16 horse vanguard black adjustment knob

[garrett1308]

Just swapped a 16 horse vanguard onto my max. As I was cleaning the carburetor, I noticed a small black knob on protruding from the side of the carb ( same side as the pull rope). It turns about 90 degrees. What is it?

[msafi65]

Idle air fuel adjustment cap. It's set at factory and capped with the limit only adjustable a small amount. Most run best at the stop turned counterclockwise.

[Countyboy]

Just cleaned my carb on 16hp Briggs. Played with the throttle adjustment for a while to get it to idle low enough so it wouldn't grind when switching gears. Finally decided to try that black adjustment knob and after a few settings found that full counter clockwise my machine runs like a top. Can get it to idle super low rpm now.