I recently bought a 2007 300ex that supposedly has a 330 kit on it. Can you take off the 330 kit and go to a 76 mm or stock bore and piston? It also smokes real bad on start up and idling, I haven't had a chance to right it around to see if it goes away. Is it possible for a 330 kit to go back to a smaller bore? Does it only require a new top end rebuild or is this bigger than I thought.