Primary Chain Case - 250 0r 350?

Information relating to the Matchless G5 or AJS Model 8 350cc Lightweight
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Re: Primary Chain Case - 250 0r 350?

Postby Rob Harknett » Thu Aug 23, 2018 11:39 pm

I guess there are many things that are never questioned. Slight changes that go unnoticed etc. I have never bothered comparing my lightweight chain cases until now. Then compared parts lists from 58 to 66 and noticed motif variations. For example, do you know if you have the correct type petrol tank cap. What year did they change from flat top to slightly domed? Better not go into that though as its another topic.

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Re: Primary Chain Case - 250 0r 350?

Postby Janet » Fri Aug 24, 2018 8:26 am

Rob Harknett wrote:
clanger9 wrote:CSRs don’t have a motif, so that’s another variation...

But in 1960 parts list G2 is the same as G2CSR which says with motif.
That means I've learned something, too. As far as I was aware, the 250CSR wasn't made until 1962. I can't finds a 1960 parts list with a CSR on it. Would you point me to the list you are looking at please as I prefer not to repeat anything I've been told unless I have some evidence of it. The 62/63/64 CSR models didn't have a motif.
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Re: Primary Chain Case - 250 0r 350?

Postby Rob Harknett » Fri Aug 24, 2018 10:29 am

Janet wrote:
Rob Harknett wrote:
clanger9 wrote:CSRs don’t have a motif, so that’s another variation...

But in 1960 parts list G2 is the same as G2CSR which says with motif.
That means I've learned something, too. As far as I was aware, the 250CSR wasn't made until 1962. I can't finds a 1960 parts list with a CSR on it. Would you point me to the list you are looking at please as I prefer not to repeat anything I've been told unless I have some evidence of it. The 62/63/64 CSR models didn't have a motif.


Well spotted Janet, I got it right in an earlier posting but made a typo in the above quote. I have edited my posting to correct the error. However as seen above I did slip up an type G2CSR which should have read G2CS.

The G2CSR was indeed introduced in May 1962. Which would have been 8 months into the 1962 model year. The G2CSR was as the G2S but with tuned engine, larger teledraulic front forks, new 6" front brake with larger lining. ( italics text quoted from manufacturers dating info to the trade which included start frame and engine numbers for G2CSR ) The G2S was discontinued Sept 1962. Which would have been the start of the 1963 model year.

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Re: Primary Chain Case - 250 0r 350?

Postby Rob Harknett » Fri Aug 24, 2018 11:02 am

http://archives.jampot.dk/technical/Ser ... Bulletins/
Lightweight owners may like to check out other variations etc. that took place on these models. Information from which, may explain some differences they may find, that do not appear in the parts lists etc. to be correct. Link above where to find this info. You may have to check all the files during the lightweight years to find all the changes not found in parts lists. Some are clearly marked that apply to lightweights only. A lot of this type of info gets lost over time, as its sometimes just a single sheet of paper. I found it well worth the effort to carefully look through literature Malcolm was disposing of on his stall at the Jampot rally. One item I never found until I went through it for the second time on Sunday.

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Re: Primary Chain Case - 250 0r 350?

Postby Martin.S » Fri Aug 24, 2018 11:34 am

My outer case is a plain cover without the motif and has 044060 L cast into it.
Being 044 then this should be a 350cc one.
Thanks All

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Re: Primary Chain Case - 250 0r 350?

Postby Rob Harknett » Fri Aug 24, 2018 12:08 pm

That's an odd number Martin ( 044060 L ) I believe there was a change after a certain engine number, not sure of that number. Could be 12120, would your engine number be lower that that. Or does someone else know for sure, what the engine number was when a change was made. Maybe that engine number, chain case changed to 044061, over to the experts.

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Re: Primary Chain Case - 250 0r 350?

Postby Martin.S » Fri Aug 24, 2018 11:53 pm

Ah - Found what I was looking for in :-
http://www.jampot.com/article_read.asp?id=34
"If you are restoring a box of bits into a 250 or 350 lightweight, or looking for a chaincase at an autojumble, the vital measurements are as follows; single row chaincase -1 3/8" - from where the stator mounts to the joint face; duplex chaincase 1 5/8" from where stator mounts to joint face.
If you have an early 250 with a single row primary chain that doesn't seem to have much go in the alternator, it just might be fitted with a duplex type chaincase. This would mean that the stator would not be covering the full width of the rotor magnet, thus reducing power output. "

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Re: Primary Chain Case - 250 0r 350?

Postby Martin.S » Sat Aug 25, 2018 9:09 am

[quote="Rob Harknett"]That's an odd number Martin ( 044060 L )


Here's one on EBAY
s-l500.jpg


And my 044060 case measures 1 5/8" as above
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Re: Primary Chain Case - 250 0r 350?

Postby Rangy65 » Tue Aug 28, 2018 8:39 am

To add further to this the primary cases are in fact the same depth its the machining for the stator that's different.

This is to allow for the duplex primary chain & sprocket to fit so the stator fits further into the chain case.

Cheers

Steve

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