the best bike shops to take it to with jetting/carburation/compression problems are the people who deal with classic 2 strokes (RDs, TZs, KR1s etc...) as they know how a 2 stroke works (most bike shops don't). as for transmission it's got to be a scooter shop really, you get your average R1 mechanic look at it and he'll scratch his head, take it apart, put it back together the wrong way round, say there's nothing wrong, charge you £60 for the pleasure and before you know it you'll be riding the thing backwards out of the shop.
Yeah and watch out for those garages that like to add about £20 more to each of the parts (like an exhaust for example) there annoying, then you charge you labour on top!