Paul:My problem years ago wasn't really the carb, it was the wife. She insisted on starting the dual quad Bird with the accelerator pressed about halfway down. That caused the backfire that ignited the fumes in the air filter and got the inferno started. She did it twice, then insisted I take the quads off. I never had a backfire, just pumped the pedal once and let off the pedal, started right up. Last year the wife decided she could not drive the Bird anymore with her new hip and knee joints, so I put the quads back on.