....I sure wish i had the answer to your problem. I
had the .80 in a Cub, and played with it for years
and never could get it to run right. Just like you, I'd
get the high speed set perfectly (just a tad rich) and
get a "happy" idle...and it would NOT transition
properly....most times it would "pop" and die. When
I did get it running half-way decent, and in the air. If I
throttled back, like in a spin....99 times out of 100 it
would die and deadstick.

I tried on board glow...no help. I had a perry occilating
pump on it for awhile, and it seemed to help, till the
bracket broke a couple times from the vibration.
Finally, after about 8 yrs (I'm not kidding, I'm pretty
stubborn) I yanked it out, and put in a new Magnum .91
4-stroke. I loved the plane. PROBLEMS SOLVED ! Same
fuel tank, same fuel lines, everything same.

I haven't touched the adjustments or the plug all year.

Dave.