i'm not good with carbs, but here is what i'm thinking.
If your carb
was set up for a HC
and now you are running it with the flaps open like a normal aftermarket AC would be, You are way out of wack.
here is a link to the directions for installing the HC http://www.kuryakyn.com/documents/installation/9420-23MC-1011.pdf
I just pulled off my Kuryakyn HC and went to a K&N. (I did not install the HC originally) The main
jet was large, (like a 180-200 had no markings on it) I needed a 172.5 for the K&N (which is basically the ac that your running now)
was a 35 (K&N needed a 40)
The air jet (inside the top of the carb under the rubber boot) had no markings on it, but the Kuryakyn instructions called for it to be a 1.3 and I needed to use the stock 2.0
I have also heard that they sometimes use a different needle for the HC, so I replaced that as well (the one used with the HC had 1 groove, so it is possible it was a stock needle)
I ended up with my PMS
at 2 turns out.
DaveJ helped me get mine figured out. I was getting about 33 mpg with the HC and I got 41.5 MPG with the K&N on my trip last week