Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board 1971 Triumph 650 Trophy TR6C Center Stand & Tank

I just purchased a 1971 Triumph Trophy 650 TR6C. I had so much fun restoring a 1971 Moto Guzzi Ambassador, that I decided to try a Triumph.
It looks like one of the previous owners tried to make this bike look like a TR6R - changed the pipes, installed an older 7" headlight etc. The engine looks and runs good - still has the single carb.
I have 2 questions (for now :)).
- The center stand tabs/mounts were cut off the frame. I can see where they were mounted, and where they were cut. I would like to install a stock center stand on the bike. Does anybody know where I can get the frame mounts/tabs, or a template so that a tab can be fabricated?
- It looks like one of the previous owners installed a smaller capacity fuel tank. It looks like the correct length, but narrower (slimline?; 1973?). I don't think it is the correct tank, but not sure. Does not look right where the end of the tank meets the seat - seat front is wider than the tank end. It definitely looks narrower that other '71 TR6C tanks I have seen on the internet. I would add a picture if I saw a way to do that here.

Any info/advice would be appreciated.
Thanks.

I hope you didn't pay too much for this one.

The first OIFs lacked any bracing of the main stand support, which consisted of a simple piece of pipe between the bottom frame cradle tubes. The stand pivots were welded on to this pipe. In use it would soon both bend and twist permanently. Later in the production run braces were added, which were simple steel strips from the main frame tube, just below the swing arm boss, down to the cross tube. The 140 got bracings between the cross member and the cradle on each side, which works well. Long tima ago I was lucky enough to get a crashed T140 frame from somewhere and transplanted the cross member over to the 71 I was rebuilding. The original support was twisted beyond repair.
If you're a reasonably competent fabricator, or have access to one, recreating the stand support isn't very hard, but if not I'd sooner just let it be. You may miss it occasionally, but you'll be able to work around it. Many bikes in the last 3 decades came without a main stand, but people learned to cope.( Though it did spawn a small cottage industry).

Sounds like you have a 72 or later tank, but even the original bigger tank was way narrower than the seat. Why they couldn't design a proper seat for these bikes is anybodys guess, after all Triumph pioneered the "twin seat" in the early fifties and kept them nice and narrow to the end, except for the 71/72 OIF models. Some joker even decided to move the seat hinges from the left side of the bike to the right, duly moved to the left again in 73.
I still like these early OIFs though, and if you're equipped with reasonably long legs, they're nice bikes.

SR

'75 - '78 GoldWings suffered from center stand mounting cross-tubes twisting under the big girl's (plus rider, often) weight. On '79 models a gusset was added at the junction of the cross-pipe that it mounts to and the main frsme rails.

Shouldn't be too hard to add to any bike that suffers from this if you have the frame stripped.

Knight57Corv,

Here's a BSA A65 frame, essentially the same as the Triumph but with an additional lug on the cross member, for the rear engine mount. This acts as an additional support. It's still easy to see how it would deform under load, especially when used as a kick stand. On a Triumph it's even worse as it lacks the engine mount, on some frames they twist right off, which may have been what has happened to yours.
I'm about to add some gusseting to the A65 frame, will post pics when it's done.

SR

I should be in good shape in the $$ area.

Thanks for the pics & info. The tabs are cut off in my bike. I am looking for a template so that I can fabricate & weld on to the frame - with added support.
So, if you or someone could create a template and post, it would be greatly appreciated.

Alternatively, if someone has a rough oif frame with good center stand mounts, I would be interested in buying the cutoff of the crossmember with the center stand tabs.
Thanks for all the help.

The tank is definitely wrong for this bike, although it is an oif tank. I need to remove the tank to see if it has the later holes for the front bracket.
The distance between the center seam and the gas cap is less than the distance on what I think is the correct tank.

Searching for the correct tank.

I don't think I'd be able to produce a template, sorry. Apart from the cross member dimensions and location, the stand lugs needs fabricating and on and on. Someone must have a crashed frame to cut up, and remember the T140/TR7 frame is identical in that area.
In fact, if it was mine I'd sooner fabricate one from scratch and place it slightly more rearward, as the balance is wrong with the front wheel up in the air. Looks funny and makes lubricating the chain and such more of a chore than it needs to be. A stand made from tubing could be made quite simply, and could for instance be made to pivot on the tubular cross member itself.

