The drop in rpm or quiting after the glow igniter is removed is an indication of a rich engine. An inverted engine will be more likely to have problems in this areaas any liquid fuel that gets into the combustion chamber will drop on the glow plug and extinguish it.

First step is to start with the manual initial settings on both needles. Adjust the high end for maximum RPM then go rich by 300 or so RPM. Now set the throttle to the slowest setting that will keep the engine running. Leave the engine at this setting and then slowly, an 1/8 turn at a time removing the screwdriver after the turn, lean the idle for maximum RPM. Go back now and re adjust the high end again. Back to the low end and repeat. This time, the idle speed should be slower this time.

Now the transition. With the engine running at idle, slam the throttle full on. The engine may blubber and gain RPM (to rich on the idle) or just die (to lean on the idle), or instantly jump to the throttle, just right. Depending on the reaction make your adjustments in baby steps, 1/16th turn at a time and see what the results are. Adjust past the peak so the transition changes from rich to lean or the other way around.Then go back a 16th turn to the good side. If you don't over adjust, you will not know where peak performance is.

I was helping a guy out with his engine a couple weeks back. When I got near the peak, he was pleased and declared the tuning good. Ikept going until it was right and there was a huge difference in response and idle.

Iwouldn't try to run below 2300 rpm on the idle with the inverted engine.And it may be that you need and on-board igniter that kicks in at 3500 or so, but that is a last resort. Try tuning it out first.

Don