Your floats are stuck/leaking. What caused it is age (but I doubt that as I've rode on motorcycles with 30+ year old needle valves) or crap getting sucked through your carbs. Most likely, it was crap getting sucked through your carbs. You need to install an in-line fuel filter and keep it changed/fresh/clean before running the bike again. This will severely lessen the chances of this happening again. Believe me, it's worth it when you rebuild your carbs and the damn things start leaking out of the overflow because a small flake of rust in the tank broke loose and held the float stuck open, requiring you take them off and take them apart, AGAIN.
