I have been having carb problems with my 98 WR 400: Initially the bike was cutting-out so I cleaned the carbs, then I took it to a dealer and he found that the slide plate had broken. The dealer replaced the slide plate but now I have a flat spot at the start of the throttle and the bike backfires when I shut it off. From reading other posts I guess that this is down to the air/fuel mixture but I am unsure how to adjust this (so was the dealer?). Could any of you guys or gals give me an idiots guide. I am not sure which screw is the air/fuel mix either. Any help greatly appreciated.