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Dirt McGirt 09-19-2010 06:47 PM

OHH MAN!?! DR650 header glowing red
Well I guess I should start by saying that I had been experimenting with which jets and mixture settings worked best for the old DR. This was while it was alot hotter and alot more humid here. I got it to where it seemed to be working about as good as I could get it.(pretty darned good)

Now the weather has changed and it is a whole lot cooler and less moisture in the air.

I have the 170 main jet, clip set at the #4 from the top of the needle slot. I had the mixture screw set at between 3/4 and 1 turn out.

The instuctions that came with my extended mixture screw from kientech said to set it between 3/4 and 1 1/8 turns out.

The paperwork that came with the dynojet kit says 2 1/2 turns out, which seems to be way too rich in everyone's opinion, including mine.

Now the issue, I just came out of my dad's house after letting the bike sit for over an hour. The bike was cold enough to need to be choked to idle.

After less than 2 minutes(of idling) the header was glowing red, never in 4 years have I seen this happen.

This made me real nervous, but once I fattened up the mixture it seemed to be back to normal.

Anybody had this happen before?

Is it semi-normal?

Is it easy to fry a motor this way?

Anything I should be worried about?

Anybody care to give me your thoughts on this? Thanks guys Dirt

jtwind 09-19-2010 07:07 PM

take this over to thumpers and the dr650 thread and you'll have better luck with the right answers

MarylandStrom 09-19-2010 07:45 PM

It happened all the time on my old Yamaha WR400 when I let it idle. I never liked the idea of it glowing, so I tried not to idle very long. But in my opinion it is pretty normal on big bore four strokes.

I think a lot of people don't notice that their thumpers are glowing red because they seldom ride at night. The glow can be seen in daylight but obviously not as easy as in the dark.

Bobthebiker 09-19-2010 08:58 PM

I've seen the glowing exhaust thing. idling excessively does that. basically what it is, is that you have all that exhaust heat building up, and no airflow to help carry said heat off, so the pipe begins to heat up and glow.

doing this isnt GREAT for your engine, try if you can to keep air flowing over it. overheating it may cause damage you dont even want to realize can be done so easy.

Jrmobb 09-19-2010 10:01 PM

glowing is normal no worries. Happens on all my bikes. Like stated previously, most people just never ride at night so they dont see it.

techforlife 09-20-2010 07:38 AM


Originally Posted by Jrmobb
glowing is normal no worries. Happens on all my bikes. Like stated previously, most people just never ride at night so they dont see it.

+1 normal.....won`t hurt a thing,no airflow cooling the header.....mine will glow red when idling and the oil teperature is only 200 degrees,so the engine itself is not really hot..


KneeKicker 09-20-2010 08:43 AM

First time I saw the "glowing pipe" I freaked too I had a 98 YZ400f and thought something was wrong. MY DRZe will do it too if it idles too long but not as quick as the YZ did.

Flatulator 09-20-2010 09:00 AM

pop open the hood on a 4 cyl car ... with a header exhaust (not a cast manifold) ... (at night) .. the exhaust is all glowing a dark red in there

looks kinda evil ... and cool

... and normal

you might not see it in daytime as well ... but at night you will

Dirt McGirt 09-20-2010 01:17 PM

Thanks for the replies guys, I feel a little better now.

I have 13k on this bike and just less than half of the miles have been at night. I have never seen this happen.

I think that I had it running extra lean and this contributed to the glow.

Once I richened the mixture it went away immediately.

Seems to be alright. Runs still, that's always a good thing:D .

Thanks again for chiming in guys, Dirt

gplassm 09-20-2010 01:33 PM

Don't worry, unless the color starts approaching *white*.

rallyhound 09-20-2010 06:59 PM


Just went for a 30 mile ride, came home and let the bike idle for 30 minutes.

Exhaust header didn't glow a bit.

Motomantra 09-20-2010 08:53 PM


Originally Posted by rallyhound

Just went for a 30 mile ride, came home and let the bike idle for 30 minutes.

Exhaust header didn't glow a bit.

Yea, Some of these guys are lost.
No, it shouldn't be glowing. On the other hand, an air cooled engine needs air flow. Don't let it idle for long.

JensEskildsen 09-21-2010 01:27 AM

Why would you let a aircooled engine idle for 30 minutes?

Do you run it without oil aswell, to check for knocking sounds? :D

Headers CAN glow red, they do get awfully warm very fast, some do, some dont glow.

Run a low rpm/throttle sparkplugcheck, it the plug is white or gray, adjust the CO screw, that could help.

diesel critter 09-30-2010 03:13 AM

fuel air ratio, spark and/or valve timing can affect how hot the exaust gets. Even cast iron manifolds can glow red, they shouldn't, often its a timing problem, or perhaps in the case of some mcycles, the timing at idle isnt really what it should be for optimal idling, cuz thats not what motor bikes are for!

Brendan J 09-30-2010 03:24 AM

Did it look anything like this ???? And this is in the daytime.

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