The cone-shaped restrictor in the air horn section is screwed down until the floating indicator rises to about midrange of its travel on one carb, then it's transferred to the other one(s) and the idle speed and screw is adjusted for the same amount of air flow. The see-through tube with the floating ball in it needs to be straight up vertical for the best results. Adjusting the idle mixture screws should have little, if any effect on the air volume, but if it's necessary to make a big change in mixture, double-check the air flow.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!