250cc single cylinder prototype

of Norton design before the AMC takeover....

This 250cc prototype was based on half a Dominator engine, and it performed well. 

After the AMC takeover, it was decided to make a short stroke twin instead, which was supposedly based on a twin design that preceded Hopwood's Model 7 design, with a gearbox (AMC lightweight origin) tacked on the back.

Despite this being not that old, I've not seen any drawings for it. Strange when I have seen drawings for the prototype 500 twin and the 350 twin engine from the early and late 40's. I have seen twin drawings predating WW2 so a twin was on their minds then, but seen nothing on a 250 single in the 50's.  

This wasn’t half a Dominator, it was a completely new design, high camshaft engine. It ran well but AMC refused to allow it into production, probably a big mistake. When they closed down Bracebridge St.in1963, Bob Collier was ordered to destroy  and scrap it, along with most of the other development machines. He did a token job of destruction by knocking a dent in the tank, then spirited it away along with other things such as the WD side-valve Dominator, Unified 650 Twin engines and various other things. He showed me all of this when I visited him in the following year. Most of it went to Sammy when Bob passed away and the rest is history. 

Checkout the 2006 August edition of CBG.

There is a very extensive article about the Norton 250 prototype single.  I believe written by Jim Reynolds.

Roy Bacon also mentions a 250 single on page 124 in his Norton Singles Book.

Its a shame that these fascinating  Prototypes lie in dusty corners of museums, they should get brought out to run and be exhibited at shows.

As Philip’s photo shows, there’s no relationship with the Dominator design. The high camshaft and sloping cylinder resembles Vincent design more than anything else. Also, the modern for 1954 looking unit construction is apparent. It’s hard to believe that this wouldn’t have been a success and it must have knocked the stuffing out of the team at Bracebridge St. to see the AMC board kill it. The only reason that I can imagine is that they might have thought it would damage sales of the existing lightweights made by James and Francis-Barnett. After wasting the time and money spent on this, within four years they decided to repeat the exercise with the Jubilee, which because mostly of cost-cutting was ruined largely by cheap Wipac electrics and made unreliable by the ignition system that wasn’t sustainably accurate enough for the short stroke design to run well for very long, which it didn’t. It wasn’t based on any previous design, the only resemblance to the pre-Hopwood 500 twin being the twin camshafts. It was a ground-up new design by Hopwood and Hele, originally intended to have each barrel and head cast in one piece. They can be made to run well consistently and I’ve done that, but I don’t kid myself. The earlier 250 was a far better prospect, whereas the lightweights were flawed as originally sold and damaged the Norton reputation. What a wasted opportunity the 1954 bike was. 

The issue regarding the failure to produce the 250cc Single-cylinder model exemplifies the crisis that was beginning to affect all the motorcycle manufacturers of the period; configuring a super new design, and one which would undoubtedly be successful, is one thing, finding the money to put the machine into production is quite another.  Realistically, AMC would have realised that there would be no ‘extra’ profits from the exercise; a new and superior machine from Norton would definitely draw customers’ money away from their existing products so there would inevitably be a significant loss within the group rather than a profit. It’s also entirely feasible that AMC were making hardly any profit at all on their smaller machines during the period in question once increased labour costs are added to the equation. There were a number of forward and then backward steps during the period; the Jubilee would have been an excellent machine if it been constructed to the original design specifications; the ES2 Mk.2 was actually an excellent machine in its own right but traditionalist saw through the transformation of the original Matchless machine into a Norton as nothing more than a marketing exercise.

Questions can be raised about all the eras of Norton production, whether from the early days with James and his fascination with 79x100mm and footboards right through to the Donington era and the various issues with 961 Commando machines - in the final analysis, it always comes down to money.  Place yourself forty years ago [1983] and try to imagine that the last manufacturer of British motorcycles is about to go into liquidation; a knock at the door ‘there’s a builder from Ibstock in Leicestershire who wants to buy the Meriden factory for the land and he’s promising to build some more motorcycles and turn them into a world-leading brand’.  The first response would be to ascertain that he knew nothing about motorcycles and had no history of making them. He had drive, but, crucially, also lots of money, over £100 million spent before a bike left the factory. He chose Hinckley because of his personal knowledge that people from that town worked very hard. He was encouraged by the district council who were trying to attract more diverse manufacturing into the area. All the factors at play for Triumph were not in place for AMC in the mid-1950s, who, historically, always lacked finance and foresight. They were responsive rather than reactive. Undoubtedly, the Commando is a greater machine because of the ex-AMC input to the design, so perhaps that should be considered their actual legacy regarding Norton. And the direct ancestor of the Commando is not the Atlas, but the P11 [discuss].   

I don’t quite see how a new and superior machine that was a 250 would draw money away from anything that Norton or AJS/Matchless were offering then because they weren’t making a 250. The FB/James brands were lower-priced “cooking” machines that wouldn’t have been direct competitors, so any effects on them were likely to have been marginal. The 250 single looked like a Norton and would have fitted in well as a starter to the existing range, as well as likely being the basis for a modern 350 that could have replaced the Model 50. Certainly its unlikely that this new design could have been produced cheaply, but as a quality product clearly ahead of any competition then, a high price might not necessarily have been a handicap, as Honda proved later with the C72 and CB72. People approved of something that looked better and bought it. Also true of the Commando, launched in 1968 at I seem to remember £456, which seemed astronomically pricey then.   Also I can’t work out why the P11 desert racer should be more of an ancestor to the fast roadster Commando than the fast roadster Atlas. It’s a quite different animal, with a different purpose. It’s certainly true that both came before. 

'Does anyone have a scan of the Classic Bike Guide article?'

John........You have to be very careful with making copies of articles.  Especially if they are not that old.  I believe you can make such for personal use but passing it on to a third person might upset the Author. Most books and magazines have a statement, usually at the front, forbidding any means of copying without permission.