not to be negative or jump to conclusions but that sound identical to my bike. i was sitting a light after riding for a while in 1st with the clutch in and all of a sudden that tapping noise started, your could be diff than mine but it never happened when the bike was cold i thought it was loose hardware but couldnt find anything loose or missing...ended up being the tranny....99 gsxr 750 paying around 2 gs to fix