The NCY 1500 rpm clutch pulley Compression Spring is specifically designed to prevent belt slip and ensure optimum acceleration for GY6 engines. 

Specifications:

• Wire Diameter: 4.2mm
• Inner Diameter: 48.5mm
• Length: 154.0mm

Compatibility: GY6 engines

139QMB-based 50cc / 80cc engines with the following engine codes:

157QMJ-based 125cc / 150cc / 169cc engines with the following engine codes:

Don't see your engine listed? If the engine code includes "QM" or "FM", this product is compatible with your vehicle.

Mechanic's Notes:

Compression springs (also known as contra springs) do two things. First, they provide lateral pressure on the drive belt to prevent belt slip. Second, they determine the rate at which the CVT transmission changes from lower to higher gear ratios. 

For optimum acceleration, match the clutch pulley transition from lower to higher gear to the peak power of your scooter. 

For example: If your scooter creates peak power at 7500 rpm and your current compression spring is transitioning to fully open at 6000 engine rpm, your acceleration will be slower than optimal. Increasing the stiffness of your compression spring will increase the engine RPM required to achieve the highest gear ratio in this example.

• Stiffer Compression Spring = More Belt Tension & Pressure + Higher RPM transition
• Softer Compression Spring = Less Belt Tension & Pressure + Lower RPM transition

Looking for more performance upgrades? This spring is also available as part of our Stage 1 GY6 150 Performance Kit!

About NCY: NCY is the aftermarket performance parts leader for most popular scooter brands including Honda, Yamaha, Genuine, Vespa, SYM, Lance, KYMCO, and GY6 / QMB powered scooters. Made in Taiwan with strict quality standards since 1997, NCY is ISO 9001 certified.

Made in Taiwan

This product is intended for off-road use only.

This product is not intended for use on public roads or land.

This product is not legal for use in California on pollution-controlled vehicles. Check local laws before installing.

*Performance upgrades are considered racing parts and are not covered by warranty.