Featured Refurb On The ‘69 T120.

After five days pickling, most of the black rust areas seems to have dissolved off leaving only spots. I haven’t yet drained off the rubbish but from what I can see using the Endoscope the floor of the tank is, for the most part, clean. There are small spots left but hopefully they should come clean with a couple more days.

But that’s too easy. There is of course always something to spoil the party and one thing that is puzzling is that there seems to be some sort of glossy, yellow/greenish coloured residue still attached in patches to the walls of the tank. It looks like glossy paint but I can’t recognise what it is. I certainly didn’t put anything but petrol in there so I don’t think it’s a sealant of any kind as it isn’t all over the inside.

I don’t remember anything like that when I used to check the petrol level while riding. I’m not even sure that sealants were a thing in the early nineties. I suppose it could be a residue of some sort from the old petrol that has separated out. Or is it possible that Triumph painted the inside of petrol tanks in the late sixties?

Probably not.

 

Just going through a folder of m/cycle magazine clippings I keep for no particular purpose, only to find an article from 1987 on tank repairs, which has a picture of the underside of a Triumph 650 tank. It has the identical damage along the centre tunnel that’s been inflicted on mine.
Weird.

 

I’ve drained off the remaining vinegar solution and flushed out the tank several times. From what I can see it mostly looks a lot cleaner and back to bare metal inside. But there still remains a residue which I think is maybe a drop out from the old petrol. Anyway I’ve sprayed the interior with WD to keep new rust at bay for the time being and I’ll see how the Tigers tank turns out in a few days. That one didn’t have any fuel left inside so should come clean in a few more days.

Here’s some of the better bits in the Bonnie tank…

 

… and some not so good

 

Yes, sealant. That’s a distinct possibility. Although when I was using the bike regularly I don’t remember anything but clean metal on the floor of the tank which I would have assumed to have been treated. Anyway I’ve sprayed the inside liberally with WD and got it standing on clean paper atm to check it out. I’m looking very carefully at those damaged seams.
I’m thinking to try electrolysis to clear up the remaining rust and I’ve got some ‘silver sheen’ paint on order for the underside of the tank when it’s cleaned up, so I need to get that out of the way before putting petrol in.

 

Yes, thanks darkman. I think I see it lifting in one of the photos.
I’ve never used MEK before. Is it used same as the vinegar treatment and then another sealer applied?

 

Thanks. That’s great. Five litres on order now.

 

Thanks. That’s great. Five litres on order now.

 

I’ve spent a week with the TEK fluid in the tank circulating it around to get out whatever remains of the yellowish coating which remains in places around the inside of the tank. It seems to move around and after a while I’ve got another layer of flash rusting patches appearing again.

I’ve drained off the TEK and have now repeated another week of the Vinegar treatment and it’s turned out a whole lot better this time. I’ve used Bicarbonate of Soda to nullify the effects of the vinegar and then power washed the inside for about a half hour. This time I’ve immediately sprayed the interior with the preservative oil so the interior remains pretty much pristine in its natural state.

I think it’s about as good as I can get it.