Well lt face it the OS 91 FX is not up to OS standard, I have try quite a few thing on this engine recommendd by BAX and still doesn't perform the way it should, now mine doesn't quite in flight but being installed in a UCD, I cannot enjoy the airplane since it get lean when I start hovering.....to paraphrase OS answer it's normal that the engines goes lean with extended nose high.....well I guess they really screw up on the other engines that doesn't get lean with hovering ie:my 2 46FX, 50SX, and my 3 140RX....to name a few.

Very disapointed, why should I have to by a K&B needle valve, or a carburator, I did pay over 300.00 cdn for this............engines, I was expecting to bolt it in do some adjustment...and that is it.