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