Some things I think I know... some things I don't know if I know, you know? I've got a CB 125 tank here that goes to a bike I've been picking away at. There's wear through the paint and a little rust inside. I could use some sage advice so I don't just stick it back on (in my haste to ride the damn thing). Pics are at the bottom of the post for reference. Question 1. There are several places where the paint has worn through to bare metal. As far as I know matching the metallic paint is impossible so I only see three options. Which is best? Shut up you ninny and just ride it. To hell with rust! Strip it and paint it. Maybe flat (ooooo, cool) or red (as it's fastest) Remove the rust, treat the metal and clear coat that sucker several times. And then go ride. Question 2. There's a little rust forming in the tank. Nothing that's leaking (yet) but I don't trust it. I'm partial to option #3. Run what you brung. What's the worst that could happen? There's this stuff called Creme. It might work for awhile. Bolts and POR-15 for you! What say you?
Do NOT use Kreem. Today's fuel will destroy it and leave a mess. For the little bit of rust you have, I'd just put an inline filter in and use it. Or you can use a commercial rust remover. If you feel you must line the tank, Caswell is the way to go. http://www.caswellplating.com/restoration-aids/epoxy-gas-tank-sealer.html
That tank looks pretty good. I would leave it alone. Original authentic finishes make the bike more valuable. Wax it, and run it! The few specks of rust inside the filler neck also don't look bad. If that is the worst of the inside, then I would forget about it.
"Picking away at" - I love it. The paint looks like it's mostly intact and still shines. If it were mine, given that the places that are missing paint are so small, I would get touch-up paint (as close as I could get, slightly lighter than darker if an "exact match" isn't possible and run it. I had good luck at an large Advance Auto store. Or, for a bit more $, an automotive paint supplier (we have a large NAPA that has paint) can mix you up a touch-up color that will probably come very close (either brush on or a spray). I'd also either do nothing except run a filter for the inside rust, or try Evap-O-Rust. I wouldn't coat it. Best of luck with the bike!
I wouldn't touch the inside or the outside, and an inline filter most certainly wouldn't hurt. If you feel as though you must clean and coat the inside my personal experience is with POR-15 and I highly recommend it.
I used kreme in the tank on my R69S back in 1996, and it's survived a good 5-6 years of 10% ethanol going through it. Kreme gets a bad rap because so many users do a crappy job of preparing the tank. A handful of nuts and bolts with wd40 isn't the right way to prepare the tank. And I think the tank looks ok too.
Progress moves on. Today, there are better materials than we had 20 years ago. I've seen more crummy Kreem jobs than good ones.
Thanks for all the replies. Plan, based on comments here and some thinking, is to just wax the hell out of it and ride. That is... after I put it back together this winter.
No question that materials have improved over time. Kreem goes back a lot further than 20 years. But that doesn't absolve incompetent prep work as the reason for failures of tank repairs done using Kreem. I have three bikes with tanks lined with Kreem going back to 1984 which are all doing just fine, thank you very much. Two of them will never see ethanol, but that's got nothing to do with concern for the integrity of my repair jobs.
Use Red-Kote on the inside of the tank. Just be darned sure that you do it in a well ventilated area.
