primary transmission washer for DERBI DERBI 50cc and 125cc

Here the spacer replacement primary transmission DERBI Euro 1, 2, 3 50cc and 125cc. Sometimes the gearbox locks. The symptom is that the bike stalls stop eg while you gear. In this case the puck is concerned, it tends to heat if the box drains are not well done. If the problem persists not recommend changing the complete transmission. The size of this room is 17x30x3,5mm. This spacer is located behind the primary transmission.