Just an observation on all of this, particularly regarding mechanics that always jump to the assumption that "it must be the carbs." Truth is, it usually is NOT the carbs, and, assuming the bike was running well before it starts abruptly running poorly, or runs well under some conditions but not others it is almost NEVER the carbs and is almost ALWAYS electrical. Still, so many shops assume it is the carbs; then they tinker with them and you can only pray that they don't screw them up. If your mechanic does not check out (and thus rule out) the electrics FIRST then I think it is problematic just how good a mechanic he is.
Take care,
Monte
