Hello, I have a Sanyang flash bj.2001, 50ccm, end speed 60km/h . km was 26.300 After a drive over a road that went up a little mountain, I stood at the traffic light and I noticed that the scooter stuttered a little while empty, when driving it is then very slowly hit to 25km/h , from 25km/h he went off again ! I go to 90% of that the clutch is down, what do you mean ? Is there often a cost-effective solution or repair of the Kuppl ung or etc. ? thank you. mfg.