81cc high performance cylinder kit for 50cc GY6 139QMB scooter engines, by manufacturer NCY
This scooter upgrade kit is a high quality kit that is perfect for upgrading your old 50cc 139QMB engine to 81cc so you don??t get left behind in today??s fast paced world
30 Day Warranty Description

81cc high performance cylinder kit for 50cc GY6 139QMB scooter engines, by manufacturer NCY.
This scooter upgrade kit is a high quality kit that is perfect for upgrading your old 50cc 139QMB engine to 81cc so you don??t get left behind in today??s fast paced world.
Installing this upgrade kit will increase your engine bore size to 81cc, and includes an aluminum cylinder, 50 mm piston, piston rings, and gaskets.
After installation, you will see an immediate increase in low end acceleration and an increase in top speed!
This 81cc scooter cylinder kit does not include the cylinder head. Use this kit with the NCY 50 mm cylinder head which can be found here:
50 mm High Performance Scooter Cylinder Head
Combine this kit with a high performance carburetor and exhaust for an even larger boost in performance. Specifications

Displacement: 81cc
Piston Diameter: 50 mm