Hi Joe,

Firstly, welcome to the Forum.

owner said it was a 60-62 (duplex frame).
have to know if it’s 3 or 4 gallon. I’m thinking 4

I assume you mean US gallons? The bigger one was ~3-3/4" British gallons = 4.5 US gallons.

I think you're right - the knee pad shows screw holes whereas the smaller one had steel plates that attached each side of the tank, the rubber knee pads hooked over them. However, post another photo. of the top of the tank - the distance between the filler cap and the centre seam will confirm.

don’t know much about triumphs of this era, I would like to find some missing trim pieces

Triumph '60-'62 pre-unit 650 parts book - tanks parts illustration and listing are on pages 60/61.

Btw, when searching for parts online, you'll get more links returned if you use the part numbers in the "'73-on format" - the alpha prefix letter replaced with two numbers and a dash; e.g. part #2, "Styling strip (left, front)" is 82-4148 in "'73-on format". Other prefixes on that page: "W" = "37-", "T" = "57-", "S" = "21-" except "S1-51" = "21-0151", "S25-3" = "60-4247", "S25-13" = "60-4248", "S26-2" = "60-2417".

Hth.

Regards,

 

Nice find that looks remarkably like the 3 gall tank but difficult to tell from the photo if you remove the knee pads it may be easier to ID
the 4 gall is more bulbus around the badges and has very defined pressings for the knee pads

 

To find out the real capacity, i fill the tank with water from a marked jug. That is dead accurate.

 

i had to do that for the tube tanks on a race bike once. the rules said the tanks had to hold at least 5 litres, but the guy who made them for me quoted capacity to me by measuring the outside tube dimensions, neglecting the 1/8-inch metal thickness. when i realized what he had done, i measured the water capacity with a burette and a graduated cylinder.

i came in at around 5.05 litres and was good to go, but it was closer than i wanted

 

Here is what it looks like under the kneepad

 

 

Hi Joe,

Mmmm ... I was rather hoping this measurement would match the corresponding one on my T150's tank (US-market T150 tank is basically the same as a pre-unit "large" tank); however the same measurement on my T150's tank is more like 2".

To find out the real capacity, i fill the tank with water from a marked jug.

'Fraid you might end up having to do this ... Fwiw, when I've had to do this, after I've emptied the tank again. I put it somewhere warm for a few days so it dries out relatively-rapidly.

Regards,

 

 

I sure didn't want to add water. The tank is perfect inside, and I did not want it to flash rust. Plus, I would have to plug the petcock holes (OK rubber stoppers) and then dry it out with acetone when finished to get the water out of the crevasses. I was just hoping there was a simple tell based on the way the tank looks. Thanks everyone for your inputs. Joe

 

So, fill it up with engine oil and measure what goes in. The oil can then be used in vehicles once drained. Petrol is the obvious choice though and then tip it into a car or mower.

 

Maybe it is that easy: The 60-62 parts manual shows the upper tank with big knee grip indents for the 4 gallon, and for the 3 gallon (lower picture) there are no real indents and the pads are help on with a "knee grip plate" - items 17 and 23.

 

Hi Joe,

Maybe it is that easy: The 60-62 parts manual shows the upper tank with big knee grip indents for the 4 gallon, and for the 3 gallon (lower picture) there are no real indents and the pads are help on with a "knee grip plate" - items 17 and 23.
View attachment 822896

Errrm ... post #2:-

Triumph '60-'62 pre-unit 650 parts book - tanks parts illustration and listing are on pages 60/61

...

add water. The tank is perfect inside

I doubt it, look at your View attachment 822862 photo. ... Nevertheless, you aren't understanding the advice that's been posted for you:-

when I've had to do this, after I've emptied the tank again. I put it somewhere warm for a few days so it dries out relatively-rapidly.

... e.g. tank with fuel taps out and filler cap off, if I put it in what's known in GB as the "airing cupboard" - a cupboard around the hot water cylinder where we store clean bed-linen, towels, etc. - ime, the interior dries in less than a day.

Btw, unless the tank's inside has been coated or you live in a desert where it never rains, open tap holes, wherever you store the tank long-term it'll continue to "flash rust" inside. If you wish to prevent this, the tap holes and the filler cap vent need to be sealed plus, just before the vent-sealed filler cap is fitted, squirt some ACF-50 into the tank.

Hth.

Regards,

 

Welcome to the Forum! As far as I know, you’re the only member we’ve had join up on purchasing a gas tank without the rest of the bike attached. I admire your eagerness. What, pray tell, do you intend to do with the gas tank once it’s all fixed up? Will you be installing a motorcycle under it?

 

Hello Badonka and thank you for the welcome. I just like the tank, its beautiful and it looks good in my workshop. I have had a few Triumphs in the past, a 1960 Speed Twin, 1973 Tiger, 1972 Daytona, and a 1970 Trophy and currently have a 2017 Bobber. I would like to get a pre unit but I already have too many bikes. I have a nice original 1981 Harley Sportster XLCH that I will likely sell in the Spring, then it may be old Triumph time again