03 wr450 running like s#$%

8 replies to this topic
  • jjewell

Posted July 02, 2006 - 05:03 PM


My WR450 runs like s#$%. At first i thought it was running rich. The plugs tell otherwise. It began with some backfiring through the exhaust but now is missing badly. I remember reading about these bikes being prone to a broken woodruff key holding the rotor failing and throwing the timing off. Anybody else experience this or have any suggestions on fixing this problem.

  • mtrablue

Posted July 02, 2006 - 07:57 PM


have you done anything to the bike? any mods or recent work? it's always good to go back to the last thing you did to look for you problem. were any of the '03 flywheel key "fixes" done? you don't give us much to go on. most of the time, when the flywheel key shears the motor won't run. it's not impossible for it to shear part way but it would be unusual. the only way to tell is by pulling the flywheel. you'll need a special puller. the other two things i can think of are, the pilot air screw has fallen out or the hot start cable is not seated right. i'd lean to the pilot air screw having fallen out. my first one (stock) did. it would start with the choke but from there it was crap.

  • Assassin

Posted July 03, 2006 - 03:32 AM


unless you use leaded fuel, don't even bother with reading plug.

  • jjewell

Posted July 03, 2006 - 07:20 AM


lets see. I put a Baja Kit lighting kit on. Installed a moose jetting kit. And installed a new hot start lever, hummmmm. I'll check that to make sure it's seated correctly. Thanks for the help.

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  • jjewell

Posted July 03, 2006 - 07:23 AM


That's news to me. How else can a guy check for a rich condition? It is a major pain in the ass removing/reinstalling plugs on that bike.

  • Numskull

Posted July 03, 2006 - 04:51 PM


If it just happened out of the blue while riding( the backfiring and missing), it could be dirt in the carb. Ill go out and drive the shit out of it for about ten minutes to see if it comes out of it or get a real good feel to what the problem is,carberation or ignition.

  • Dodjy

Posted July 03, 2006 - 06:21 PM


Make sure you check the valve clearance. Backfiring through exhaust can also be caused by exhaust valve burning out or lack of clearance. Hopefully it's only a jetting issue, but if it just happened out of the blue, it's worth checking.

  • jjewell

Posted July 13, 2006 - 08:32 AM


Thanks for the help! I loosened my hot start cable and all is well for now. :ride: :ride:

  • tony1970

Posted July 13, 2006 - 09:53 AM


unless you use leaded fuel, don't even bother with reading plug.

Where the hell did you get this information?


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