AJS Model 18CS Bitsa identification

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Feral
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Joined: Sat Feb 17, 2018 10:54 am
Location: WARWICKSHIRE UK

AJS Model 18CS Bitsa identification

Post by Feral »

Hello to all,

Although I have owned a couple of AJS for a few years, I am just getting around to sorting them out and a novice to the marque. I am hoping that somebody out there can tell me about my bike.

It looks like a Model 18CS, but the engine and frame numbers have been messed about with making it impossible for the dating team from the club to identify it, so I was hoping that the keen eyed amongst you can help me out.

The bike is clearly a bitsa, cobbled together from what ever parts were available.

I have done some research online and asked a few local enthusiasts what parts it could have been made up from, but I am stumped when it comes to the frame. It is obviously a heavy weight frame, but the sub frame is unusual as it has a bracket low down on the near side, just above the rear foot rest bracket (see attachment). I would appreciate it if somebody could tell me what this is for and which bike it came from.

There are some other obvious anomalies, the rear mudguard bracket is too long and the there have been some strengthening plates crudely welded in front of the jampot mounts.

To give you all the information that I have, I believe the engine is as the V5 states, a 500cc, but I won't know for sure until I take a look inside. The V5 states that it is a 1951 model, but the true year is anyone's guess.

I believe that the forks are from a 1947/8 model as they have fill holes as appose to drain holes. This would tie in with the gear gear box as that is a 1948. Apart from the rims being changed to alloy and 18 inch on the back, that is as far as I have got.

I would appreciate any guidance so that I can confidently order parts in the future.
sub frame.jpg
Thanks in advance.
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Rob Harknett
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Re: AJS Model 18CS Bitsa identification

Post by Rob Harknett »

Try dating, the year will be dated on the frame number. What ever engine is fitted will show its year and model, which may not be the same as the frame. But you will need to discover what your bike consists of for parts of various large lumps.
SPRIDDLER
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Re: AJS Model 18CS Bitsa identification

Post by SPRIDDLER »

Rob Harknett wrote:Try dating, the year will be dated on the frame number.
Feral wrote:...........the engine and frame numbers have been messed about with making it impossible for the dating team from the club to identify it,
'There is a tide in the affairs of men
Which taken at the flood............'
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Rob Harknett
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Re: AJS Model 18CS Bitsa identification

Post by Rob Harknett »

SPRIDDLER wrote:
Rob Harknett wrote:Try dating, the year will be dated on the frame number.
Feral wrote:...........the engine and frame numbers have been messed about with making it impossible for the dating team from the club to identify it,
Only read the first line, so made comment only on that. if it has a V5 I guess there's no point in dating apart from eyesight of parts. So that will need more pictures
Feral
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Joined: Sat Feb 17, 2018 10:54 am
Location: WARWICKSHIRE UK

Re: AJS Model 18CS Bitsa identification

Post by Feral »

Thanks for the comments.

When I had it dated, the frame number showed that it was a light weight. The first two digits have been changed.

What is the bracket on the sub frame above the rear foot rest bracket for? Has anyone seen this before?
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Rob Harknett
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Re: AJS Model 18CS Bitsa identification

Post by Rob Harknett »

Could it be for a sidecar?
Dixter
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Re: AJS Model 18CS Bitsa identification

Post by Dixter »

I believe Rob is correct. A further clue is the large bolt directly above the tax disc holder. Normally this is a stud with nuts on either end. On this bike, the fastener is intended to carry an angled support tube for a sidecar or similar attachment.

Ciao, DC
Dick Casey
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Feral
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Joined: Sat Feb 17, 2018 10:54 am
Location: WARWICKSHIRE UK

Re: AJS Model 18CS Bitsa identification

Post by Feral »

Thanks Rob and Dixter,

That would make sense.

I have looked at lots of pictures of AMC machines on the internet and not seen this before.

Would I be right in assuming that the frame or at least the sub frame was originally from one of the road going models?
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Rob Harknett
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Re: AJS Model 18CS Bitsa identification

Post by Rob Harknett »

Side car I'm sure would need a fitting to go in side car front tube lug, the bracket in question, also as also mentioned under the saddle where the stud is replaced with another stud only threaded one end, side bolt eye on the other end.
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