A gee-whiz carb question

[Chris Cochran]

Ok, I'm about to get a new-to-me set of carbs next week so this question about my original carb set is one out of curiosity only.

I noticed, when I first took them apart, that the fuel/air screws underneath really surprised me. Instead of them being about two full turns out, carb one was completely tightened, and carb two was only about a fourth of the way turned out from bottom. The other two carbs were right at the two turn position.

The bike "did" run" like that but only when fully choked and it wouldn't idle down at all. Even after I did my first ever efforts at carb cleaning/rebuilding, and I had them all set at two turns, it would only run on full choke (which may be due to a vacuum leak) but the way it ran and sounded was the same as when the F/A screws were "wrong".

Any idea as to why the fuel/air screws would be so far turned in?

[Nails]

My guess is that someone was trying to get the bike to run better and thought turning these screws would help, plus probably not turning them like (that person) thought s/he was. (It is hard to adjust these on the bike.)
Lots of folks have bought a non-running bikes when this kind of thing was all that was wrong.