I have read about the identical problem from others and I have tried the advice given to them but still the problem persists. Please offer your advice (Graybeard) are anyone else. Follows are the facts:
1. engine is OS FS91 that I have just adquired.
2. engine had not been run in 3 yrs but was kept in after-run oil
3. engine top-end and bottom-end transition running is excellent
4. engine idles great when glow ignitor is on plug
5. once ignitor is removed, the engine runs approx. 10 seconds and dies suddenly without a fade
6. low end needle has been adjusted both ways and no difference
7. hi end needle has been adjusted correctly
8. fuel tank is new but checked out thoroughly
9. 2 new OS "F" plugs have been tried with no effect
10. engine has been run 20 minutes with ignitor installed on plug at varying speeds
11. the fuel used works great on another OS FS91
12. It was suspected that after-run oil was fouling plug since engine is mounted inverted but no longer believe it
13. fuel is 15% wildcat
14. the carb was stuck initially but freed-up
I am beginning to think that the answer is to provide battery power to plug always during flight or possibly carb has debris at least partially fouling carb and it may need cleaning or just perhaps more run time. I appreciate your ideas and advice.....Wayne