2014 yz450f bog and backfire at wot

4 replies to this topic
  • 14yamahayz450f

Posted January 31, 2016 - 08:18 AM


Im tryen to see if anybodys had similiar problems with there 14 450s. i just put a new spark plug in a week ago. its got aproximately 150 hours. Its hard to start couldnt get it to kickstart yesterday i had to bump start it. When i get it started it idles fine but when i go wot it backfires and bogs at higher rpms. Ive only used 91 premium any help is apreciated.

  • 15thumper

Posted January 31, 2016 - 08:59 AM


I'd check valve clearance

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  • Monk

Posted January 31, 2016 - 09:24 AM


I'm going to guess the injector is plugged...

  • grayracer513

Posted January 31, 2016 - 04:40 PM


That or the fuel filter.  One thing that happens with fuel injection that looks completely different than with carbs is that since EFI is one steady stream from gas tank to injector, build up in the filter ends up as a flow limit.  The system will deliver all the fuel you need and run perfectly normally, right up until it can't anymore because of the clog, and opening the throttle past that point makes it run bad.  

  • 14yamahayz450f

Posted February 13, 2016 - 08:30 AM


I put the dirtbike in the shop thinking it was the valves. The clutch and throttle were adjusted to tight. I rode it yesterday and everything seems to be fixed.

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