Bike restoration advice

[Farmingstock]

Hello all

I’m restoring a CR250 and the frame looks to have some internal surface rust, is there anything that I can do to get at this before painting?

I’m sure blasting wouldn’t get to it so was thinking about dipping it/zinc plating or equivalent? Has anyone done this before?

Cheers

[WD Forte]

I used to flood old frames and swinging arms with old engine oil
after painting and let most of it drain out before assembly
This worked well for me.
I recall doing this to a rusty swinging arm I repaired/welded in 2005
which was still sound in 2020 when I flogged the bike.
____________________
bikers smell of wee

[Robby]

Blast it first, then see how much metal is left.

[stinkwheel]

You could block all the holes and fill it with evaporust/deox-c then hose it out, then spray a corrosion inhibitor (like waxoyl or ACF50) up in there after painting.

White vinegar would also work and is much cheaper, takes about 24-48h. You'd want to flush thoroughly then neutralise with some bicarb solution if you do this because it'll flash rust almost as you watch once it's drained.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Stripperbo]

For that internal rust, filling the frame with something like Evapo-Rust or Deox-C could be a good move. Just plug the holes, let it sit for a day or two, and then flush it out.
White vinegar works too, though it's a bit harsher—just remember to rinse well and use some bicarb to neutralize afterward, or it’ll rust up again real quick.
Once you’re done with the rust treatment, you could coat the inside with a corrosion inhibitor like ACF-50 or Waxoyl. That way, you’ve got a layer of protection before painting. If you’re into the restoration vibe but want to skip some of the rust battles, maybe look at something like the E Ride Pro SS—all electric and no frame rust to worry about.

[jeremyr62]

Or if you are a skinflint, use a tin of black treacle diluted with water and let it sit for weeks.It works the same way as Evaporust but is virtually free and slower. All those chelating rust removers work better if you can periodically remove any residue to expose the rust. Won't be easy with the inside of frame but even flushing it out with hot water will help before putting the rust remover back. I cleaned a rotten VFR1200 centre stand with treacle and water mix and it took weeks but it got rid of all the rust completely.

[Ducked]

Aircraft with tubular steel frames use/used linseed oil, so if its good enough for them...cant remember if that was "boiled" linseed (which sets faster) but I'd think inside a frame there wouldn't be a big hurry, and untreated linseed might soak in better, especially where there was already surface rust.

In Taiwan (AFAIK) I cant get linseed so I've been using sunflower as a rust treatment, which also sets but more slowly.

Where there is access, rubbing with aluminium (for example,crumpled foil by hand, or flattened beercan disk in a power drill) with veg oil as a binder generates a metallic "primer" paint in situ. Surfaces roughened by corrosion pick up more aluminium, so its to some extent self-adjusting. The aluminium can also tend to fill in the pits in corroded fork chrome.

I'm not sure whether veg oil is better than motor oil inside a frame, but I'd think a follow-up with MO a year or two after veg treatment might be optimal, and tend to limit mold that might otherwise develop in an enclosed space like the inside of a frame tube.

[Ducked]

Thread cleaning:-

Take your beer can, and empty it.
Stick your bolt in the emptying orifice
Rotate the pull tab against the bolt with your thumb, forcing the bolt against the sharp edge of the emptying orifice.
Rotate the bolt back out.

If you neglected to fully empty the can your beer residue is rusty.

(RTFM!)