[akh]

Hi there!

I'm trying to clean up and remove rust from my exhaust pipes. I belive they are stainless steel.
I have tried polishing with and soaking in vinegar and baking soda, but that did not do very much. Right now I'm trying to polish with autosol chrome polish (which should also work for steel) and that works okay on the parts that are not covered in a layer of rust and it removes rust among the smaller dents in the steel. This seems to be okay, albeit slow, and I suppose the smaller dents aren't a concern.

There is a somewhat thick layer of surface rust on some parts of the pipes, in particular the parts that are facing forward / against the road. The pipes look completely smooth on the inside so it hasn't gone all the way through yet, at least. How much of a problem is this and what can be done about it? Can this kind of rust be removed using chemical methods (diet coke and aluminium foil) or does it require polishing with steel wool or something else?

What would be a good choice for dealing with this kind of exhaust pipe rust, should I polish it completely and paint it / wrap it, or can it be kept under control in some way?

Thank you!

 

[goldy]

Are you sure they are stainless steel? It's hard to tell from pictures and there are so many grades that sometimes it can be hard to tell...most grades are not ferromagnetic, but some are.

If the pitting is bad enough, you may have to resort to emery cloth strips, start with a fairly fine grade and progress to finer grades until you get it to the point that it will respond to a buffing wheel...this of course depends on the type of finish you want.

As far a keeping it clean goes, there is nothing that works like a regular application of elbow grease....and then there is the ceramic powder coat option.

 

[akh]

I'm not at all sure that it is stainless steel, I don't know much about identifying metals, but it was my best guess. The metal is attracted to magnets, but I'm not sure if that makes it ferromagnetic. How does this affect the removal of rust?

Do you think the rust layer can be removed without sanding, for instance using some chemical method? I'm thinking that would be a good thing to try before starting sanding, if it might work.

What kind of finish can you get from using emery cloth strips? I'm not after anything specific, but then again, I don't really know much about this.

 

[goldy]

Using different abrasives of increasingly finer grades you can bring stainless to the point where is is almost like chrome, but I am beginning to doubt that these are actually stainless steel.
It's hell of a lot of work to go to...I would recommend that you get them ceramic coated...if that's too expensive, then just get out the high heat black paint and make it easy on yourself.

 

[o1marc]

Are you sure they are stainless steel? It's hard to tell from pictures and there are so many grades that sometimes it can be hard to tell...most grades are not ferromagnetic, but some are.

If the pitting is bad enough, you may have to resort to emery cloth strips, start with a fairly fine grade and progress to finer grades until you get it to the point that it will respond to a buffing wheel...this of course depends on the type of finish you want.

As far a keeping it clean goes, there is nothing that works like a regular application of elbow grease....and then there is the ceramic powder coat option.

Just FYI, Ceramic coating has nothing at all to do with powder coating other than some powder coaters also do Ceramic coating. Ceramic is a wet paint process and not dry like powder.

 

[DesmoDog]

Using different abrasives of increasingly finer grades you can bring stainless to the point where is is almost like chrome, but I am beginning to doubt that these are actually stainless steel.

This only works for certain grades of stainless. 409SS, which is what most automotive systems are made of these days, will not polish well. Grades of stainless that attract magnets do not polish well IIRC. Most polished exhaust systems are 300 series stainless, which turns gold/bronze/brown when it gets hot. Or purple if you get it REALLY hot, like if one cylinder is misfiring, don't ask how I know.

Kinda moot though since stainless doesn't rust. Yes, 409 will corrode but it doesn't get red rust. I also don't know of any company that chromed stainless steel exhaust systems so I'd have to say the chances this system is stainless are right around zero. I'm guessing you're looking at the typical chrome plated carbon steel. Fighting the rust is a losing proposition. To do it right would take a boatload of work. When I found myself in this position a few years back i did a temp fix of wire brushing the surface then spraying it with high temp paint. This was simply so I could ride it until I could come up with a new exhaust for it.

