I have a new GMS 40 I am getting ready to break-in. While examining the carb and the manufacturer's manual I have a few questions.

The diagram of the carb shows 3 adjustment screws, High Speed(function obvious), Idle needle, and throttle stop screw.

The instructions indicate to adjust the idle stop screw "to approximately the diameter of a pin" when the throttle is closed. Are they refering to the gap between the idle needle and the spray bar?

I removed the Throttle adjusting screw and removed the carburetor rotor. As far as I can see, this screw seats into the groove on the rotor but I really can't understand it's purpose other than to guide the rotor to move in and out as the throttle arm is moved.

Any insight or advice is greatly appreciated

The reference is to the size of the carburetor opening when you close the throttle to the idle position. You want about a 3mm gap between the needle and the nozzle when the carb's open to full throttle. That sets a rich idle mixture which you will lean once you have the high-speed mixture set.

If you close the barrel all the way, and adjust that screw in....it will open the
barrel to an idle position (to a diameter of a pin) or so. However, if you want to
be able to shut the engine off using the throttle trim on the radio (which is the
normal procedure) you must back that screw out until the barrel closes completely
or the engine won't shut off.

FBD.

Baxter and Dave

Thanks Guys