Air and gas mixture screw

I think that's what it is called.

Tim, on any carb, your going to start at about 1 1/2 turns . From there you would turn them in or out to obtain the highest rpm on the motor.
Do the idle screw at idle, and the high speed at 7/8 full throttle. If you get no change the carb is dirty.
You should see some change turning it a half turn at a time.
Turning in should make it stall out, and then turn out to get your highest rpm's.
Roy

Roy,

Which of the Onan engine uses that carb?

Thanks Roy and Chuck

Tim N, the carb is to give him an example of the screws. Some guys dont even know they are there.
Roy

After adjusting the screw there was no difference in the idle so I guess that means that the carb is dirty. I think what happened was I put new points and condenser in and decide to start it with no air cleaner on. I put everything together and it ran alright when I first started mowing but half way thru the engine started surging. It did this when I first got it a year ago. I cleaned the carb and put new plugs in and it ran great. So I guess I have to do it again