Racing Big Bore Cylinder Set. Kit includes cylinder, piston, rings, piston pin, cir clips, head gasket, and base gasket.

Performance items are not returnable.

We recommend that you use our QMB139 performance cylinder head (see Related Items) with this set as some stock cylinder heads will not fit. Use with an un-modified stock head can cause serious engine damage.

*You may need to modify your engine case to accommodate the larger cylinder.

• Upgrades to 80cc
• Cylinder Bore: 50mm
• Cylinder Sleeve Outer Diameter: 54.9mm 
• Wrist Pin Diameter: 13mm
• Total Piston Height: 34.8mm
• Compression Height (from center of wrist pin hole to top edge of piston): 18.3mm