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Rust removal from a painted tank ?

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Grewth:
Here is my collection (so far) of 750F tanks.
CB750 in Flake Sunrise Orange with unfortunately a nasty dent in the top.
CB750F1 in rust all over, inside and out.
And CB750F2 in quite good condition except for a sodding great dent on the LH side.
All three are mucky on the inside,  fuel residue and maybe a failed liner on the F2, the F0 and F1 have loads of rust inside,  both fixed and loose flakes.
Fortunately none of them seem to have rotted out yet (I know where to look).
Ideally I'd like to use the Orange tank on my project bike, with it's 50 YO original paint.
I'm just wondering what the best way of dealing with the rust would be,  without damaging that paintwork any further  ? [ Guests cannot view attachments ] [ Guests cannot view attachments ] [ Guests cannot view attachments ]

Athame57:
If the dent in the orange tank is free of any creases I think it could easliy be pulled out.
https://youtu.be/dity9_i6UVY

Grewth:

--- Quote from: Athame57 on June 15, 2025, 05:25:25 PM ---If the dent in the orange tank is free of any creases I think it could easliy be pulled out.
https://youtu.be/dity9_i6UVY

--- End quote ---

There's a nasty crease just by the hinge point of the filler flap, unfortunately.
I've no doubt that some of the dent may pull out with DIY  paintless dent removal tactics, but not that crease which annoyingly runs across the panel line.
A professional could probably get it near perfect, but it's unfortunately not worth it for an old, faded, chipped paintwork

Oddjob:
Not sure if I saw this on this site or the yank site but they use a process called electrolosis iirc. It’s essentially a large cork or plastic bung that seals inside the opening with a large bent nail sticking through it, they then fill the tank with water ( there may be something in the water, not sure) and then attach a battery charger to the protruding end of the nail and the tank. Evidently the electrical charge forces rust off the inside of the tank and makes it attach to the nail or bolt. After a few hours, remove the nail and clean off the rust and keep repeating until all the rust is removed. From all reports it’s an excellent way or doing it and dirt cheap. Rinse the tank in diesel afterwards to prevent flash rust.

Sure someone one here who has done this can expound on any parts I’ve got wrong. 

Athame57:

--- Quote from: Oddjob on June 15, 2025, 07:36:49 PM --- Rinse the tank in diesel afterwards to prevent flash rust.

--- End quote ---
According to this youtube, and there are quite a few, you won't even need to that, unless perhaps if you are going to store it.  I gather that it does need to be done in a well ventilated place though, so not in your bedroom!  ;D
https://youtu.be/OGjtx2BgK-U?si=hwR--QUGHkMm-VXx

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