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

illf8ed said:

The fact that 235xxx was used on both standard 750 and 850 machines is still a mystery. Speculation the 750s were left over material after the April ‘73 stoppage of 750 production.

Click to expand...

The problem with that is the long stroke 750 '235's have early (Feb. March.) '73 date stamps and seem to have been mostly Hi-Riders and a few Roadsters with drum brakes and 30mm standard carb/head engines. The 'last' 750 MkV models (22xxxx, 230xxx) appear to have been disc brake, 32mm carb, RH5 and RH6 head models.

illf8ed said:

For the short stroke 750 was there a way to physically distinguish the cylinders from standard 850 such as one cooling fin less?

Click to expand...

The 750 short stroke barrels are basically 850 barrels. I believe the (steel) conrods are longer and the pistons are different.

L.A.B. said:

The problem with that is the long stroke 750 '235's have early (Feb. March.) '73 date stamps and seem to have been mostly Hi-Riders and a few Roadsters with drum brakes and 30mm standard carb/head engines. The 'last' 750 MkV models (22xxxx, 230xxx) appear to have been disc brake, 32mm carb, RH5 and RH6 head models.



The 750 short stroke barrels are basically 850 barrels. I believe the (steel) conrods are longer and the pistons are different.

Click to expand...

Looks like these will remain a mystery. The one for sale locally is an 850 with 4 73 date on the frame ID plate. I’m not tempted. Honestly if I had room for another there is a ’51 model 18 locally I would be more interested.

jimbo said:

the data plate and trans match . I think the engine stamping is factory . Heres a theory; it is messed up because the normal 850 stamping process was not followed . Maybe a different person? Probably because of the unusual number.

Click to expand...

Hello Jimbo
Owner of 235592 here, the "mystery" bike on CL in Morgan Hill CA... Here is what I was told by a knowledgeable Norton fellow in the UK regarding the engine stamping:

The stamp was made up in a block on a bench and then the case put under the block, one hit had to give all the characters enough force to make an impression, looks like one faint hit followed by a larger one slightly off position and then maybe the 5 was rehit again. A forger would machine the pad to remove all the original numbers before adding new ones so it looks genuine to me and a friday special. The characters are the right font.

Make of this what you will, but it rings true to me, especially the bit about it being a "Friday Special" - in other words, stamper either had an extra pint or two at lunch on a Friday, or was in a hurry to end the week and get to the pub!

halcyonhoward said:

Hello Jimbo
Owner of 235592 here, the "mystery" bike on CL in Morgan Hill CA... Here is what I was told by a knowledgeable Norton fellow in the UK regarding the engine stamping:

The stamp was made up in a block on a bench and then the case put under the block, one hit had to give all the characters enough force to make an impression, looks like one faint hit followed by a larger one slightly off position and then maybe the 5 was rehit again. A forger would machine the pad to remove all the original numbers before adding new ones so it looks genuine to me and a friday special. The characters are the right font.

Make of this what you will, but it rings true to me, especially the bit about it being a "Friday Special" - in other words, stamper either had an extra pint or two at lunch on a Friday, or was in a hurry to end the week and get to the pub!

Click to expand...

Further, this is what the same gent had to say about the 235xxx number sequence "mystery":

a 235000 serial number was originally set aside for the Short Stroke 750 racers, i.e. an 850 bore with a short stroke crank. As the factory was in a mess this range of numbers did end up being used on some std 850's. They were using 850 cases and barrels on the short stokes anyway. So your bike is not fake and genuine. Only issue is the records are a mess for this period and so your numbers may not be there.

Indeed, the NOC UK has no record of 235592, I have asked Andover Norton but based on the above along with earlier info in this thread that may also come up blank...

Yesterday I did confirm that 235592 has the standard 850 89mm stroke, so - sadly for me! - it is NOT a short-stroke 750... But at least I now know that the numbers are legitimate, making it an unusual 850 indeed... I have updated my original CL post accordingly:

halcyonhoward said:

a 235000 serial number was originally set aside for the Short Stroke 750 racers, i.e. an 850 bore with a short stroke crank. As the factory was in a mess this range of numbers did end up being used on some std 850's. They were using 850 cases and barrels on the short stokes anyway. So your bike is not fake and genuine. Only issue is the records are a mess for this period and so your numbers may not be there.

Click to expand...

Plus several long-stroke 750 Hi-Riders (and a few drum brake 30mm head/carb Roadsters).

halcyonhoward said:

I have asked Andover Norton but based on the above along with earlier info in this thread that may also come up blank...

Click to expand...

AN has records for 235510 to 235515 but that's all it seems.
https://andover-norton.co.uk/en/factory-records/
I don't think it has been mentioned if they were complete machines or not, or what they were.

halcyonhoward said:

...Yesterday I did confirm that 235592 has the standard 850 89mm stroke, so - sadly for me! - it is NOT a short-stroke 750... But at least I now know that the numbers are legitimate, making it an unusual 850 indeed... I have updated my original CL post accordingly:

1974 Norton 850 Project Bike UPDATE!! - motorcycles/scooters - by...

FIRST, a big THANKS to all who replied when I first posted my 1974 Commando project back on January 16! NOW, here is a very short summary of what I have learned about this bike since then, and what...

sfbay.craigslist.org

Click to expand...

Good of you to explain in your listing. Can't ask for more than everything you were able to uncover.