Hi, I have been looking into different parts catalogues to go along with my Bonneville, full set up below from what I have figured out about it.
I am seeing quite a few different catalogues out there and have been searching on this website and many places showing the covers but not showing the bikes in the pages themselves. I found a couple in the 1972 range but there are small differences between them and I know the one that states it's for 1972 bikes, does not have mine in it.
I found one earlier today that had the same kind of round intakes set up but now lost it. I guess what my question is which do I go off of for my bike in particular?
1972 Triumph Bonneville 650 T120V (Frame S/N starts with JG, Engine S/N starts with EG) Frame states it's a T120R, although the engine says T120V.
The "R" in the frame number designates as a "road" bike as opposed to the "C" for Competition or off road. The V in the engine number designates it's 5 speed.
A p.o. has fitted pre-'71 air filters ("intakes") with after-market sidepanels, which makes your bike look more like a pre-'71. Afaict, it's been nicely-done too. :thumb
'72 is a strange 'season'. Meriden started to fit 5-speed 'boxes in calendar March 1972. There is a short range of numbers where 4- and 5-speeds are mixed but, long before your bike's engine was built in May ("E"), they were all 5-speeds. That's why your bike's engine's model code is "T120V".
Frames had the engine number copied on to 'em when the engine was installed on the production line - that's why bikes were dispatched with 'matching numbers'.
"T120R" was the 4-speed model code; I'll also make an educated guess that the (T120R) frame's "S/N" is lower than the (T120V) engine's? Meriden used the same contiguous number range from the '71 season so, if my guess is correct, the frame originally carried an engine built in calendar August ("J") 1971, near the beginning of the '72 season.
You guys are right in that it has some 71' features looking at the 71' parts catalogue. Another question I have now is that, could it be one of the first off the lot T120Vs? I have this feeling (and I could be wrong) but knowing how a lot of companies like to mass produce stuff. Just had some extra 71' frames and as they were transitioning from straight T120Rs to T120RVs then comes the T120V for the 5 speeds they mounted the V onto the R frame maybe? The front mudguard if you look at the parts catalogue, if you compare page 8 of the 71' to page 5 of 72' you will see the similarities between the two. In fact I don't see any difference between my forks on my bike when comparing to both the 71' and 72' catalogue. Just some rubber added to the middle. Which the rubber isn't mentioned in either. The 72's then you will see these are similar to my pictures. The months are pretty close. Also seeing that the T120R is an export model and has varying differences, and that the frame has JG in front stating it was made in 1972 along with the EG on my engine also stating it was made in 1972. Part of the "evolution" of the bike maybe?
If this is the case on say the manufacture's part. What should I be going off of as far originality goes, original for the frame? Or original for the engine? The one difference I can tell that makes it a bit more confusing is that it has a pull tab for the seat and not just a latch that you lift up to release the seat. What year started using this? Because I don't even see this in the 71' or 72' catalogue. Stuart I know you commented in my other thread about stainless I decided I was going to go the route of OEM instead. And now I'm here. haha
This would make sense except the second letter is a G which states it was made in 1972. Both of which have the G in their codes, but are off a few months in the year. Also that would mean they weren't stamped the same day. Wouldn't that just be a 1972 T120R with a code of JG? Did they never stop making the Rs?
That bike is a mix of parts.Front forks are 71 and it has the early 71 front mudguard.The rear grab rail is also from a different year as it droops a little and should sit higher up behind the seat.Looks nice though and the PO or even earlier has altered it with parts available i suppose.
Depends. '71/'72 had (circular?) brackets with small holes for the reflectors, '73-'78 had triangular brackets for the rear indicators. Some do 'droop'; Meriden used the same centre-to-centre length from shock-mounting slot to mudguard-mounting slot as the 'dry frame' grabrails, but a shorter shock-mounting slot; John Healy has advised previously that there were/are also pattern ones around.
To sum up all those paragraphs above I can only add that I would call your bike a very nice tidy "mutt."
If your frame has provisions for the plunger seat latch it is a very late, 1972 or 1973-up T140. A 1971 and 1972 seat would have right hand hinges and a seat latch on the left side.
The seat is late 1972 or 1973-76ish T140.
The engine is a 750 (TR7 or T140), with 7 fins on the cylinder (Count the fins and number of head bolts) - other clues is the late T140 primary cover. If it is a 1971-72 it will have 8 cylinder fins and 9 head bolts.
The front end is clearly 1971. In 1972 the forks were polished. Inside they are the same.
The pipes are a non-crossover set from a 1970 (or earlier) 650.
The mufflers are from the same.
The "pedestrian slicer is from a pre-oil-in-frame model with the cutout for the upper fender brace and mounted backwards.
The side panels are an aftermarket set used to change the style to an earlier bike.
When the bike left the factory the frame and engine and model numbers were the same. There is a story behind the numbers, but that is another completely un-related story.
If your frame has provisions for the plunger seat latch it is a very late, 1972 or 1973-up T140. A 1971 and 1972 seat would have right hand hinges and a seat latch on the left side. .
