Another head gasket question(1965)

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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Another head gasket question(1965)

Postby Ib-Denmark » Sat Feb 15, 2020 10:22 pm

After a rebore i now was going to assemble.
The bike is a G12 1965.
I was happy because i had already 4 head gaskets lying in my shelf.
BUT they dont fit.
Of course I knew that the stud size had changed and I had thougt that I could just resize the stud holes in the gaskets.
THE PROBLEM is of another kind: The spigot in the cylinder top measure 77.7 mm and the hole in the gaskets are only 76.4mm.
If they had been copper it had been easy to rezise, but they are composite and I dont want to tuch the reinforcement copper ring.

My question is then: Did the diameter in the spigot change over years??

By the way: If I find some ,which will fit, I will not be afraid of using composite again (not the same ones) because the old ones had done the job for 10 years and 25.000 km. :D

Regards Ib

Sunday morning: I just found that Steven Surby list a set of gaskets for G12 1964-67 Hope that will help me.

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Re: Another head gasket question(1965)

Postby ajscomboman » Sun Feb 16, 2020 12:00 pm

Diameter changed in 1960 so I suspect yours are up to 1959.

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