Dave

I have a 140L that I am having a proplem with. I am running an APC 16x10 prop at about 8500 Rpm. The needle valve is about 2 1/2 turns out and the regulator 1 turn below flush. If the regulator is near flush the transition is much too rich. Usually I can't get it too run rich at the top end even if I about it to 3 turns or more, although the engine will sometimes alternate between really reving up and running slightly rich after running at lower throttle for a while. The main needle valve is very insensitive. It tends to quit in the air If run at about 1/3rd throttle for a few seconds. It idles well but often changes idle speed by the end of the flight.

I changed the regulator plunger,diaphram, gasket - no change.
The tank holds good pressure.
I checked the valve settings.
When warm there is compression, but not great.
I am running S&W 30% low viscosity blend.