Tuning an engine is an art form. It's kind of like tuning a guitar. You have to listen for the changes and react accordingly. Generally on small OS engines, like you have, turn the needle all the way in until it seats carfull not to put any undo torque on it that would mar the needle seat or needle. Then turn the needle out 2 turns. The "fp" engines have "air bleed" carburetors so you will see the idle adjustment screw going horizontal accross the front of the carb body and a pin sized hole in the center of the carb body. That screw restricts airflow through that hole. The starting point for this is to have the end of the screw obstruct half of that hole so adjust that screw to that point. Select a prop apropriate for your engine otherwise tuning will be more difficult or even impossible. You are now ready to start the engine!

Allow the engine to run to temperature at these settings vary the throttle to keep it running. You may have to leave the glow ignighter on to keep it running. After the engine is warmed up (about one minute running) open up the throttle to full and listen to the engine. It should sound kind of "four strokey" with an occasional pop and burble of unburnt fuel as well as a smokey sloppy mess exiting the exaust. Turn the high speed needle (HSN) in to lean the mixture just a few clicks at a time giving 5-10 seconds for the engine to react to the changes untill you get to a "two strokey" sound. You know, like a dirt bike You should still have a good smoke trail but not so much oily goo exiting the exhaust. This is now a safe setting. You can fine tune this by ear or tachometer. Slowly a click or maybey two at a time lean it listening to the engine speed. when you get to the point it wont go any faster or has even slowed a little go back to the richest setting that gave the highest speed. Then turn it open 2-3 clicks more. The speed will drop some but you will get that back in the air. If you take it all now it will burn up you engine in the air.

For the low speed you may be fine right where it is at. Allow the engine to idle and listen for the "pops and burbles" of being too rich or that smooth "two strokey" sound. Do not try to make this adjustment while the engine is running. stop the engine prior to any changes to this idle screw. If you have that "four strokey pop and burble" then you unscrew that screw just a touch to allow more air into the idle mixture. If it's already smooth and two strokey, then it's probably just fine but you can close that screw a little untill you get the rich setting then back it back off so it just goes into the propper two stroke setting.

This is how I tune my engines. It has worked for every engine I have ever used and I have never burnt up an engine by going too lean. With engines I am unfamiliar with I look up the factory needle settings as a reference and then use my own technique here to tune it in. As a note, remember the idle screw on these airbleed engines lean when you unscrew them and richen when you screw them in. This is OPOSITE of how a dual needle carburetor works. Good luck.