run25duck

Stall problem, can anybody tell me how to fix this. I have a 2-year old Fazer 600. Daily commute takes me five miles on local roads, then fifteen miles on motorway, then, after five or ten miles in London traffic it starts miss-firing, stalls and/or needs loads of revs to get away from lights. Have found that if i stop, turn off and restart, then the problem goes away, and the engine runs normally. But this doesn't happen every time.