Put a shee petcock on it, with a fuel filter and always shut fule of after riding. God knows what there putting in gas these days..i had a similar problem with a little sled i had and it sat for a while with fuel in the carb and well my float wasnt a float any more it was a sinker.. also it can work both ways by not getting enough fuel. Carbs should be cleaned often because any little tiny particle that sneaks past the petcock can clog things and make things stick. (I myself use a fuel filter on everything.there pretty cheap)' go with a shee petcock. And like someone said before take float off and hold it under water if any bubbles,,,,replace. Make sure float is set correctly...has it been sitting for a while before this started to happen??? Someone should sticky shut off fuel after riding!!!!! And whenever cleaning carb check the floats, i can't imagine how many headaches this would save..