Originally Posted by
mk13
but is it surprising that I am one of the only guys to have this problem?
The microbubbles I see in nearly all my engines. But I don't see them agglomerating into big bubbles.
If the solenoid is making hard contact with the housing, then that should be OK, especially if you used lubricant (oil is as good as vaseline, heck, a drop of spit would do the job).
Originally Posted by
mk13
I use the fuel of my lawn mower, 95E10 + 10% synthetic 2-stroke oil (I think this fuel is 3 months old)
The fuel should be OK, I use 95E10 as well, and my fuel jug (11 litres when mixed) easily lasts for one year or more without causing any problems, so 3 months old fuel should most definitely be OK.
I am a bit stomped here, and all I can think is to see what happens if you put a bit of fuel into an open jar for 30 minutes before filling your plane with it, just as an experiment to see whether the evaporation of the most volatile components does reduce the problem.
Meanwhile, keep working on the fuel curve, get the engine as lean as possible in the midrange. Leaner running reduces vibration.
Remember: as long as ignition timing is set properly (28 deg before TDC), it is near impossible to damage the engine with a lean run: It is not a glow engine anymore, and gassers simply stop when too lean.