Hello Congster!

Back in '93 I bought a ASP .61 and installed it in a C.G. Super Chipmunk. Several times I tried to fly the plane , but most of the times it flamed out and resulted in a dead stick landing. Never really investigated why the engine did'nt want to run properly so it ended up a hangar queen untill 2000. My son started to fly pretty well and insisted on taking the Chipmunk with the troublesome ASP. The plug burned out on the first flight and I changed it to a O.S. # 8 . What a difference, it runs like clockwork and is very dependable. ( Although I wished it was a .91 in the plane for more vertical performance.)
Moral of the story: Try a OS # 8 and feel the difference, I'll bet it will run better. Also check the carburetor fit, I replaced the O-Ring where it seats into the crankcase.