Upgrade or replace the primary transmission on your Yamaha Zuma 4T 50cc with this Polini Primary Gear Set (202.1406). Includes a 16-tooth helical-cut primary drive shaft and a 51-tooth spur-cut crown wheel with a splined bore, both in polished and phosphate-finished high-strength steel alloy.
The Z=16/51 ratio replaces the stock factory primary gears and allows the engine to pull taller gearing for increased top speed once sufficient power is available. Precision-machined to tighter tolerances than standard OEM parts for improved durability and smoother engagement.
