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Tank Differences - 71 OIF

9K views 57 replies 14 participants last post by  KADUTZ 
#1 ·
Some confusion on whether my tank is original or not. Bike is a 71 - is there anyway by searching the Engine/Frame number somewhere I can work out if it is a US bike or not?

The tank on it currently fills to 11.5ish litres (3 US Gallon, 2.5 Imperial Gallon), and looks like a US slimline tank. It has the tank brace holes in the bottom.

The seam around the bottom of the center mounting tube has been bent out of shape, due to tank being mounted too far back, mounting bolt being at an angle and rubbing against bottom seam, in order to miss forks at full lock.

The original receiver hitch on the frame for the captive bolt is knackered, and also looks like its not the original one. However, upon measuring its location it does not seem TOO far out.
Does anyone have an exact measure on the original bolt center location?

Is the tank actually a 72 as it has the bottom strap holes? OR is there a chance its the original 71 and is just hitting due to the dodgy mounting bracket? Are non slimline tanks (or the "original tank" that should be on the bike-if this isn't) shorter front to back?

Sorry for lengthy post. Wondering if I should get another tank, or try and repair seam with solder, re-line tank, and clean out frame & re-weld a new mounting bracket (PITA!).
 
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#3 · (Edited)
Hey Kadutz I can go outside and take some measurements of my 72 frame. Are these about the same or pretty similar? I would just need to know what to measure if so.


And brogan I do know by reading the parts catalogue here. http://www.classicbike.biz/Triumph/Parts/1970s/1971PartsManualTriumph650s.pdf

It states that for the 1971 Triumph Bonneville it is a 3-6 gallon gas tank. So I think you are good as far as how much gas it should be holding. I remember reading about the Rs and Vs I am not sure what type of bike you are referring to so I am guessing but here at this wiki it talks about The Rs being an export model, which can be found on the left side of your frame. It would say on the frame (like it does on mine) T120RXXXXX. https://en.wikipedia.org/wiki/Triumph_Bonneville_T120

Once you tell us the frame and engine letters we could help a bit more just with parts catalogues alone.
 
#9 · (Edited)
So now at least you know for a fact your engine is a 4 speed, made in 1971, it makes it easier in case you are one of those people who want your frame and engine S/N to match. Unfortunately since mine is 1972 when they started introducing the 5 speeds my frame and engine S/N don't match where the frame says JG T120R and my engine says EG T120V. Meaning they were both made in the same year at least but different months. I think it's just easy to tell they were still fitting the old T120R frames to T120Vs. I am not sure how far into the future that goes if they ever start matching, but that's just my bike I am talking about.

What do you mean by possible re-stamp? Because if it's the same S/N as the engine it's not a bad thing to have. Some people like their S/Ns to match.

You know also a small tid-bit. You were only fourth months away from having a rare bike. lol
 
#6 ·
Ah hah. Hmm. My row of numbers sits slightly lower on that plate and has obvious paint drips showing its been repaired/resprayed in that region., although is stamped in a very similar, difficult-to-read style.
So just got to figuring, and it turns out the PO has really done me in mounting the dodgy bolt the way it is. the mount not having the rubber mid section has caused tank to slide back on frame into seat under vibrations, causing bolt angle to get greater and greater till it started rubbing on tank tube and finally bending/squishing the seam and started leaking.
Hoping a *very* good solder job and stripping & relining inside will contain it, but not positive on my chances? Then again it is a "seam" so is probably running/trickling its way through and would be an easier thing to seal than rust holes/cracks etc?
 
#8 ·
I have the original tank for my Feb 71 USA model.Larger than the later narrow tanks and no under tank brace.The tank should sit on 2 horeshoe rubbers and even these are made in different sizes.My tank could also come into contact with the forks when moving the bike around and the answer was to weld the bolt fixing about 10mm further back along the frame.I then used a threaded bar for a new bolt so i can cut to the length i need for the rubber type i use.Often seats differ at the nose and the early 71 would have a fairly flat front edge on it.It is very common for the seat to touch the tank as the seat is on sliding hinge mounts having forward and back movement.Dont look at my profile pic tank as that is the UK tank i fitted for a year.My bike has the early 71 tank fitted at the moment.I also have a spare on the shelf.Difficult to weld these tanks as the rust makes them very thin.Liners,i tried and they just dissolve so i weld mine if a leak appears.Just make sure its leak proof before you paint.
If you put a photo on,i can tell you if it is a 71 US tank.
 
