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.

 

My original intention for cleaning up the petrol tank was to keep it as original as possible and to that end I’ve spent some little time trying to get it into a state that I can repaint the underside silver locally up to a cheat line where the curvature of the sidewall takes over from the flat bottom and polish the Olympic Flame upper side as it wasn’t in too bad a condition considering it’s years. That was the plan until I removed the taping that I’d used to protect the top surface around the filler neck and a small patch of paint came away with it. Unfortunately the cleaner that I’d been using had managed to creep under the tape and softened the paint enough to lift as it was removed.

‘Plan B’ is now to repaint the lifted area and try to blend it in with the rest of the top of the tank. I’ve now just overhauled my old Airbrush, a leftover from when I used to make model aeroplanes, and ordered up the necessary spray cans. Just to complicate matters Olympic Flame is a ‘candy’ translucent colour which makes the possibility of a successful match just about impossible. Nevertheless, the alternative is a complete repaint. Watch this space.

 

While on a petrol supply theme the carburettors are now off. It’s taken about a week of soaking in WD just to unscrew the air filter backplate from the carb body and to be able to withdraw the throttle and choke slides without damage them or scratching anything. I removed the float bowls to find 25 year old petrol, surprisingly still in a liquid state, but have a residue of the same black junk as was in the tank. Anyway I’ll be passing the carbs over to my son who cut his teeth on getting a Honda V4 set of carbs to work on a refurb he did on that a couple of years ago. We’re also getting an ultrasonic cleaner between the two of us.

 

Thanks darkman. I know that’s what it’s going to have to come to. I’ll have to practice a bit first though.

 

Just to keep me going here’s a piccy of THE ultimate Bonneville which I keep in the garage for inspiration.

 

… and here’s one I almost made a bid for on eBay until the bidding went through the roof…