#1-You can't leave a Banshee idling, while sitting still for long, as they need air moving through the radiator, to cool them, and #2-it's lean, way lean. That's why it won't shut off. You've either got an air leak, or the wrong jetting. Don't start it, until you fix the problems, unless you want to do a top end rebuild, which you may end up doing anyways.