Originally Posted by jaka

Hi!
The carb works like any other two needle carb except this one has an exentric screw that moves the fork (which governs the idle needle) either to the right (leaner) or to the left (richer). You don't have to loosen any screw to adjust the idle ,just turn the idle screw and the fork will move.
This OS carb is a much better carb than the old perry carb.