Honda-Kymco-Peugeot Polini clutch spring

The hardness of the clutch spring determines whether the mechanism opens the clutch to engage with the bell at higher or lower engine revolutions.

A stiffer spring will make the clutch "engage" at higher revolutions and, as a result, the motorcycle will take off faster from a standstill and you will notice better acceleration. In other words, a soft spring is like starting in "second gear", while with the stiff spring it is like starting in "first gear". 

Attention!! when making your choice, because if it is too stiff, you will need more power and more RPM to start from a standstill.

When changing the spring, the variator must be readjusted.

White Spring---15% stiffer
Blue Spring---30% stiffer