My sons "new" AJS Model 20

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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My sons "new" AJS Model 20

Postby Daveinater » Sun Jul 16, 2017 8:33 pm

Hello all,

We are brand new to the AJS world. My father in law up in Canada bought a brand new 1956 AJS Model 20 (s/n 562028613) and rode it with his girlfriend (later wife) all over Canada. He eventually sold it to a buddy (to buy his first Harley) and lost track of the buddy...and the bike. About 40 years later, he received a call from his buddy's widow saying he wanted my father-in-law to have his bike back. He was thrilled!

He got it back but it was heavily altered, with high rise bars, an ugly plexi windshield, front mud flap and (really ugly) home made engine guards. But it ran and he was happy to have it.

About two years ago, he passed away and gave it to my son, who is thrilled to have a special part of "Pop" with him. For the past year or so, the bike has been in a shop in Atlanta specializing in British bikes. Just yesterday, we picked up the bike. We wanted it to stay as original as possible, so the shop put original style bars on it, new seat upholstery (material from U.K. using the original pattern), all the crummy aftermarket stuff removed, and some new paint on the petrol tank.

We now have a few questions we would appreciate answers to:

1. The mechanic stated that the chain cases are notorious for leaking so he left it dry, recommending we lube the chain every couple hundred miles. Since I fly airliners for a living, I'm real big on sticking with running engines the way they were designed to run. Looking through this forum and online, I'd much rather run it with oil, just up to the level of the chain, but would like to fit the bike with one of the improved T-section seals that I read about in this forum. I've reached out to John Diederich from the US AJS Club but haven't heard back yet. Is there another source for this? I know some run ATF fluid in the chain case, while others swear by oil. I'll probably run the same 50 weight oil that has been put in the crankcase.

2. The Smith speedo works but we need to figure out the trip meter reset. His speedo has a brass colored shaft that sticks out the back side, with a hole drilled through (see photo). Based on the research I've found here, most owners refer to a cable that comes off the back of the unit. Does anyone know what is supposed to go here?

3. Lastly, the petrol tank on this bike has a pretty sharp crease in it, just forward of the AJS emblem on the left side. Body shop and dent removal people have both said it's not repairable without cutting away the section, re-welding and chroming it....more $ than we care to invest. Are there used tanks available anywhere?

I'm sure we will have more questions. I always try to do our own research in these forums before asking a repeat question so if I've missed the answer somewhere, please forgive me! We are new Jampot members, and we look forward to learning more about this piece of our family history. My son says he'll never let this bike leave the family.

Thanks for your help and advice.

Image

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Last edited by Daveinater on Mon Jul 17, 2017 11:34 am, edited 1 time in total.

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Re: My sons "new" AJS Model 20

Postby Rob Harknett » Mon Jul 17, 2017 9:25 am

Look on page 5 here http://archives.jampot.dk/technical/Spe ... _Views.pdf
part no. 373 fits on the spindle coming from the bottom of the speedo with a split pin, they come in 3 lengths I think 4" should suit you bike. You pull and turn this to reset the speedo trip to zero miles.
You say you may have a few questions to ask. Remember you only have 90 days free use of the club forum. May be a good idea to join the club. Not sure if club spares has a new tank, you can advertise free as a club member to try and find one. If you do find one, I may cost just as much to restore as it would to get yours repaired. Maybe the cost of repairing your tank is the cheapest option .

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Re: My sons "new" AJS Model 20

Postby helloluketurner » Mon Jul 17, 2017 10:12 am

Great story & a wonderful thing for your son to have & look after.

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Re: My sons "new" AJS Model 20

Postby helloluketurner » Mon Jul 17, 2017 10:13 am

& it'd be a shame to ditch the original tank.

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Re: My sons "new" AJS Model 20

Postby Daveinater » Mon Jul 17, 2017 11:29 am

Rob Harknett wrote:You say you may have a few questions to ask. Remember you only have 90 days free use of the club forum. May be a good idea to join the club.

Hi Rob!

Thank you for the information!

I joined the club before I posted. I'm just finding my way around here....is it not showing I'm a member? I also paid for the spares discount subscription thing.:shock:

Re: the part number 373, I've seen the part you're referring to on EBay but what is throwing me off is the fitting coming out of the back of the speedo appears to be a male end with a cross-drilled hole, Amd part number 373 appears also to have a male end (with a cross drilled hole as well). Not sure how these would fit together. I must be missing something.... :?:
Last edited by Daveinater on Mon Jul 17, 2017 11:47 am, edited 2 times in total.

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Re: My sons "new" AJS Model 20

Postby 1608 » Mon Jul 17, 2017 11:29 am

Super looking and intact bike. Agree with answers so far, except I'd keep the original tank and have it repaired to an acceptable degree. Tanks of this age will inevitably need some repair, rust removal even welding and then probably lining of some sort, not to mention the cost of postage to the USA. The general consensus these days is that 50 grade oil is too heavy for the chain case and can cause clutch drag. A light oil or ATF is preferable, and oil instead of grease will also lube the cush drive and clutch rollers etc. Stick out for the upgraded seal.

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Re: My sons "new" AJS Model 20

Postby Daveinater » Mon Jul 17, 2017 11:40 am

Here are a couple more photos, taken for my Mother-in-Law, up in Canada after the bike came out of the shop:

Image


Imagej

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Re: My sons "new" AJS Model 20

Postby Janet » Mon Jul 17, 2017 12:16 pm

Daveinater wrote:I joined the club before I posted. I'm just finding my way around here....is it not showing I'm a member? I also paid for the spares discount subscription thing.:shock:
Your member status is showing on my screen.

Welcome to the club.
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Re: My sons "new" AJS Model 20

Postby Daveinater » Mon Jul 17, 2017 12:37 pm

Aaah, thanks Janet. :-)

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Re: My sons "new" AJS Model 20

Postby SPRIDDLER » Mon Jul 17, 2017 12:46 pm

Welcome, Dave and son. It's great to have that history and that you're bringing it back to 'used' standard spec'n with it's family patina. The Model 20 and the G9 (its Matchless equivalent) are arguably the most fun and robust of the AMC twins for carefree riding.
I expect that an Owners and a Workshop Manual and the Spare Parts List have been handed down to you, but if not they (are much more) can be found here:


http://archives.jampot.dk/

As said, 50 weight oil will be too thick for the chaincase and could produce clutch drag. BTW - Don't be tempted to use a multigrade for the chaincase as such modern engine oils contain friction inhibitors which are not desirable for the clutch plates. (Other opinions are available, just as they are with most of the replies to owners' enquiries ;) ).

I've never had a twin so may be wrong, but I believe that the improved chaincase seal is also available from the Club spares service.

Enjoy!
Last edited by SPRIDDLER on Mon Jul 17, 2017 2:13 pm, edited 1 time in total.
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