it's a 2stroke thing. it is done at wide open throttle.

Once the engine warms up, pinch the fuel line going to the carb. Listen to the engine. If it revs up more (higher pitch) you are rich. Adjust the needle. Give it time to settle on the new position, and repeat the proceedure.
Once you get to where the engine does not rev up more, you are at peak rpm. DO NOT FLY at this setting. Richen it up a few clicks You have to account for the uloading in the air. If you fly with this setting you will lean out in the air and possible over heat.
I alway leave it plenty rich (3-5 clicks) just to make sure it gets the oil and stay cool.