04 WR450 glowing red header

14 replies to this topic
  • mbeck76

Posted October 26, 2005 - 01:22 PM


I am new to the whole 4 stroke world but this doesn't seem right. I have an 04 WR450 absolutely love the bike but I have noticed when warming it up. The header starts glowing?? It doesn't happen while riding just when its sitting idling. Is it running too lean? I have put all mods on it and it seems to be jetted right the plug has a nice tan look. It doesn't hesitate or bog out. I just have never seen this before. Anyone else out there with this issue??

  • XT2YZ

Posted October 26, 2005 - 01:27 PM


Uh oh! Better do a search. There have been many many posts on this. It is normal for them to heat up and glow if it is just idling. I think it was put best when someone said "they are like sharks, they like to keep moving."

  • Trail Rider 7

Posted October 26, 2005 - 01:29 PM


If you leave the choke on to long the header will get cherry red.

  • Rich_in_Orlando

Posted October 26, 2005 - 01:48 PM


Better sell it.

  • byggd

Posted October 26, 2005 - 02:13 PM


If you leave the choke on to long the header will get cherry red.

That should be the opposite. A lean mixture burns hotter than a rich one :banghead:

  • Matty05

Posted October 26, 2005 - 04:35 PM


Your exhaust gasses can get up to 900 degrees celcius.
I think I would glow too if I were that hot.

  • ibleedblu

Posted October 26, 2005 - 04:54 PM


I had an 03 WR450, it did the same thing. Ialso did some research & everyone told me it was normal. I had the bike for 3 years and never had a single problem with it. :banghead:

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  • rushfan

Posted October 26, 2005 - 06:41 PM


Better sell it.

Yup!!! It's broken. Buy another one. :banghead:

  • Punisher660

Posted October 26, 2005 - 07:35 PM


Don't worry about it....the YFZ quad does it as well as the YZ and WR. In fact, I think even the new Raptor 700 does it to. Its what happens on the 4 strokes I guess :banghead:

  • ibleedblu

Posted October 26, 2005 - 08:33 PM


If you touch a HOT pipe your going to get burned....... These motors just have an attude!!! :banghead:

  • srhines67

Posted October 30, 2005 - 09:05 PM


I have 99 YZ 400 and WR 400. Checked with local service and in fact they glow when there is not airflow over them. If your not boiling over I would just try not to idle for so long. Anyways, I don't think it is anything new or abnormal. Just ride it. It happens to every one of them most people just never notice it because you only see it at dusk or in the dark. During the day you usually don't see it.

  • ovrrdrive

Posted October 31, 2005 - 02:13 AM


That should be the opposite. A lean mixture burns hotter than a rich one :banghead:

Should be but its not.

My FZ1 even had a warning in the manual from Yamaha that if you let it warm up regularly with the choke for too long it would discolor your pipes.

The engine is definitely making more heat at idle with the choke on. Compared to the idle without the choke, the choked idle has more fuel burning and is higher.


Posted October 31, 2005 - 08:55 PM


I Had The Same Promblem With My 05. Took Off The Air Pump Went Away.

  • ShadyatBest

Posted October 31, 2005 - 10:05 PM


those bikes run super lean, 1-2 inches of red is okay but 12+ inches is bad news. My buddy couldnt get his to cool down until he bought a jd kit. Fatten up the pilot jet to a 50 and that should help

  • crashing_sux

Posted October 31, 2005 - 10:37 PM


That should be the opposite. A lean mixture burns hotter than a rich one :banghead:

Six of one half a dozen of the other.

A lean mixture burns hotter but a rich mixture burns slower. When it burns too slowly the mixture is still burning in the header, plus there is less time for the heat to transfer into the piston, head, and cylinder wall, resulting in higher exhaust temps.


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