The problem with advice is most people use the Keihin PWK carb. If it runs better with the choke on, that indicates lean to me. Possibly it is lean on the needle so when you give it throttle, it goes lean and dies. You say you think it fouls the plug. Did you pull the plug and see if it was fouled?
If it is a bike carb, it is set up for gravity feed. It is not so much gravity feed itself that is usually the problem. You won't see the problems with that tank until you start riding it. A bike tank has a low spot where the valve is. When your fuel gets low on that spun aluminum tank, it will slosh back and forth across the hole the fuel goes out of. Some other notes about those tanks, the hole in the tank is often very small compared to the fuel line. You may need to drill out the hole. They don't clean the inside of those tanks so you you don't want to just throw fuel in it and go. They often have aluminum shavings from when they drill the hole. If you didn't run a filter, those shavings will clog the inlet and cause erratic jetting.
