Model 20 black plugs

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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sunnybob
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Location: Milano, Italy
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Re: Model 20 black plugs

Post by sunnybob »

1608 thank you for the answer. The electrode was probably cleaned by the saddle bag where I put it when I changed it (was midnigth in a service area). This plug has a "normal" extension. Before that one an old mechanic of English bikes used two Bosch W7DC with prominent electrode. They both went bad after 40/50 miles as usual. When changing I noticed a scraped electrode in one of them so I did not use any more prominent plug. I suppose it has been worn by a valve :shock:

I tried also Champion N5 but it is always the same thing. After 40/50 miles the go on vacation :(
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