XS2 gas tank / saving my paint job from gas incursion

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Gary tried to warn me.
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When I was assembling my XS2, he said that he had seen a number of gas tanks with expensive paint jobs ruined by gas creeping into the paint job around the petcocks and the filler neck. He did a little write up about how he had done this on one of his restored gas tanks.
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I had a great reluctance to do this. Frankly the idea of scraping beautiful new paint off of my gas tank WAS a little horrifying to me.

Well I’ve had gas in the tank for five months now and I’ve been keeping a close eye on it and a couple of weeks ago I noticed the paint beginning to swell , right at the edges of the petcocks. UH OH !!
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I drained the gas tank and pulled the petcocks off. Oh boy! That’s ugly, I think I’m just in time to do something about it. You can see some blue Hylomar residue there too.
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Here I have taken an Xacto knife and done an initial trim around the petcock, the paint is very soft. I trimmed to just past where the paint was soft.
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After trimming off the loose material, I put the cleaned up petcocks on and traced the edges. Now I trimmed the paint to about 3mm beyond the edges of the petcocks.
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I cleaned the area I intend to seal with epoxy. Be sure to remove any oil film.
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I’ll be using JB Weld clear 2 part epoxy. This stuff sets up fast, be prepared to work quickly. I taped a piece of foil on my bench and used a throw away artist brush to apply it. When I was done, just throw it away.
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Here it is right after I applied it. As soon as I had both sides done. I moved it out to sit in the sun for a while to help it cure.
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I was careful to coat the bare metal and just over the edge of the paint. Leaving the entire area that the petcock sits on bare metal.
Here is the finished job , it’s really not visible , even from a low angle like this.
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I am hopeful this will be an effective and permanent repair. I went on the JB Weld website and they claim it to be gas and oil resistant. But hopefully gas will not even touch it. The gas filler neck was already done by the painter.

Edit: Read down to post #9 where I explore the possibility that I contributed to the paint failure.

A Cautionary Tale
: After reinstalling the petcocks, I put the gas tank back on my bike and filled the tank back up. I had the petcocks apart when I was working on the tank and when I re assembled them, I had something outa alignment on one of them and gas started dribbling out of it and going all over my painted case! Crap Crap Crap!! You should’ve seen me running around like a chicken with my head cut off, trying to catch the gas that was spilling and quickly remove my tank , so I could drain it again! Then I had to quickly wash the gas off of my cases before it wrinkled the paint.
Drained the tank....fixed the petcock....refilled the tank ( this time off of the bike until I was sure it wasn’t going to leak.) So now everything is back together and no leaks, and I didn’t have to make my tank ugly to do the epoxy job. So whadya think? :geek:

Gary approves!
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I'm gonna have to follow this one Bob. I've got a beautifully painted factory matched '75 Star Black tank stashed away that will likely need addressed in this manner. It was professionally painted and sealed quite a few years ago but has been stored in a box ever since and never been mounted. It's part of my secret stash of parts for my resto project when I reclaim my workshop in the near future. Keep us posted how this holds up.
 
I'm gonna have to follow this one Bob. I've got a beautifully painted factory matched '75 Star Black tank stashed away that will likely need addressed in this manner. It was professionally painted and sealed quite a few years ago but has been stored in a box ever since and never been mounted. It's part of my secret stash of parts for my resto project when I reclaim my workshop in the near future. Keep us posted how this holds up.

Yeah, will do. I don’t know why some tanks seem susceptible to this and others do not. I seem to recall seeing NOS gas tanks that had the petcock mounting area taped over and bare metal underneath. But the old white gas tank I was running was painted and never gave me any grief. It seems kinda random.
But I do believe it’s worth looking at your paint, any time you’re down there working on your bike.
 
