Every new flying session, you should always do the following the first time you fire up any engine.

As soon as the engine is running, and you've pulled the glowplug wire, and you're opened the throttle to full, you should open up the needle valve until the engine runs 4cycle. Then turn the needle back to find your high speed setting.

By always taking the engine to a 4cycle, you insure that you never run that first flight too lean. You're just taking it to a 4cycle for insurance, and you're going to set the needle right away to the good flying setting, but you're insuring that you find that flying setting from the safe direction, rich.

Those old hard piston/sleeve engines need the insurance. They're prone to damage if run too lean, especially on the first flight of the day.