another thing that you have to look at is what type of air filter do you have on the carbs. If you have those little foam things that just slip over the horns then forget it you will never tune it right....
Brent is correct on the holder vs. jet. How do you know you are running rich? Have you put an Air/Fuel meter on it? I ask because you would think mine was rich at idle because I get a puff of smoke and it seems to be a little rich but on the dyno cruising at 1,2,3,4,5000 RPM we watched what it did when it swapped from the idles to the mains and it was interesting...65 idles I was rich 60's I was lean...now I have to stay at 60's and play with holders to see what I get
Just alot of fiddling to get them perfect.
Matt