Restoring & Modifying 1971 OIF TR120

[Rudie]

I appear to have a Norton 06-5748 'Majorca' bar, but perhaps a replica cut a teensy bit long...?

Ime, the parts wholesalers - who commission parts if they do not make them - can be careless particularly about handlebar overall widths ... The most infamous recent example seems to have been caused by all the wholesalers' desire to sell as many of the same parts as possible under different part numbers, regularly without understanding why the part numbers were different originally.

As I say, the Triumph UK bars for front disc brake were always the same shape as the earlier ones for drum brake, but the disc brake ones were a little wider - around 28" rather than 26" - because the UK disc brake hose is straight into the master cylinder, the straight parts at the ends of disc brake bars were longer particularly so throttle, switches and master cylinder all fitted without the hose pushing on the speedo or tacho.

Given the wholesalers' desire above, one decided the same UK bars could be supplied for both disc and drum brake part numbers; however, the part they had made has the narrower drum brake width, meaning master cylinder, switches and throttle now do not fit properly ... Otoh, had they chosen to make the disc brake bars, the additional width on a drum brake bike is unnoticeable ...

Although sometimes wholesalers' carelessness works for (some of?) us ... I like the shape of the pre 73 Triumph US bars, except when turning with the steering on full lock, when the bars' 32" width means one bar end is an uncomfortable stretch. In common with several others I have read online, I shorten these bars by removing around an inch from each end so joy when I discovered recently L.F. Harris had produced a batch only about 30" wide ... until I tried to fit the throttle ... that bar end was around a millimetre oversize ... By the time I got them back to the retailer hoping for an exchange, he was sold out.

 

[NM Bonny]

Ime, the parts wholesalers - who commission parts if they do not make them - can be careless particularly about handlebar overall widths ... The most infamous recent example seems to have been caused by all the wholesalers' desire to sell as many of the same parts as possible under different part numbers, regularly without understanding why the part numbers were different originally.

As I say, the Triumph UK bars for front disc brake were always the same shape as the earlier ones for drum brake, but the disc brake ones were a little wider - around 28" rather than 26" - because the UK disc brake hose is straight into the master cylinder, the straight parts at the ends of disc brake bars were longer particularly so throttle, switches and master cylinder all fitted without the hose pushing on the speedo or tacho.

Given the wholesalers' desire above, one decided the same UK bars could be supplied for both disc and drum brake part numbers; however, the part they had made has the narrower drum brake width, meaning master cylinder, switches and throttle now do not fit properly ... Otoh, had they chosen to make the disc brake bars, the additional width on a drum brake bike is unnoticeable ...

Although sometimes wholesalers' carelessness works for (some of?) us ... I like the shape of the pre 73 Triumph US bars, except when turning with the steering on full lock, when the bars' 32" width means one bar end is an uncomfortable stretch. In common with several others I have read online, I shorten these bars by removing around an inch from each end so joy when I discovered recently L.F. Harris had produced a batch only about 30" wide ... until I tried to fit the throttle ... that bar end was around a millimetre oversize ... By the time I got them back to the retailer hoping for an exchange, he was sold out.

Ah, well that explains the 8" end portions--or certainly the usefulness of that dimension. Indeed, assuming I do end up running this DIY disc brake conversion, I'd have to either modify or get rid of the OEM switchgear--at least on the R/H side.

I do not run signals to accentuate the lines of the bike, so have unsoldered the remainder of the wires and am only using the lower momentary buttons to actuate the late '60s VW relay hidden above the horn under the tank on the L/H side (HI/LOW beam), and the horn on the R/H side.

I've drilled the bars to pass the wires inside (see photo). This produces a very clean, uncluttered look but raises some issues with the need for a master on the R/H side, assuming I end up running a disc brake. If I have to eliminate the R/H switchgear, there is a second momentary button in the upper position on the L/H pod I could connect to the horn. However, I prefer not to have to think about which button to push if someone begins to pull out in front of me suddenly...

If push comes to shove, I could install a standalone momentary button on the R/H side, like those used on the '51 FL (2nd pic - R/H side is similar). The only universal master I found with a bore size closest to ideal and aesthetics reminiscent of this Bonneville's original levers should arrive this week. It comes with a matching clutch lever--but of course that would mean I'd have none of the original switchgear on either side. I'm not thrilled about that prospect, as I really like the way it looks. So, I may just have to train my muscle memory to use both momentary buttons on the L/H pod...

Finally: I can polish the OEM L/H lever to roughly match the chrome lever of the universal master, but can one polish the OEM switchgear pods? Or is the 'shell' or outermost layer on the castings too thin to safely do that?

