half pulley Polini Air Speed Evolution for Piaggio

Half pulley Polini Air Speed Evolution PRE: a pulley as it is also used in the Polini PRE Race engine type.

The advantage of this pulley is in the manufacturing. Pulley and fan wheel are CNC-machined and milled from one piece. So no more plastic fan wheel, therefore allowing extreme durability at maximum acceleration. And also no extra fan wheel, which does not withstand the G-forces or temperatures.

Absolutely tuned for the maximum.

The fan wheel no longer has internal teeth and must be tightened to 50Nm. The flank angle of the belt running surface is 14°. The lack of external gearing for the electric starter is mandatory at this tuning level.