Running my Y 63 yesterday. Could not fly for other reasons. At max RPM I could hear a crackling noise. This indicates to me that I am having <u>predetonation occurring</u>. Engine accelerates well, rapidly. Idles good. Using OS Type F glow plug and Byrons 20/20 fuel. Can anyone confirm detonation and what's the cure? I already replace the diaphragm in the regulator. Original diaphragm would not let me get over ~8,400 RPM and detonation wouldshut the engine down.

I had to replace the gasket between the rear crankcase and the carb set up, it was leaking oil.While in there noted that all was okay, nice and oily indicating good lubrication going on.

Advice please.

Chip