AJS 1937 Model 8 Spark Plug

Information relating to Matchless and AJS Models built prior to 1939
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AJS 1937 Model 8 Spark Plug

Postby Diana3899 » Mon Jun 05, 2017 7:36 pm

Can anyone please advise me as what modern spark plug I should be using in my AJS 37/8.

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Re: AJS 1937 Model 8 Spark Plug

Postby Rob Harknett » Mon Jun 05, 2017 9:18 pm

You can still get the old type from Greenspark plug co. Champion 16. 18 m.m. 1/2" reach should still work OK with todays higher octane fuel. It may run a bit hotter than it did on 1937 fuel. If you want a modern 18 mm 1/2" reach try one that runs quite cool in the range that will disperse heat more quickly. The old bikes are not that fussy, I use what ever old 18mm 1/2" reach I can get my hands on.. At least the old plugs can be cleaned, unlike modern plugs with un glazed central electrodes. Cleaning will actually damage them and cause them to foul very quickly.

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Re: AJS 1937 Model 8 Spark Plug

Postby Diana3899 » Tue Jun 06, 2017 9:21 am

Rob,

Thanks for response.

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Re: AJS 1937 Model 8 Spark Plug

Postby thornebt » Tue Jun 06, 2017 2:43 pm

Champion 16 was renumbered K-9 in the 1960s. The equivalent NGK plug is NGK A7. If you want a plug that's easier to source you could try an NGK A6, an alternative is an NGK AB6 which is the same as A6 but has a slightly smaller 13/16" hexagon. The '6' heat range is a slightly colder plug. Cheers. Bruce.

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