#11 · (Edited)
my 72 T120 (five speed and tank brace) had non-matching title and stamped numbers.

the motor and the frame are T120VDG52754, while the original title was T120RVDG52754, the only difference being the R on the paperwork but not on the bike.

i had the title changed to match the bike in texas when i moved from one state to another.
 
#12 ·
Would have to take some pics of tank alone to show it better, these are all i have for now.





Engine AND frame number are BE10573 or something like that, T120R

I think i'm just gonna have to get some gnarly paint stripper and repair the thing as best as I can, try get it soldered up good and proper at a radiator shop or something.
Anyone know a paint stripper that will remove a POR-15 liner inside? And think it would it also remove traces of body filler around seam to be soldered?
 
#14 ·
no idea if this is any use.




The red tank is what came on my early 71 (a T120R as delivered to Australia) and I think if it isn't the original tank it is at least the same as would've been fitted to the bike originally - it has a seam.

The grey primed one is a T140 tank I bought a while ago not realising at the time that there were different shaped OIF tanks - found out when I put them side by side.


The tanks have a noticeably different profile towards the seat end - the older one seems flatter there but wider. I like the older shape - it doesn't look as bulbous as the later one.

I am having trouble finding one like the older one at a reasonable price (I have been looking for one in better condition than the current one - despite it looking shiny on the outside it is badly corroded and rust has started to lift the paint on the outside :().
 
#15 ·
The white tank is a slim tank and not normal for 1971.Jonksters red tank is a USA export tank and is correct.I know of the problems getting a correct tank.These can be around £200 for one that needs dents removing but not too rusty.Out in the colonies,they would be almost impossible to find.The Indian tank makers are not making these 71 style tanks yet,but their range is getting bigger each year.
Some of these original tanks do come up on ebay in the USA except the postage might be as much as the tank.I recently sold a leaking 71 tank at £146.The buyer then advertised it without declaring it leaked,the leak was under the paint and it would swell and then go back down,and it was sold again at over £200.My sale did declare a leak.
Most noticeable with these tanks is the upper surface is rusting and holes appear in the top of the tank above the fuel.This is caused by Ethanol use.For this reason,i include a little 2T oil into my tank which might slow it down.
 
#18 ·
On the subject of tanks...I've been working on a 71 that was sitting in my shop...It has the wider tank that is starting to spring leaks from several locations.I repair fuel tanks for other people but I understand trying to repair these tanks is a waste of time because once they start leaking it never stops...I don't want to use sealer...
Will any OIF tank fit this 71 frame? This is a cafe styled bike so originality isn't important..
 
#22 ·
Those tanks are often around the £200 mark in the UK.Last one i sold was at £146 for one with a small leak.I still have 2 good ones though.Not going to part with mine as they are prepared for fitting at the next colour change.
Purple at the moment with a spare one in gold and black on the shelf.
 

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#23 ·
Stuart I posted that first one before I even made the thread about parts catalogues...the second one makes sense. No the company "Meridin" probably never did. But somebody did. Being here in the United States we got the R models meaning they were the export ones so getting a V in it could have been whoever got it off the boat here or just someone looking to upgrade without even caring to change the frame number. I get it, nobody knows how my bike is what it is, and there are multiple things that could have made it what it is now.
 
#29 ·
Hi Jacob,

Being here in the United States we got the R models meaning they were the export ones
Nope; you've been confused by others posting without the necessary accurate grasp of historical detail:-

. Before the '71 season, the "R" suffix had been a US-market-only Triumph designation since the '62 model year; Meriden used different suffix letters for what were termed 'UK & General Export' models.

. '71-on, Meriden dropped several model variants and used the 'R' (and 'C') suffix for both markets' models, although US-market bikes still got things like higher handlebars and smaller fuel tanks than equivalent UK&GE bikes.

. For reasons I know not, while 'V' replaced the 'T' in T150T and the 'R' in T120R, it was added after "TR6R", the TR6RV being superseded by the TR7RV.

The VIN on your bike's frame left Meriden on a '72-model-year 4-speed 650, the engine almost certainly built in calendar August 1971; the engine might've been installed in the frame later but - irrespective - the VIN on the frame would've been copied from the VIN on the engine.

so getting a V in it could have been whoever got it off the boat here
Unlikely - US Triumph wasn't some half-arsed cottage industry, it imported thousands of bikes a year, for which it had to account to both US customs and (at the time) BSA in GB. All would've taken a dim view of a complete bike worth hundreds of dollars going missing.

Hth.

