It's not transition, it transitions amazing with a 12.25x3.75. I replaced the fuel tubing everywhere, and checked for leaks and found none. I found a different problem, airbubbles in the fuel line. Everytime the bubble hits the carb, it leans out a lot. I tried adding more padding to the fuel thing, but no dice. Air bubbles still keep coming. I really didn't use the right padding. I used regular foam cushion and some carpet madding. Should i get real foam rubber?

The carb on there isn't the actual Webra carb. My engine genius friend i bought it from, took the helicopter stuff off of it and converted it to an airplane engine. He didn't have the original carb, and the carb on it is pretty bootleg, even though its not the problem, i think im gonna go over there tonight and get a different carb, and have him look at my setup.