Originally Posted by
AeroFinn
Yes, it sounds strange. I think no conclusive results was achieved in my testing as the engine was under running-in phase. I will test the engine with 10% Aerosave and 5% nitro.
By the way, I don't get why the piston / liners would suffer of the lower oil content if YS CDI and Evolution radials are happy with 6-9% oil. The non-bushed connection rod may be an issue, I dunno. It's funny to read that some have had problems related to connecting rod failures with 20% oil in the fuel for some reason? Maybe due to a too tight fit of a connecting rod & crankpin in conjunction with failure to carry out running-in phase properly?
Anyways, I'm leaning towards thinking that the main thing is ensure the engine gets good cooling, i.e. a proper baffking arrangement s applied or the engine is exposed open to airflow without cowling.
It' seems the "old school" approach is to partly compensate inadequate cooling by having excess amount of oil in the fuel which is then thrown out of the exhaust to cool down the otherwise too hot running engine.
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