OBARK, the idle speed screw is not the "barrel adjuster" up on the throttle. I think you may be referring to that. That is to take the free play out of the throttle. The idle speed screw is usually the larger center screw on the carb. It sticks into the carb right in the middle where the slide is. It actually sets how far the slide can close or move down. The idle mixture screw will be smaller and on the downstream side of the idle speed screw. A good starting point for both screws is typically 1.5-2 turns out. First set the idle speed, then fine tune for max rpm with the mix screw. Then turn the mix screw 1/8 turn back out to richen it a tad more. You may then have to re-adjust the idle speed screw to lower the rpm's back down to where the wheel doesn't turn on the center stand. Once the carb is set you can check the throttle grip for free play and adjust it with the barrel adjusted on the handle bar. The service manual will state the free play. It's usually about 2mm.
