Unusual cylinder head

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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AJS 500
Posts: 38
Joined: Wed Aug 05, 2015 5:27 pm
Location: KENT UK

Unusual cylinder head

Post by AJS 500 »

I purchased the photographed head and barrel thinking the head was for a 1960 on 650 as the Latino said 500, the barrel is a 500 (66mm) bore.
All the info I have states they the different fins didn't come in until 1960 onwards G12 etc 650.
I wanted the valve caps and seats as a pattern. As it turns out this is fitted with the longer valve stems and springs and has the same Spring seat and cap as the later G12, so I've machined some nice ones for my G12 project.
Can anyone identify which early model had the afore motioned changes made to the 500 as all the ones I've seen did not have these fins under the exhaust port or longer valves etc. The exhaust outlet is 1.5" and the top spigot is 3". ImageImage


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dave16mct
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Joined: Mon Jan 01, 1990 12:00 am
Location: LANCASHIRE UK

Re: Unusual cylinder head

Post by dave16mct »

This is a 1960-0n 500 head (like the one on my bike), they changed when the 650 did.
Dave.
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AJS 500
Posts: 38
Joined: Wed Aug 05, 2015 5:27 pm
Location: KENT UK

Re: Unusual cylinder head

Post by AJS 500 »

Cheers Dave did wonder if they had. It was sold as a 1955 head and barrel. Didn't think it was right.


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