103 SPX/RCX (ref: 297231)

DOPPLER is one of the few parts manufacturer to offer this type of product. Like in the good old time of the mopeds races, the central engine spring is an esential option to the variator and the clutch pulley. It offers to adapt the variator's progressiveness to the rpm. It enables to adjust the spring's hardness and to avoid spinning. The engine spring is mounted on a nylon ball joint.