ORIGINAL: DaveB
I agree, your engine sounds a little rich and is running in the 4 cycle mode when less than full throttle. When I set my high speed needle valve, I will lean it to maximum and then back off an 1/8 of a turn or a little more, after the engine is broken in of course.
DaveB
When you say back it off....do you mean you will lean it further 1/8th of a turn....or richen 1/8th of a turn? This only happens between 1/2 throttle and 3/4 throttle.