Norton 650 Unified Twin

https://walridgemike.wordpress.com/2016 ... fied-twin/

Here’s something you don’t see every day. Norton’s 650 unit construction twin, a bike which never went into production. My good friend Anthony Curzon owns two of these, the one pictured above having just been assembled, utilizing the Matchless frame. Anthony’s other machine uses a Norton slimline featherbed frame and I had the pleasure of taking it for a spin around the South London suburb of Croydon a few years ago. The motor revs very freely and is remarkably smooth. The head resembles that of an A10 and, as with BSA twins, the camshaft is to the rear of the crankcases.

Click to expand...

Thanks for posting the link.

One of the many projects that came to nought !
No mention of how the supposed overheating was solved ?
Nor that it took many decades to get it together and running,
better than never we suppose.
All that work for no gain ?

first i've heard of this engine

https://walridgemike.wordpress.com/2016 ... ifed-twin/

https://www.google.ca/?gws_rd=ssl#q=Ant ... ified+Twin

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.

from what i've stumbled on, i didn't get the impression that there was any particular interest/value in these engine/bikes?

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......

There was an article and pictures of this deveplopment motor and bike in Classic Bike September 2004. Never seen anything on the 250 horizontally laid 5 speed box lump AMC were developing....so a friend working at AMC once told me about. One part of the tale was that the development model was clocked at just over 90mph by the plod and the rider booked for speeding.....another was that after spending over £100,000 on development the Directors cancelled the project saying no one would want a 5 speed 250 single....and what did Royal Enfield produce not long after, with its exploding 5 speed box!!
The picture of the motor shown on page 33 is interesting in that it shows how the hole up the inside of the drive side crank was SUPPOSSED to be so the drill used to clean it out left NO stress raiser directly beneath the big ends outer 90 thou stress reducing radius. Unfortunately the people doing the job did NOT often do the job as per the drawings and the consequence is that cranks break at this point....with expensive consequences.
Of course as one friend said to me several decades ago as I told him about the stress raiser I thought only I had found.........'" Oh did you not know about it??? I thought you did. I have been removing it from my and customers road and race cranks for decades ...the cranks break if you dont".
If EVER you have your crank in bits CHECK it and if the stress raiser is in the wrong place get the drive side half checked because it could be well on the way to complete failure. A friend and I had all our second hand cranks checked and I ended up with two more timing side halves than drive side halves having lobbed two drive sides into the scrap bin as they were already on their way to failure ...NOt that you could see it with the naked eye. If the crank is still OK get the streess raiser moved and polished out BEFORE shoving the motor together. And IF the person you ask to do the job does not know what a stress raiser is GO ELSEWHERE very fast and NEVER use that person or company again.
No spell or grammer checks done.