GY6 50cc (139QMB) 81cc 50mm Big Bore Gasket Kit

81cc Big Bore Gasket Kit for GY6 50cc Engines

This gasket set is made for 50mm bore kits fitted to GY6 139QMB and 139QMA 50cc scooter engines. Moving to a 50mm bore raises the displacement to roughly 81cc, so this kit suits anyone replacing gaskets during a rebuild or repair. It is one of the GY6 50cc scooter parts that helps maintain a proper seal and dependable running in your engine.

What Is Included

The set contains a coated head gasket to hold combustion pressure in place, giving the engine a sound seal. A paper base gasket is also supplied to form a snug join between the cylinder and the crankcase. Rounding out the kit is an intake gasket, which fits between the intake manifold and the cylinder head to keep airflow steady.

Fitting Tips

Before installing, wipe down every mating surface so it is clean. The gaskets are generally meant to go on dry, and the head nuts should be tightened evenly in a cross pattern to the specified torque. Doing this helps each gasket seat properly and keeps the seal intact.

Specifications

• Bore Size: 50mm
• Displacement: 81cc (with 139QMB stroke)
• Includes: Head gasket, cylinder base gasket, intake manifold gasket
• Engine: GY6 139QMB / 139QMA 50cc 4-stroke
• Fits: GY6 139QMB / 139QMA 50cc 4-stroke engines with a 50mm big bore kit (81cc)

Fitment

Fits:

• GY6 139QMB / 139QMA 50cc 4-stroke engine (with 50mm bore, 81cc big bore kit)

How to choose: Check that your cylinder bore measures 50mm. This set will not fit the stock 39mm bore or kits of 52mm and above.

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