ORIGINAL: mikenlapaz
Is the engine installed upright or inverted? Can you fuel it and turn it inverted before starting to see if engine /carb aspect has any affect? (Like in a sling with restraints)
It is mounted inverted with a Mueller wrap-around header into a cannister muffler inside the fuse. The next thing I am going to try is swapping the exhaust a for a pitts style muffler to see if by chance my exhaust setup could somehow be causing this issue.