Eliminate belt slip and improve throttle response with the Naraku Machined Variator Drive Face. Engineered specifically for the 50cc QMB139 (GY6) engine platform, this high-performance component is the definitive upgrade for riders seeking smoother power delivery and increased drivetrain reliability. Unlike standard cast faces, this Naraku unit is precision-machined to ensure a perfectly flat contact surface, maximizing belt grip and efficiency throughout the entire RPM range.
This drive face is a performance upgrade for the 139QMB / QMB139 engine family found in:
Mechanic's Note: The drive face is the outer half of your transmission's "pulley" system.
Pro Tip: Over time, the stock face develops "grooves" from the belt that kill your top speed. Replacing it with this Naraku unit restores your original gear ratio transitions.
nstallation Hack: This face does NOT include the kick start gear or fan—make sure to swap those over from your old unit or grab a fresh Kick Start Claw if yours is worn!
SKU: 137-29 MPN: NK900.59 Vendor: Naraku
