Excessive header pipe bluing

Back when British bikes ruled the roost and before the Jap bikes set the new standard an old trick was to wrap a few turns of copper wire (from an electrical cord) around the header pipe as close as possible to the head. For some reason this stopped the pipes blueing. When a friend bought one of the new water cooled BMW Gs he tried this. The pipes blued down to but not past the copper wire. As I said I have no idea how/why this should work.

I'm sorry to disagree with people on here, but having ridden commandos for 40 years, on a daily basis in my youth. I never road in a parade (an earlier poster). If pipes are turning blue then something is out of kilter, either timing or carb tuning. Straw was a normal colour. Having said all that if you're wringing it's neck road racing flat out all the way then they could get a little blue.
Terry

aussie said:

Back when British bikes ruled the roost and before the Jap bikes set the new standard an old trick was to wrap a few turns of copper wire (from an electrical cord) around the header pipe as close as possible to the head. For some reason this stopped the pipes blueing. When a friend bought one of the new water cooled BMW Gs he tried this. The pipes blued down to but not past the copper wire. As I said I have no idea how/why this should work.

Click to expand...

I have not heard of this before now, but the following may explain how/why it works.

The wire will create air turbulence that disrupts the laminar boundary layer that is "stuck" to the otherwise smooth pipe. A laminar layer of air is actually a good insulator, so if one can disrupt it and cause it to mix with the surrounding airflow, then lower surface temps will result on the pipe. The process is similar to stirring the contents of a saucepan on the cook stove to remove the hot layer at the bottom and mix it with the fluid above.

Similarly, surface roughness on cylinder barrels causes the same effect, so cylinder fins should not be polished or coated with anything that results in a smooth finish.

Slick

lazyeye6 said:

Snorton74 said:

I coated the new exhaust pipes on my Triumph Tiger with a product made by Kreem (see below). After 5,000 miles they still
look like new with just a slight blush of golden color at the bend. It is a good practice to get yer bike perfectly tuned with
old pipes before installing the new ones. Yes, it is easy to misadjust a Mikuni with the air screw. This product is an inexpensive solution.

http://kreem.com/blueshield.html

There are a number of high temp paints and ceramic coatings that can be used to coat the inside of exhaust pipes to control
heat. Most are more expensive and some are very very expensive. Do a google search.

Click to expand...

Click to expand...

Well….. this Kreem seems to be so good at being able to withstand a temperature of 1800 degrees you wonder why they don’t make heat resistance paint that you can put on the exterior like the barrels, but if you scroll down on the instructions ;
“Crystobalite (crystalline silica) formed at high temperatures (above 1800 degrees F) can cause sever respiratory disease.”

So perhaps not :!:

Bernhard said:

lazyeye6 said:

Snorton74 said:

I coated the new exhaust pipes on my Triumph Tiger with a product made by Kreem (see below). After 5,000 miles they still
look like new with just a slight blush of golden color at the bend. It is a good practice to get yer bike perfectly tuned with
old pipes before installing the new ones. Yes, it is easy to misadjust a Mikuni with the air screw. This product is an inexpensive solution.

http://kreem.com/blueshield.html

There are a number of high temp paints and ceramic coatings that can be used to coat the inside of exhaust pipes to control
heat. Most are more expensive and some are very very expensive. Do a google search.

Click to expand...

Click to expand...

Well….. this Kreem seems to be so good at being able to withstand a temperature of 1800 degrees you wonder why they don’t make heat resistance paint that you can put on the exterior like the barrels, but if you scroll down on the instructions ;
“Crystobalite (crystalline silica) formed at high temperatures (above 1800 degrees F) can cause sever respiratory disease.”

So perhaps not :!:

Click to expand...

Do barrels get that hot? Hard to believe. There are several quality high temperature paints on the market designed for engine
(barrels) exteriors. I have successfully used VHT brand.

Odd how the same subject crops up in different lists & forums at the same time. Here's a post I wrote yesterday on the bevelheads list. Mind you, I'm quoting a 20 year post here.....

