AJS 18CS Trials bike

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Cjay59_LAPSED
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Re: AJS 18CS Trials bike

Post by Cjay59_LAPSED »

Scrambler 500 1957.jpg


It was the scrambler frame bracket at the top of the rear shock, that I was trying to highlight, this looks the same as your frame bracket. (on the Trials version it is quite different).

AJS Frame.jpg
Bay District.jpg
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db133
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Re: AJS 18CS Trials bike

Post by db133 »

Hi

Nice to be back, kind regards to all.

I have engine no ; 50 S over 16 MC then 12521 looks unmolested .
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Cjay59_LAPSED
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Re: AJS 18CS Trials bike

Post by Cjay59_LAPSED »

Some other information to try and help.

The AMC gearbox went into all models for 1957.

The shorter wheel base for the 16MC was achieved by mounting the rear fork pivot to the front of the vertical seat tube in 1956, in 1957 this frame was modified to take Girling rear shocks, as were the other models and small ribs were added to the oil tank and toolbox lid.

In 1956 the 16MCS scrambler and its larger version 18CS were fitted with the all-alloy short stroke engines. These had the push rod tunnels cast integral with the cylinder. The frame was very similar to the road range but had an extra brace between the tops of the rear damper supports.

AMC Trials 1957-65 Top 1 : 3rd 1.56 : 2nd 2.44 : 1st 3.24

Sprockets 18CS 1956-65 E 19 : C 42 : G 16 : W 42 Top ratio 5.803 Gearbox Type AMC Trials.

Then here is a picture of, as Roy Bacon describes, "The 18CS of 1958 in its trials form without lights but with other road gear".

But according to other information in his book they didn't build them!! and it should essentially be the same as the 1957 model, that they didn't build. So you can see why it's difficult to answer your questions, I include the Bay District photo because another avenue is the dealer who imported the machine, maybe they had records.
AJS 18CS 1958.JPG
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fullchoke
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Location: Oregon

Re: AJS 18CS Trials bike

Post by fullchoke »

Thanks CJAY59, you have real interesting information. Aside from the missing parts like the loop and chain guard, mine has a much smaller seat, no air box, a large sprocket, a chromed chaincase, and oil tank and a smaller Amal carb (1 1/8) than the one listed for the scrambler. I can't see if the handle bar and mount are different but the bars are unusual on mine, but maybe all AJS are like that. Someone mentioned that AJS stopped making the 18cs Trials version in 1955(was that you?), but I seem to have one from 1957. Really appreciate your help in figuring this out!

Thanks

Clive, I would like to join, but I'm retired and funds are especially limited right now, so I need to make due at this time. Sorry to put you through all these approvals.
fullchoke
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Joined: Tue Sep 07, 2021 5:32 pm
Location: Oregon

Re: AJS 18CS Trials bike

Post by fullchoke »

Someone else pointed out to me that the bike is definitely a competition scrambler, but not a trials bike like I had hoped. Apparently no Trials bikes were made with the slab sided oil tank. Everything I've learned from everyone that has helped with this, points to a scrambler, that was fitted into a Trials bike, buy a prior owner. Since they couldn't buy one, they made what the factory wouldn't. Now I'll be looking for the parts it's missing. It may become a slow process, because parts are becoming hard to get and the fact my wallet is rather thin right now.
Really appreciate everyones help!

Thanks
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Cjay59_LAPSED
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Re: AJS 18CS Trials bike

Post by Cjay59_LAPSED »

You're very welcome to the help, if you use Facebook you can find me here, https://www.facebook.com/groups/329027254430129 , join the group, you will also find a few other guys from the US are there too. You may also enjoy reading my website pages, https://ajsstormer.wordpress.com/ , the slab sided oil tank was introduced in 1956 without ribs, in 1957 three ribs were added, and some were slimmer, there was also 50 Matchless flat-trackers built which you don't hear mentioned very often. Best wishes and enjoy your machine, Cliff..

AJS Stormer 1976.jpg
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fullchoke
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Re: AJS 18CS Trials bike

Post by fullchoke »

Two Beauties there, nice setting too!

In my quest for information. I came across 2 different magneto's, 1) Competition, and 2) Racing, and not to say there aren't others. What is the difference between the 2? Were there different models of each, and were there many changes between years?

Thanks
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