First, I set timing, adjust cam chain tension, and then I tune at idle with mercury manometer, then check at 2500-3000rpm, using the idle screw to adjust RPM.
I then fiddle with it a bit to get the closest they can be at both rpm's.
I have noted on my bike, the cyl 1 carb sucks a higher vacum than the others at idle, but the same at 3000rpm as the others when i only tune for 3000rpm, and #1 can be equal at idle, but end up haveing less vacuum at 3000.
So i split it, and if anything have it pull a slightly bit more equal with the other carbs at 3000 than idle, it makes a little difference IMO in overall performance, ON MY bike.
But then again, i was balsy(foolish?) enough to drill out a few of the air passages on these carbs while they were totally dismantled.
l8r