Restoring & Modifying 1971 OIF TR120

[CarlS]

Awesome work! Your skills are amazing.

 

[NM Bonny]

Awesome work! Your skills are amazing.

You're too kind. Seemed like the obvious way to exploit those unused holes and bushes...

...ahhh, I think I might be able to attach the choke control to the fairing itself, inside, just below the windscreen's mating edge.

 

[NM Bonny]

Okay: I think what I'll do is ditch the rubbers in the headlamp mounting bosses, so I can install much larger bolts for more clamping force on the dash panel.

Why do that? Because I've designed what amounts to a monocoque dash, and its rigidity depends on making the triple clamp's headlamp mounting bosses stressed members of the structure.

That is, it'll be fashioned from a single piece of .063" aluminum plate bent double, with the two 90-degree bends at the forward edge creating an upper and lower surface equivalent to the thickness of the gauges' rubber mounting groove (which measurement I can take from the OEM steel mounts).

So, here's a possible fabrication sequence:

1. decide on shape of dash face & determine appropriate gauge spacing
2. establish final height of monocoque and mark primary structural bends on aluminum sheet
3. determine gauge centers' distance from bends for cutting
4. cut gauge holes--don't forget to leave notches to prevent rotation!
5. mark outer profile of dash (both halves - top half will include tabs to bend down and in at sides if possible)
6. mark mounting holes (both halves)
7. cut outer profile
8. make first primary bend in metal brake
9. bend tabs at the sides, if any (these would need two bends to contribute to the strength of a monocoque box - their bottoms could be riveted and the fasteners wouldn't show)
10. hammer second primary bend & align gauge holes
11. check fit on mounting bosses & adjust as necessary
12. drill and rivet side tabs
13. break edges, scuff, and paint upper face with black wrinkle finish
14. attach dash with stainless bolts & washers (maybe chrome acorns on top, though stainless hex heads would match the fork tube caps--and all four could be polished to match the steering head tension nut...)

 

[CarlS]

You're too kind. Seemed like the obvious way to exploit those unused holes and bushes...

...ahhh, I think I might be able to attach the choke control to the fairing itself, inside, just below the windscreen's mating edge.

That sounds like an ideal location.

 

[Rudie]

clip-ons
lost 2" in width from the 28" flat bars

I had adjustable "ace bars" on my T160 for a while. One of the problems was, when my foot slipped on some gravel as I was paddling the bike backwards, not enough leverage to lift the bike back upright, I had to drop it, roll away from it, stand up and pick it up. Only my dignity damaged but, as this was in front of a bunch of people watching a group of triples departing an exhibition, the damage was severe ...

However, I appreciate your twin is much lighter than an electric start triple and you might be taller than me.

will need a shorter brake hose (sigh...) and may use a 90-degree fitting I've got lying around to aim the hose to the L/H side rather than straight down. I think I'll wait until the fairing mounts are in place to decide.

Fwiw, I do not use hydraulic fittings that make a sharp bend at the master cylinder - always hose straight out of the master cylinder then I try to match the curves of hose and clutch cable.

in NM the wind gusts can be sudden and fairly strong, so I'm eager to see how she fairs zipping out HWY 550 north toward San Ysidro and Cuba across the unsheltered mesa.

Aiui, the important thing for stability despite crosswinds is the centre of pressure should be behind the centre of gravity. E.g. one reason 1950's "dustbin" fairings were banned from racing was their large surface area on each side generally moved a bike's CP in front of its CG, causing or exacerbating undesirable instability at high speed.

1" x 1/8" aluminum bar
that'll replace the steel rear brake backing plate strap. I'll drill some 37/64" holes (or thereabouts) to further lighten it
break the edges of the holes to prevent cracks or tears from forming

If "break" is the same in the US as "ream" on this side of the pond,

What to do with the P-clamp holes? I suddenly remembered talking about putting warning lights there...

Many bikes fitted with clipons, the standard choke lever was/is mounted on a short piece of tube fitted between the standard handlebar mountings on the top yoke ...

