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I was reading about how to polish the stock header on my 1990 Dr 650 and what I read said that it was stainless steal but when I stuck a magnet to it the magnet stuck. Does this mean its just low grade stainless? How would I go go about polishing it?

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From Wiki:

There are different types of stainless steels: when nickel is added, for instance, the austenite structure of iron is stabilized. This crystal structure makes such steels virtually non-magnetic and less brittle at low temperatures. For greater hardness and strength, more carbon is added. With proper heat treatment, these steels are used for such things as razor blades, cutlery, and tools.

(italics mine)

Most stainless is non-magnetic. The later DR ('96 on) headpipe is non-magnetic SS.

However, my older DR (pre-96) has a common mild steel exhaust system.

I am guessing the headpipe on your '90 is NOT stainless. :bonk:

James

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The 300 series stainless has nickel and chromium added and has a face centered cubic structure, the same structure as aluminum. This structure is NOT as strong as face centered cubic but at the same time doesn't rust since it's own oxide layer protects it. It is non magnetic.

The 400 series is body centered and magnetic.

Stainless steel is NOT as strong as normal steel. Example. The tensile strenth of SS is about 36000 psi while a steel is 54,000 or better.

The only feature about stainless is it doesn't rust.

As stated it's low temperature brittlement is also very good. Meaning it will not break prematurely at low low temperatures. Not many of you have access to liquid nitrogen so you will not see the difference.

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Don't bother polishing, get them coated. There's a place here in the San Diego area that can coats automotive headers for $200-$300, so a single header pipe shouldn't be that much. You can choose black, grey, silver.

There must be something like that close to you. Any place that does powder coating can do thermal coating...

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I was reading about how to polish the stock header on my 1990 Dr 650 and what I read said that it was stainless steal but when I stuck a magnet to it the magnet stuck. Does this mean its just low grade stainless? How would I go go about polishing it?

I don't know what the pre 96 head pipes are made out of. The 96 and up units are stainless and can be polished. You will get the normal gold tint (blueing near the exhaust port) after some time. JetHot is another good option for coating your head pipe... :bonk:

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