I don't think the frame is a T140 since it says T120R on the left side of it. Unless someone cut off the back end and welded a new one on. It can hold the plunger knob, can this same frame set up also use the bolt and latch system as well with the same hole? Like can I just buy the latch and have it fit where the plunger is sitting currently? That would make me feel better knowing my seat can stay down now if possible. I don't really want to drill anything.
The engine is a 750 (TR7 or T140), with 7 fins on the cylinder (Count the fins and number of head bolts) - other clues is the late T140 primary cover. If it is a 1971-72 it will have 8 cylinder fins and 9 head bolts..
I'm not counting any 7s but as far as base nuts go I have 8 and I have 8 cylinder block fins (black), and 6 cylinder head fins (counting that smaller one as well) [gray]. It states 4 cylinder head bolts in the catalogue, which I counted on mine.
Scroll down until you see the T120 with the white tank and side pipes.
Compare your seat with the one on the bike in this link. Notice yours is much thinner.
Compare the location of the rear frame seat rail attachment point to the main frame. Notice yours is much lower. These low frames did not appear until very late in the 1972 production year. They were destined for the 1973 750 models, but a few found there way onto late 1972 650 models.
Now 650 cylinders have 8 fins and 750 (short rod ie. T140) have 7 fins. I have down loaded your picture and blew it up in photoshop. I can only count 7 fins. (The picture is pretty low resolution). The 650 for this model would have 9 cylinder bolts - four 3/8" in head, four more 3/8" in the rocker box and 1 5/16" in the middle between the rocker boxes. The 750 would have 10 cylinder bolts - eight 3/8" and two 5/15" in the middle between the rocker boxes.
Note that your primary cover is from a late Meriden right shift 750.
Note that your rocker box covers are of the four bolt variety used on the 1973 750. (I believe some of these found there way onto very late 1972 models, but I have no reference as to what motor number they were changed from four individual screw-on covers.)
Just because the frame is JG doesn't mean it was made in August of 1971. The low frame, and the left hinge plunger seat arrangement, was only used at the end of the 1972 650 model production year it could just as well be in the first week, or so, August of 1972.
There are several legitimate, and several illegitimate, reasons for the serial numbers on the frame and engine to be different, or not what you would expect to see. Without looking at them it would not be right to make any comment. Not only are there copies of original stamping dies available there are several sources for the Triumph logo available to re-stamp engine numbers.
Note that your rocker box covers are of the four bolt variety used on the 1973 750. (I believe some of these found there way onto very late 1972 models, but I have no reference as to what motor number they were changed from four individual screw-on covers.)
With so many of the 1971-72 models made, and the total lack of interest by the general public in owning one, they became very cheap to own. In the day one could pick-up one of these bikes for not much more than $500.00. I have seen really nice ones sold for under $100.00.
A lot of very savvy owners picked these bikes for their daily ride. You could be on the road for next to nothing. If you needed a part you just bought another donor 71-72 and picked the pieces you needed from it.
I can picture one of these bikes: solo seat, spray can paint job, soft leather bags large enough to hold lunch thrown over where the back of the seat would have been. They became the work horses of the British bike business and kept a lot of dealers alive when Triumph closed. You know when you actually ride these bikes they need tires and chains. You would need several years of parts books to sort through all of the parts that found there way on these bikes. It is why I call them mutts.
As it turns out your low frame, right shift, bike was much sort after. There weren't a lot of them made, especially in a 650 condition. 1973-1976 were pretty lean years of Triumph production.
How about a picture of the numbers and the cylinder.
Sure I can do that. Although the frame number is painted over so unless you are looking really closely to it, it might be a bit hard to make out on here for you I will turn it on it's side so you don't have to turn your head. :grin2:. But the engine frame number is clear as day.
If it's hard to make out any of these. The engine reads T120V EG55899, the frame reads T120R JG32106, and the amount of fins is 8.
Digging through some reference material I found reference to the first lowered frame in 1972 as starting with engine number CG50414 (these references are often suspect). These bikes would not have found there way to the dealers floor in the US until June at the earliest. If the truth be known most languished in warehouses from lack of sales. A lot of these bikes didn't see the light of day until they were sold as a part of the Buy-Fly scheme in 1973.
That's good to know at least. At least we narrowed the frame to a 71'. I can at least go off of the parts book for that in the 71' now, and change it all back to 71' style but the engine I just have to go off of the 72' if it needs any fixing. Thanks for the help.
If your frame has the low seat rail and the plunger lock it did not come from the factory with that serial number. The number would have to be CG 50414 or higher.
Yah, it could have used some clarification....so basically the number stamped is just a randomly stamped number either from the factory, the people who owned it or somewhere through the years the frame has been cut up and re-welded as my guess. Because somehow I have a frame that reads T120R JG 32106 and has a plunger knob. I can see how the seat would be wrong and how having the correct one would fit at least because someone placed the wrong model seat onto it that requires the latch method and that it's slightly too high for this model frame.