 

[NM Bonny]

I had adjustable "ace bars" on my T160 for a while. One of the problems was, when my foot slipped on some gravel as I was paddling the bike backwards, not enough leverage to lift the bike back upright, I had to drop it, roll away from it, stand up and pick it up. Only my dignity damaged but, as this was in front of a bunch of people watching a group of triples departing an exhibition, the damage was severe ...

However, I appreciate your twin is much lighter than an electric start triple and you might be taller than me.


Fwiw, I do not use hydraulic fittings that make a sharp bend at the master cylinder - always hose straight out of the master cylinder then I try to match the curves of hose and clutch cable.


Aiui, the important thing for stability despite crosswinds is the centre of pressure should be behind the centre of gravity. E.g. one reason 1950's "dustbin" fairings were banned from racing was their large surface area on each side generally moved a bike's CP in front of its CG, causing or exacerbating undesirable instability at high speed.


If "break" is the same in the US as "ream" on this side of the pond,


Many bikes fitted with clipons, the standard choke lever was/is mounted on a short piece of tube fitted between the standard handlebar mountings on the top yoke ...

As usual, lots of good information, Rudie.

On the aerodynamics of 'dustbin' fairings, this recent Cycle World article is fascinating. Had no idea about Guzzi's pioneering role. I'm now regretting not having designed my own fairing, kind of...

Interesting idea on the choke control. Can't do that, of course, with my new warning light setup. This may be a two-pipe problem, as Holmes would say...

Some possible options, if I can't find a suitable place for the existing friction disc-style unit, are: (1) going to a turn-and-lock pull knob like the one in my '67 Midget, mounted on the dash panel or in the fairing; or (2) making up a sliding lever-style affair.

Of course, some people just ditch the choke control, but I think it's an ingenious design by Amal, in that unlike ordinary choke butterflies, it is completely removed from the air flow when not in use.

My 400' driveway is gravel and a bit squirrelly here and there. I would be really upset if I dropped the bike in the driveway and damaged the paint (the fairing is easily sanded and polished). However, I can lift my '51 FL with short drag bars, and it weighs a lot more than this thing, which feels like a bicycle in comparison. (I'm 6'2" or a little more.)

 

[NM Bonny]

The fairing arrived and good thing I installed clip-ons. No chance a flat bar would've fit.

No mods to mounts needed aside from drilling and cutting J-bolts - see below.

I will tell Markus so he can adjust fitment on website to include '71-'72 OIF models. Rudie: is neck of frame similar on '73-later bikes, so he can expand fitment even further?

Only additional thing needed was a rigid back plate for the lower mount, shown in 3rd pic. I just threaded a chunk of 6061-T6 laying around to 3/8-24, opened the metric hole in mount up a smidge, and was able to bolt on the fairing's lower mounts, attach the fairing, and align in horizontal plane L-R before beginning on upper mount.

Watch it when tightening lower mount to frame because steel plate is too thin on mount, so it bows easily... it's designed to go flat against rectifier mount...

Also: had to Dremel a little steel tab hanging down from neck (not sure of purpose) to slide bolt up between down-tubes to meet plate up inside of gussets.

Finally: theJ-bolts won't reach back of gussets but will slip into wiring holes. Just need to trim them and extend threads--or just bend up some all-thread... right now extra length limits travel... and that's it!

Controls and master cylinder clear at full lock w/steering lock engaged (before inserting J-bolts), but just barely (1/8").

Loads of room for my planned dash... looks cool!

Weirdest thing... front wheel didn't need even the slightest weights to balance. First time for me...

 

[CarlS]

That fairing looks really good!

 

[NM Bonny]

That fairing looks really good!

Not too shabby, eh?

The headlight is crap--pretty chrome bucket but useless, shallow reflector and lousy lens. I should've had him widen the opening to 7" as I was initially intending...

