Por me.

[DanielMc]

Irz - I hear good things about cleaning out old paint and rust etc. from tanks using soda and electrolysis. I planned to do this on an old R100 tank prior to using POR15 on it, but bought a replacement instead so cannot comment directly.

[chasbmw]

It seems to me that the issue in the uk and Europe is that the new ethanol %s in gas is stripping the linings that people fitted earlier to seal pinhole leaks, the linings just come off producing a grunge that blocks up everything. So whatever product you use, make sure that it will deal with increased levels of ethanol. The fuel in Europe that is causing the issues has either 10 or 15% ethanol. It eats paintwork as well!

[lrz]

So, the stripping is complete.

As for pinhole-s, yes there are two. Check out the underside of your tank (/7 era at least), you'll note one side has a flat portion next to the petcock while the other side does not. No flat spot would be better.

First thought was to have it brazed but in the interest of time I am thinking to silver solder instead.

Any input?

[Ray from Indiana]

Here's tip you should take seriously. The PO of my bike attempted a POR 15 lining job. He let it pond near the petcock where it formed a pond about 1/8" thick. That pond cracked, let corrosion of the metal initiate under the POR15, and caused me to redo the whole mess. Advice: Make sure you don't create a thick pond of the stuff so it can stay flexible. Thin coating is ok. What a pain in the arse! Not only was I intent on removing the POR15 but the BMW red liner as well. I got the POR15 out easily enough but the BMW red stuff was a pain. I used a chlorinated solvent that would take the hide off your bones but hardly touched the red stuff.

I used this procedure:
soak, swish, soak again.
empty contents thru a filter to save the solvent, re-introduce the solvent
repeat
used 3/16" nut ( about 3 dozen ) to rattle around, repeat above.
drain and filter again
take to carwash for HP spray cleaning inside, got to step one
total duration 1 month calendar time

[Deleted User 62]

So, the stripping is complete.

As for pinhole-s, yes there are two. Check out the underside of your tank (/7 era at least), you'll note one side has a flat portion next to the petcock while the other side does not. No flat spot would be better.

First thought was to have it brazed but in the interest of time I am thinking to silver solder instead.

Any input?

I really have no clue which is better, but a thought just occurred to me: why couldn't you just pour some epoxy in the offending area from the inside? You could save your paint and actually fill/strengthen the rusted area. Of course, the epoxy would have to be fuel proof.

[Ray from Indiana]

I would think a high melt silver solder would be ok. I would prefer that over the epoxy to avoid the cracking I described above.

Soldering would of course result in a paint job ( $$ or WORK )

[lrz]

Ray-well understood. Your PO applied POR15 over the factory lining?! That is a mess. I purchased the kit, from stripper to finish coat, mostly because I've tried to put my days of caustic chemicals behind me & didn't want 1/2 gallon of each sitting around. Professional painting, even acrylics=TOXIC. For $50, seems a good buy.

Instead of silver solder I visited my friend the custom bicycle builder-GREAT STUFF!, who recommended 50/50 solder done w/ propane; worked a treat in, literally, seconds. So, there's a tip for future reference.

[lrz]

It seems to me that the issue in the uk and Europe is that the new ethanol %s in gas is stripping the linings that people fitted earlier to seal pinhole leaks, the linings just come off producing a grunge that blocks up everything. So whatever product you use, make sure that it will deal with increased levels of ethanol. The fuel in Europe that is causing the issues has either 10 or 15% ethanol. It eats paintwork as well!

E15 is now the norm?

I thought I recently heard the new movement in the US is to end $ubsidies for ethanol corn; I was hoping we'd avoid E15 here. IMO older motors will not tolerate it well if at all.

[chasbmw]

Irz

To be honest I'm not quite sure if E15 is the norm now, getting anything But E10 in Germany seems to involve paying a premium for 98 octane gas. I'm in Greece at the moment where you can never be sure what you are buying! I will check in Italy and France on the way back

Charles

[Sibbo]

Something to consider, if you have one pinhole, most likely there are others coming soon. I'd do some judicious tapping with an awl in the same area and see if swiss cheese is lurking. The Por 15 is an option, but flawless preparation is a must or the results will be less than satisfactory. For the time, energy and dealing with nasty chemicals involved, I'd consider finding a good used tank for replacement.

The first tank I owned was sent by the painter to a radiator shop. They chemically cleaned it and either they or the painter soldered up the holes and lined the tank. I think it is right that there is usually some corrosion that you don't see at first.

Chuey

If you want to get rid of the corrosion rather than just harden it up with a rust converter the easiest method I know is to fill the tank with a mixture of 1 part molasses and 3 parts water and leave for 3 weeks .it will look as if it had been shot blasted inside . ..... and will leak like a sieve from all the new holes !