I'm not all that familiar with ceramic coatings but I doubt it would be worth the money on a used rusty system? I would think the prep work to get it to stick would be expensive?

 

[o1marc]

This only works for certain grades of stainless. 409SS, which is what most automotive systems are made of these days, will not polish well. Grades of stainless that attract magnets do not polish well IIRC. Most polished exhaust systems are 300 series stainless, which turns gold/bronze/brown when it gets hot. Or purple if you get it REALLY hot, like if one cylinder is misfiring, don't ask how I know.

Kinda moot though since stainless doesn't rust. Yes, 409 will corrode but it doesn't get red rust. I also don't know of any company that chromed stainless steel exhaust systems so I'd have to say the chances this system is stainless are right around zero. I'm guessing you're looking at the typical chrome plated carbon steel. Fighting the rust is a losing proposition. To do it right would take a boatload of work. When I found myself in this position a few years back i did a temp fix of wire brushing the surface then spraying it with high temp paint. This was simply so I could ride it until I could come up with a new exhaust for it.

I'm not all that familiar with ceramic coatings but I doubt it would be worth the money on a used rusty system? I would think the prep work to get it to stick would be expensive?

The prep work would be the same as any new pipe would be. Sand blast with the proper media and profile and shoot the ceramic. It is more worth than spending big money to replace them. Your last few posts have made me lose any confidence in what you say on the subjects, you seem to be greatly misinformed.

 

[goldy]

Well, I'll be damned...my old trade school teacher once told me that if I ever had a day that I didn't learn anything new, I could say I had a bad day. This is a good day!
I have a buddy who does powdercoating and ceramic coating too...I just assumed it was a similar process. Thanks o1marc for setting me straight.

Oooo, some grades of stainless rust...especially around here, but it usually cleans up pretty easily.

 

[o1marc]

I made my intake manifolds out of SS bends and 5/16" plate. They rust like crazy if you don't maintain them. These polish up like chrome.

 

[akh]

This only works for certain grades of stainless. 409SS, which is what most automotive systems are made of these days, will not polish well.
(..)
I'm guessing you're looking at the typical chrome plated carbon steel. Fighting the rust is a losing proposition. To do it right would take a boatload of work. When I found myself in this position a few years back i did a temp fix of wire brushing the surface then spraying it with high temp paint. This was simply so I could ride it until I could come up with a new exhaust for it.

The prep work would be the same as any new pipe would be. Sand blast with the proper media and profile and shoot the ceramic. It is more worth than spending big money to replace them. Your last few posts have made me lose any confidence in what you say on the subjects, you seem to be greatly misinformed.

Without being completely sure about the type of metal they're made of, do you think the rust can be removed using emery cloth strips or possibly a wire brush? I don't really want to spend money on new pipes or ceramic coating (not on this bike at least) so how about the high temperature paint option? Is it durable enough and what is required before painting? Any recommendations for paint, how high a temperature resistance?

 

[o1marc]

Without being completely sure about the type of metal they're made of, do you think the rust can be removed using emery cloth strips or possibly a wire brush? I don't really want to spend money on new pipes or ceramic coating (not on this bike at least) so how about the high temperature paint option? Is it durable enough and what is required before painting? Any recommendations for paint, how high a temperature resistance?

You can use sandpaper or emory down to about 800-1000 before polishing them out. I heard mention of chrome, you're pipes are not chrome plated are they? If they are and that pitting is through the chrome then you're pretty screwed on fixing it easily. More often than not, in my experience, high temp paints aren't very durable.

 

[akh]

You can use sandpaper or emory down to about 800-1000 before polishing them out. I heard mention of chrome, you're pipes are not chrome plated are they? If they are and that pitting is through the chrome then you're pretty screwed on fixing it easily. More often than not, in my experience, high temp paints aren't very durable.

800-1000? What is that in regular (european?) grit? 80-100?

