it could be two causes for this. One the floats and needles are worn and should be replaced or the possible the drain screws on the side of the carbs are not shutting off. They will drain out the overflows if not tight. Best thing is go to siriusconinc.com and order some carb kits and rebuild. You wil have to order floats seperately if you need them. Order deacceleration valves at the same time. 4 kits will be about $175