Well, a broken ring won't cause plug fouling on a two-stroke, but it will destroy the cylinder. I doubt that is the problem. It sounds like either the float is sticking, or you have blown a crank seal. Try pulling the plug out, hold the throttle wide open and the kill switch on (to prevent a spark from igniting the gas fumes:eek: ), then kick the bike through about a dozen times to clean it out. Install a new plug and see how it runs.