Ok
Now I have tested my FA-125a CH-Ignitions CDI a bit more with low nitro / low oil fuel. (10% Aerosave + 5% nitro)
Compared to 17% Aerosave / 15% nitro the max rpm seems to be very closed the same. Maybe 50rpm less with the low oil /low nitro fuel. The engine temperature were no problem (max temp i was able to measure with an IR gun was about 115deg celsius after prolonged full throttle. That was closed to the park plug at the rear of the engine. Outside temperature was pretty cold about 7 deg celsius, though.)
Timing set at 30,5 degrees BTDC.
In order to achieve smooth low idle I played with various LS needle settings. I tried both richening and leaning the LS needle with very,very small increments (like 2 minutes at a time) up to about 3/4 to rich and 1/4 turns to lean. No help, nada. The engine seems to have rough idle no matter what I try. This is confusing. I did not have time to test my regular Saito fuel (17% Aerosave / 15% nitro) which seemed to produce a lot smoother idle when I tried the CDI for the first time.
I'm not giving up yet but it seems new ideas to test are needed
The fuel can be, of course, bad but I remember having tested the same jug on my Lasers about 3-4 weeks ago without any issues so this is not avery probable scenario. I also keep my fuel at a steady ambient temperature.
Please find a link on a video. As you can hear from the video the LS is set so lean that the engine rpm doesn't drop instantly to low idle when backing from full throttle. Yet the engine stumbles and misses beats when idleing. The idle rpm also fluctuates. I really appreciate if anybody has good ideas as to what to try next!
https://www.youtube.com/watch?v=FhV9daOPEBs
-Artto