Norton 650 Unified Twin

seattle##gs said:
I suppose the cam is in the usual spot but I don't see how it's driven.
Click to expand...
No need for guesswork - Mike P confirmed it's behind the cylinder block, thus no twin cam layout like the small twins, and probably no geared drive either.
It looks like Norton mirrored the Domi camshaft layout, so I guess it's an intermediate gear and a chain drive to the camshaft. A gear drive for the camshaft using standard Domi parts is known to fail, as Jim Comstock has shown. My guess is that Norton played it safe and kept the old arrangement.

- Knut
 
norton bob said:
From memory the motor is 77.5x68.5 stroke, so oversquare . The mains are around double the size of the Atlas . So the bottom end is very strong . The crank is a one off that Anthony had made by Nourish .The featherbed version looks a bit less tidy . I dont think Norton would have used the Bed frame , They would have probably shortened it and changed it in other ways . Its a pretty heavy lump so a lighter frame would help. It was road tested at 120 mph as a prototype that needed a fair bit more work.Very hard to kick over now its bedding in . The old Atlas feels like a Navigator in comparison the longer stroke helping to get it over compression . It would really have needed an electric start and a big battery . A sort of brit Harley further down the line after boring and stroking out to 9oo cc or there abouts .
Click to expand...
According to this article by Anthony, the frame was going to be oil bearing and called the “Pluto”.


 
cliffa said:
According to this article by Anthony, the frame was going to be oil bearing and called the “Pluto”.
Click to expand...
No, they were not. The Pluto frame was an AMC development, the Unified Twin a Norton Bracebridge Str development. If you read the complete article, it states that the engine doesn't fit the frame. None of the board meeting notes suggests these projects were to be married. The Pluto frame was destined for AMC's big singles and twins. A scaled-down version was intended for a new G4 250cc model.
In the end, due to multiple deferrals instructed by the board, the P8 project had become outdated, and subsequently evolved into the DOHC P10, which was a much more modern design, incl. a 5 speed gearbox. The design influence of the P10 by the P8 is quite evident.

- Knut
 
Rohan said:
Anthony Curzon had the remains of 2 engines, for the past oooo 4 or 5 (?) decades now.
At last he has them up and running....
Supposedly he has also written a book on them and the hybrids (and 650 ?), last heard of he was looking for a publisher.

When BSA and Triumph came out with unit twins, Nortons probably figured they better follow suit,
and started developing their version of a unit 650 twin. Late 1950s, apparently.
It had a few teething troubles (overheating ?) and wasn't proceeded with.

Instead, they developed stronger cranks for the Norton 650, and the downdraft heads that became the 650SS.
Before coming out with the 750cc Atlas not that many months later.
So they must have all been on the drawing board together, not to mention being tooled up for production.
Click to expand...
well the Norton 650 was built from november 1960 and was named the Norton Manxman 650 some 10 months before any 650ss or standard or delux models witch were late 1961 to late december 1962 then bracebridge closed and it was some two months after the 3 Norton models contiued to be made and these where the model 88ss and 650ss and Atlas750 by then
 
mdt-son said:
No, they were not. The Pluto frame was an AMC development, the Unified Twin a Norton Bracebridge Str development. If you read the complete article, it states that the engine doesn't fit the frame. None of the board meeting notes suggests these projects were to be married. The Pluto frame was destined for AMC's big singles and twins. A scaled-down version was intended for a new G4 250cc model.
In the end, due to multiple deferrals instructed by the board, the P8 project had become outdated, and subsequently evolved into the DOHC P10, which was a much more modern design, incl. a 5 speed gearbox. The design influence of the P10 by the P8 is quite evident.

- Knut
Click to expand...

Norton P10 - Wikipedia

en.wikipedia.org en.wikipedia.org

www.classicmotorcycle.co.uk

Norton 800cc dohc | The Classic Motorcycle

Norton's experimental 800cc dohc The need was pressing, the calendar relentless. Under Dennis Poore, the Wolverhampton-based Manganese Bronze Hold ...
www.classicmotorcycle.co.uk www.classicmotorcycle.co.uk

BritTwit

Thread 'Prototypes'

Was the original Commando ever assigned a prototype number by the factory?
I know the P10 was the ill fated 800cc DOHC twin, and the P11 eventually became the 750 Ranger.
But did the Command design begin as a coded prototype?

pix (click on for close up)


www.breakoutcards.co.uk

Norton P10 - 1965 - Custom - Atlas Motorbike Fact File Card

Hole Punched To Fit In 3 Ring Binder01 904 72 07Make: Atlas EditionsYear : 1999-2001Size Approx : 185mm X 250 mmExcellent ConditionFront And Back Of Card Shown In ScanIndividual/Single CardFree Shipping On Any Amount Of Additional Cards/StickersCombined Shipping Discount Only Applies To Items...
www.breakoutcards.co.uk www.breakoutcards.co.uk

 
walridgemike.wordpress.com

Anthony Curzon – P11 Guru!

Pretty well anyone who has had anything to do with Norton & Matchless P11’s will have heard of my good friend Anthony Curzon. On my annual trips to England I usually spend a pleasant and…
walridgemike.wordpress.com walridgemike.wordpress.com

Rohan said:
Anthony Curzon had the remains of 2 engines, for the past oooo 4 or 5 (?) decades now.
At last he has them up and running....
Supposedly he has also written a book on them and the hybrids (and 650 ?), last heard of he was looking for a publisher.

