GY6 50cc (139QMB) Scooter 39mm 50cc Cylinder Kit

39mm Cylinder Kit for GY6 50cc Scooters

This 39mm Cylinder Kit serves as a full top-end rebuild solution for 50cc scooters equipped with the 139QMB engine. Ideal for scooters showing signs of oil burning, compression loss, or general wear, this kit provides everything needed for a fresh rebuild. It is one of the straightforward GY6 50cc scooter parts to replace at home.

Complete Kit Components

This kit includes a cylinder, a piston, piston rings, a wrist pin, fasteners, dowel pins, and all necessary gaskets. The stock 39mm bore size makes it a direct replacement for original components, ensuring a simple installation process. The provided gaskets cover the head, base, and intake, so you have all essentials in one package.

Installation and Maintenance

Before installation, ensure that all gasket surfaces are cleaned thoroughly. New gaskets are included to facilitate a proper seal. Following installation, it's advisable to adhere to a break-in period for the initial miles to ensure performance is maintained.

Specifications

• Bore: 39mm
• Displacement: 50cc
• Overall Cylinder Height: 70mm
• Cylinder Sleeve Outer Diameter: 44.7mm
• Engine Type: 4-stroke, air-cooled
• Includes: Cylinder, piston, piston rings, wrist pin, 2 circlips, 2 dowel pins, head gasket, base gasket, intake gasket
• OEM Part Number: 151-257

Fitment

This cylinder kit is compatible with various models of 139QMB and 139QMA engines.

• 139QMB
• 1P39QMB
• YN139QMB
• JJ1P39QMB
• BD1P39QMB
• BN139QMB
• 139QMA
• 1P39QMA-2
• Common scooter brands: Tao Tao, ZNEN, Peace Sports, Icebear, Jonway, Wolf, Baccio, Bintelli, BMS, Schwinn, SunL

Not sure it fits? Contact us with your scooter's make, model and year and we'll confirm the fit before you order.

Shop more: GY6 50cc Scooter Parts (139QMB) · GY6 Scooter Parts · Scooter Big Bore & Cylinder Kits · Scooter Parts