01 yz 426 backfiring and cutting out on acceleration

4 replies to this topic
  • cjp426

Posted January 15, 2011 - 06:26 AM


Fairly new to 4 strokes so any help is appreciated.
I've recently purchased a 01 yz 426, the problem I have is when I try to rev the engine, it just backfires, pops, and cuts out, at idle the bike is fine, and I have no trouble starting it hot or cold, I have replaced the sub wiring harness and removed the carb and cleaned it. But the problem still exists!
Please help!!!

  • ttr250dude

Posted January 15, 2011 - 09:37 PM


Sounds like jetting problems.

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  • cjp426

Posted January 16, 2011 - 01:45 AM


Hi, Thanks for the reply, What would I need to do to solve this, my knowledge is fairly basic,

  • DeeCee

Posted January 16, 2011 - 06:49 PM


Check that the small wire at the bottom of the ignition coil is properly in place. If this comes loose, it can cause problems like you describe.

  • cjp426

Posted January 17, 2011 - 04:10 AM


Thanks dee cee I'll try that, I've also noticed that the new plug I have installed is looking a little worse for wear ( black with carbon ) after only idling and revving the bike a couple of times, the bike seems ok till anything over 1/4 throttle, from reading the manual and seeing the state on the plug, I'm guessing that the bike could be running rich,
so I'm thinking I need to lean it out on the jet needle, this would mean stepping the clip down one notch or more, I'm a little hesitant to start playing with the jetting as I'm no expert in carbs.... So I was wondering what everybody thought before I do so.

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