But the old white gas tank I was running was painted and never gave me any grief. It seems kinda random.
I think it comes down to two things. First, cleaning. Gas literally works it's way into the metal and can remain there for months even though the outside appears completely dry and clean. Chemical cleaning, muriatic acid... acetone...MEK, something like that. Numerous soakings and scrubbings is the only way to properly clean it.
Second is the paint, it has to be good quality. And that's especially true of the primer... which is where most people scrimp. Once the gas has worked it's way under an edge, a bad primer will just accelerate the debonding of the topcoat.
In my day I've painted dozens if not hundreds of tanks. Never had a petcock problem. The SG tank has had fuel in it since spring with no signs of problems.
 
I think it comes down to two things. First, cleaning. Gas literally works it's way into the metal and can remain there for months even though the outside appears completely dry and clean. Chemical cleaning, muriatic acid... acetone...MEK, something like that. Numerous soakings and scrubbings is the only way to properly clean it.
Second is the paint, it has to be good quality. And that's especially true of the primer... which is where most people scrimp. Once the gas has worked it's way under an edge, a bad primer will just accelerate the debonding of the topcoat.
In my day I've painted dozens if not hundreds of tanks. Never had a petcock problem. The SG tank has had fuel in it since spring with no signs of problems.


I should’ve mentioned this in my initial post. There is at least the possibility that I contributed to the softening of my paint that was under the petcocks. In my enthusiasm to achieve a nice, leakproof seal, I put blue Hylomar on a number of the components, the mounting screw threads, the sealing washers, and the sealing o ring.
Contrary to Hylomars instructions, I did not wait for the solvents to evaporate off before assembling the components.
I honestly didn’t think about it. I thought it would be easier to assemble before the Hylomar set up. I did a little post mortem research on Hylomar by pulling up its MSDS and found it contains dichloromethane, which is a pretty volatile solvent. By assembling the petcocks before the Hylomar had the opportunity to gas off, I may have trapped potentially harmful solvent vapors, or worse yet kept the solvent in a liquid state because it was in a sealed environment.

I also found a reference to this happening to a bike owner on a Suzuki owners forum. So, it’s just speculation , but I should’ve covered this in my first post.

I have edited my first post to include this reference.
Bob
 
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Just a note from my experience: The original 1981 factory paint has amazing petrol resistance under the petcock base. When I prepared my tank for painting I left the original paint on where the petcock fits plus an extra 1/4" beyond the edge of the petcock base. I sanded the paint surface flush up to the edge of the petcock base to allow the new coating to key in. This way I avoided the issue.
 
I should’ve mentioned this in my initial post. There is at least the possibility that I contributed to the softening of my paint that was under the petcocks. In my enthusiasm to achieve a nice, leakproof seal, I put blue Hylomar on a number of the components, the mounting screw threads, the sealing washers, and the sealing o ring.
Contrary to Hylomars instructions, I did not wait for the solvents to evaporate off before assembling the components.
I honestly didn’t think about it. I thought it would be asker to assemble before the Hylomar set up. I did a little post mortem research on Hylomar by pulling up its MSDS and found it contains dichloromethane, which is a pretty volatile solvent. By assembling the petcocks before the Hylomar had the opportunity to gas off, I may have trapped potentially harmful solvent vapors, or worse yet kept the solvent in a liquid state because it was in a sealed environment.

I also found a reference to this happening to a bike owner on a Suzuki owners forum. So, it’s just speculation , but I should’ve covered this in my first post.

I have edited my first post to include this reference.
Bob
Interesting investigation, Bob !

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... the possibility that I contributed to the softening of my paint ...

... a little post mortem research on Hylomar by pulling up its MSDS and found it contains dichloromethane,

Hmmm, dichloromethane is the active ingredient in paint stripper, gasket remover, and the good ol' no-longer-available carb cleaners.

Yup, I can see that stuff doing a number on the paint...
 
In the early 80s there was a major concern that the use of dichloromethane based paint strippers in poor ventilation could result in heart attack. I met an old guy in Australia in 82 who this happened to and he had joined a group to try and get the solvent banned. I do not know if a link was ever proven but there is a note on Wiki indicating the problem relates to those with pre-existing heart problems.

Edit: the amount in Hylomar is low and the level of exposure working on an XS will be pretty damn low.
 
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