Seems to be working fine except right at 1/4 throttle.  Rolling on throttle I get a little flat spot there, sort of.   Since I ride at 1/4 throttle lots, I stay there sometimes, then I get just a bit of irregular running, not quite surging, not as obvious as hunting.

The flat spot suggests rich.  

The irregularity suggests lean.

Which circuit might this be?  Suggestions?

Volly, try the white spacer mod.

d, wheel of fortune sound? check the torque on the drive pulley.

1/4 throttle is where the needle starts.
Just under that is float level.
I'd try checking float level, and then if that is right (and the gasket face is the right level +/- 1 mm) then I would richen it on the needle.

Flat spot doesn't neccesarily mean rich. Irrerugalirity is too vague to define in this context. My bet is that you are a shade rich on the float, and a shade lean on the needle, and settig the float will point out the needle as the culprit.

Cool.
Srinath.

Stock air filter, new and clean, Dyna exhaust.  55 / 155  / 1/2 spacer.  This one was running incredibly lean - I tweeked up progressively.  The performance jump from 52.5 to 55 and from 152.5 to 155 were very distinct - the exhaust pipe temperature at high cruise speed clearly dropped, too.  Just now this hole in between.

I'm at 800 ft, but go up to 6000.

I'll pull out the filter and do a short test ride.  The stock filter has a lot of area.  Somehow it breathes fine at WOT and everywhere else.  Why would it not breathe fine at only one moderate demand position?

I have/had the same symptom.  Weak spot in the throttle position used for cruising at around 45mph.  I had a 55 pilot (w/holes) and tried going back to the stock 52.5 and it seems to have helped, though I can still feel it some.  Before that I tried leaning the needle out some (~1/3 spacer => ~2/3 spacer), but that was certainly *not* a move in the right direction.

I'm wondering if the decreased back pressure exhaust is accentuating a preexisting weak spot in that low range.  

How high is the needle then? Wish I knew.  I can fix spot lean pretty easy, although I've only done it for sweetening the idle.

If that is the case, and this is a lean spot, then the fix is easy.  I recall my grandfather doing it many times when I was a child.  A quick pass of the file over the needle to sweeten the mix right there!