My GL1100A wasn't idling properly. Culprit was #4 cylinder. Could tell because exhaust was cooler than others. Good spark. Good plug (swapped with #2). That left idle circuit #4 carb. Used a Phillips 2" long bit. Used a prybar to firmly engage the head and a 1/4" wrench to turn the Phillips bit. Got bowl off, both jets were clean. Found idle mixture screw passage clogged. Cleaned out with a wire and carb cleaner. Used folded up paper towels to catch carb cleaner as it came back out to preserve paint on engine cases. Idle was fine after proceedure. Don't know if trick will work with other carburetors but as luck would have it, #4 was accessible this way. I also used a small magnifying mirror and flashlight to look up into the passages. Used needle nose vise grips to position the bit on the rear float bowl screw.
