Seems like a 750 serial number on an 850 (2008)

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Yellow_Cad

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Why would an 850 Roadster with 4/74 on the plate have matching numbers (motor and frame) 235,XXX? Weren't the 200,000 numbers used for 750s?
 
850's started in the 300,000 range. 750's finished in '73 sometime from memory. Is the motor an 850 or a 750?
 
As far as I know, all 850s had 300000-on serial numbers? And 235- being far outside of '73 750 production, the last known 750 being number 230935.

Just a long-shot, but is there any chance that this "850" is one of those 200 or so "750" 850s - the short stroke 750cc version of the 850?

Didn't they have one less fin on the barrels (8 instead of 9?)

That could explain the odd 235XXX number?

Edit: The information above is now known to be incorrect.
 
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Thanks L.A.B. I don't have it only looking at it. I will try to follow up on the fin count. If what you speculate is the case, is that version of Commando desireable or not?
 
Yes, very much so. But can't see it being fitted to a roadster as they were for racing and fitted to production racers, but after all these years who knows.
 
kommando said:
But can't see it being fitted to a roadster as they were for racing and fitted to production racers, but after all these years who knows.
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Yet, on the back cover of Roy Bacon's "Norton Twin Restoration" book is a photo of such a short-stroke Roadster!

The same photo and a caption reading "Short stroke 750, part of a small run for 1973" can be found in Steve Wilson's " Norton Motor Cycles" book. Maybe the production run carried over into 1974, or more were made?

But there's a good chance this will turn out to be another one of those unsolved Norton mysteries!
 
It has nine fins when counted at the back side of the jug. Also, the number cast into the jug is 063850. Any other thoughts?
 
Yellow_Cad said:
It has nine fins when counted at the back side of the jug. Also, the number cast into the jug is 063850. Any other thoughts?
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-Back to the unsolved mystery theory then!
 
I think that the only way that we might be able to take this further would be with photos of the ID plate and the motor number. Is the plate fitted with the hammer-drive screws ?

The suspicion has to be that someone has put a 750 Identity onto an 850 but slipped up by retaining the 850 build date. Maybe he had the title to a 750 or perhaps the insurance was cheaper.

Assuming that it's not a complete Bitsa, other clues to look at are large sump filter ? Breather on rear of timing chest ? Fork yokes marked 'ANG' underneath ? Is gearbox number the same ? Does swing arm have the reinforcing gussets on the cross-tube ?

Nothing here will give a definitive answer.
 
I can understand your thoughts but this bike has not been around very much. It has 9,000 plus miles on it and the guy selling it is the second owner and had it for twenty something years. He has all the original dealer info and all the numbers check out. From what I can remember, it didn't leave the dealership until 1977. In its life it has had a blown head gasket (repaired but causing it to sit for ten years idle), electronic ignition added, black box changed for a straight filter, and black tip mufflers replaced by Dunstall type.
 
The longer you've owned a bike, the more chance there is to change things :)

Does the headstock have a stamped F1xxxxx type number ? For early 1974, I think it should have.

It seems inconceivable to me that even in Norton's chaotic state someone could have stamped so wrong a number. 325xxx or 335xxx for instance would be far too late which means at least two digits would have to be wrong on all components.

The surviving factory records are not complete but there are generally enough clues to follow what was going on. In my opinion there is something not quite right here.

Has anyone in the U.S. ever tried to track down any surviving import records ?

I would be fascinated to know what the gearbox number is. Are all the crossed circle stamps present ?
 
The cross circle stamps by the engine serial number are there but I am not sure how many there should be.
 
Just one before and one after - That's 850 practice, isn't it ? My '72 750 doesn't have them.

Curiouser and curiouser !
 
From my memory (I just saw the bike a few hours ago), these circles were at least in front of and just after the serial number.
 
Any thoughts on whether or not the things that I described about this bike including the month and year of manufacture make it a good or not so good Commando to have. It is a fairly neglected (carport with cover so lots of surface rust on chrome and sat with gas in it for 10 years and won't run so I can't hear it run) virgin bike so it will require a lot of clean up so that is expected but don't want to many inherent issues to deal with such as soft cams, some negative based on the strange serial number, etc.
 
Yellow_Cad said:
Any thoughts on whether or not the things that I described about this bike including the month and year of manufacture make it a good or not so good Commando to have.
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If you want it, and you are able to buy it at a price you are willing to pay, all the paperwork is in order, and there are no signs of any efforts to obliterate or over-stamp any other numbers, then why not?
You may never find the reason for the odd numbers, although you never know, somebody someday could come up with an answer?


I think I'd still want to check if it had an 80 mm stroke or not, though! :wink:
 
The 1973 850 brochure includes reference to the short-stroke 750 which was available as an engine unit or as a Roadster. It states "polished aluminium head" and this certainly seems to be the case, looking at the close-up engine picture. Quite why they chose for poorer heat dissipation on a tweaked engine is a bit of a mystery :?
 
L.A.B. when you say that the 80mm question could be answered further are you thinking that the number of fins does not answer the lenght of stroke question positively? Is there any way to positively answer the stroke question without tearing down the motor?
 
Yellow_Cad said:
L.A.B. when you say that the 80mm question could be answered further are you thinking that the number of fins does not answer the lenght of stroke question positively?
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That info about the shorter barrel could be wrong, as it was just something in the back of my mind that I thought the barrels were shorter? The barrel number you gave is just the casting number, so would not be conclusive either way.
Looking at the photo of the short stroke 750 on the back of the Norton Twin Restoration book I can't say that the barrel looks any shorter?
Of course that bike could have been a mock-up done for the photo session? As the only visible thing that identifies it as being a 750 is the decal on the sidecover and lack of pinstripes?



Yellow_Cad said:
Is there any way to positively answer the stroke question without tearing down the motor?
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Measuring with a pencil or rod down the plug hole would probably answer that question as there's a fair difference between 80mm (actually 80.4mm) and 89mm.

79x100 said the short-stroke engine is mentioned in the '73 brochure, and it is also mentioned as an engine option for the John Player Norton in the '74 brochure. The short-stroke engine had steel conrods apparently? And I have a couple of images borrowed from ebay of a pair rods that were advertised as being "Norton Commando Short-Stroke Steel Conrods".

But the chances are this is just an odd numbered 850, -so I don't want to get your hopes up over nothing.
 
L.A.B. said:
But the chances are this is just an odd numbered 850, -so I don't want to get your hopes up over nothing.
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That seems the most likely scenario. A friend of mine bought an 850 basket case a while back. The engine numbers had been filed off and restamped 200xxx to match the 1972 750 frame that came with it. He said the stamping looked pretty good and probably would have fooled someone who didn't know anything about Nortons.

Debby
 
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