Regards,
 
#25 · (Edited)
Did I read somewhere that at the time they did not consider BSA/Triumph as a unit, but as separate entities and each must meet the number for homologation.
What do you mean by "just someone looking to upgrade". As I mentioned before, if it wasn't the factory or one of their authorized dealers, anyone adding that letter to their VIN on the frame to make it what the factory/dealer did would have been guilty of VIN tampering which is a felony here. Stuart corrected me by establishing the "V"s addition by the dealers after the bikes had arrived on our shores. Of course the engine number is not a legal VIN number so you can do what you want to them.
 
#26 ·
Did I read somewhere that at the time they did not consider BSA/Triumph as a unit, but as separate entities and each must meet the number for homologation.
This is open to interpretation and not real clear. In order for the Triumph and BSA racing Triples to use the 5-speed at Daytona in 1970 there needed to be 50 5-speed gearsets cataloged and available to dealers for sale to customers. By 1970 BSA had consolidated the BSA/Triumph US distributors. Triumph dealers were offered BSA franchises and BSA dealers were offered Triumph franchises. They were 1 company. The 50 gearsets were cataloged probably in Nutley, NJ, which was the BSA distribution center and also became the Triumph East Coast distribution center. The original Triumph East Coast distribution center in Baltimore, MD became a storage facility. So the same 50 5-speed gearsets were available to Triumph dealers and BSA dealers at the same time from the same facility. It's semantics whether the AMA considered BSA and Triumph as separate entities. The same 50 gearsets satisfied both manufacturers homologation requirement.

Scott
 
#31 ·
Stuart,
Triumph didn't need 200 T120RV in 1971 to satisfy the AMA Competition Congress rules. I am not disputing that Triumph sold the 1971 T120RV. I am absolutely disputing the reason why.

After the 1968 season the AMA Competition Committee became the Competition Congress. The new rules making body was made up of delegates from chartered Motorcycle Clubs, professional riders, and corporate manufacturers. This Competition Congress changed the Class C rules for the 1969 season by eliminating the 750cc side valve and 500cc overhead valve displacement limits and replacing that with a 750cc limit regardless of the number of valves. The new rules applied only on dirt tracks for 1969. There was a new provision that 200 motorcycles had to be produced and for sale to satisfy the rule. There was also an allowance for racers to modify their motorcycles with certified available parts. This provision led to the use of special frames, forks, gearsets, etc. (so long as the engine cases did not deviate from the production engine).

After the 1969 Daytona 200 motorcycle journalist Gordon Jennings claimed all 25 bikes were illegal and that he could prove it. He claimed Triumph was using special frames and 5-speed gearboxes in the race that were not available for sale to the public.

For 1970 the AMA tried to enforce the Class C rules to the letter as they had never done before. Harley Davidson attempted to satisfy the 200 motorcycles requirement for the iron XR750 by signing a certificate of intent to build the machines throughout 1970. The AMA refused to accept this and forced HD to actually built 200 iron XR750s before the season. HD had to contract with an outside company to build/assemble the required 200 bikes and have them certified by Earl Flanders.

Similarly Triumph and BSA had to prove that 50 5-speed gearsets were available in the U.S. for purchase before the Daytona race as these were considered acceptable owner modifications. These Quaife 5-speed gearsets were received and cataloged before the race and the Triples were allowed to use the 5-speed. This episode has been written about extensively in many books. Doug Hele commented about it in several interviews that he risked being fired if the AMA disqualified the Triples at Daytona.

Even with the AMA rules crackdown every single bike in the 1970 Daytona 200 was probably illegal in some way. Honda used magnesium engine cases in their CB750 based racers and disguised front forks that tapered down to 35mm for measurement purposes but were actually 37 or 38mm. Honda also used a close ratio 5-speed gearset that was unavailable to the public.

Once these changes were certified and accepted by the AMA the modifications were considered legal. HD didn't have to build another 200 iron XR750 for 1971. Triumph didn't have to build 200 North Framed Triples for the North frame to be legal. BSA did have to build 200 A70L twins to use the twin in flat track racing because this was a change in engine displacement and internals.

Again these changes happened during 1971 production. That is not in dispute. If the 1971 T120RV was produced to satisfy an AMA Class C regulation then why isn't there any documentation. There would have to be owner liability releases as well as official documentation. Instead there is just posts on message boards.

