Norton 650 Unified Twin

Fast Eddie · Jun 2, 2024

seattle##gs said:
I suppose the cam is in the usual spot but I don't see how it's driven.

Looking at the above pics, I’d guess the cam is behind the block. Can’t see any evidence of there being space for it up front?

mdt-son · Jun 2, 2024

seattle##gs said:
I suppose the cam is in the usual spot but I don't see how it's driven.

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

cliffa · Jun 2, 2024

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 .

According to this article by Anthony, the frame was going to be oil bearing and called the “Pluto”.

http://workingatamc.london/images/design_tony_denniss/Curzon%20Unified%20Twin%20(amended).pdf

mdt-son · Jun 2, 2024

cliffa said:
According to this article by Anthony, the frame was going to be oil bearing and called the “Pluto”.

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

annajeannette · Jun 7, 2024

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.

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

Fanfan26 · Jul 24, 2024

It can be seen on this video from May 19, 2024 at 3.29

74ok · Jul 24, 2024

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

Norton P10 - Wikipedia

en.wikipedia.org

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

Thread 'Prototypes'

Mar 16, 2020

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)

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

Norton P10 - Google Search

74ok · Jul 24, 2024

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

Anthony Curzon – P11 - Google Search

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.

R

Post in thread 'Norton 650 Unified Twin'

Apr 8, 2016

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......

norton bob · Jul 25, 2024

The book is written but with such a limited market ,i think the cost will be prohibitive , and its a very thick book!.

Norton 650 Unified Twin

Similar threads