RE: OSFxi 46
First off, make sure you have a new glow plug and are using good-quality, fresh fuel. Make sure your fuel system in clean and has no leaks anywhere.
To begin, set the idle mixture to be very rich. Make sure the high-speed needle is opened about 2-1/2 to 3 turns out from closed. Start the engine at part throttle and then advance it to full. It should be running at full throttle, but very rich. Some fuel may spit out of the carb. That would be normal for a very-rich setting. With the battery still connected to the glow plug, start to lean the high-speed needle so that the engine will advance in RPM. It should do that.
If the engine has been properly broken-in, it should be able to accept the needle and allow you to lean it to peak RPM. If the engine will sustain running at peak RPM, then you can remove the glow plug battery and start to find the idle.
Gradually retard the throttle and adjust the low-speed mixture as needed to keep the engine running well. Since you know it started out very rich, you know it needs to be leaned. Lean a little at a time.......retard the throttle a bit, adjust as needed....do it again, and again until you find the idle RPM and mixture that will give you a good idle and a good acceleration. You can get a very low idle, but it may also not allow you to have a good acceleration. That's too low. Accept a bit more RPM so that you can have good throttle transition.