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Hi all, I'm getting to the final stages of my 71 R75 rebuild. I tried using Kreem in the fuel tank as the original lining in it had started coming off. The Kreem has pulled loose as well.
Has anyone tried the POR 15 motorcycle tank treatment? I used some POR 15 on exterior rust once and seemed to work real well. Well enough, I was thinking of using it in the tank. I have also seen another product "Red Kote". Is one product better than the other? Any recommendations will be a great help. I'd hate to have to do this a 3rd time.
Thanks, Ron

I used the Caswell sealer at the recommendation of my local independent mechanic.

https://www.caswellplating.com/epoxy-ga ... ealer.html

Be sure you have a warm place to leave the tank while it cures.

I have used both POR and Red-Kote.
Most important, though, is the prep of the tank before coating.
No matter what I've used to coat the inside of the tank, I used the first 2 steps of the POR process.
The first is a detergent. I used a length of small sized chain to shake in the tank with the solution to scrub.
The second step is a zinc phosphate solution. I used the chain again here.
I used the POR in a Triumph, BSA and Yamaha and have not had any problems. I used Red-Kote in a BMW as the red color was similar to the OEM coating, although not the same. It is more candy-apple translucent vs. the OEM "primer red" coating.

That said, the owner of the R90S I caretake sent the body pieces out this winter to have repainted. Haven't gotten them back yet, but the painter recommended using Caswell. He said it's much better than either POR or Red-Kote. Since we haven't gotten the pieces back nor had any time living with the newly coated tank, I can't give any other feedback.

Hey Mel, with the Caswell it sounds like you really do not have to get rid of all the rust. Is that true and how is your tank holding up?

Ron Baker wrote: ↑Wed Mar 13, 2019 11:16 am Hey Mel, with the Caswell it sounds like you really do not have to get rid of all the rust. Is that true and how is your tank holding up?

It's been 8 years and it looks great inside. All gas has ethanol in my state, and my home is a VERY humid place on the coast.

I'd prepped the tank by filling it with vinegar twice. First time, to remove the old red BMW lining. Later, to shake some screws around in it and to remove the rust sheen that had formed once the lining was out.

How does vinegar react to the paint? Were you working with a bare tank or what kind of precautions did you take to protect the paint.

Kurt in S.A.

Kurt in S.A. wrote: ↑Thu Mar 14, 2019 8:58 am How does vinegar react to the paint? Were you working with a bare tank or what kind of precautions did you take to protect the paint.

Kurt in S.A.

I've been busy so I haven't gotten back to this thread, but I used the vinegar after the nice paint went on the tank. I used rubber corks in the fuel tap bungs and had the filler cap installed for the bits where I was shaking the tank around. I was otherwise VERY careful with the vinegar around the shiny paint.

I'd have done it before paint, but my painter was taking a dent out of the tank as part of the process.

I had used the Kreem before I took it to the painter. It only had one dent in the top, so I don' think that was the cause. From the way it is falling off inside, I don't think I did good enough job prepping it. I'll not make that mistake again. Leaning towards the Caswell. I like the idea of epoxy.

In 2002 I used Kreem in a tank , so far it's held up fine. I did the chain/bolts and nuts thing. I washed the tank out with soap and water. rinsed and flushed with methanol. Prep is the key the methanol dries the inside of the tank. I'll use something else next time I do a tank