I would do the pinch test. Start your engine, and carefully pinch the fuel line at the carb. The engine should rev up for atleast five seconds before it dies. If it does not rev up and just quits, you are too lean. If it revs longer than 7 or 8 seconds then you are too rich. That will set the low end. After thats set, open it up to full throttle. slowly lean it out until it quits gaining rpm. If it dies, richen it up 2 turns and start again. Once you get the peak rpm, richen it up so till the engine losses 400 rmp, or once you hear the engine change to a lower pitch, make it about a little less than a 1/4 turn richer. That will give you a starting point. Another test you can do it take out your fuel tank and with all the lines attached, put the tank underwater, while keeping the ends of the lines out. Pinch off one line, and blow in the other. Look for bubble coming out of the tank or tank neck. That will show you if you have a sealed tank. I hope this helps.

I forgot to mention, make sure you dont have the clunk and the vent reversed going to the engine. That could cause the problem also.