P.S. - I see now that I've got the bars shifted just slightly to the left in the P-clamps. I'll rectify that when R&Ring the headset bearings and races.

 

[Rudie]

master on the R/H side
If I have to eliminate the R/H switchgear

The Triumph 73-78 master mounting mates with the existing switches on your bike, but you are then limited to a 5/8" i.d. original Lockheed type cylinder or the similar looking aftermarket 13 mm. i.d.

universal master
comes with a matching clutch lever--but of course that would mean I'd have none of the original switchgear on either side. I'm not thrilled about that prospect, as I really like the way it looks.

One possibility is a countryman of yours - David Madigan - makes what he calls "backshells" to mount bar switches like your bike's without the lever pivots. Unfortunately, he does not have a website but I will start what this site calls a "Conversation" with you containing his email address.

I prefer levers clamped separately to the bars from the switches. One build that impressed me a few years ago was a T150 (they originally had the same switches as your bike) with Hinckley ST switches, master cylinder and clutch lever mountings, the levers then aftermarket for Hinckleys - unfortunately, I cannot post the photo as its size exceeds the site limit.

For the T160 in 75, Lucas produced a very compact - 1-1/2" wide - left hand switch group incorporating headlight main/dip, turn signals, horn and headlight flash (horn button pushed upwards):-

... this was subsequently used on the 76-78 twins and is also patterned by Sparx; I have used these on pre-71 Triumphs originally without turn signals as they bolt on in place of the pre-71 dipswitch/horn button and work with the standard chromed clutch lever. Also meets your criterion of being polished.

Otoh, the T160 and 76-78 twin right hand switch group is an imho ugly modification of the switches on your bike, the black lever substituted with a bright red one for engine kill, one momentary button used on the T160 for the electric start, the other button unused - look online at any image of Triumph 19-1961?

Nevertheless, I wanted a kill switch and I was eventually recommended to Royal Enfield #144354:-

... however, further work for you (apart from needing to polish it) would be:-

. that switch takes the cable end of the throttle, you would need to replace your bike's twin throttle cables with the arrangement Triumph used on UK twin carb twins - single cable on the throttle into a one-into-two "splitter" under the tank for the two cables to the carbs;

. either modify that arrangement's throttle cable outer to fit the Enfield housing or have that cable made - I have access to Venhill ...

... but then of possible interest to you is the throttle with the larger diameter cable pull (1-1/2" o.d. vs the 1-3/8" o.d. of a standard twin cable throttle) can be used, gives a slightly quicker throttle action.

universal master
comes with a matching clutch lever

If View attachment 56133 is the clutch lever, you know that it should not pull more than the 1" of cable inner the standard levers pull?

can one polish the OEM switchgear pods?

Yes. However, they need to be lacquered soon after or the alloy dulls quickly.

I can polish the OEM L/H lever to roughly match the chrome lever of the universal master

The T160/76-78 twin left hand switch group above works with the chromed clutch lever Triumph fitted in most other years.

 

[NM Bonny]

The Triumph 73-78 master mounting mates with the existing switches on your bike, but you are then limited to a 5/8" i.d. original Lockheed type cylinder or the similar looking aftermarket 13 mm. i.d.


One possibility is a countryman of yours - David Madigan - makes what he calls "backshells" to mount bar switches like your bike's without the lever pivots. Unfortunately, he does not have a website but I will start what this site calls a "Conversation" with you containing his email address.

I prefer levers clamped separately to the bars from the switches. One build that impressed me a few years ago was a T150 (they originally had the same switches as your bike) with Hinckley ST switches, master cylinder and clutch lever mountings, the levers then aftermarket for Hinckleys - unfortunately, I cannot post the photo as its size exceeds the site limit.

For the T160 in 75, Lucas produced a very compact - 1-1/2" wide - left hand switch group incorporating headlight main/dip, turn signals, horn and headlight flash (horn button pushed upwards):-
View attachment 56149
... this was subsequently used on the 76-78 twins and is also patterned by Sparx; I have used these on pre-71 Triumphs originally without turn signals as they bolt on in place of the pre-71 dipswitch/horn button and work with the standard chromed clutch lever. Also meets your criterion of being polished.

Otoh, the T160 and 76-78 twin right hand switch group is an imho ugly modification of the switches on your bike, the black lever substituted with a bright red one for engine kill, one momentary button used on the T160 for the electric start, the other button unused - look online at any image of Triumph 19-1961?