SR

no template , but a couple of images ....1st shows the 71 tabs ( crossbar looks , maybe torqued ? )
2nd.shows tabs with gussets moved lower , started in 72
3rd shows , probably enough to refabricate



images "snagged" from
https://triumphbonneville120.co.uk/1971--1972-triumph-650-frame-details.php

Posting pictures- you are a premium member so you can. Here is how I do it. I am on an iMac so I drag my desired pic on to my home screen from my photos. Next when posting content here on the forum, use the "Full Editor" button. It is to the right of your "Post Reply" button. Full Editor button brings up a screen that allows you to drag pictures into it, up to 5 images I think. When you are done with images and text, hit the post reply button, NOT the preview button. Hitting the preview button screws things up somehow and you can't post your reply. Hope that helps....

Thanks Roger. I was thinking about fabricating a "better" stand mount & using an origin center stand, but wanted something to start with. Thanks for the info!!

Thanks Quinten. I may be able to use the frame schematic.

Quinten.
I scaled-up the frame tab area from the schematic you sent. I think I can get a good image for a CNC'd mount...thanks

Roger,
If you were going to move the center stand forward, what is your best guess as to how far forward you would place a new crossmember?
I am going to try to find a good '71 center stand P# f12627 / 83-4941. I think the length is 10 1/8" from center of mount bolt to bottom of stand foot?

Attached is a picture of the tank installed on the '71 TR6C. What is it .

... I think he said rearward .
which would make the stand easier to lift ... but also less stable .

Just looked at my 72 and I can see about 1/2" of the oil cap and the same amount of frame in front of the cap. There is also about 3" from the tank to the forks. If you have 3" to the forks maybe the seat is wrong?

some 71 pics for tank/seat placement reference .

Looks like I've got the wrong tank or seat? Oh well, it's been like that for 37 years now. I guess I can live with it.

could be ?
im guessing the 71 was a one year only seat ... beacuse
in 72 they changed/lowered the seat rail height .
( this isnt perfect documentation. , just some e--bay images of seat-pan under-sides)
71. flatter rectangular seat pan , with fat front , its own hinge-side and smaller fender-dish

72 , bigger-fender dish and seat angle , reversible hinge mount ... and narrower front

My 72 is a 72 1/2. Frame modification to lower seat height. Perhaps that explains the difference?

The tank is a 72 and the seat 71. Early 71 they had the sculpted 3 UK gallon tank from the start, while the boxy 4 gallon option came later in the season. The small tank wasn't introduced until the 72 season. Personally I like the bigger tank better for range and comfort, though the small tank was apparently favored by many, and would be nicer on an offroad oriented TR6C I guess. The slabby tank never appealed to me at all.

To balance the bike better the pivot needs to be placed further back, not forward. There's little room for it and I didn't quite succeed with it when I transplanted a crossmember on to an early 71 some 16 years ago. That's why I suggested a made from scratch stand to pivot on the crossmember itself. The member would probably need to be lower but one of the benefits could be a much bigger bearing area than on the wear prone originals. Another problem with the original stand was its height, which made it heavy in use. I'm not sure but think that the T140 stand may be shorter?

SR

Thanks Roger. This is really helpful.

Right, pivot to the rear.

Happy to finally have an identification for the tank - it was diving me crazy.

Just to clarify the tank differences:

- A 1971 Trophy 650 gas tank = 3.5 US gallons (from parts catalogue specs).
- A 1972 Trophy 650 gas tank = 3.5 US gallons (from parts catalogue specs).
- The 1972 tank is smaller, slimmer, but holds the same amount of fuel?
- The 4 gallon tank is the "slabby" tank that you do not like? Were they a UK option only? Never on a production US TR6C?
- Since the center mount tank with the center seam was a 2 year production, only a '71 tank is the correct tank for a '71 Bonneville/Trophy/Tiger?

Sorry for all the questions, but I just want to find the correct tank.

After I find the correct tank, I am going to sell the '72 tank. Are the '71 and '72 tanks worth about the same $$ or is one scarcer than the other?

Again I appreciate your help. It is moving this project forward.

Why in the photos of the '71 bike are the hinges on the right, but on the '72 seat they are on the left?

Only those running the show from Umberslade Hall at that time would know, but by now, they're all DEAD.