GY6 50cc (139QMB) Final Gear - 52 Tooth (Long Case)

GY6 50cc Final Gear for QMB139 Engines

This final drive gear is made for GY6 50cc scooters and works with both short case and long case engines. You can pick between two tooth counts, 51 or 52, to match your engine. Like other GY6 50cc scooter parts, it forms part of the scooter's drivetrain and helps move power through the transmission. If the splines look worn or the scooter slips under load, swapping out this gear will help restore proper performance.

Teeth: 52, for long case engines (51 tooth is the short case gear)

Function of This Part

The final drive gear sends power along the transmission to the rear wheel. Grinding sounds or slipping are common signs that it has worn and needs replacing.

Specifications

• Number of Splines: 19
• Inner Diameter: 18mm (peak to peak)
• Thickness: 15.7mm
• Fits: GY6 50cc (QMB139) engines with a long case, 52-tooth final gear

Compatibility

Compatible with:

• QMB139 50cc/49cc engines (long case, 52 tooth)
• Various unlisted makes and models with QMB139 engines (long case)

How to choose: Only install the 52 tooth gear in a long case QMB139 engine. Short case engines take the 51 tooth gear. Confirm the gear has 19 splines and an 18mm inner diameter.

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