Well, it kinda looks like it affects air flow from one of the little tubes at the carb throat down to the emulsion tube. I'm not sure if more air into the emulsion tube causes it to draw more fuel, or just adds more air. From empirical observation just now, adding more air to that circuit seems to make it richer. Closing the screw more makes it start stuttering at about 10-15 MPH and won't go faster than that.
Naturally it started snowing at the exact instant I finished putting it back together, so my testing was limited and I haven't checked how the spark plug is looking after a few full throttle rips down the alley.
I do seem to have a bit better acceleration now, with less sag off the line. My top speed might have dropped a bit though. I was pulling maybe 28 MPH with the stock carb, and now I seem to top out at 25. I think it's still progress though. I might have over-oiled the new air filter a little bit too. Or fouled up the plug a bit from putting a tiny bit of oil in the cylinder after changing cylinder/head gaskets and cleaning everything up.
That chart is awesome but only a couple parts of it apply to my bike. I don't (yet) have a slide-type carburetor. I think a Mikuni and a new intake will be my next upgrade once I've got a bit more money saved up. Mainly just to get the damn carburetor out of the frame so I can work on it easier.