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Glowing red header pipe (2003 F650CS)


jshirlemy

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The title sums it up, but here is my problem(?)

 

After riding home from work about 10 miles at a mean speed of 50 mph (or just when the engine is hot, I'm assuming), I noticed that the header pipe is glowing red from the exhaust manifold to about 5 or 6 inches down. After I kill the engine, it returns to normal quite rapidly.

Also interesting, I can only see it at night.

 

I've heard of this being a normal occurrence, but it seems strange to me. I don't want to put off today what is going to destroy my engine tomorrow.

 

Unfortunately there are zero BMW mechanics in my town. No one seems to have a clue.

 

Any thoughts?

Thanks...

 

-Jeremy

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baggerchris

If no one answers here, google The Chaingang and go over to their website and ask them. they are an internet club devoted to the f650 single and ALL of it's versions, yours included. I learned a lot from them when I had a single Cylinder GS.

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bugsplatter

I had an '03 F650cs for seven years, nearly 40,000 miles, never noticed this glowing. Didn't look for it, but never noticed it either, nor did anyone point it out to me.

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My '89 GS did that. Too lean. Yours is injected or carbed? Carbed you may be able to change jets. Injected, you could power commander.

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  • 4 weeks later...

Not very solid answers so far...

 

Steel starts to acquire color as temps go to about 1000.

Sounds way hot but isn't. Exhaust gas temps on well tuned street 4 stroke engines are in the 1200 plus range. (eg I have a mildly modded SC300 Lexus that makes about 400 rwhp at 15 lbs boost- its steady state highway EGT is about 1250 degrees and it is still running on vacuum with stock Toyota programming, not boost, at highway speeds unless I downshift)

 

So a slight dull reddish color is not something to get terrified about for a machine with a single wall tubing header. The first time I noticed in on my RT it caught my attention but I've tuned enough motors to know not to worry..

 

Yeah going a lot richer at idle to lower EGT will stop it from being noticeable at stops but you really don't want to drop EGTs so low that it can't ever show- it costs power and efficiency.

 

A more interesting situation is what happens with turbochargers run at performance limits. I have a large port, track only rotary motor with a very large turbo running a lot of boost. Between the large ports and turbo boost it gets a whole lot more oxygen than a stock engine can so requires larger injectors and pumps to feed it. Burning almost 1/2 gallon per minute at track speed, its EGTs to get maximum power are about 1700 degrees- way way up in the danger zone and NOT sustainable for long (it turns its wastegate into stainless steel taffy at those temps, for example). So I try to keep EGTs below 1600 which is the upper limit of what is tolerable for short period use...In those conditions the turbo glows like a yellow firebll when the hood is lifted at night and the housing actually starts to get translucent so you can see a blade shadow through the steel. Quite unnerving even when one is used to it. Extensive heat shielding required to prevent fire. Boost and temp gauges are highly visible and alarmed also- needs careful attention at full tilt..

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