Most carbs run at a basic setting of one turn out on both screws, fine tuning would be done from there, the L screw will adjust the mixture from idle, through acceleration to half revs, the H screw will adjust the mixture from half revs to full throttle. Both screws are fuel, not air screws, so screw in to lean the mixture and out to richen. Always start with the L screw, this should be adjusted to get solid idle and crisp acceleration, if it trys to stall increase the mixture a little at a time until the desired running is achieved, the H screw will increase the max rpm so be aware if it revs beyond factory spec it could easiley seize, max rpm should be checked with a taco.
Husqvarna man, February 2010