It's important to remember why stainless & chrome get these colours.
Nearly 20 years ago, Charles Falco (professor of optics at the Uni of
Arizona wrote a very good description of this. I had to dig into the you
Brit-Iron archives to find this:

"At 07:20 PM 8/26/98 -0400, you wrote:
> _> physics ruins restorations._
>
> _And sometimes new underwear._
>
> _One o' the early substances used for mirrors was quicksilver, which some_
> _folks call mercury. Tends to hang with a fella'_
>
> _Listen, while you're on this metal reflectivity kick, why don't you_
> _advise as to how come stainless, chromium, and other alloys change color_
> _(ok, change the color(s) they reflect) when they get hot as hell._
>
> _For example, when the exhaust pipes turn blue, what gives? Are we_
> _looking at some sort of compound between the chrome and stuff in the_
> _air, or what?_

The colors you're seeing on formerly-hot pipes are the result of an
interesting phenomenon: the destructive interference of specific
wavelengths/colors of light due to the formation of semi-transparent
oxides
that are of roughly comparable thickness to the wavelength. Note that
the
visible spectrum covers ~7000 Angstroms (red) ---> 4500 Angstroms
(violet),
and that 10,000 Angstroms = 1 micrometer = ~39 micro-inches. As a rough
approximation that's good enough for the present discussion, light with
a
wavelength that is approximately 4x the thickness of the oxide will be
absorbed by the film rather than be reflected. Such a film is called a
"quarter-wave anti-reflection coating." Thus, if an oxide is, say, ~1750
Angstroms thick, light near the red end of the spectrum (7000 A = 4 x
1750)
_won't_ be reflected, leaving mostly blue in the light bounced back to
our
eyes.

> _Howcome you (I) can remove discoloration of Stainless steel by_
> _mechanically gouging it off with a wire brush, but if I try to remove_
> _the bluing from chrome, the chrome comes off with it?_

The reason is the head of your stainless steel fastener is ~1/4" thick,
so
polishing away a few few micro-inches of oxide removes a negligible
amount
of the fastener. However, decorative chrome plating is only a few
micro-inches thick (~500-1000 Angstroms) to begin with, so by the time
it's
blue or yellow, all that's left of the plating is a transparent film of
chrome oxide anyway.

> _The exhaust bluing thread hasn't been around for a week or two, maybe_
> _this time it could present some science._

Amal jetting doesn't kill chrome, physics kills chrome.

Charles Falco"

---
Steve Borland
steve@it.dk

Bernhard said:

“Crystobalite (crystalline silica) formed at high temperatures (above 1800 degrees F) can cause sever respiratory disease.”

So perhaps not :!:

Click to expand...

Just don't grind it up fine and breath it and you will be fine.

aussie said:

an old trick was to wrap a few turns of copper wire (from an electrical cord) around the header pipe as close as possible to the head. For some reason this stopped the pipes blueing.

Click to expand...

I recall hearing or reading about this years ago and always assumed that this was due to the superior thermal conductivity of copper when compared to the chrome plated exhaust pipe. The copper wire was sinking away the heat with the added surface area of the wraps and superior thermal conductivity, keeping the conduction through the steel from going further down the pipe. As Slick has stated, it may also be turbulence. I really never gave it much thought back then but figured I would share this with everybody anyway.

Dances with Shrapnel said:

aussie said:

an old trick was to wrap a few turns of copper wire (from an electrical cord) around the header pipe as close as possible to the head. For some reason this stopped the pipes blueing.

Click to expand...

I recall hearing or reading about this years ago and always assumed that this was due to the superior thermal conductivity of copper when compared to the chrome plated exhaust pipe. The copper wire was sinking away the heat with the added surface area of the wraps and superior thermal conductivity, keeping the conduction through the steel from going further down the pipe. As Slick has stated, it may also be turbulence. I really never gave it much thought back then but figured I would share this with everybody anyway.

Click to expand...

I will agree that Dances' explanation may be as valid as mine. It may be both conduction and turbulence, but which is the greater, is a matter of conjecture.

Except for the fact copper will eventually take on an ugly green color, it may be worth a try.

Slick

As I said I do not know why/how this works. Of interest the copper wire will change colour to a matt black.

I used the two or three turns of copper wire on my exhaust pipes right up close to the finned nut. Anchor the wire round one of the fins out of sight, works a treat. Copper is the best conductor of heat that is easily available and wicks the heat out of the pipe before it colours the chrome. I notice the 961 Commandos blue their pipes a treat, probably a function of running weak to achieve emission targets.