RE: Evolution 1.00 vs OS 91 FX
DS,
Fuel running out of the carb is generally due to siphoning from the tank. The carb is below tank level. You shut off the engine and the line to the tank is full of fuel and starts downhill. I've seen a tank get emptied completely more than once. Some put a tee in the line with a fuel dot at the high point then unplug it after flying. Some use a hemostat on the line if you can get to it.
Sometimes inverted engines are hard to start because all of the oil in the cylinder pools right on top of the glow plug.