I recently bought a '03 sportsman 600, have added 26" mudrunners and a k&n air filter. I have never ridden it
with stock tires, but since swapping to a k&n filter and changing to ngk bkr7es plugs it seems "flat" at wot, and the plugs are white.
It runs great at slow speeds and at mid throttle, so assuming otwas lean at wot I've swapped out the stock 155 main jet to a
160, only now it barely goes over 45 mph... should i trie a 157 1/2 main, or lower the needle??? Does anyone have any
suggestions?

 

If your plug is white you are to lean..... you wanna try a bigger jet which you already have done so, try the 157 1/2 jet. If that helps great. If not you need to raise your needle to let more fuel into the carbs.[img]i/expressions/face-icon-small-wink.gif[/img]