The contrast spring of the rear idler pulley is of considerable importance for adapting the variator to the power increase at the highest requirements.

Following the installation of conversions with high torque and power values, it can happen that the drive belt slips on the pulley or the rear idler pulley does not match the movement of the unit pulley mounted on the crankshaft. In these cases, it may be advantageous to provide the rear idler pulley with a higher spring pressure; the two springs manufactured have a higher spring pressure than the standard spring:

10% BLUE (Maxiscooter)
7% WHITE (Scooter 50)
15% BLUE (Scooter 50)
In any case, we point out that the springs with higher pressure should only be installed when really necessary; the best performance is always achieved by using the spring with the lowest pressure that allows the transmission of power. Higher pressure springs tend to wrap around the belt between the pulleys, increasing belt wear and reducing transmission efficiency. Before replacing the spring, check the wear of the belt and the proper functioning of the variator.