Here's another tech freebie from the mind of CJ. (Sorry, no profit here for the makers of Slick Wille Gear Lube).

Someone ever asked you how to adjust the mixture on their carb., and you didn't know if it was an air screw or a fuel screw? Here's a simple rule of which I know of no exceptions. I'm pretty sure the old Bings, Amals and the "Jackoffs" that came on the CZ's do not violate this rule. Today fuel screws are found mostly on Dell`Ortos only.

The mixture screw is intuitive, in that turning out means more of something and turning in means less. If it is an air screw, out means a leaner idle/off-idle mix. If it is a fuel screw, out means a richer mix.

The rule: A fuel screw will be located on the engine side of the carb slide, while the AIR screw will be located on the AIR inlet/AIR box side of the carb. slide. Just think air-to-air.

The fuel/air screws are a good temporary fix for idle/off idle richness or leaness during a trial. For these temporary settings, ignore the number of turns out and get it to run the best possible within the available range of the screw. If you have a blubberingly rich situation, of course don't temporarily screw an air screw so far out that it can fall out.

Happy Trials to You
-CJ