Polini performance CVT torque spring for the Yamaha Zuma 50 and Minarelli-based 50cc scooters. Runs 15% stiffer than stock, applying constant lateral pressure against the rear pulley sheaves to keep the drive belt loaded within the optimal powerband. Eliminates mid-range transmission lag, sharpens throttle response, and improves back-shift response on deceleration. Made in Italy.
Off-road use only. Not intended for use on public roads or land. Performance upgrades are considered racing parts and are not covered by warranty.
Tuning note: A stiffer torque spring alters CVT balance. If the transmission stays in a low ratio too long or over-revs, increase roller weight slightly to counterbalance the new spring rate.
Installation tip: The rear clutch pulley is under heavy internal tension. Always use a dedicated clutch compressor tool when loosening the retaining nut.
California Prop 65 Warning: www.p65warnings.ca.gov
