yz450f wont idle when warm


9 replies to this topic
  • findley

Posted October 19, 2009 - 05:28 PM

#1

Hey guys first post and I am new to dirtbikes as well. I did make an effort to search my issue but I found nothing that related. If I missed the post for this I would be grateful if you could send me the right direction. My problem is this I bought an 06 yz 450 that was a racing bike but had all stock parts back on it. Right away i discovered when it got warmed up it wouldnt idle and the warmer it gets the higher i have to keep the idle, on one occasion it was 1/2 throttle. so far I have put in a new sparkplug, cleaned the carb multiple times, checked the valves, new fuel. It will idle with the choke on. I am almost convinced it is an electrical issue, any thoughts?

  • l_campionero

Posted October 19, 2009 - 05:31 PM

#2

Have the carb cleaned out by a reputable dealer. I have had issues with both a WR250F, and a YZ250F, and professional cleaning solved the problems.

  • 426 NOOB

Posted October 19, 2009 - 06:15 PM

#3

Hey guys first post and I am new to dirtbikes as well. I did make an effort to search my issue but I found nothing that related. If I missed the post for this I would be grateful if you could send me the right direction. My problem is this I bought an 06 yz 450 that was a racing bike but had all stock parts back on it. Right away i discovered when it got warmed up it wouldnt idle and the warmer it gets the higher i have to keep the idle, on one occasion it was 1/2 throttle. so far I have put in a new sparkplug, cleaned the carb multiple times, checked the valves, new fuel. It will idle with the choke on. I am almost convinced it is an electrical issue, any thoughts?


to me it still sounds like a carb issue. Either the pilot is plugged or it is the wrong size. When you say it was put back to stock, what sort of performance parts were on it?

  • 426 NOOB

Posted October 19, 2009 - 06:20 PM

#4

Have the carb cleaned out by a reputable dealer. I have had issues with both a WR250F, and a YZ250F, and professional cleaning solved the problems.


also, most of the time it is just a jet. It has always been easier for me to just buy new ones instead of trying to clean them which always fails for me.

  • findley

Posted October 19, 2009 - 07:06 PM

#5

I have no idea what performance parts were put in the carb, I just assumed it had. I do know it had some other than factory exhaust on it. the pilot is a new 45, I also had a 48 in there and one of them quickshot 2 on there but it was no help

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  • grayracer513

Posted October 19, 2009 - 07:58 PM

#6

The relationship of temperature to the problem is telling you that your idle circuit is too rich. The #45 should be the right size pilot, so try the adjustment process:

http://www.thumperfa.../jetting.htm#PJ

http://www.thumperta...ad.php?t=327405

  • spark250

Posted October 21, 2009 - 12:30 PM

#7

fuel screw!

Make sure you have no air inlet restrictions as well. Clean air filter?

  • findley

Posted October 22, 2009 - 03:43 PM

#8

I tried to start the bike tonight, used the choke it cranked right up. A little bit of coolant leaked from around the waterpump, probably something to do with it sitting for a couple weeks. any way after 30 seconds I turned the choke off and it continued to idle very high, I attempted to turn it down but nothing happened!!! no matter wich way 1 turn up or down did not affect the idle then it dropped and died. it cranked right back up but then died this continued for a while then I got mad and walked away, the pilet screw is backed out 3/4 turn. It may be a dirtyjet somewhere still, I dont want to believe it tho because I payed an atv repair guy a good chunk of money to clean it, twice. SO, should i take it to a yamaha dealer and know it was cleaned right, or take another course of action?

  • findley

Posted October 22, 2009 - 03:47 PM

#9

the air filter is clean and not over oiled

  • findley

Posted November 02, 2009 - 07:53 PM

#10

Thank you for the suggestions, I ended up taking it to a dealer to be repaired. the problem was indeed a dirty jet in the accelerator pump. they said they had to pull the carb off twice before they finally got it clean. total bill $118, lesson learned.





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