Check the crank fit. If you are "lucky" it is tight. I have found 2 tight compared to 1 loose. Tight can be fixed! And they took back the loose one and replaced it no problem! I LOVE this engine!!! (own 15 of them! Have only run 9 so far, but generally, the fits work just fine)
Tight - lower rpm, burned plugs, hot running. When you disassemble the engine and clean it totally dry, the crank is still not free in the crankcase.
Loose - wobble in the shaft, blowing fuel out the nose of the engine
Just right - totally clean and dry, spinning the crankshaft in the case will produce a couple or more rotations, and there is no noticeable fuel blowing out the front end when running.
On ONLY the AP Wasp, you can do a conventional lapping procedure on the crankshaft. No other small engine I know of has a bronze bushed shaft bearing! I still polish in my cranks, rather than lapping them.
Lapping an aluminum crankcase will leave grit embedded in the case material, and induce premature wear! Oil-wet sand, polish and then clean the crank outside the case, and then recheck the fit.
I have detailed this procedure elsewhere, and you can find it with a search.