Like Hub said, it's usually caused by an overly lean mixture...unfortunately, with the exception of a few pipe/muffler manufacturers, they put a disclaimer right on their adds that they are not responsible for blueing as that is a result of tuning of the motorcyce and not the manufacturing of the pipes/mufflers.
There's a lot of opinions out there about chrome and heat dicoloration. It's really just a combination of physics and chemistry. Get chrome plating above 900 degrees F and it will discolor. Exhaust gases at the head are routinely above 900 degrees. As for lean conditions causiing it, apparently it can be caused by rich conditions as well. This from the Khrome Werks website:
"Is exhaust bluing a warrantable condition?
No. All chrome plated steel exhaust pipes or mufflers will "blue" or discolor when the surface temperature reaches 900°F. This can occur if the fuel mixture is too rich. Instead of the charge burning mostly in the combustion chamber, the mixture continues to burn after the exhaust valve opens, down the pipe, causing extreme heat and bluing of the metal and its plated surface in the most restrictive areas - most commonly the bends or the baffle area. Cleaning products, such as Blue Buster™, are available and when properly used are quite effective in removing most discoloration from pipes. Heat shields are now available for 3" mufflers."
In my experience, you can lessen but not completely eliminate discoloration, regardless of how well the motor is tuned. Painting the inside of new pipes with high-temp paint helps some. But heck, when I first started riding, folks liked that blue/gold color around the heads--it meant the bike actually got ridden. Back then, those who didn't like the blueing wrapped thin copper wire around the top of their pipes to act as a secondary heat sink but not even that stopped it entirely. Most though, saw it as a badge of honor sort of thing. Like faded Levi's as opposed to brand new. Times have changed. And that's why heat shields have gotten larger and larger.
Now if you're getting discoloration down around the mufflers, there might be something to complain about, chrome-wise, or something wrong elsewhere.
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Topic: Blued Mufflers (Read 5151 times)