Hi Bax,

I am using a 91 FX in a 90 size patternship in which the engine is mounted inverted.I am using FAI Fuel (20 % castor oil and 80 % Methnol Fuel) with #8 OS plug. The only modification I have made to the engine is this that I have removed the silencer baffle to increase power.

The problems associated with the engine are:

It will never start in inverted position so I have to tilt the aircraft upright to start it each time although ample fuel is supplied to the carb------Why doesn`t it start inverted


When the aircraft is airbourne and upright the engine runs well, however when I do inverted flight ( i.e. engine comes in upright position) the engine leans out and picks about approx 1000-1200 rpm more than when it was running in inverted position and continues to run leaned for about 2-3 minutes even if I revert back to upright flight after that the rpm drops to the original upright flight rpm.

Best Regards,

Khizer