Brown stains on exhaust pipes

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<DIV>Hi all</DIV> <DIV>I have fitted a set of stainless exhaust pipes from Keihan to my triple. I've done about 150 miles and the tops of the pipes have a dark brown discolouration on them on the outside of them where they curve down just after they exit the cylinder head.</DIV> <DIV>I was expecting blueing and yellowing but not this.</DIV> <DIV>Is this discolouration normal, and if so, is it removable and once removed will it return.</DIV> <DIV>If it isn't normal should I contact Keihan about it.</DIV> <DIV>Thanks</DIV> <DIV>Simon</DIV> <DIV> </DIV>
 
<DIV>I used to work for a Truck Exhaust Mfr, building prototype systems, the vertical ones with the Polished Tailpipes, and we got exactly the same questions from the truck drivers.</DIV> <DIV> </DIV> <DIV>Its perfectly normal and polish it out of you like and expect to do the same thing after the next time you ride it. Its not a fault with the material, its a natural process.</DIV> <DIV> </DIV> <DIV> </DIV> <DIV>My humble advice for you to ignore :)) is enjoy the bike and  forget about the pipes, it shows you ride it, thats a good thing, after cruising round classic shows viewing bikes with unmarked down pipes.</DIV> <DIV> </DIV> <DIV>Probably less likely with Chrome, except at the top where you will eventually see blue pipes instead, or try an internal ceramic coating.</DIV> <DIV> </DIV> <DIV>Best intentions.Rob</DIV>
 
<DIV>...have this tooo.  polish it to make shiny b but as Rob says, its a waste of time really trying to get back to silver....just be grateful your bike runs sweetly and you havn't had to spend 4mnths and money on a re-build, eh?!</DIV> <DIV> </DIV> <DIV>Nick 7<IMG height=19 src="/forum/msnemoticons/emwink.gif" width=19></DIV>
 
<DIV>Hi Simon,</DIV> <DIV> </DIV> <DIV>As the others have said, it is completly unavoidable. SS oxidises light brown to begin with, then through shitty brown to purply-brown as temperatures increase. If you clean it of, it will come back on the first run. (Chrome oxidises blue etc, SS does not).</DIV> <DIV> </DIV> <DIV>Keihan use 304 SS I think, it is possible to chrome plate 304, but requires a special nickel pre-plate to gain correct adherence. Chrome plating oxidises about 100-150?C higher than raw SS.</DIV> <DIV> </DIV> <DIV>Paul H</DIV>
 
<DIV>Hey Simon. It could be worse, you could have brown stains on your underpants <IMG height=19 src="/forum/msnemoticons/emwink.gif" width=19></DIV> <DIV> </DIV>
 
<DIV>Thanks for all the info guys.</DIV> <DIV>I suppose I should should give it one extra wipe !</DIV> <DIV>Simon</DIV>
 
<DIV>I get my stainless pipes etc back to brilliant polished/new look every couple of years (oh allright every ten years) by taking them to the polisher in the winter.</DIV> <DIV>CLEM</DIV>
 
<DIV>I have used pickling paste, designed for removing discoloration after welding stainless steel, this simply paints on then rinses off with water. It is quite a nasty acid so if you are doing the pipes on the bike it is a good idea to cover the surrounding areas. After leaving the pickle on the pipes for five minutes the brown oxide just rinses away with lots of cold water, a quick buff with solvol and the pipes look new again. The oxide can also be removed with grey scochbrite and wd40 altho' this requires a bit more elbow grease it does bring the pipes up nice again, finish with a bit of solvol and some more elbow grease.</DIV> <DIV> </DIV> <DIV>   Keith.</DIV>
 
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