03 yz450 Wont idle low


3 replies to this topic
  • 777tj

Posted March 19, 2010 - 09:49 PM

#1

my 03 yz450 is backfiring under decel... and whenever i get the idle semi dialed, when i give it gas it kicks to a high idle and wont idle low again. any ideas

  • grayracer513

Posted March 20, 2010 - 07:42 AM

#2

That is a "hanging" idle. Caused by a lean condition. Backfiring under decel is also either a leaky exhaust or a lean idle. Try dialing in the pilot screw first:
http://www.thumperfa.../jetting.htm#PJ

If that doesn't work, check for external vacuum leaks around the intake manifold, and check your valve clearance.

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  • Ronus

Posted March 26, 2010 - 06:17 AM

#3

valve clearance will cause idle problem at low idle?

  • grayracer513

Posted March 26, 2010 - 08:21 AM

#4

valve clearance will cause idle problem at low idle?

Yes..





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