The Cafe Thread

[grado]

[grado]

[grado]

[grado]

[oldironnow]

[Allred]

750cc Triumph Triple in a Manx "Featherbed"

[Allred]

A nicely done unit construction Triumph in a slimline featherbed.

Clipons, rearsets, sweptbacks, Goldies, concentrics, tein clocks, alloy rims and a TLS front brake. Looks like a 4gal (imperial) alloy tank, dual racing seat.........and one of those awful central oil tanks!

[Allred]

An very nice early single carb pre-unit 650 Triumph in a Norton featherbed (pretty sure that's a Manx not a wideline).

Twin clocks, clip-ons, rear-sets, no swept-backs, and peashooter "Commandor" mufflers.

Nice alloy tank, dual racing-style seat

Over-size 4LS front brake, alloy rims, and the dreaded central oil tank!

[Allred]

A lot of nickle, chrome and alloy on this one!

[Allred]

<nabble_img src="unit_in_slim.jpg" borde

A later rendition of a Triton using a later unit-construction T120 in a slimline featherbed, using modern tires brakes etc. "0"/>

[Allred]

If you couldn't find a Triumph engine, you could drop a 650/500 A10/A7 BSA twin in a Featherbed frame and create a "NORBSA"



Or, if you could find a Triumph motor, but not a Featherbed frame, you could drop a pre-unit Triumph into a BSA A10/A7 frame and create a "TRIBSA"

The BSA frame was WAY better than the Triumph abomination, but not in the same class as the Norton Featherbed.

The pre-unit A10/A7 BSA engine was a fine engine, but not as tuneable as the Norton or Triumph.

The Triumph gearbox was horrible, the BSA (Burman) gearbox was fine, the Norton (AMC) gearbox was wonderful.

[Fatfatboy]

Interesting notes, Allred.
Was the NORBSA a direct bolt in or was there some frame modifications needed?

[Allred]

FatFat Said: "Interesting notes, Allred.
Was the NORBSA a direct bolt in or was there some frame modifications needed?"

No frame modification needed per-say, the Norton Featherbed is very spacious due to its "continuous tube" design, what was needed for any/all of these configurations was special engine plates that matched the particular engine with the particular frame.  

All of the pre-unit motors looked good in a featherbed, and the BSA A10/A7 frame is a nice looking frame too and looks nice with a pre-unit Triumph motor in it, but the later Triumph unit construction motors never really "looked right" in a featherbed, they sat too high and too far back, and, well, just didn't look right.

The later Trident/Rocket3 motors look fine in a Featherbed.

I always hated to see central oil tanks fitted to anything in a Featherbed, firstly you had to have a hole in the seat to access the filler cap, (or remove the seat completely every time you wanted to check the oil level)  secondly it left you with nowhere to put the battery, and thirdly it spoiled the look and balance of the frame and the rest of the bike. The original oil tank and battery box are fine, and if you want some glitz, have them chromed.

I love the look of the large BSA A10/A7 oil tank and battery box, I think they compliment the frame and general balance of the bike, as in the TRIBSA pictured above.

[Allred]

A period shot of a pre-unit Triumph in a Slimline Norton Featherbed.......with stock oil tank and battery box retained (chromed).

Shot must have been post-1967, when Amal concentrics were introduced.

[Fatfatboy]

Wow! Allred, you’re an encyclopedia on the old Brit race bikes.

Thank you.

[Allred]

Yeah, as the saying goes....."I was there", so it was all common knowledge to us "Ton-up Kids".

At the time I spent my extremely meager apprentice wages on making my cafe-racer wideline Norton 600 Dominator as fast as I could. Paul Dunstall was a god-like hero and he received a large portion of my hard-earned money........ 10.5:1 pistons, MK IV hi-lift camshaft, flat-foot tappets, S&W valve springs, gas-flowed downdraft cylinder head, lightened pushrods, lightened & polished rocker-arms, etc, etc,  

5 gallon (Imperial) gas tanks were de-rigueur, as were clip-on handlebars, rear-set footrests, alloy fenders, alloy triple yokes, swept-back headers, etc. all very expensive items on a teenager's servitude wages!

[Allred]

The "fashion" for café racer gas tanks was to follow the styling of the race bikes of the time, particularly the Manx Nortons, which, to be sure of having sufficient fuel to complete a 5 or 6 lap race at the IOM (200+ miles) used 5 gallon Imperial (6.25 US) gas tanks. The styling filtered down to the street bikes, as did the clip-on handlebars and rear-set foot pegs.
It was a halcyon time compared to the current often relatively small size of standard gas tanks, a street café racer of the time would return between 40 and 65mpg (Imperial) depending on how hard it was ridden, and so searching for gas stations wasn't usually a problem as you could ride for 250-300 miles on premium lead-added gas before even thinking about looking for a fill up.

Most café racers of the time favored the 5 gal Imperial (6.25 US) gas tanks, but around 30% of riders went for the "Short Circuit" alloy gas tank which was usually around 3 gallon Imperial (3.75 US) or less capacity which could reduce the distance to as low as low as 120 miles when ridden hard.

When the Japanese arrived with superior machines in terms of power, acceleration, top speed and features the gasoline consumption figures took a dive, you don't get something for nothing, and something like a Honda CB750 would return 45mpg Imperial (36mpg US) to as low as 25mpg Imperial (20mpg US) when ridden hard. ………and the sister Kawasaki 2-strokes triples are legendary for low-teen gas consumption figures!

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[oldironnow]

Allred wrote

<nabble_img src="unit_in_slim.jpg" borde

A later rendition of a Triton using a later unit-construction T120 in a slimline featherbed, using modern tires brakes etc. "0"/>

Excepting for a bit of quibble over the wavy front brake discs, very nice.

[Allred]

A VERY nice example of a Triumph Triple in a Manx Featherbed.......


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[oldironnow]

Allred wrote

A VERY nice example of a Triumph Triple in a Manx Featherbed.......


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Very nice.