I'm no Polaris mechanic, but after many years of ridin' 2-strokes hard, I know they can sometimes get in the mood not to rev. I don't know the terrain you rode last leading up to this or the weather, humidity or temperature. All I know to tell you is if it's sputtering, you could have some tank sweat, line or carb problems. If it's bogin' down or moanin' you definately have carb problems. Or, sometimes if mods are new, they run ok for a while and all whaked out after some hours. If you don't have fouled plugs I wouldn't think it would be the electrical. I'D CHECK THE TANK, LINES, AND GET NEW FILTER JUST IN CASE. IF THAT ISN'T THE PROB, HUNT DOWN THE ONE WHO DID YOUR WORK.
A project in progress......brought to a screeching halt (3/09)....Time for a new 450R!
'08 Monster Kawasaki KFX450R (Black) #450R
Jardine RT99 Exhaust + Holeshot GNCC's
'99 Sport 400 (XC)
Out of a time capsule... bone stock, new condition (6/08)... A few mods since then