OK I am using the stock airbox top not modified w/ K&N filter, & Carbon Tech exhaust, Factory pro stage 1 jet kit everything else is bone stock---I am using 130 main jet, Slide needles 2nd position from the top & 37.5 pilot jets that is the set up as of now( had 40 pilots-too much), I tried moving the slide needles to the top position this did not work so put them back air screws 3 turns out-if I go in it gets worse-3-4 turns out works. I am still getting a little stumble off idle under load. I am thinking of trying the 127.5 main jets that I have and see what I get-the stumble is not real bad and goes completely away over 4K rpm. It should take me about 1 hour to change the main jets and get it back together. It's a lot better but not exactly where I want it-- though it is now rideableMy stock carb bike is exactly this, so if you sort it out by all means share!
Edit: to get to this relatively satisfactory performance I went back to the stock airbox lid, put Db killer's in the exhaust on their 2nd quietest setting and fiddled excessively with the needle height and idle enrichment settings. All new needles on a zero mile NIB carb. Now after 1,200 miles on two sets of plugs with perfect looking burning I've accepted the low rpm performance although it does rush through the 2-3krpm's very quickly with a Nichols flywheel and a 41 tooth rear!
Could be a co-incidence but in the last week I've replaced the throttle cables and for a while the "surging, unevenness" at steady throttle was worse until I loosened the return throttle cable. Now while I can still hear and feel the steady throttle roughness below 5k, I can no longer see the variation in the tach. Slightly too tight throttle return cable amplified the unsteady issue.