It happens on the ground and in the air.

The problem was a reality whenI used the stock muffler. Has never used a pitts muffler on that engine, thats what im gonna do. Off course, that will probably not solve the problem.

I dont think it is loose linkage. The planewho I crashedis anyway gone.The fuel path has been replaced once or more. The needle housing has been checked for dirt many times

Later this winther Im gonna bench-test the engine before I mount it in the cub.

On the engine, the carb is turned 180 degrees from original position, thefuel inlet on the carbis at the opposite side of the needle. The fuel line between the needle and carbis then a bit longer, compared with the original position. Could this be a possible reason?