I ran a 1S for more than a season. All of the Axial engines I've had needed to run rich. They wanted to be in the 220F range. I ran 20% as well. Check and seal the engine for air leaks. The carb is fine. I actually changed the carb on a Werks .28 to this carb and it tears.... Some locals said that the o-ring for the high speed wore out fast and the needle would move. I never had that problem.