235xxx

I have recently aquired what appears to have originally been a 1973 MK5 750 Hi Rider. It came to me in partial Roadster form but still sporting the small headlight and TLS drum front brake. I'm in Brisbane Australia, the machine is an ex USA import, last US owner was in Collinsville, Illinois
The machine has matching frame, engine and trans numbers 235224 which the UK Norvil people tell me is virtually impossible but I have read old threads on this site detailing a significant number of 235 series 750's and even some 850's. There is also another 73 Hi Rider (235280) listed on this sites Tracker
Official records, such as they are, indicate that the 235 series was used ONLY for the 750 short stroke racing engines and that only a handfull (around 20?) complete 235xxx machines left the factory, all with the short stroke race engine.
Does anyone have any accurate information on how, where and why this apparent numbering anomoly originated? And are there any other known examples of it outside of the US of A?

Collinsville is about 20 minutes from here. From what's been said here about short-strokes, I have to doubt any made their way into production machines from the factory. It would have 850-type through-bolted cylinder barrels with possibly one less fin. If your ex-Hi-Rider has base nuts all the way around the cylinder-to-crankcase junction, it's not a short-stroke.

Danno said:

Collinsville is about 20 minutes from here. From what's been said here about short-strokes, I have to doubt any made their way into production machines from the factory. It would have 850-type through-bolted cylinder barrels with possibly one less fin. If your ex-Hi-Rider has base nuts all the way around the cylinder-to-crankcase junction, it's not a short-stroke.

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Ah yes. I should have been more clear about that. Mine is definitely not a short stroke. It is a standard 73 750 engine with 89mm stroke and 750 barrels, not the 850 type. From what I've picked up on other threads this seems to be not unusual for US bikes
I have found references elsewhere to some road bikes that left the factory with the short stroke engine. One source said that at least one was built for publicity shoots and displayed at the 1973 Earls Court Show but no one knows where it is now. Another source said there were "several" made But my particular interest lies in the standard 750's, and possible 850's with the 235 number sequence.

Auscar1 said:

The machine has matching frame, engine and trans numbers 235224 which the UK Norvil people tell me is virtually impossible but I have read old threads on this site detailing a significant number of 235 series 750's and even some 850's. There is also another 73 Hi Rider (235280) listed on this sites Tracker
Official records, such as they are, indicate that the 235 series was used ONLY for the 750 short stroke racing engines and that only a handfull (around 20?) complete 235xxx machines left the factory, all with the short stroke race engine.
Does anyone have any accurate information on how, where and why this apparent numbering anomoly originated? And are there any other known examples of it outside of the US of A?

Click to expand...

From several previous discussions the "official" information is now known to be incorrect because the records for the majority of the "235" models no longer exist.

The "235" series seem to have been mainly long stroke 750s, many of which were Hi-Riders.

https://www.accessnorton.com/NortonCommando/850-vin-numbers.11203/#post-155281

Known "235xxx" serial numbers from the forum, given by our members who either own/ed these particular bikes/engines or where we've seen some photographic evidence. Model information given where known.

235017 ... 2/73, 750 (Hi-Rider?)
235035 ... 1/73, 750 (Roadster) [Added 8/12. Seen on Aus ebay]
235036 ... ?/73, 750 (Roadster, drum ft. br.) [Added 1/13. Seen UK ebay Canadian re-import]
235056 ... Gearbox only
235118 ... ?/73 750 (Re: NOC forum) (crankcase and other engine parts seen on UK ebay 12/2012)
235138 ... 2/73 750 (Hi-Hider?)
235146 ... ?/73 750 (Hi-Rider?)
23519x ... ?/73 750 (Possible Hi-Rider?)
235234 ... 1/73 750 (Re: NOC forum)
235237 ... ?/73 750
235430 ... ?/?? 750 (Re: NOC forum 1/13)
23553x ... ?/74 850 (Roadster)
235565 ... 4/74 850 (Roadster)
235576 ... 750 Short stroke engine
235638 ... ?/74 850 (Roadster 2A)
235713 ... 750 Short stroke engine (72/73 750 crankcase?)

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79 x 100 said:
235016 - SYX 167M - Hi-Rider 745cc registered to Norton Villiers Europe - 01/Feb/1974
235142 - OGT 474L - Hi-Rider 745cc registered to Norton Villiers Europe - 11/Jul/1973
235155 - SYX 157M - Hi-Rider 745cc registered to Norton Villiers Europe - 01/Sep/1973
235328 - PTF 851M - Hi-Rider 745cc - Black - registered to Sports Motorcycles - 01/Sep/1973
235387 - SYV 362M - Hi-Rider 745cc registered to Norton Villiers Europe - 01/Aug/1973
235399 - SYV 363M - Hi-Rider 745cc registered to Norton Villiers Europe - 01/Aug/1973
235435 - SYX 158M - Hi-Rider 745cc registered to Norton Villiers Europe - 01/Sep/1973

and finally - a real oddity...

Frame 235610 - Engine 830018 - Roadster 850cc Red, Supplied to Gus Kuhn and registered as GYE 832N on 17/Jan/1975

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I know they made both 750s and 850s for the 1973 model year (750s may have been leftovers) but the visual differences are apparent.

I think the short stroke idea was to reduce piston speed on the race track and still stay within displacement limits while taking advantage of the stronger 850 cases and other updates. Probably zero advantage to putting one in a street bike instead of an 850.

Thanks one and all. The info you have provided has pretty much cleared up my confusion. Clearly the 235xxx number sequence was NOT used exclusively for the short stroke race engines as claimed by some others I enquired of. My own machine 235224 long stroke 750 probable Hi Rider converted to Roadster can be added to that list.
And a happy Norton Christmas to all!