Put stock slider springs back in, for one... go back to basics. May not help, but won't hurt. The sliders are vacuum operated, less spring pressure means it's running much richer than it should at low vacuum (WOT). Sounds like it could be the culprit.
And don't believe everything you read in forums (even me!)... Many times ppl put in what they THINK is correct when often it's just plain wrong... (ok, NEVER me, lol)
Running with a stuck choke plunger will make for rough idle and a little sputtering at 1/4 to 3/4 throttle, but great at WOT... This one I know cuz i ran that way, then adjusted my needles to overcome the rich mid throttle... until i found out my choke was stuck on. Ran great except for the Harley idle sound. Then I fixed my choke, returned the needles back to where they were, all good.
'01 Scrambler 400, K&N
'02 400ex, piped, jetted, K&N, Lonestar +2 A-arms, Lonestar anti-vibe
'02 400ex, DiamondJ +3 A-arm widener, Lonestar anti-vibe
'02 660 Raptor, DiamondJ +2 A-Arm widener, YFZ shocks, LSR anti-vibe, piped, jetted, K&N
Last edited by Quadmaniac; 03-14-2008 at 02:25 AM.