Nevertheless, I wanted a kill switch and I was eventually recommended to Royal Enfield #144354:-
View attachment 56151
... however, further work for you (apart from needing to polish it) would be:-

. that switch takes the cable end of the throttle, you would need to replace your bike's twin throttle cables with the arrangement Triumph used on UK twin carb twins - single cable on the throttle into a one-into-two "splitter" under the tank for the two cables to the carbs;

. either modify that arrangement's throttle cable outer to fit the Enfield housing or have that cable made - I have access to Venhill ...

... but then of possible interest to you is the throttle with the larger diameter cable pull (1-1/2" o.d. vs the 1-3/8" o.d. of a standard twin cable throttle) can be used, gives a slightly quicker throttle action.


If View attachment 56133 is the clutch lever, you know that it should not pull more than the 1" of cable inner the standard levers pull?


Yes. However, they need to be lacquered soon after or the alloy dulls quickly.


The T160/76-78 twin left hand switch group above works with the chromed clutch lever Triumph fitted in most other years.

No - the clutch lever in post #62 is on my '51 FL 'paint shaker' (that is a 1" flat bar with a similar bend and length to the 7/8" flat bar I got as an alternative for the Bonny, incidentally), but very good to know the clutch pull requirement. The universal master mentioned earlier arrived today, so I'll check it out this afternoon or mañana and post some pics.

Yes - I prefer separate switches and lever fulcrums, too, as you see in the photo of the 'paint shaker's L/H bar end. That said, in this case I'm aiming for a balance of OEM '70s Triumph parts with aftermarket or bespoke stuff, in order to achieve what I hope will be a good-looking vintage build but with heightened functionality.

As the balance, thank you yet again for the amazing amount of useful information. I'll mull all of this over and we'll see what looks and works best.

 

[NM Bonny]

Here is the universal 14mm bore master I got for (wait for it...) $17.88 on Scamazon w/free shipping. It has an ingenious external mechanical brake light switch but otherwise is so-so in the fit-and-finish department. As you can see, the lever is the same length as the OEM '71 Bonny cable lever, but the profile is slightly different.

I chose this one mainly for the bore size but the aesthetics aren't awful. I slipped it on the $13 flat bar for this photo. At any rate, if I'm able to design a viable caliper adapter per the earlier posts, we'll give it a try and see how it works.

 

[NM Bonny]

Just me again. "Oh, no," thinks you.

I think rounded edges easier on eye and fingers?

View attachment 55885

So I finally found some time to try this suggestion on a template, and didn't like the result. What you end up with is a little ear lobe-shaped tab fore and aft that looks great if viewed from 90 degrees to the bike's long axis like this photo. Yet the moment you start walking toward the front or rear, it ironically makes the side covers look less 3D.

But I appreciate the suggestion, as I thought it'd look better, too.

I am (still) waiting on the smaller Bonneville script transfers from the UK to finish deciding on the polish-and-paint scheme design. They told me I should've chosen the tracking number option, but that costs as much as the transfers themselves... ah, well. Maybe I'll just wait another week...

 

[NM Bonny]

The smaller transfers came in at last from the UK, and here are my options (see photos).

The larger decal comes in the '71 OIF block letters or the earlier script version; the smaller one is from an earlier bike (not sure where it goes, exactly).

My dilemma with the larger one is that I'd envisioned making am oval depression to receive white paint and the decal, but regardless of whether I use the bead roller with tipping dies or make up a stamp-style die as I did with the ignition key depression, I can't do that on the radius--necessary with the larger decal(s), which are too long to fit in the flat portion of the covers (the ignition key on the R/H cover precludes raising the decal sufficiently to fit).

There is, on the other hand, room for a smaller oval depression to fit the very compact 'Bonneville 120' script. Probably too small for me to make consistent, tidy depressions with the tipping dies, but I can make up a stamp-style die for use in the arbor press.

So, the paint-and-polish scheme alternatives I am mulling over are:

1) polish cover to mirror finish, then add white stripe with integrated, color-matched 'mist blue metallic' stripe leading back to larger white oval containing the big decal, and continuing stripe back to aft edge of cover; or

2) same treatment but with small oval depression to receive white paint and compact 'Bonneville 120' script.

I think either would look cool, but for some reason feel like the depressions might make the covers look more 'factory works' and three-dimensional than flat covers--which are fairly standard for flat-track racers, etc.

 

[NM Bonny]

I should earlier have shown this bike's crankcase breather setup. I have never liked that gray garden hose running up alongside the fender, any more than I liked the floppy scavenger return and OIF vent/shosh hoses. So, I bent up aluminum pipes to replace those, as you see here.

