I'm completely new to gas engines. I have always flown glow so here's my problem. How do you adjust the idle RPM. I have a DA-50 with a bolly 22x10 for break in. There is not a idle stop screw and when I close the throttle arm all the way It still Idles at 2200 to 2300 rpm.I can't get it any lower and I would like it to be 1700rpm or so. I have not touched the mixture screws they are factory set.

Thanks

Firstly, you must always adjust the mixture screws on a new gasser. They are not "factory set" but rather set to a known position so that you have a starting point by which to begin adjusting.

The low needle on a gas engine affects the carb mixture from idle to full open throttle. The high needle affects the carb mixture from a little past half throttle to full throttle.

Set the low needle first for good idle and responsive transition to about one third throttle when you work the throttle from idle to mid rapidly. Once you have the low needle set for a reasonable transition then adjust the high needle to max rpm with a tach, and back the needle open a little to make sure the mixture is slightly rich by observing the rpm decrease by approximately 100 rpm from peak.

Now to set your idle after the carb has been adjusted properly, use your ATV's(automatic travel volume) on your transmitter to adjust the low end of your servo travel to your targeted rpm range. Make sure that you do this with your throttle trim at mid-range setting.

If the rpms slows down on vertical lines whilst flying, open up (CCW) the high needle about 1/8th turn and fly again.

When my throttle arm is closed untill it stops I still have about 2200 to 2300 rpm. Is there a way to adjust the arm or butterfly?

Is the butterfly completly closed? Perhaps I don't understand your question. I don't have my two DA50's to refere to as they are off to DA for the mod's. Are you sure there's no idle stop screw? I thought mine had a stop screw on the carb.

There is an idle stop screw on the DA-50. It's a big phillips head screw with a spring on it that's pointy on the end. The screw is on the opposite side of the carb from the side with the throttle arm.

Some carbs have the idle stop not externally, but half hidden in the carb body close to the butterfly shaft. Take a close look.

The screw is supposed to be on the opposite side of the arm but it has been removed

Normally, when the butterfly valve is closed amd not stopped by the pointed idle adjustment screw, it seals rather completely if it can move freely. Since the angle of the valve when closed is not exactly 90 degrees, the valve side is beveled (not perpendicular). If the plate plate is fitted to the shaft the wrong way up, the valve will not close, causing high idle.
Idle mixture setting will suffer as well.