@bullpen. Been ages since this topic came up! I can't remember exactly what the issue was, but according to the Stockholm Köpenscooter mechanic it was that the factory had installed the incorrect gear on the bike. They ordered a replacement part which took weeks to arrive and after that I was back up to speed - max 54-55kph though if I recall. AND THEN one year later....... the bike was stolen by some scumbags from Jakobsberg Centrum. Was found trashed in nearby woods the day after. Bought another Kymco, believe it or not! (Sucker for punishment!) It's a Like 50 and no issues at all, goes great and maxes out around 60kph.
Did you buy from Köpenscooter (Mipecorp)? They should definitely be able to fix it for you, most likely the same issue I had.
