Rust Converter/Phosphoric Acid

[xp_wannabe]

G'day fellas,

I am trying to restore the expansion chamber on my MX bike.

The pipe is a Pro-Circuit "Works" finish pipe, which just means it is raw steel...

They look like this when new:



But after just a few rides (so the previous owner says) mine is looking like this..



That is actually after I have had a crack at it with Septone Rust Converter.

My process went like this:

Spray pipe with degreaser, scrub the whole thing with 5 row wire brush
Degreased and hosed off
Wiped down/dried with clean rag
Brushed on rust converter (undiluted)
Left on for 30 minutes
Attacked again with wire brush

The rust converter did bugger all... The biggest difference was the step prior to that with just degreaser and wire brush...

I have degreased, hosed off, dried and reapplied the rust converter.

I am going to leave it overnight, will this hurt the metal?

Thanks in advance, Mark

[cs123]

It won't hurt the metal from my experience.

What are you trying to achieve?

You might be better of getting it ceramic coated.

[kevvy101]

Hi, a "rust converter" is a cheap and lay persons way of metal treating the steel. A phosphated or "rust converted" substrate should be dull grey in appearance as the conversion coating is a rudimentary iron phosphate coating. If you wish to revert to the original appearance of a high lustre metallic finish, chrome plating would be the best as this is a metal coating which is extremely hard wearing and gives the added advantage of a high lustre metallic finish.
Cheers.

[my67xr]

chrome wont last too long on an expansion chamber, they get very hot.
after a couple of rides it would be cooked and discoloured.

get yourself some rubber gloves, im guessing you used them before
and some 3M Green scotchbrite pads, cut into 1/4's.

pour a little rust convertor on the scotchbrite and rub the metal.
work in circular motion, as it doesnt leave as noticeable marks in the finish.
work your way along the piece, concentrate on a 10cm area at a time.
when you are happy with the area,
get a damp cloth and quickly give it a wipe.

post up some pics then.
im sure you will be happier with the results.

also when it is all done, use some decent brand extractor paint,
you can get it in clear , and a heap of other colours too.

ceramic coated would be your best option though.
even though that can still discolour, but its super tough stuff.

http://www.jet-hot.com.au/
http://www.pacemaker.com.au/ceramic_coat.html
http://www.performancecoating.com.au/

[aquahead2001]

If you look at the original pic of the new piece you will see the blue bands around the weld, they are the original heat affected zone from welding. Once you fired the bike up and used it in anger, you have in effect, turned the rest of the pipe into heat affected material too. Its near impossible to return the pipe to its original look I think you'll find.

The welds on the orginal piece that do not have the blue bands have been post weld cleaned using some sort of acidic wash and a good scrub or media blast. If you would be happy with that look, do the acid wash and media blast/scrub on it, but being steel without any coatings, as soon as you use it, it'll just "blue" again and start to corrode.

The ceramic coating was a good suggestion if you want it to keep the same look all the time.

[grey_esp]

if you want that polished metal look, Id just be using a flapper wheel on the grinder and give it a buff, it will rip the rust off pretty quick.

[ebxr8240]

I would have used thinned down hydrochloric acid..
And or abrasive solution and scotch brite type cloth..

[my67xr]

is that a yamaha pipe?

if you search around they may be a stainless version avaialble too?
but that will still discolour somewhat.
but will be easier to maintain, polish such as Autosol stainless is good
and if you go mad with it, it will get a mirror finish.

with my IT200

[my67xr]

oops, double post ^^ ?

i dont know if they are available for your bike, but stainless steel versions are also an option.
then it will only need a quick polish with Autosol stainless or the like
or if you wanted to go mad with it you could bring up a mirror like shine too.
http://autosol.com.au/metal-polishin...-exhausts.html


i have an 84 IT200, original the steel expansion chamber was a little rusty.
i wire wheeled what i could, then gave the whole lot a light sandblasting,
this gives something decent for the paint to key to.
then gave it a couple of coats of VHT flameproof black.
http://www.vhtpaint.com/products/flameproof/

or this paint, i highly recommend this...if you can find it.
some motorbike shops sell it.
http://www.amazon.com/dp/B00230GIX8/...8&linkCode=asn

[rijruna]

Radiator repair shops usually have a cabinet glass-bead blaster. Doesnt eat away the steel on the already very thin walled pipe like afore-mentioed flap-disc.
Cheers
Rij
Edit... I'' v over 40yrs of working as blacksmith/boilermaking to draw on if that gives me the confidence the advise light-touching with beads. Distance or a low pressure use gives the 'light-touch'