Air/ fuel tuning
I missed it the first time through too. :D
Some of it depends on your engine too, I mean, I don't run mine as lean as I can because I'm closer to detonation than I wanted to be. It also depends on the carb. I spent months (on and off) trying to deal with an off-idle spot with my 340. It was either too rich or too lean, never could get it right. I tried both a 670 street avenger and a 770 street avenger. With both I had no issues tuning idle, cruise and WOT, but off idle I was sunk, same with transitioning from cruise to WOT. Then I found some other folks with low(ish) idle vacuum engines and 4 speeds that had issues with tuning vacuum secondary carbs. I went to a mechanical secondary 750 DP and had it well sorted in a couple days.