The high and low screws are almost always fuel, not air screws, basic settings would start at one complete turn on each, and fine tune from there, the low screw will adjust the amount of fuel fed to the engine at idle and up to half throttle, the high screw will adjust max rpm, try to find out the manufacturers max free running rpm, and set this with a engine taco, if the engine is sluggish to pick up increase the low screw a little at a time until it picks up smoothly.
Husqvarna man, December 2009
