the reason i replaced the carb was because the clamp over that elbow from the intake was busted and couldnt clamp on at all. i bought a 17mm perf. carb and then it ran really hard with the old air filter on. i took it off and it ran much better so i bought a performance air filter as well. i ordered a new petcock but i dont know that it is the problem. i pushed in the primer and gas is definately getting to the carb.