Thanks for the reply Jeff,
When the engine is cold, it runs about 850 to 900 RPM and a little shaky. If I split the linkage when cold and add air, the engine speeds up to a max of 1200 RPM. When the engine is warm, it runs at 800 RPM and smooth. If I split the linkage when warm, the mixture is only slightly rich at idle and good at the other RPMs. When driving, engine runs well and plugs look normal.
I removed the fip air filter with the engine cold and felt a strong suction, but the RPM did not change. When warm, there is virtually no suction. That seems normal.
My goal is to try to increase the cold idle speed to 1000 or 1200 RPM. Decreasing and eliminating the air valve shims made only about a 50 RPM difference. But when I open the venturi or open the air screw, the idle speed goes where I want it. Problem with using the air screw, is that my warm idle would then be too lean. I am trying to find a way to add air to the cold idle without adding fuel thereby leaning the mixture.
I hope that helps!