However, I have that way cool LED drop-in stand-alone, hi/lo spot which I got for the BPF OEM headlamp, so will adapt that bulb to the H4 reflector which came with the fairing, and I'll be good to go. It'll take some fiddling but I'll get her done eventually...

 

[NM Bonny]

The unbalanced LF Harris pipes came in from TBS, and they're flawless. The Acousta-Fil packing arrived yesterday from the UK to upgrade the Dunstall replicas, so I've got nearly everything I need in-hand to complete the bike. Unless the primary or clutch parts are worn...

I think it'll actually be on the road before winter!

 

[NM Bonny]

Well... shoot. This morning, I did what I hadn't done yesterday--throw a leg over the saddle, and... my knee touches the rear tip of the lower.

The metal comes to a fairly sharp point just there, so I can't very well leave it alone. Also, unfortunately, when I trim the trailing tips back, I will lose the nice rolled edge along the top. (The Ducati OEM fairing lacks the rolled edge.)

So, I'll make up a cutting template to provide sufficient clearance that maintains a good-looking profile, and think about whether I can leave enough material to reestablish the rolled edge--at least a little.

If you look at the Duck's lower trailing tips, I think they describe a steeper angle--closer to vertical, that is. So, a little less length and a slightly steeper angle after the radius, and I think it'll look good.

It's 2mm aluminum, so easy to form and--as Sikatri found out--bring back up to a polished finish. So the modification will be invisible when completed.

 

[CarlS]

Well... shoot. This morning, I did what I hadn't done yesterday--throw a leg over the saddle, and... my knee touches the rear tip of the lower.

The metal comes to a fairly sharp point just there, so I can't very well leave it alone. Also, unfortunately, when I trim the trailing tips back, I will lose the nice rolled edge along the top. (The Ducati OEM fairing lacks the rolled edge.)

So, I'll make up a cutting template to provide sufficient clearance that maintains a good-looking profile, and think about whether I can leave enough material to reestablish the rolled edge--at least a little.

If you look at the Duck's lower trailing tips, I think they describe a steeper angle--closer to vertical, that is. So, a little less length and a slightly steeper angle after the radius, and I think it'll look good.

It's 2mm aluminum, so easy to form and--as Sikatri found out--bring back up to a polished finish. So the modification will be invisible when completed.

That extra work is disappointing. But you will get it done.

 

[NM Bonny]

That extra work is disappointing. But you will get it done.

This restoration/modification has taken so long, so much thought and tinkering have gone into its somewhat meandering path, that I try to take a Japanese Zen-like approach: it's as much about enjoying the process and getting into the quality of the work as it is arriving at [x] objective. So, I don't really find unexpected jogs in the path disappointing, if that makes any sense...?

I think with 2mm aluminum, I can either use a Dremel cutter wheel or my saber saw with tape on the foot to avoid needless scratches.

If I clamp the trailing pieces to some 1/4" pine plywood scraps I have left over from the doors and bottoms of the cutting board and frying pan tray drawers I just made for the kitchen remodel, that should keep the aluminum from jumping around and tearing with the reciprocating blade...

Then, I can just break the edges and either try blending in a tapering-off rolled edge or just leave the 'lobes' unrolled. The Duck's fairing has no rolled edges, so it ain't like I'll be slumming without them!

 

[NM Bonny]

I realized that I hadn't done a final proof of concept fit re: the rear-sets and muffler on the L/H side. And I wanted to see how the OEM muffler mounts might work. The muffler clamps aren't tightened yet in these pics, so they'll be tucked in and up a little more than you see here......

Looks like minor tweaks is all that's needed. I'll probably make new mounts because only one bolt hole reaches and I'd like two grabbing the muffler's welded-on channel mount, as with the original setup.

The LF Harris unbalanced pipes fit better than any exhaust I've put on any vehicle in ~50 years of turning wrenches. Just outstanding jig work, no bending, stretching, opening up holes... The Dunstall replicas look great, kind of Buck Rogers in the 1st Century look with those multiple-hole outlets!

