Am in the process of buying an 85' Vulcan 700 from a buddy who doesn't have time to work on it. He bought it as a project & is now passing it on to me. Bike starts, but you have to hold the choke. If you let go of the choke, the bike dies. & If the bike idles by itself, when you roll the throttle, it just shuts off. Is this just a simple problem where if you take the carb off & replace it, all will be well? Or is it something more? Any advice will help guys, thanks!