Actually, the old style carbs worked well if you knew how to adjust them. They were 2 jet carbs, which is completely different from any carb we have today. At full throttle, both jets were used. This means the low end needle really affects the top end.

You adjusted them backwards from normal. You set the low end first, then went back and set the top. Normally, we get the top end set, then idle down and set the low end mixture. Doesn't work on the Fox. Every time you touch the idle needle, you must reset the top end. Those people who like to tweak the needles all the time never could get them running.