With the O.S. Max .61 RF-P engine, we usually prop it so that it will turn in the high 11,000's at full throttle when leaned to peak.

With the pumped engine, we NEVER open the needle more than 1-1/4 turns out from closed. It will be too rich otherwise. Since you have the non-ringed version, advance the throttle to full and then immediately lean the engine so that it is running in "2-cycle" mode. Running it too rich will damage it and not allow it to break in properly.

Once the engine is run-in enough to lean to peak, you want to lean the engine as far as possible without detonation or RPM drop and leave the needle there. DO NOT lean to peak and richen it.

You should have no problems with your 80:20 fuel. Because you have no nitro, you may want to make sure you're using an O.S. #8 plug or even the #a# plug, which is a little hotter than the #8.

You may wish to examine the O.S. FAQ pages:

http://www.osengines.com/faq/index.html