Header pipe glowing red

[Spagz89]

Gday guys, my 09 WR450F header pipe glows red after starting and idling for only 1 minute. Any recommendations on what’s wrong with my bike? 
cheers in advance. 

[NYMXer]

Over rich from using the choke too long on a very thin wall header pipe

[Shooter88]

Nothing is wrong with your bike. This is normal if you let it sit and idle. My '04 that I used to have did the same thing. In fact, my '21 YZ450 does it as well.

[FORMA MOTO]

3 hours ago, NYMXer said:

Over rich from using the choke too long on a very thin wall header pipe

wrong

[FORMA MOTO]

3 hours ago, Spagz89 said:

Gday guys, my 09 WR450F header pipe glows red after starting and idling for only 1 minute. Any recommendations on what’s wrong with my bike? 
cheers in advance. 

.....and what state of tune is your bike and what did you change to cause this new symptom?

Glowing if full daylight is NOT normal, even if you have the Titanium YZ header.

You have a LEAN CONDITION that can be caused by a dozen different things.

Most likely a partially clogged pilot jet passage.

We need to know more information about the condition and tuning.

Edited June 11, 2021 by KRAYNIAL

[mxaniac]

If your timing is off you'll get some combustion in the exhaust causing this.

[donwann]

mxaniac, beat me to it. You may not have enough timing advance causing your ignition to be to late in the cycle. This causes part of the fuel charge to be burned in the exhaust. Check your timing. I had a '79 Blazer with a small block 400. It was pulling pretty weak and I noticed the exhaust manifolds were glowing red all the time. Found out the mechanical advance fly weights on the distributor wear rusted in place, the only advance I was getting was from the vacuum advance canister. Pulled the fly weights off and cleaned and polished them, and the old Blazer pulled like a beast!

[Randy300XC]

Every 4-stroke race bike 250, 450, 525 I’ve ever owned did it. A pipe that glows 6 to 9 inches out of the head is completely normal, 0 to 6 inches is better. Beyond that and you could be on the lean side. Most of the time it only shows at night or in the dark. They don’t really like to idle too long. 

[FORMA MOTO]

1 hour ago, donwann said:

mxaniac, beat me to it. You may not have enough timing advance causing your ignition to be to late in the cycle. This causes part of the fuel charge to be burned in the exhaust. Check your timing. I had a '79 Blazer with a small block 400. It was pulling pretty weak and I noticed the exhaust manifolds were glowing red all the time. Found out the mechanical advance fly weights on the distributor wear rusted in place, the only advance I was getting was from the vacuum advance canister. Pulled the fly weights off and cleaned and polished them, and the old Blazer pulled like a beast!

Non adjustable timing

[gpaton]

Make sure the hot start lever isn’t on or it’s cable/lever that it isn’t hanging up. 

[Randy300XC]

[screaminsquirrels@comcast.]

On 6/10/2021 at 2:34 PM, Shooter88 said:

Nothing is wrong with your bike. This is normal if you let it sit and idle. My '04 that I used to have did the same thing. In fact, my '21 YZ450 does it as well.

Yep, don't worry about it.

[Spagz89]

On 6/11/2021 at 12:01 PM, mxaniac said:

If your timing is off you'll get some combustion in the exhaust causing this

[Spagz89]

Is the best way to clean your Carby and jets to dismantle and remove completely to clean out with carby cleaner? Or can you get some kind of fuel additive that will clean it out when running? 

[PopWill]

The best way is to pull it and clean it. Every passage, nook and cranny. The only way to know for sure is to go all the way. Also run a little fuel out of your tank into a clean container. Make sure you’re not introducing trash into your carb.

[Taffy]

spagz

for once Kranky Kranium made some sense - ignore all other comments.  Those orange headers in those photos are aftermarket thin wall racing systems flat out on the dyno.  your bike is at Tickover FFS!!!!

Try adjusting the pilot screw undone (ACW/CCW) underneath which will richen the mixture and cool the engine.  if you are lucky, you kill two birds with one stone.  It was lean so you (will have) improved the mixture ratio which will show in not only the idle going up ( a good sign) but also the pipe going back to normal.  then lower the idle.  

you can have burning in the exhaust because they are rich.  this is secondary burning...a delayed but continueing flame or because it is lean.  when lean they run at 1,300 degrees.  normal is 800 degrees.  rich is 600 degrees.  flames for two diffferent reasons.  maddening isn't it!

regards

Taffy

[Michael Dyer]

When I first got my 03 wr450, I opened up the airbox and replaced the trashed stock exhaust with a Lexx mx midpipe and muffler. At this point my header pipe glowed like yours. I installed a larger main jet and went from a 45 pilot jet to a 48. Seems to have solved the problem, but I still never let it sit and idle for extended periods.

[FORMA MOTO]

The OP still has not divulged the state of tune of the bike in question.

Without that info, everything is just a guess

[FORMA MOTO]

On 6/12/2021 at 12:49 AM, Taffy said:

spagz

for once Kranky Kranium made some sense - ignore all other comments.  Those orange headers in those photos are aftermarket thin wall racing systems flat out on the dyno.  your bike is at Tickover FFS!!!!

Try adjusting the pilot screw undone (ACW/CCW) underneath which will richen the mixture and cool the engine.  if you are lucky, you kill two birds with one stone.  It was lean so you (will have) improved the mixture ratio which will show in not only the idle going up ( a good sign) but also the pipe going back to normal.  then lower the idle.  

you can have burning in the exhaust because they are rich.  this is secondary burning...a delayed but continueing flame or because it is lean.  when lean they run at 1,300 degrees.  normal is 800 degrees.  rich is 600 degrees.  flames for two diffferent reasons.  maddening isn't it!

regards

Taffy

Man Karen, you are in rare non-sensical form again today

[Taffy]

On 6/14/2021 at 2:35 AM, KRAYNIAL said:

Man Karen, you are in rare non-sensical form again today

what did he say?