Scott
 
#32 ·
Hi Scott,

Triumph didn't have to build 200 North Framed Triples for the North frame to be legal.
Aiui, the "200" applied to the engine, gearbox, etc. not the frame and cycle parts; that's why BSA produced 200-odd of 5-speed T150V and A75RV and A75V engines in road bike cycle parts but not 200-odd North frames with twin-disc forks in North yokes. Aiui too, the AMA 'claiming' rule was supposed to stop factory-backed teams building exotic specials, which also nearly caught out Doug Hele and the BSA/Triumph team.

Any necessity to produce 200 of a particular frame/cycle parts would've excluded US frame makers like Trackmaster, etc.?

If the 1971 T120RV was produced to satisfy an AMA Class C regulation then why isn't there any documentation.
For the same reason there isn't any "documentation" with a '71 T150V, A75RV, A75V or A70L?

However, you're missing the point. If you look back at Jacob's posts, he was confused by the appearance of "T120RV" in the front of the '72 parts book, connecting it incorrectly to the "T120R" on his bike's frame and "T120V" on his bike's engine. My explanation was to show how "T120RV" came about on some '71 bikes; the reason these '71 bikes were produced is irrelevant to my explanation to Jacob.

Hth.

Regards,
 
#35 ·
I'd rather sell in the UK mate, its a massive hassle here trying to post things like tanks and very expensive, I shipped an XS650 tank to the US a year or so ago and it cost £65 ! Theyre very strict about what you can send now , I took a chance and stated on the label it was a 'toolbox' as they wouldnt accept 'fuel tank' !
 
#36 · (Edited)
inner profile

FWIW, I'm in the middle of sorting my May 1971 TR6C which, I'm fairly certain, has the original (dented!) tank.
If you dig around you will find that the tank support (saddle) rubbers fitted at the time are flat-topped. That's what mine came with but they are old and a bit hardened so I'm replacing them. But I could only find replacements with domed tops, so I'll have to trim the dome off to make them the same as the old ones. At some point they must have changed the "tunnel" profile from squared-off to curved.
My point is that if you have the original tank it should have a flat-topped "tunnel" suitable for the original flat-topped rubbers. Here's a link to an illustration, showing the later, domed version. I will have to trim about 1/4" straight across the top to suit my tank to reproduce the flat-topped profile. Hope this helps:
http://www.triumph650parts.com/store/p214/Triumph_OIF_Tank_Rubber_83-4932.html

PS: My tank has no fittings for the brace, so that must have been a later modification.
 
#37 ·
FWIW, I'm in the middle of sorting my May 1971 TR6C which, I'm fairly certain, has the original (dented!) tank.
If you dig around you will find that the tank support (saddle) rubbers fitted at the time are flat-topped. That's what mine came with but they are old and a bit hardened so I'm replacing them. But I could only find replacements with domed tops, so I'll have to trim the dome off to make them the same as the old ones. At some point they must have changed the "tunnel" profile from squared-off to curved.
My point is that if you have the original tank it should have a flat-topped "tunnel" suitable for the original flat-topped rubbers. Here's a link to an illustration, showing the later, domed version. I will have to trim about 1/4" straight across the top to suit my tank to reproduce the flat-topped profile. Hope this helps:
http://www.triumph650parts.com/store/p214/Triumph_OIF_Tank_Rubber_83-4932.html
I ordered a tank support from India yesterday at £4 for one.Just wanting to see how well made it is.I intend to replace my 45 year old ones.For the UK tank,i fitted some nice blocks of wood for supports.Well,it works and i had some spare wood at the time.
 
#39 ·
PIC request please?
Mounting hardware for OIF tank (71 if possible but not necessary).

I've looked at the parts manual, but what I cant work out is what stops fore/aft movement of the tank under vibes?
The very reason my seam at bottom of mouting tube and leaking (now stripped inside liner and soldered/fixed at tank repairers) is because of this movement.
Looking at parts manual, rubber "balloon" appears to be above crome 'plug' that catches top fixing.
I'd think thered be one down low that the lower part of bolt passes through, to keep it 'snug' in tube if you know what i mean.
 
#47 · (Edited)
Google found this,
hence my confusion with parts manual;

http://www.jockeyjournal.com/forum/showthread.php?t=55135

I am a total loss as to your confusion. If you are using a '71/'72 tank ( It WILL have a seam for the chrome strips) use the '71/'72 mounting hardware. If you are using a '73 or later tank use the 73up mounting bits.


Regarding your question forward aft motion. You have 2 forward buffers 2 horseshoe buffers and a bolt exerting downward pressure. Properly done NO problem.


K
 
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