red hot yz450 exhaust

hey guys.........i need a little bit of the proud owner of a 2003 yz450 all supermotod out........i got injured last month so i havent touched my bike in about 5 weeks.. finally got the cast off today ran into my garage and started the bike......left the bike running, ran into my house and grabbed my helmet and gloves... i get back to the garage 4 minutes later and my exhaust manifold (im not sure thats what its called but the place where it connects to the engine all the way back, halfway the the can) was glowing red hottt....anybody has any ideas why this is happening, what the problem mmight be and what i can do about it

i would really appreciate any info available



Ken, you're gonna get flamed for this... just watch n see....while you wait, if you search for this issue you'll find 1000000 threads (ok maybe not _that_ many, but a whole lot of them) about it.


hey guys.........i need a little bit of the proud owner of a 2003 yz450 all supermotod out........ started the bike......left the bike running, ....4 minutes later .....
Don't tell me, I'll guess that your exhaust was glowing red. Let me warn you, you're going to catch flak for this one. :thumbsup: It's TOTALLY normal. They don't like idling for any extended period, and 4 minutes is about two and a half minutes longer than needed to see red. It's a combination of no air over the radiators, the aggressive exhaust valve timing, and the retarded ignition timing at idle in neutral that causes it. No harm done as long as you don't hit the pipe with anything hard, and no one gets burned.

Now watch they come.

Odds are the jetting is a little lean. This happens with changes in the temperature and other weather conditions. Four strokes get very hot if you let them idle and the pipes will glow to begin with, but you don't notice until you see it in a poorly lit area such as a garage. One time I wanted to see how a leaner pilot jet would feel in my 450 just to get a feel of what I had, and when I started it up in my garage, the pipe started glowing bright red, I put the pilot back to what it was supposed to be and the pipe didn't get nearly as hot. Hope this helps.

Now watch they come.

No comments from me :thumbsup:

I will I will............get out the weenies and marshmellows Ken - it is time for a weenie roast and a sing along to Kum bye ya!!!!!!! :thumbsup::lame::p

Welcome to TT.................

OMG!!!! not the dreaded red hot header. Say it aint so. Man your bike is toast now but I'm willing to help you out. I will give you one dollar and take that basket case off your hands. No need to thank me for this, I will bask in the warm glow of helping out a fellow TT'r.

Sorry to rush off but I have to go answer some "Will my fully modded xr70 beat a ____ in a parking lot drag race?" type questions.

Well, maybe just this, and only this time





Welcome to the forum.

thanx everybody for all your help..........i appreciate the info and you guys not bashing me too bad.....i feel so welcome here

no track day til saturday i guess il have to go out now and see if the cops will chase me a bit


It sounds like an oil issue to me...are you using Rotella? It's really the best. :thumbsup:

I think he gets the idea, so that will be all.

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