How do I adjust the throttle on my Briggs 28N707 motor? ?

Could be many things, start with the throttle cable first, does it move at the carb end when you open the lever on the dash, is the cable clamp tight on the cable against the control plate, when you move the lever on the dash is the carb control lever moving fully on the carb, if the answer to these questions are yes, i think this is now a dealer job, playing around with carb linkages and increaseing engine revs beyond factory spec will end in failure.

Husqvarna man
May 2010