Turn the needle valve in, If the engine starts to die, it is too lean.

Now turn it out until it starts to get a little sloppy (rich).

Now turn it back in and listen to the RPM. It will peak, and as you continue to turn, it will go lean again. back it off to where it had first peaked. Then with someone holding the Tx, and engine at full throttle, hold the plane nose up (straight up), and see if it leans out. If it does, richen it some more, if it doesn't, go flying!