Keep in mind that 2-stroke glow engines are compression
ignition types....like diesels. The most effective way to eliminate
pre-ignition and detonation in any engine.... is to #1 retard the
timing, and #2 lower the compression.

The only way to effectively retard the timing in a glow two-stroke
is to lower the compression. But, we shouldn't really have to do that.
The real problem comes from excessive heat. Too much heat in the
combustion chamber....no matter what the cause, or combination
of factors....and the "knocking" noise are a bad thing. []

We can create our own problems with our planes, by taking a perfectly
good engine....eliminating about 90% of the cooling, by wrapping a cowling
around it. Then we put a Pitts muffler on it....and just doubled the heat inside
the cowling.

Now lets put a nice big prop on that baby....a little more heat won't hurt....

And the fuel thing....some motors just like certain types of fuel/nitro/oil combos
and will run completely differently on one type or combo....than another.

The last denominater....the airframe. Not really designed with engine cooling as the
primary factor. Big fat fuse, big fat cowling....big fat wing. Less than great speed/cooling
....and, under heavy engine loads most of the time.

End result....knock, knock....[X(]