hi mate,
washer or spacer is typical for aftermarket tuning variators.....example: malossi got it...coz im using it...
u can see that belt is in wrong position when ur twist throttle with open case.....
another way is to see where is ending screw with original variator - its gonna be same place as aftermarket...need to be....plates are the same size and belt is 30 degrees....
so if u miss washer, belt will overheat and snap....