When the scooter is driving, there is a knocking sound behind the shaking road surface, and sometimes the throttle and throttle will be loose.

Pritzker (inside the front pulley) is excessively worn because the displacement of the pulley (that is, speed change) depends on the position of Pritzker, and its guide rail is steeper and steeper from the inside out. When the engine speed changes, due to its different wear conditions, small wear has great ability to overcome centrifugal force. When it is thrown out first and in close contact with the pressure plate, it will not make a sound or make a small sound, while large wear cannot be thrown out at the same time. In the process of throwing, there will be a sound when touching the pulley or the pressure plate, because there is a time difference between it and the one that is not worn when throwing. This sound makes you very unhappy, hehe, so: open the pulley and check the wear of Polybead. If it's not serious, just apply proper grease. If it is serious, replace it with a new cornucopia, the weight is 16, 18 g and so on. Hehehe, I hope she won't bother you again.