The latter isn't visible as it's under the tank, but it joins the main breather pipe as per stock just above its outlet from the primary cover, immediately ahead of the battery (behind the side cover). I use a silicone reducer and aluminum AN fittings to join the silicone reducer to the 1/2" aluminum main breather circuit which exits, as you can see, under/inboard of the R/H muffler.

The main breather pipe is 1/2" aluminum left over from the '51 FL project. The 'paint shaker' is a 74 CID engine with an essentially identical oiling and breather system to the '71 Bonny, and it uses a 1/2" breather standard. So, I don't anticipate any issues with an engine ~60% of its displacement. If any issues do emerge, I can always add a second breather, which I've heard mentioned in the Lemon Drizzle Gang's OIF video linked earlier, and a nicely-finished cafe racer OIF I found.

In that event, does anyone know where on the engine the second breather is added?

 

[Rudie]

smaller transfers
from an earlier bike (not sure where it goes, exactly).

On the tank, centre aligned with the filler cap centre, positioned on the other side of the central seam from the filler.

If you look at the 1970 Bonneville brochure, enlarge the image of the tank top, you will see the smaller version of the "block letters" decal positioned there (btw, the "block letters" are actually 69 onwards on US market bikes).

Afaict from brochures (artwork not always accurate), the "script" lettering decals were first fitted in 67 to many (but not all?) models, they were succeeded in 69 on US models by "block" lettered but what Triumph termed "UK & General Export" models continued to be fitted with "script" lettered until the end of 70; 650 parts books before 71 also titled the Bonneville "120".

 

[NM Bonny]

On the tank, centre aligned with the filler cap centre, positioned on the other side of the central seam from the filler.

If you look at the 1970 Bonneville brochure, enlarge the image of the tank top, you will see the smaller version of the "block letters" decal positioned there (btw, the "block letters" are actually 69 onwards on US market bikes).

Afaict from brochures (artwork not always accurate), the "script" lettering decals were first fitted in 67 to many (but not all?) models, they were succeeded in 69 on US models by "block" lettered but what Triumph termed "UK & General Export" models continued to be fitted with "script" lettered until the end of 70; 650 parts books before 71 also titled the Bonneville "120".

Interesting... okay, thanks. Of course this is not a 'concourse correct' restoration, but it's still cool to learn how they were originally used.

Now, I need to make some sketches and mull over what I want to do. Frankly, I like my custom application of the small Bonneville 120 decal more than the top-of-tank OEM positioning! "You say po-tah-to..." (no accounting for taste, as they say...)

My personal/professional life has overwhelmed me of late, so guess it's okay that I've got some thought and sketching work to do rather than the shop stuff I'd rather be doing... but I had really wanted to get the thing running before it gets too cold to ride...

 

[Rudie]

I like my custom application of the small Bonneville 120 decal more than the top-of-tank OEM positioning! "You say po-tah-to..." (no accounting for taste, as they say...)

No worries, just answering your "smaller transfers ... from an earlier bike (not sure where it goes, exactly)" query. If you use the small ones you have on the sidepanels, you could always get another small one for the tank top, just to remind you what you are riding when you are riding ...

 

[NM Bonny]

No worries, just answering your "smaller transfers ... from an earlier bike (not sure where it goes, exactly)" query. If you use the small ones you have on the sidepanels, you could always get another small one for the tank top, just to remind you what you are riding when you are riding ...

Absolutely, much appreciated.

Yes - I'm almost certainly gong to be selling the '51 FL, but until then I will need a reminder that I'm on a more lithe motorcycle with actual rear suspension!

 

[speedrattle]

1976 honda 360 sidecovers are a perfect fit on OIF machines. the seat hinge on the 1972 is on the weird side, but there is a cutout in the honda cover that fits it perfectly. i cant recall which side the 71 seat hinges on?

i used a pair for a long time until i switched to K & N filters which didnt allow for sidecovers at all

 

[NM Bonny]

1976 honda 360 sidecovers are a perfect fit on OIF machines. the seat hinge on the 1972 is on the weird side, but there is a cutout in the honda cover that fits it perfectly. i cant recall which side the 71 seat hinges on?

i used a pair for a long time until i switched to K & N filters which didnt allow for sidecovers at all

Oh, cool, thanks! I'll keep them in mind (not so crazy about the aftermarket 'air box eliminators' many people mount to OIF bikes) if ever I want to go with those pancake chrome filters (prefer K&N cones with the emerging lines of this bike, I think). The hinges on my '71 OIF Bonny are on the R/H side; the latch--like from an old lunchbox--needs a little TLC. I may make up a new, polished latch from some leftover aluminum sheet used on the covers...

