Headers glowing red
04-12-2008 | 09:06 AM
#1
Thread Starter
Member
Squid
Joined: Oct 2006
Posts: 63
Headers glowing red
Hi! I was wondering if the exhaust headers are supposed to glow red when running the bike.
I had changed the plugs yesterday and it was already dark when I got to finish the job. I started the bike, got it warmed up and revved it up and down a little, I tried to rev it to 4000rpms and let it stay there revving for about a few seconds when I noticed that the front header is glowing red like it was about to melt and looked at the rear header and found the same thing. When you return it to idle speed it wont glow but try to rev it up to 4 or 5k rpms in a few seconds it will glow red hot.
Just want to ask if this is normal or not. It was almost dark when i did this that is why I can see the glowing of the headers. I have after market cans with no baffles, k&n filter, denso iridium plugs, and the carbs are running #45 slow jets on both carbs with #185 rear jet and #180 front jets. The needles are set in clip #6 (meaning the lowest clip position).
Any info will be greatly appreciated, thanks!!
I had changed the plugs yesterday and it was already dark when I got to finish the job. I started the bike, got it warmed up and revved it up and down a little, I tried to rev it to 4000rpms and let it stay there revving for about a few seconds when I noticed that the front header is glowing red like it was about to melt and looked at the rear header and found the same thing. When you return it to idle speed it wont glow but try to rev it up to 4 or 5k rpms in a few seconds it will glow red hot.
Just want to ask if this is normal or not. It was almost dark when i did this that is why I can see the glowing of the headers. I have after market cans with no baffles, k&n filter, denso iridium plugs, and the carbs are running #45 slow jets on both carbs with #185 rear jet and #180 front jets. The needles are set in clip #6 (meaning the lowest clip position).
Any info will be greatly appreciated, thanks!!
04-12-2008 | 10:12 AM
#3
Junior Member
Squid
Joined: Aug 2006
Posts: 16
It is normal and common for single-walled exhaust headers. I have a 2005 Honda CRF450X, 2003 VTR1000, and 2006 KTM 950 Supermoto. All except the 450 have stock jetting, and the headers on all my bikes glow red in the dark. This is partly due to the lean mixture that comes with factory jetting. My 450X has a larger jet, which presumably makes for cooler combustion chamber temps and it still glows red.
This has been discussed ad nauseum on www.crfsonly.com (see the 450X forum)
This has been discussed ad nauseum on www.crfsonly.com (see the 450X forum)
04-12-2008 | 11:38 AM
#4
Slacker
Superstock
Superstock
Joined: Jun 2005
Posts: 489
From: San Antonio, TX
? Is the PAIR system still hooked up??
If so, then my guess is that you have way too much raw fuel going into the exhaust system ( #6 clip position is overkill for most VTRs), and that fuel being ignited by the PAIR air injection system. This would cause overheated head-pipes. My bike had a rich flat spot with the clip on #5, I went to #4 and the power smoothed out very nicely. There are other possibilities as well, as others will post up soon.
If so, then my guess is that you have way too much raw fuel going into the exhaust system ( #6 clip position is overkill for most VTRs), and that fuel being ignited by the PAIR air injection system. This would cause overheated head-pipes. My bike had a rich flat spot with the clip on #5, I went to #4 and the power smoothed out very nicely. There are other possibilities as well, as others will post up soon.
04-12-2008 | 05:47 PM
#5
Senior Member
MotoGP
Joined: Jul 2007
Posts: 6,110
From: NW North Carolina
It indicates a lean condition and usually a very thinwall header pipe.
I have not noticed it on my VTR but my CRF450R will glow after just 1-2 minutes after startup. It will also start puking coolant out after 4-5 minutes at idle. Jetting is spot on.
I have not noticed it on my VTR but my CRF450R will glow after just 1-2 minutes after startup. It will also start puking coolant out after 4-5 minutes at idle. Jetting is spot on.
04-12-2008 | 07:06 PM
#6
Out of my mind, back in 5
MotoGP
Joined: Nov 2006
Posts: 6,109
From: Skurup, Sweden
Well a very slight glow is normal with single wall headers... This since you are not moving and have no airflow... but a distinctive glow that fast probably means it's running hot... Pair combined with excessive fuel seems a likely suspect... could be others too thoo...
04-13-2008 | 06:47 AM
#9
Senior Member
MotoGP
Joined: Jul 2007
Posts: 6,110
From: NW North Carolina
Let me start by stating that my knowledge is with off-road dirt bikes and ATV'S. But I have extensive knowledge in that arena.
Yes, lean is too much air. A lean condition is not enough fuel where a fat condition is too much fuel. A lean condition will run hotter while a fat condition will run cooler.
Think of it like this. The "Fat" condition supplies an excess of fuel. The excess fuel then transports the extra heat away from the motor. A lean condition is starving the motor a little of fuel. This starvation creates a stronger hotter burn.
In racing we sometimes say "Lean is Mean". You typically run better in a leaner circuit but the motor reliability is greatly diminished.
Yes, lean is too much air. A lean condition is not enough fuel where a fat condition is too much fuel. A lean condition will run hotter while a fat condition will run cooler.
Think of it like this. The "Fat" condition supplies an excess of fuel. The excess fuel then transports the extra heat away from the motor. A lean condition is starving the motor a little of fuel. This starvation creates a stronger hotter burn.
In racing we sometimes say "Lean is Mean". You typically run better in a leaner circuit but the motor reliability is greatly diminished.
04-22-2008 | 11:40 PM
#12
Senior Member
SuperBike
Joined: Jul 2004
Posts: 1,015
Sure helps in the tight woods and somewhat useful when i convert her to Supermoto Street riding.
Yes the headers will glow red, usually it hard running and typically related to a lean condition. Lean is fastest, but too lean is dangerous and damaging to the engine.
04-23-2008 | 04:58 AM
#13
Senior Member
SuperSport
SuperSport
Joined: Dec 2006
Posts: 880
From: Victoriaville, Quebec, Canada
Adjust your TPS to spec (Greg mod), the CDI may not provide enough advance and burn partially in the exhaust, the jetting may be lean as said above, this slow down the combustion a great deal and finish in the exhaust. Since it happens in both cylinder at once it's not a vacuum leak or carb trouble. Pull a plug after making it glow, kill the engine right away, if the carbon turned white you are lean, if not a timing light would provide a great deal of information
04-23-2008 | 05:47 AM
#14
Senior Member
MotoGP
Joined: Jul 2007
Posts: 6,110
From: NW North Carolina
The CRF450R frame down tube makes a great overflow bottle. If interested PM me and i can give you the skinny on how to do it. Really easy to do. My 04 has been that way for 3 years now.
Sure helps in the tight woods and somewhat useful when i convert her to Supermoto Street riding.
Yes the headers will glow red, usually it hard running and typically related to a lean condition. Lean is fastest, but too lean is dangerous and damaging to the engine.
Sure helps in the tight woods and somewhat useful when i convert her to Supermoto Street riding.
Yes the headers will glow red, usually it hard running and typically related to a lean condition. Lean is fastest, but too lean is dangerous and damaging to the engine.
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