GY6 50cc (139QMB) Adjustable Drive Sheave (Premium)

Adjustable Drive Sheave for 50cc CSC Scooters

This adjustable drive sheave is made for 50cc scooters that use the 139QMB engine. It can raise acceleration and push up top speed, so it suits riders who want more performance from their scooter. It is one of the GY6 50cc scooter parts you can fit yourself at home, and it offers a clear gain in both speed and torque delivery.

Performance Benefits

The drive sheave uses slots arranged in a more linear layout, which helps move torque from the engine to the wheels more effectively. Better power transfer means quicker acceleration and a higher overall top speed. Riders should notice a more responsive scooter, particularly when riding around town.

Installation Details

The kit arrives complete with the rear pulley, bearings and nut, so it is ready to fit as soon as you open the box. When installing on a CSC go model, you will need clutch slider pins for the part to fit correctly. Have the right tools on hand and follow standard installation steps to get the best result.

Specifications

• Outer Diameter: 118.7mm
• Inner Diameter: 33.5mm
• Includes: rear pulley, bearings, nut
• Fits: GY6 50cc 139QMB engines: CSC Bella Classic 50, CSC go, CSC go MAX, CSC Nitro Sport 50, CSC Pug 50

Fitment

Compatible with:

• CSC Bella Classic 50
• CSC go (requires CSC clutch slider pins)
• CSC go MAX (requires CSC clutch slider pins)
• CSC Nitro Sport 50
• CSC Pug 50
• 139QMB-based 50cc / 80cc engines (engine codes 139QMA, 139QMB, 1P39QMB, 1P39QMA-2, YN139QMB, JJ1P39QMB, 139FMA-2, BD1P39QMB, BN139QMB, 147QMD) and other QMA and QMB models
• Any engine whose code includes "QM" or "FM"

How to choose: Compare your engine code with the list: 139QMB, 1P39QMB, YN139QMB, BN139QMB and similar codes, or any code that contains "QM" or "FM".

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