Engine won't run properly

SOURCE: Polaris Xpress 300. Won't start, backfires through carb sometimes

Sounds like maybe the needle and seat in the carb letting gas through.

SOURCE: starts missing and backfiring after running for

hi there it only starts to back fire when the engine is hot this points to incorect valve clearances os slightly damaged valve seats this is only oticable when the engine is hot due to heat expansion the clearancea would be an easy fix but to doo valve seats the cylinder head would have to be removed which is quite a big jo although i would try the valve clearances first unfortunatly i do not have the clearances but im sure i atv shop would tell you or if you have the manufacturers service repair manual it will te you in there hope this helps ben

Wade Mobley

• 513 Answers
• Posted on Nov 13, 2009

SOURCE: Polaris 500 idles fine but when i give it any gas

the idle air mixture might be off or sometimes a bad spark plug can cause it

SOURCE: 2004 sportsman 600, bogs down bad at half throttle.

Check that your choke is working correctly
Your timing may be way off as well

SOURCE: dieing out

have 04 polaris predator 500 doing the same thing, when giving full throttle it seems to be hitting a limiter a couple of 1000 rpm below full rpm, but will only start with air box disconnected from carby and spitting gas out, might be buggered T.P.S unit have bought new Keihin Flat CR carby with T.P.S on it so to replace one on thumb throttle as it has taken some knocks ( should be able to test T.P.S with volt meter when pushing the throttle), a cdi unit and coil will see how that goes.