Best thing to do is if you think your close, put it in the air and run it full throttle for a minute or two. Pull back to idle and land immediately and shut off engine. ie. no taxing around. Let it cool down and pull the plug. If the center electrode is tan, you're just right. Black means too rich, and white is too lean. Adjust high needle 1/12th turn one way or the other depending on if it's black or white and retest. Don't forget if you adjust the low, this will effect the high speed mixture as well.