Have you done any mods to it without re-jetting to match?
Did you THOROUGHLY clean the pilot jet passages?
It could be off a tooth on cam timing... inspection will be necessary to determine this. Looking at the valves and the timing marks on the flywheel to see if TDC co-incides is a start.
'01 660 Raptor, Burgard +2+1 arms, YFZ Shocks, LSR anti-vibe, CTR pipe, jetted, K&N
'01 Polaris Scrambler 400, K&N
'02 Honda 400ex, Big Gun pipe, jetted, K&N, Lonestar +2 A-arms, Lonestar anti-vibe
'04 Suzuki LTZ400
'16 RZR XP4 1000 Turbo