If it was an Echo you would first set the idle mixture at best speed using a tach and reduce it until the clutch no longer engages with idle speed screw. Then using the tach at set full throttle at max speed and reduce the rpms down by 100 by enriching the mixture.
Note idle mixture usually affect high speed thus this way you set it first; otherwise, you fighting yourself. On single mixture screw you just tune to max rpms minus 100.
The service manual does not cover carb adjustment procedure.