When BSA and Triumph came out with unit twins, Nortons probably figured they better follow suit,
and started developing their version of a unit 650 twin. Late 1950s, apparently.
It had a few teething troubles (overheating ?) and wasn't proceeded with.

Instead, they developed stronger cranks for the Norton 650, and the downdraft heads that became the 650SS.
Before coming out with the 750cc Atlas not that many months later.
So they must have all been on the drawing board together, not to mention being tooled up for production.
Click to expand...
R

Post in thread 'Norton 650 Unified Twin'

Its pretty neat that the prototype engines have survived, and been built into bikes.

But at the time they were pretty secret I think, and very little info has come out about them until quite recently.
I sort of thought they'd found the engines problematic, and didn't even proceed with them once finding that.

It would be good too if Anthony's book on them is ever published, but this has been bandied about for years/decades,
and nothing seems to happen. He is expecting to make money ?, authors do it for love !
The inside story could be good to see, if he had access to it......
 
The book is written but with such a limited market ,i think the cost will be prohibitive , and its a very thick book!.
 
It's obvious the engine doesn't fit the frame very well (mainshaft to swing arm pivot beeing too large). A unit engine needs a shorter cradle. However, the way Norton Bracebridge Str. designed the cases, they are obstructing the swinging arm on any frame. Maybe Norton tested the engine in a rigid frame? Or on the testnench only. Anyway, the video reveals the powerplant was far from production ready. It's a feat by Anthony Curzon managing to shoehorn it into a G15 frame.

The road video made me dizzy - I had to quit! Oh man - Paul Henshaw loves to talk.

- Knut
 
All of the engines internals were missing ,so had to be specially designed ,drawn up and made , Crank ,rods, valve gear , clutch mechanisms ,gear change, ignition ,outer casings etc. A mammoth task for someone without engineering background or any facilities . Without help from some very tallented people it would have never been done . The Jack Moore twin (an even earlier prototype !940 's ? ) is a similar project by another SNOC stalwart . Mind boggling determination and hard slog, has brought these back to life.
 
Last edited:
mdt-son said:
It's obvious the engine doesn't fit the frame very well (mainshaft to swing arm pivot beeing too large). A unit engine needs a shorter cradle. However, the way Norton Bracebridge Str. designed the cases, they are obstructing the swinging arm on any frame. Maybe Norton tested the engine in a rigid frame? Or on the testnench only. Anyway, the video reveals the powerplant was far from production ready. It's a feat by Anthony Curzon managing to shoehorn it into a G15 frame.

The road video made me dizzy - I had to quit! Oh man - Paul Henshaw loves to talk.

- Knut
Click to expand...
The video made you dizzy?
 
baz said:
The video made you dizzy?
Click to expand...
I am referring to the 15 mile ride recorded in the video above. Try full screen mode yourself! The combined effect of a bumpy ride (or a poor fork damping) and the camera position affects the brain - mine at least!

- Knut
 
mdt-son said:
I am referring to the 15 mile ride recorded in the video above. Try full screen mode yourself! The combined effect of a bumpy ride (or a poor fork damping) and the camera position affects the brain - mine at least!

- Knut
Click to expand...
👍👍👍Ok
I must be lucky
I'm not affected by anything like that
 
Unit construction 4-stroke twins are garbage. In the1960s, everything needed to look like a space-ship. Motorcycle manufacturers were not selling motorcycles to dedicated motorcyclists - their potential customers were the kids who wore desert boots and duffle coats. The Triumph T100A had a splay port head and a 65.5mm stroke crankshaft. If done properly, it should have been faster than the 500cc Manx. The works bike which Percy Tait rode had the proper timing side main bearing which did not appear in the road bike until 1973. But if we bought the 60s T100, where would we get a gearbox ? With pre-unit bikes, we could use almost any motor with almost any gearbox.
My short stroke 500cc Triumph motor was built out of 650 parts. But I was too mean to buy the 6 speed close ratio gearbox which it badly needed. I did not usually lower the gearing on it - that made it dangerous.
Some people fantasise about short stroke motors - I get nervous even thinking about it. If you believe peaky high horsepower motors are good for racing, you are an idiot.
My Seeley850 sat unraced for 25 years because I did not believe in it - I am surprised at how good it is. What it can do in corners is almost beyond belief.
 
acotrel said:
Unit construction 4-stroke twins are garbage. In the1960s, everything needed to look like a space-ship. Motorcycle manufacturers were not selling motorcycles to dedicated motorcyclists - their potential customers were the kids who wore desert boots and duffle coats. The Triumph T100A had a splay port head and a 65.5mm stroke crankshaft. If done properly, it should have been faster than the 500cc Manx. The works bike which Percy Tait rode had the proper timing side main bearing which did not appear in the road bike until 1973. But if we bought the 60s T100, where would we get a gearbox ? With pre-unit bikes, we could use almost any motor with almost any gearbox.
My short stroke 500cc Triumph motor was built out of 650 parts. But I was too mean to buy the 6 speed close ratio gearbox which it badly needed. I did not usually lower the gearing on it - that made it dangerous.
Some people fantasise about short stroke motors - I get nervous even thinking about it. If you believe peaky high horsepower motors are good for racing, you are an idiot.
My Seeley850 sat unraced for 25 years because I did not believe in it - I am surprised at how good it is. What it can do in corners is almost beyond belief.
Click to expand...
What has any of your rambling got to do with this post??
It was 1969 when the unit triumph 500 changed
to a ball race on the timing side
And as for "what you're Seeley does in corners is beyond belief "
Ermmmmmm 🤔🤔🤔🤔🤔
 

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