I'm pretty sure they are not chrome plated, but yes chrome plated carbon steel was mentioned by DesmoDog.
Both the muffler and the pipes are aftermarket parts that the previous owner put on. I'm really sure the muffler is chrome plated and I supposed it would be affected in a similar way if the pipes were also chrome plated. I might be wrong though.

No one really says anything about chemical methods, how about for instance oxalic acid or something like that, as mentioned here: http://www.caferacer.net/forum/technical/21924-removing-rust-2.html, or is it only on chrome?

 

[o1marc]

800-1000? What is that in regular (european?) grit? 80-100?

I'm pretty sure they are not chrome plated, but yes chrome plated carbon steel was mentioned by DesmoDog.
Both the muffler and the pipes are aftermarket parts that the previous owner put on. I'm really sure the muffler is chrome plated and I supposed it would be affected in a similar way if the pipes were also chrome plated. I might be wrong though.

No one really says anything about chemical methods, how about for instance oxalic acid or something like that, as mentioned here: http://www.caferacer.net/forum/technical/21924-removing-rust-2.html, or is it only on chrome?

Not 80-100, you'll never polish out the scratch marks left from that aggressive sand paper. Wire brush the heavy oxidation off and then sand with fine sandpaper till smooth and them polish the rest out.
Polished carbon steel pipes would rust within minutes of polishing, no one does that.

 

[Dean]

If you promise not to laugh, a few coats of Mop & Glo on steel pipes prevents rust. It gets a faint golden tint after a few heat cycles, but it really works. A trick used by the 2T guys with raw steel chambers. No, really, stop laughing ! It is one of legendary Dave Friest tried and true tricks/

 

[akh]

I have sanded a bit with some 320 grit sandpaper which I think is actually emery on paper. It's brownish wet/dry sandpaper in sheets, I haven't been able to find emery cloth strips anywhere around here (Copenhagen).

I haven't worked much on it due to lack of time and I think I will get some brush for a power drill to speed things up before finishing off with the sanding. It seems to be working okay though, the rust layer from before is mostly flat now, with a few indents.

Do you think this will rust quickly if left unpainted after polishing and applying some chrome polish?

 

[o1marc]

Yes it will rust. The old rust has pitted the surface so there isn't going to be much you can do to make it really shine for any period. I would high temp paint them, ceramic coat them or wrap them to make them cosmetically more pleasing. But as a chrome shiny pipe they are done.

 

[akh]

Yes it will rust. The old rust has pitted the surface so there isn't going to be much you can do to make it really shine for any period. I would high temp paint them, ceramic coat them or wrap them to make them cosmetically more pleasing. But as a chrome shiny pipe they are done.

Okay, how clear should it be before painting or wrapping? Does wrapping create issues with trapped water? Otherwise I'm thinking that wrapping might look better for longer than the high temp paint, though I'm not sure if it will look weird on the mostly standard CB400N that they belong to.

 

[o1marc]

Those pipes are far enough gone that I wouldn't worry about what the wrap will do. I would high temp paint them to help seal them from rust, wrap them and silicone seal them according to the directions.

 

[kerosene]

but wrap will make them disappear (rust away totally) faster. the 800 grit mentioned earlier is exactly same rating in europe and us. Its just very fine - you can find paper up to at least 1200 - its very very fine and about polishing, not about removing material in big amounts.
use heat resistant spray paint. Highest rated decent brand you can find. It will work okay. Don't wrap it.
If you can sand blast it then do it but don't if its not handy for you. They will never bee pretty as new but you can get decent service life out of them with the paint.

above are my personal opinions for keeping the bike on the road - not for show or selling the bike. If you are just trying to sell it wrap could work (still paint 1st). One reason to avoid bikes with wrap...

 

[Mark Burton]

Give them a few coats of heat resistant paint and lay it on a little heavier around the rough area. When its fully dried, sand back lightly with some 800 grit wet and dry paper as the paint will fill some of the pit-marks. Re-apply more paint in light coats and you should have a smoother looking finish.

Wont ever be 100% by doing this, but the result will be better.