NCY 1500 RPM Compression / Contra Spring | GY6 125-200cc CVT

Fine-tune your CVT transmission's shift point and eliminate belt slip with the NCY 1500 RPM Contra / Compression Spring for GY6 engines. Engineered for the rear clutch pulley, this performance spring is a direct upgrade for riders looking to optimize acceleration on 125cc, 150cc, 169cc, and 171cc GY6-based scooters. Key Features Prevents belt slip by increasing lateral pressure on the drive belt Raises CVT shift point for optimized acceleration at higher RPM 1500 RPM rating — stiffer than stock for performance-oriented tuning ISO 9001 certified manufacturing Made in Taiwan Specifications Wire Diameter: 4.2mm Inner Diameter: 48.5mm Length: 154.0mm RPM Rating: 1500 RPM Compatibility Fits 157QMJ-based 125cc / 150cc / 169cc / 171cc GY6 engines with the following engine codes: 157QMJ 161QMK 152QMI 1P61QMK YN1P57QMJ 1P52FMI 154FMI JJ157QMJ 1P57QMJ BN157QMJ BN161QMK-A Other QMJ, QMK & QMI models Mechanic's Notes Compression springs (also called contra springs) serve two functions: they apply lateral pressure on the drive belt to prevent slip, and they control the RPM at which the CVT transitions from lower to higher gear ratios. For optimum acceleration, match the clutch pulley transition RPM to your engine's peak power band. If your engine peaks at 7500 RPM but your spring transitions at 6000 RPM, you're leaving performance on the table. Stiffer Spring = More belt tension + higher RPM transition Softer Spring = Less belt tension + lower RPM transition This spring is also available as part of our Stage 1 GY6 150 Performance Kit . This product is intended for off-road use only. Not intended for use on public roads. Not legal for use in California. California Prop 65 Warning: www.p65warnings.ca.gov