I found a nice spot for the choke control lever, totally hidden but accessible to the rider. I'll make up a little mount from some scrap 1/8" aluminum bar I've got laying around. It'll be easier to use than on the handlebar R/H side, as I can use my non-throttle hand by just reaching down ahead of my knee...

Windscreen isn't tight in this photo, BTW...

 

[CarlS]

Looking mighty darn good. Master craftsman work. .

 

[NM Bonny]

All righteeee then.

Here's the choke control, hidden inside the L/H lower trailing portion of the fairing. It just threads onto the fairing fastener, supplanting the nut, and snuggles against the fairing mount's flange to keep from rotating.

Works great. Now, I can reach it with my left hand while keeping my right on the throttle. After I trim the trailing tips for knee clearance, it'll still be hidden from the side view.

I'll probably put some blue loctite on the aluminum threads, as it's replacing a nylock nut and I don't want it vibrating loose at speed.

I know lots of people ditch these, but I think it's a neat lever and my aim is to retain a mixture of as much OEM stuff as possible while creating my unique vision of a '71 OIF Bonneville.

 

[NM Bonny]

More challenges...

The cables for the gauges foul the upper fairing mount well before full lock with the planned triple tree-mounted dash. So, the straightforward solution is to mount the gauges to the fairing at three points, per the attached photos: long, triangular side tabs will extend down to affix at the headlight mounting bolts; and the curving forward edge will bolt to the windshield's center top fasteners (maybe all four, not just two).

It'd be a little like the '78 BMW 1000 with its full fairing, which had two small gauges fitted just under the base of the windshield--but here they'd be the primary gauges.

This would present an advanced sheet aluminum bending challenge, as I've never tried an attached, curved flange, which would require shrinking skills and tools. Far easier with my lack of advanced sheet metal skills and tools would be to bend up the flat dash with triangular tabs reaching down to the headlamp mounting bolts and a curved forward edge: easy to cut out that template... Then just weld on a flange which bolts to the windscreen fasteners.

I could buy a spool gun ($261 with aluminum wire) and some pure argon gas ($250)... yeah, much cheaper to pay a skilled aluminum TIG welder his minimum shop charge for a single bead 7" long.

Or I could just rivet or bolt on a couple of tabs. With stainless button-head allen screws, that'd look fine as well--but not as nice as a smooth, sanded weld forming the forward edge...

 

[NM Bonny]

Ahhh... perhaps no need! I can very likely just form the edge by hammering onto a two-piece clamped form, which I can make from wood I have laying around. This guy is doing the same with steel sheet metal...

This isn't that tight of a radius and 5052 H32 forms reasonably well. I'll try a leftover piece I have and see if I can form this flange without tearing the aluminum...

 

[NM Bonny]

Uh, yeah... no way. That guy (and others) are forming thin-gauge automotive sheet metal. This .063" aluminum does not form like that--and my study with a wooden mock-up revealed an asymmetrical, compound curve. (This is a hand-hammered fairing, after all...)

Also, even a welded-on flange would describe a compound curve--so would still require shrinking. No thanks...

So, back to the drawing board. Took a fresh measurement, made a cardboard template, scratched my head a little, and settled on a simple, folded dash panel design I can make with my metal brake.

The dash will be angled back toward the rider to clear the master cylinder on the R/H side and also to avoid reflections (though those should be minimized by the smoke windshield).

The dotted lines indicate folds. The two small tops tabs bend down to attach invisibly to the windshield's top center fasteners, so there'll be a clean line where the dash meets the base of the windshield/top of the fairing.

The outboard tabs bend down to clamp to the upper mount's struts. The tach and speedo cables are just long enough--since they don't move with the handlebars--to work fine, I think.

Should have the headlamp and controls wired, and the dash painted and installed, in the not-too-distant future...

 

[sikatri]

The flatter and lower the dash the better. It was a bit tricky on mine even with a dash ordered from a company specializing lay flat solutions.