Minarelli horizontal clutch pulleys d=122mm Top performance

Pulleys clutch d=122mm Top performances for Minarelli horizontal.

Unlike a conventional clutch pulley set, this system integrates a variable profile cam mechanism that allows the engine to remain at its maximum power range constantly, maximizing both acceleration and recovery. The increased diameter of 122mm compared to the standard 107-115mm provides a larger contact surface with the belt and a more effective transmission ratio.

The system is based on two cam profiles with different inclination angles (angle α), selectable by repositioning three anchoring pins. The profile with the greater inclination (higher α angle) is calibrated for medium-low preparation levels, while the profile with the lower inclination optimizes response for high-performance setups. This adjustment allows you to modify the clutch engagement point and adapt the transmission curve to the engine’s specific power map.

The converter is made of high-strength steel with heat treatment, and incorporates needle bearings and sealing O-rings. The kit includes a racing contrast spring with a preload increased by 16% compared to the original, which reduces power loss due to slippage and improves response feel.

Features

• Pulleys diameter: 122mm (increased compared to the standard 107-115mm) for greater transmission capacity and better torque utilization.
• Adjustable cam system: Two interchangeable cam profiles via anchoring pins, allowing you to adapt the inclination angle (α) to the engine’s preparation level.
• Competition-grade materials: Made of high-strength alloy steel with heat treatment to withstand high temperatures and extreme workloads.
• Racing spring included: Contrast spring with +16% preload to reduce slippage and improve instant power transmission.
• Technical compatibility: Specifically designed for Minarelli/Yamaha 50cc Horizontal AC/LC engines (Aerox, Nitro, Booster, Jog R, etc.).
• Technical maintenance: Requires periodic inspection of pins and cam grooves, and replacement of molybdenum disulfide grease every 10,000 km to ensure proper functioning of the cam system.
• Important note: On Booster 2004 models, it is necessary to partially machine the crankcase ribs due to the increased diameter of the pulleys.
• Usage classification: Component designed and approved exclusively for competition use. Not suitable for use on public roads.