Well, we will see how these turn out--as you can see, plenty of room even for taller K&Ns if I ever wanted them. These petite cone filters look nice, should breathe sufficiently well on this little engine, and there may be room for those finned insulators if the phenolic resin jobs don't do the trick (have to install longer studs to accommodate them, as mine are still stock length).

My first time fabricating from sheet aluminum, so as much an exercise in tinkering as custom bike-building, but then that's part of the attraction for me.

 

[speedrattle]

the only images i have showing how they fit the hole are these old photobucket pictures:

maybe they'' ll show up? im having image difficulties.

its not hard to fabricate mounts for them on the top, at the rear where the stock airbox peg is, and then with a simple spring in front holding them together. i used them because i lost the original airbox and sidecovers when i changed carburetters. since then i have fitted large K&N filters that dont allow any side covers at all, so the machin looks incomplete but runs very well.

cheap at swap meets. i bought another pair at a BSA swap meet, of all places. twenty bucks for both and he had two more he wanted to sell me.

 

[NM Bonny]

the only images i have showing how they fit the hole are these old photobucket pictures:

maybe they'' ll show up? im having image difficulties.

its not hard to fabricate mounts for them on the top, at the rear where the stock airbox peg is, and then with a simple spring in front holding them together. i used them because i lost the original airbox and sidecovers when i changed carburetters. since then i have fitted large K&N filters that dont allow any side covers at all, so the machin looks incomplete but runs very well.

cheap at swap meets. i bought another pair at a BSA swap meet, of all places. twenty bucks for both and he had two more he wanted to sell me.

I can see the images just fine, thank you.

Very cool, nice to have alternatives!

 

[NM Bonny]

Well, my brake R&D is interrupted by personal stuff that will persist for a few weeks at minimum, but I needed to take a break from the stress, so came up with what I think will be the design for the side covers (attached sketch).

My challenge was that I haven't got much left from the pint mixed up to paint the tank and fenders, and didn't want to mix up another pint just for side covers--because much of them will be polished (a pint is the smallest amount one can mix up to get the proportions of color, pearl, and metallic correct).

So, either it'll be as represented here--which uses the least amount of the remaining color in the bottom of the tin, and which I'm 99% confident will be enough to form those thin stripes. Or if I can fill the reservoir of a small, hobby-sized airbrush, that should be sufficient to make the indicated 'white' portion tank/fender colored, and the indicated thin stripes would then become white, together with a narrow white block or oval, upon which I'll float the water slide "Bonneville" decal--which is gold, of course.

I am worried that if I don't use white beneath the gold decal, it the lettering won't show up very well. Any thoughts...?

In either case, the paintwork would then get sanded with 1,000 grit wet sandpaper, followed by a catalyzed clear coat, per Classic Transfers' recommendations (and my own leanings, to protect from petrol and the elements).

 

[NM Bonny]

Life has been seriously intervening with my tinkering, and frankly has thrown me for quite a loop these last couple of months (deaths, divorces, and disasters, oh my!). But I'm back at it and preparing to R&R the headset bearings and races as they feel notchy. Also, just ordered new bushes and dust excluders for the swing arm--which I'm sure, based on the condition of the headset, need replacing, too. Got the bush-extraction/replacement tool, as it was amazingly cheap from a UK supplier.

The weather has been splendid lately here in the high desert, if quite chilly. But after I finish modifying the clutch cable on my '51 Harley FL--because I need something to ride to keep from going insane--and when the parts come in for these two bits, I'll dive into the primary & clutch inspection, alternator upgrade, install the tranny sprocket and new seal, fix the headset and swingarm, and fire her up.

I need to give her a go to decide whether I will indeed proceed with the front disc conversion imminently or stick with the OEM TLS front brake at least for the interim. I do not feel safe testing her out with the notchy headset--and of course would need different spokes to fit the aluminum rims discussed earlier, depending on which front brake hub I settle on.

Happy New Year to all of you.

 

[sikatri]

Wow, that’s a lot at once. Hope your new year starts off with less excitement!

 

[NM Bonny]

Wow, that’s a lot at once. Hope your new year starts off with less excitement!

Thanks for that; it's been a profoundly disorienting and depressing year. As I'm sure many on this forum would agree, it's hard to quantify the value of tinkering with a vintage Triumph and looking forward to a Spring ride on a refurbished and (mildly) modified mount. But suffice to say, that value increases exponentially with the accumulation of negative stuff in one's life.

I will try to remember to strap on the GoPro for the initial ride down the canyon and along the Rio Grande to see how I like the TLS front brake and test the transmission.

Here's a photographic Happy New Years card from the front courtyard...