Gasket Missing - Not sure??

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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Harleyboy
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Gasket Missing - Not sure??

Post by Harleyboy »

I've purchased a gasket set for the planned rebuild of my 16MS 1955. When I dismantled the inner timing gear cover with bushes I found that the magneto was stuck/adhered together, is there meant to be a gasket to stop any potential oil leaking or had it just stuck together over time due to engine heat etc.
If there is meant to be something could some one point me in the right direction; I've looked at couple online AJS part books but can not seem to identify one. Hopefully I've made sense.
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Rob Harknett
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Re: Gasket Missing - Not sure??

Post by Rob Harknett »

Ashampoo_Snap_17 March 2021_10h53m33s_001_.jpg
No such gasket listed in your parts book.
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Pharisee
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Re: Gasket Missing - Not sure??

Post by Pharisee »

When I re-instated the magneto on my '54 G3/LS, I fitted a nitrile "O" ring between the magneto and the inner timing cover. It was 38mm internal diameter with a 4mm section and fitted perfectly.

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Andy51
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Re: Gasket Missing - Not sure??

Post by Andy51 »

Hi, I did the same for the magneto on my '54 18S. The hole in the rubber washer (not part of gasket set) was too large and had small gaps round the inner side. An O ring fitted perfectly inside and gave a complete seal, important as water can get in and seize up the Lucas ATD - which is why I had to remove the cover in the 1st place! Cheers, Andy
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clive
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Re: Gasket Missing - Not sure??

Post by clive »

Assuming you both have the correct SR1 magneto for a 1955 350 or 1954 500 with the Advance unit then there is a rubber seal between inner timing case and mag face.

http://www.amoc-parts.com/store/comersu ... duct=21502

This is quite thick and makes me wonder how the mag could be stuck to the case without it, the mag should not be over that far.
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Pharisee
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Re: Gasket Missing - Not sure??

Post by Pharisee »

clive wrote:Assuming you both have the correct SR1 magneto for a 1955 350 or 1954 500 with the Advance unit then there is a rubber seal between inner timing case and mag face.

http://www.amoc-parts.com/store/comersu ... duct=21502

This is quite thick and makes me wonder how the mag could be stuck to the case without it, the mag should not be over that far.
I fitted one of those rings when I rebuilt my M18S, but it was much too thick to put on the G3/LS. Fitting the "O" ring was a better solution than fiddling about cutting the hard rubber ring down to size.

Before anyone suggests that the magneto was not correctly positioned on the G3/LS... I can assure you that it was. :D :D

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Rob Harknett
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Re: Gasket Missing - Not sure??

Post by Rob Harknett »

I picked up a ring intended for a vacuum cleaner, for 50p off a car boot sale stall. ( SR1 mag fitted ) It proved to be a perfect tight fit. Not wanting to take all the bits off to fit it, I cut it. Then just pushed it in with the join unseen at the bottom. It's been there over 30 years now.
56G80S
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Re: Gasket Missing - Not sure??

Post by 56G80S »

I found the AMOC Spares ring to be too thick as well.

I did cut it in order not to stress the casing. I cut the ring to ensure a good fit once all assembled (Rob H's approach) and then put a black tie wrap round it to ensure the cut closed up. Hardly noticeable.

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Re: Gasket Missing - Not sure??

Post by Harleyboy »

Thank you all, yep found a thread on this after posting but many thanks for all your comments.

Must say Pharisee looking at the photo's your bike looks to be A1, unfortunately mine will not be in that league but will hopefully be my first successful project and look tidy and run.

Regards
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clive
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Re: Gasket Missing - Not sure??

Post by clive »

Hang on folks the original post was about a 55 16MS. This would have originally been fitted with an SR1 Magneto as in Pharisee's first photo. Thicker rubber is for this. The second photo is of an N1 magneto which naturally sits much closer to the inner timing cover. The N1 mag bikes have no seal listed and most of us come up with bodge to seal it. For me I use clear plastic pipe like the stuff you used to get with a lead acid battery to run from the breather.
My point about it was if either an N1 mag was being used or an SR1 without the auto advance retard it would have to be much closer to the inner chaincase. So how about some more information on the resolution Harleyboy so that anyone else doing a search with a similar problem can see the conclusion?
clive
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