header pipe color

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radiofun1

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May 15, 2011
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Hello,

One header pipe on my 74 850 is a distinct blue while the other is golden. Is that caused by a difference in the output from the coils and is it something to be concerned about?
 
I have one pipe blue and the other gold from heat. I asked my wife's uncle who is a bike mechanic (who also took my Commando for the first ride) and he said that is normal due to heat. The bikes you see with perfectly shiny chrome headers are double walled (one pipe inside another) and the outside pipe does not discolor but the interior one does.
 
Pretty common but indicates temp higher at least one time than the other.
Timing imbalance on single fire ignition like points would be first suspect.
Fuel mixture imbalance suspected on dual fire ignitions like Boyer, if dual carbs.
Spark plugs function to spark right and heat range to air leaks always suspect.
Can't ignore pipe construction/quality side to side too.
Tan to golden implies too rich for best power @ WOT or SS pipes.
Too blue implies too hot excess O2 lean burn but leaner yet implies too coo not enough fuel too burn hot. Aricraft tuning for best cruise fuel use is worth reading up on for our air cooled push rod wonders.
 
How did ya tell, did the pipes un-blue or ya put new headers on and still only tan?
You can get the Blue off but leaves dull chrome so must polish hard to shine again. I just figure same as dust on tires, just means healthy enjoying it. Creamic internal coats are claimed to keep the chrome color better longer. But nothing beats a second show covering.
 
Your pipes should be uniformly blue and they should be blue an equal distance from the head. Otherwise one side is too rich or as hobot says your timing might be off (with points). If the blueing extends more than 5-6" past the bend one side might be too lean (hot).

Yes, they are all that way, sir.

Greg
 
I watched a fellow at the classic car races messing with a Ferrarri v12 Testarossa I believe it was. This is the early one not the fancy new one. He was putting a dab of spit on his finger and dabbing it on each header pipe. He was checking the exhaust temperature of the running engine. You can tell a lot about a machine problem by the temperature of the various components.
An O2 sensor in modern cars generates a tiny voltage from the temperature of the exhaust gas and relays the data to the car's computer which in turn varies fuel mixture. On any multi cylinder engine, if you have a cold or cool exhaust, that cylinder is not doing its job for some reason. Don't burn your hand or fingers though! Get a fancy point and read temperature gage at Harbor Freight.
 
hobot said:
How did ya tell, did the pipes un-blue or ya put new headers on and still only tan?
You can get the Blue off but leaves dull chrome so must polish hard to shine again. I just figure same as dust on tires, just means healthy enjoying it. Creamic internal coats are claimed to keep the chrome color better longer. But nothing beats a second show covering.
Click to expand...

don't know for sure, sync may have had nothing to do with the pipe color but getting it right made my bike run much better....anyway worth checking out, one cylinder working harder than the other might contribute to a difference in exhaust pipe color
 
hobot said:
How did ya tell, did the pipes un-blue or ya put new headers on and still only tan?
You can get the Blue off but leaves dull chrome so must polish hard to shine again. I just figure same as dust on tires, just means healthy enjoying it. Creamic internal coats are claimed to keep the chrome color better longer. But nothing beats a second show covering.
Click to expand...

thought about this a bit more, it is indeed hard to tell for sure...though the mufflers are now about the same temp by touch after a ride and they were not before I synced the carbs, but to be a little more scientific and precise will get temps from the header pipes using a infrared thermometer at work as I'm curious and want to know if the cylinders really are balanced heat wise now.
 
OH Kwel, I've been eying remote thermometers as want to know too. Takes a higher end model to read full EGT range. I ran 1000's of miles on Ms Peel with dual EGT probes and CHT rings but the EGT 'needles' require holes in header and no one makes the hose clamps in small dia. range for Cdo headers for pretty mounting. I've still got the nasty ole test headers with O2 bungs to boot, but Peel got upside down twice and ruined the meters. Let us know what ya learn or stumps you further.
 
What kind of temps are we talking here, I have a Fluke with the thermistor and I think it reads well over 500°F? I've had it on my wood stove over 530° F. May be that something I could use to see how the carburation is working on the pipes?

Dave
69S
 
1200 to 1700 F is common EGT range at full throttle. 5 t0 7 hundred is common at idle.

An O2 sensor does not measure the temp of the exhaust. It compares the oxygen content of the exhaust with the content of ambient air by using a permeable membrane.
 
Just rode my 750 to work and left it idling in front of the shop. Got out the Fluke 87V with the 80T-IR infrared temp sensor.

Pipes at the first elbow where at about 175 F.
Second elbow 110 F.

The head at the fins was just shy of 250 F
The cylinders were the same on the fins dropping to much less at the bolting flange at the base.

And the points cover was at 82F!

Ambient temp here is about 60F. This is hardly conclusive of anything but interesting just the same.

Russ
 
Your infrared temp sensor is not going to give you a good reading on a chrome or polished surface or any reflective surface. Read your manual. Jim
 
I would think that the cylinders being painted black would be close. The aluminum is not that shiny. As for the pipes, I am not going to spray them flat black to try to get a more accurate reading. As I said it is "hardly conclusive"...I didn't mean to mislead anybody nor was the information intended to be anything but sharing a curiousity developed by reading this thread.

FWIW-the siding on the shop is tan metal and there is an aluminum backed thermometer attached to it. The infrared sensor shows the same temp as the thermometer when pointed at the aluminum and the tan metal. Again, hardly conclusive but at least I made a small attempt to test the sensor on a known quantity.

Carry on,
Russ
 
Russ, I didn't mean to bust your balls, just wanted to point out infrared sensors are of limited use on a engine. I know I have compared the readings I have got from mine and found out the only place the infrared agreed with the thermocouple on my bike was on the flat black side of the oil tank. The thermocouple in the oil read within a few degrees of the infrared pointed at the side of the tank. The engine and exhaust temps were way off. Jim
 
I read up on IR thermometers and was not aware of emissivity affecting accuracy and that shiny chrome in particular will give a very inaccurate reading (though better IR thermometers can have the emissivity input)...but in my original post I said I was going to use the IR thermometer to compare the header pipes and it should work OK for that (but will also check the exhaust nuts and head since they are less reflective). I work in telecom power and we use IR thermometers mostly that way, am looking for hot spots that indicate trouble with electrical conductors, connections, also diesel engine exhaust manifolds,, turbos etc. more that an absolute accurate temperature reading
 
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