Restoring & Modifying 1971 OIF TR120

[NM Bonny]

I have a new (relatively) top-end job on my Bonnie and it should, I say SHOULD be broken in by now and it does use some oil. More than one might expect. As I recall, way back in '78, that it did use a bit of oil, so on long trips I took a few gallons extra . . . ha.

Oh, and it has NO oil leaks and does not smoke either.

Ah, okay… thanks for the data. I now know what I’ll be doing with one of those end compartments on the tail trunk…

 

[Lordmac]

the bulk of the 4 lb reduction came from ditching the OEM drum

Four pounds, eh? Without that heavy OEM disc and caliper, I would'uh thought six, but hey, that means you can load up on Mexican food dinner and still be in class weight!

I really like your disc set-up, though. You know how the originals perform . . . real, uh, let's say shy. It might be cool if SOMEBODY had an easy-to-do kit for a direct replacement of the OEM caliper on T140s with light-weight aluminum or magnesium or palladium or beryllium or nuklearilium stuff. The few replacement parts out there I have seen don't make me too excited, you see.

 

[NM Bonny]

Four pounds, eh? Without that heavy OEM disc and caliper, I would'uh thought six, but hey, that means you can load up on Mexican food dinner and still be in class weight!

I really like your disc set-up, though. You know how the originals perform . . . real, uh, let's say shy. It might be cool if SOMEBODY had an easy-to-do kit for a direct replacement of the OEM caliper on T140s with light-weight aluminum or magnesium or palladium or beryllium or nuklearilium stuff. The few replacement parts out there I have seen don't make me too excited, you see.

Well, I don’t know how it compares to an OEM disc setup; that 4 lbs figure is vs. the OIF conical drum brake. A cast iron caliper could well be double the weight of the aluminum Wilwood model (that’s pretty typical for aluminum vs steel for [x] volume of metal)—and wouldn’t have 4 pots, but probably two. You get better modulation with several, smaller pots.

Why does it matter? Well, 4 lbs has a considerable moment of inertia, so with the existing springs and dampening in these forks, what you get is a more responsive suspension in terms of handling uneven pavement while leaned over in a sweeper—and a tire that’s in contact with the pavement for a greater percentage of [x] time frame during a hard stop on blacktop ripples, etc.

There is a British-made, big brake conversion that I think I posted to earlier in this thread—but it’s for OIF bikes with existing disc brakes, so wouldn’t fit my bike's triple tree width. Also, I didn’t like the way it looked… Yuck.

Ultimately, I like designing stuff and wanted the lightest possible, most powerful, simplest setup I could come up with. Also, using a Harley-spec rotor means a bazillion designs and competing vendors. Then there’s the aesthetics, and finally anticipating manufacturing considerations for the bespoke caliper adapter.

Put all those considerations together, and this is what I came up with. Far safer, easier to service, and downright sexy!

 

[Rudie]

You know how the originals perform . . . real, uh, let's say shy.

Never understood the complaints about the 73 onwards single disc on twins; I bought my T160 brand new with exactly the same parts, the single front disc only became marginal (I like good brakes) when I carried a passenger and/or I became able to use the engine's power (the T160's a good 50 lb heavier than a twin). I do wonder if some of the complaints are down to owners pottering about, using the brake gently most of the time, glazing the pads ...?

What pads are fitted in your T140's calipers?

It might be cool if SOMEBODY had an easy-to-do kit for a direct replacement of the OEM caliper

There always has been: 70/71 Formula 750 triple racers had Lockheed aluminium alloy calipers more than two years before the road bikes got the steel calipers; the Co-op fitted a different version of the alloy calipers from 82 - all the alloy and steel calipers are based on those fitted to tuned versions of the 60s British Mini car. Current version is https://apracing.com/special-vehicles/motorcycle/brake-calipers/cp2696-38e0 I have three of the earlier handed versions on my T160.

There is a cheaper version by Wassell. Afaict, Wassell have somehow managed to get their hands on a version Lockheed licensed years ago to Grimeca, who metricated all the dimensions and threads; as with much Wassell stuff, several people I know who have fitted the calipers have had trouble with them.

 

[Oldboy]

Two questions. I’m hoping someone can clue me in to what is the normal range for these bikes:

One - The rocker cover bolts seem to loosen a smidge after several hours of running--together with the clamps holding the ‘manifolds’ for the Mikunis (look to me like just slices of fuel filler hose). I’m obviously more interested in knowing whether it’s normal for the rocker cover bolts to want to loosen, as my ’51 FL, aka The Paint Shaker, also has a 360-degree crank but doesn’t do that.

As for the carbs, I plan on fabricating some lightweight supports. Right now, they essentially dangle on the ends of the ‘manifolds,’ and unlike the similar hoses for the Bings on the Beemer, the air cleaners do not help support them...

Two - Oil consumption. What is typical for a Unit 650 in decent running shape?

I made new rubber hoses for my 750 Bonneville Chopper using appropriate size automotive fuel tank filler hose. You may have to look harder than I did back in the mid 1990s but it will support your carbs like they are solid mounted.
If you want extra security or dressup, go to a hardware store and buy a couple no hub connectors with the fluted aluminium wrapping and use the aluminum and stainless clamps over the hoses.
Yes my engine still uses the same rubber hoses I made in 1991.
Promise you will not need braces if you do this

 

[NM Bonny]

I made new rubber hoses for my 750 Bonneville Chopper using appropriate size automotive fuel tank filler hose. You may have to look harder than I did back in the mid 1990s but it will support your carbs like they are solid mounted.
If you want extra security or dressup, go to a hardware store and buy a couple no hub connectors with the fluted aluminium wrapping and use the aluminum and stainless clamps over the hoses.
Yes my engine still uses the same rubber hoses I made in 1991.
Promise you will not need braces if you do this

I think NAPA still sells fuel filler hose. I feel like I bought some for a hot rod project a few years back… I’ll check it out. But these may be sufficient in combination with your next suggestion...

Wow… I never would’ve thought of no-hub connectors. I will see if they exist in the right dimensions for this bike. Cool!

 

[Oldboy]

I think NAPA still sells fuel filler hose. I feel like I bought some for a hot rod project a few years back… I’ll check it out. But these may be sufficient in combination with your next suggestion...

Wow… I never would’ve thought of no-hub connectors. I will see if they exist in the right dimensions for this bike. Cool!

You can buy one that's 1-1/2" I believe. You can also buy any size, drill the rivet and cut them down to size. Check my build on the 1973 T140V chopper and you may be able to see them in action.
I also use them to secure my air cleaners on the 38mm Lectrons I used but those are 3" and use Cummins Semi radiator hose and 2bbl car mini air cleaners.