RE: top flite corsair build questions
The idle screw is on the opposite end of the carb from the main needle screw. If you have been idling good and are now having problems, don't touch the idle screw yet! Did the idle problem start after the muffler problem? Has the weather changed recently? Has your fuel been left open for a while? Have you changed fuel brands?
A friend of mine was having terrible idle problems with an O.S. engine. As it turns out, he had bad fuel. It had been left open and had absorbed moisture from the air. With a weather change you may now be too rich or too lean. That main needle adjustment does affect idle.
Just check the idle screw to be sure that it is not loose and takes some pressure to turn it. I wouldn't adjust it yet. At this point, I would just tinker with the main needle. What I did was set the main needle 4 clicks to the left of max rpm.