Frame:
Lets look at the frame itself and not the numbers for a minute. There were at least 3 frame revisions between 1971 and 1973 for the T120. These involved lowering the seat rails where they contact the main oil bearing tube in order to lower the seat height. Along with these changes were changes in the seat itself and the seat latch. Based on which side of the frame the seat latch type (plunger v. latch) and hinges are located can date the frame. Coupled with the seat rails shows this frame was probably made at Meriden (the factory) for late 1972 production. Production years are not calendar years. 1972 production would most likely have stopped in Summer 1972. For the 1973 model year production would have begun in August/September 1972. Here's why this is important: The 1973 T120/T140 frame was different than the 1972 frame. The plunger and hinges traded sides. Based on this information your frame was probably produced in the summer of 1972 but that does not mean the frame became a 1972 T120V motorcycle. This has all been explained by Stuart and John but gets confusing because these changes were coupled with other changes and actions at the factory.
Motor:
The motor is clearly a 650 but it has some parts on it that were not standard for the 650 in 1971-72. The primary cover is quite interesting in that it does not have the hole for the shift lever in it. That primary cover style was used on the left shift T140 of 1976 onward. The 1973 primary cover is different which means your primary cover would have been used on the 1974-75 right shift bikes but very few were produced and sold due to circumstances at Meriden. The rocker inspection caps have 4 screws holding them in place. These changed to 6 screws for 1974 production. The 4 screw covers were used from late 1972-73. The engine number prefix EG means May 1972 which would be late 1972 production. It appears from what you have presented so far that the motor is a late production 1972 T120V with a later (rare?) primary cover fitted.
What does any of this mean: The engine prefix seems to represent what the engine is and does not look to be re-stamped. The only glaring thing that was not available in a 1972 T120V is the primary cover which could have been changed later. The frame is most certainly a late production 1972 frame due to the lowered seat rails and position of the seat hinges / plunger. So how could these seemingly correct year parts (frame and engine) make absolutely no sense?
The frame number is obviously incorrect. It has been re-stamped to fit an early production 1972 T120R. Is this the work of "crooked f..kers"? Maybe / maybe not. Lets say that Joe crashed his 1972 T120R and bent the frame in Spring/summer 1972. Joe took his bike back to the dealer for repair. The dealer ordered Joe a new unstamped frame which would have been the current version (Spring 1972 = low seat rails and plunger on the left). The dealer re-stamped the frame which was completely legitimate to match Joe's engine and re-built his bike to new condition with a mish-mash of early and late 1972 parts. Joe sold the bike to Bob. Bob was used to Japanese fours and blew up his engine by wringing its neck at 8000 rpm for hours and hours of fast highway travel. The bike is no longer under warranty but Bob wants his "mo-sheen" to be TIP-TOP. So the dealer has a wrecked 1972 T120V in the back that needs a new primary cover. The original engine is swapped with the dealer's wrecked 1972 T120V with the replacement primary cover. Since the bike is titled and registered as a 1972 T120R the engine numbers are left as is. The bike itself is no longer a 1972 T120R and has a collection of parts on it from different years and seems to make no sense. Obviously the work of those "crooked f..kers" and their re-stamp kits or the life of a 40+ year old motorcycle that was used as intended.
So if I had to guess, I would say this mongrel is titled as a 1972 T120R? If so, leave the numbers as-is. The only people who can tell the difference between these parts are us. The DMV and the police have no idea about minor frame alterations within model years.............unless of course they read this thread. Uh-oh!
Not so straightforward; when the frame seat tubes are lowered, certainly some of the underseat parts - sidepanels, air filter, battery carrier, etc. - are changed also. John Healy will likely know more details.
This might've been the reason for the aftermarket sidepanels and pre-'71 air filters?
Yes you are correct Stuart. Frame number is early production 1972. I corrected my post. So hypothetical Joe's bike was a high seat 1972 T120R that he crashed and got a replacement low seat frame. Everything else rings true. I don't think those retro covers were available when the frame would have been re-stamped. Probably added later. Maybe due to ill fitting early 1972 inner and outer airbox covers. The rest of the bike is a mashup of parts mostly from 1972.
Yes Stuart pointed this out. I corrected it in my post.
Jac0b561: What you have is not what it started life as. The T120R JG3201 is not what you have any longer. It started as an early production 1972 T120R with the high seat rails and probably a cut down thin seat (which was Meriden's 1st attempt to lower the seat height before they changed the frame, twice). Since its build date it has had the frame replaced with a later production 1972 frame. The engine has also been changed. Its hard to say if the other cycle parts came from the original high seat early production frame or not. There has been some debate whether the high seat air filter boxes (both inner and outer) will fit a low seat frame of the same year. Many have come to the conclusion that they won't. Your bike does not have the original air filter boxes so that point is moot but maybe a clue to the non-stock retro sidecovers and air filters.
All of this is an attempt to sort out for you, what you have, free of charge. Forget about parts books for a minute. Understand what you have. And then download this correct parts book for the collection of parts that make up your motorcycle: http://www.buffaloschools.org/webpages/srook/files/1972partscatalog-650_twins.pdf
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