Read the directions, the big thing is not to go fiddeling with the needles too much the factory settings are a good place to start. If you mess with the needles too much you will get the main spraybar out of wack and then you will not be happy. There was an article in RCM probably 10 years ago about the correct initial set up. I got a copy and filed it away so far I haven'tr needed it. The high speed is normal unscrew to richen.
The low speed works backwards unscrew to lean and the idle mixture affects the high speed needle, so go back and check it after every idle mixture adjustment.
I have about 5 gallons through mine and love it.
Sparky