hello
at what rpm you have problems???
what is the prop you are using , pitch and diameter??
the engine is good for a sunday flyer plane, I am using gas with no alcohol, no problems with deposits in the carb.
Good starting, my carb have only one needle, High speed; enlarged throath with round file to near 3/8, opposite side to small holes in the venturi.
Using standard timing in the coil.
Happy landings
Jose