Ajs model 31 chain case leaking

[1revinkevin]

I am new to this and to the ajs the bike is a 1959 and has a oil leak from the rear of chain case (where the gearbox goes into chain case ) I’m wondering if anyone can help me out by sending me a spread diagram of the inside of the chain case … just drips non stop when running

Thanks Kev

[Yves.Astein]

Hi Kev,

Welcome to old english motorcycles. This welcoming should also answer your question I have two Matchless and they both leak. There are numerous threads on this topic. For example:

viewtopic.php?t=10626
Or
viewtopic.php?t=649
… just use a search.

There are some gaskets you can purchase. Club spares has them in paper. And I believe Fecked sells them in a bit thicker. I have tried them all including self made ones. None worked for me. My aluminum casing is quite dent. So I guess I would have to mill it down, but I haven't felt like bothering with it.

As you will read in the threads above, there are some people who manage to get them dry. So don’t feel discouraged by me giving up after trying for quite long.

Yves

[1revinkevin]

Thank you so much for a reply I will check oil level so sure !!

[JEAN-NOEL]

Hi Kevin,
Two sources of leakage should be investigated:
- those from a defective seal: if the two halves of the casing are not dented, the original seal with a good seal compound should suffice. I tried with Wellseal, but it wasn’t effective. The grey silicone Loctite seal did the trick.
To improve the joint surface of the two half-cases, I ran them on a thick glass onto which I glued sheets of sandpaper
- those from the primary shaft of the gearbox: I installed a V seal between the clutch and the crankcase. The situation has improved.
Also be careful not to leave the bike too long on the prop stand: in this case it is the oil of the gearbox that leaks at the level of the chain sprocket.
Kind regards;