1960 G9?

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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1960 G9?

Postby CobraCommando » Tue Nov 27, 2018 9:42 pm

Hello,

New member here, just starting on a new project using a G9 engine.

The cases I have are stamped 60/G9 and there is no oil relief clearance in the timing side casting, also the heads have the newer cooling fins under the exhaust ports. I thought they only made the G9 up to 1958 though. Is this legit?

Thanks!

Robert

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Re: 1960 G9?

Postby ajscomboman » Wed Nov 28, 2018 9:35 am

CobraCommando wrote:Hello,

New member here, just starting on a new project using a G9 engine.

The cases I have are stamped 60/G9 and there is no oil relief clearance in the timing side casting, also the heads have the newer cooling fins under the exhaust ports. I thought they only made the G9 up to 1958 though. Is this legit?

Thanks!

Robert


Probably not, the timing side should definitely have the relief in it from the oil filter tunnel and it should be an alternator case. The heads are correct if the valve sizes match the factory spec and are not in fact 650's. 1960 500 heads are not overly common and they do have the 3 cooling fins under the exhaust port. I've set spare that I'll never use but it's costly to ship to the US.

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Posts: 2
Joined: Tue Nov 27, 2018 9:34 pm
Location: WA, USA

Re: 1960 G9?

Postby CobraCommando » Wed Nov 28, 2018 9:00 pm

Hmm, maybe a mismatched set of cases then. I have a matched set incoming. I checked the bore and it's 69mm so either bored out for G9B pistons or actual G9B barrels, I don't know if the factory just bored out existing stock or had separate production for the G9B. They're getting replaced anyway, this project needs to be a 500 for salt flat racing class.

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