450 not running smooth

4 replies to this topic
  • Audun

Posted September 03, 2006 - 05:49 AM


HAve a problem with my 03 wr 450.. It doesen`t run smooth unless I have over 50% throttle or riding uphill or high speed. Feels like it fails to ignite every 5-10 sec.. I have a high comp piston and new jetts.. The spark plugg have a nice milkchocolate color when I ride it hard, but it gets very dark and seems it gets to much gas when I keep to the speedlimits..

Where is the problem?

  • 642MX

Posted September 04, 2006 - 06:29 AM


Sounds like your float level maybe off. Or you may have too big of a pilot jet. Its getting rich and loading up at low rpms?? right?

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  • Audun

Posted September 04, 2006 - 11:52 PM


Think Ive fixed it! I just tok the needle out and remounted it one notch down.. So now it seems to run perfectly, but Im stilll thinking about putting inn the 170 main jet..

  • PfM

Posted September 05, 2006 - 02:06 PM


...so, you moved the needle up ?

  • Audun

Posted September 06, 2006 - 12:26 AM


No.. I Moved it dovn so that the engine get less fuel from 1/8 to about 1/2 throttle.. I first i took it for a ride.. hard riding gave the sparkplug the right colour, the same when ideling, so then when i tried it for slow riding the plug got al black.. so the engine got to much fuel at this throttle range.. Still aint perfect at the low end so i have to work a litle on the mixture screw..


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