Special scramble Manx engine

I doubt that is a genuine engine number. A metal label held on with screws just looks wrong to me. Puts a question mark over the whole bike. Also where is the upper bevel box cover? 

The Bracebridge Factory built some Manx engined Scrambles bikes in the early 50s. 

Neatly built up machine with a magnesium conical hub at the rear.  Is that a nickled frame or moly tubing ? Bit special with a non cradle set up.  Swing arm with rear adjusters also ….

It’s clearly been hung together in race trim for a few seasons so must have been reliable. I’m sure Richard will give us the heads up on that particular motor.

To fit an ID plate professionally shows more credit to its builder than a non, or corrupted Identity. Casings in this game were susceptible to internal and external damage, retaining the number on replacement casings shows integrity.  

What area does it live in?  Should try raise some history on local scrambles entries. Or maybe the owner can fill in some history.  Les Archer made a huge impact on the European Motorcross scene on such a machine. With one of our members owning one of Archers machine in the South of France.  I’m sure there will be further to come on this one.   

Very nice, desirable machine.

Jon

ended up in the US:

https://photos.thecreeper.net/Motorcycle-Stuff/Clubman-Awards-2014/i-f7Rfk7H/A

Hi Christian, if you would like any help with the identification, please don't hesitate to email me at recordspostwar@nortonownersclub.org .

The plate that replaces the engine number appears to be missing the last digit 4507*. If you would like me to look into this further, let me know. Your crankcases look to be from the Featherbed era in style but Richard is probably the best bet for engine specification. 

Kind regards,

Paul.

Hi Christian/all.

  Just getting sorted after one of the power cuts yesterday !     If the engine number is correct, this is a 1952 350 DOHC 40M which looks possible as the rear frame section looks like the early type featherbed with the upright shock absorbers. The bottom half of the engine also looks the same period which will be an 88mm long-stroke 350. The barrel looks a proprietary part with only 6 fins and it is possible this might be a conversion to make a short-stroke 500 which would explain the yellow race number plates that are used for the 500cc capacity class. The cylinder head fins have been drastically shaved back, so probably run on dope fuel, and the cambox although being a SOHC, will still fit the cylinder head. The forks and front wheel are obviously much later and also the AMC gearbox which looks a very tight fit against the engine.

   Although the bike looks to have been built with purpose, I think it lacks the quality of build of the Archer machines. I would think this bike was built, copying as much as possible, the succesful early Archer specification at a later date. Having said all that, unless there are any records from Archers, nothing is definite and we can only use our best judgement.

This came up on the singles fb group - similar looking frame?   

Submitted by Christian Wyss on Wed, 03/01/2024

In reply to Another Les Archer creation....by Michael Rettie

The best known

The best known with the curved frame from a Commando.

To my knowledge a commando frame wasn’t involved! -

Les Archers frame was based on a featherbed if thats what you mean?! The frame in your pic could be one of Eric Cheney’s he  was good friends with Les. I suspect this is a replica bike build to race in the pre 60/65 class in the 90s/00s - I’d certainly be happy to take it around the track! 

Dan 

…to the picture Dan put up. Front engine plates, footrest arrangement, carb. Strangely it seems to be a late 50’s machine that has had an extended life into pre 65 guise with what look to be Cerriani forks and small hub front wheel.  more pictures especially with tank off would be good 

cheers

Jon

Christian, I think that’s one of Les Archers bikes, You probably know he successfully campaigned on it back in the day, As you describe his frame was sort of based on the Featherbed and had distinctive curved front downtubes as shown in the picture from the museum, there are some similarities with your bike but my guess is someone had Les’s bike in mind when the built it.

I’m asking around to see if anyone remembers or has any old pre 65 programmes it but as a non UK bike that might be a forlorn hope!

I’ve copied your pic below for ease of viewing! 

Christian

Is it still in Switzerland or in the UK?  I know a few riders who would like to take it for a spin! (Or you could bring it to one of the Pre 65 classic Scrambles!

(Heres hoping) 

Dan 

Hi Christian/all.

   Our camshaft Norton specialist Barry Stickland pointed me to Mick Walker's book " Manx Norton " in which he included a short chapter on Les Archer and his Nortons. I have attached scans of the 4 pages and if you zoom in on the photo of the engine, is does look very much like the subject of this post, but not sure on the cycle parts.