I took the bike out for it's first long ride, well about 20 miles. By the time I got home the idle was at about way too fast. I discovered that the whole top of the carb had unscrewed. I have always thought there was an air leak & it always idled too fast, the air screw did nothing. After fixing the carb I was able to set the idle. I road it for a few miles this morning & am very happy. These concentric float, cable slide carb used to be a main stay of motorcycling. Most have 3 circuts 1. the idle or float lift 2 the mid range or needle circut 3 the high speed circut or main jet. They usually have a stop or idle adjustment. This little carb has no idle adjustment except for the cable adjustment. The air screw probably is for low speed to mid range tunning. I did use it to bring down the idle and it all seems ok. It runs a little rough at 10 mph or so then smooths out over 15 feels good with a load on it. With the gas on it pulls right through the rough spot. Unfortunatly 10 to 12 is a good bike lane speed. I will get this all dialed in.