The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: manxman on 14.11. 2017 17:49
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Being a novice in BSA Plunger motors I was under the assumption that the primary chain, clutch, and motor sprocket were duplex. When I opened the primary on my newly acquired 1953 A10 motor I was surprised to find a triplex chain, clutch, and sprocket! Any answers?
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I found the same and was also surprised at the level of sophistication in an engine this old. Rather different to the expected single-row primary chain.
Errr...so what was the question again... *conf*
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I wondered if the triplex was standard across the range or what year the change was made?
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Twin chain on my plunger...
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Triplex was introduced in the A50/65, so someone has done a conversion.
Cheers
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The 1954 data book shows the A10 Super Flash was fitted with a triplex primary chain, and was available on other plunger twins and A10 to special order.
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Well there you go. A day doesn't go by that I don't learn something.
Cheers
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Mine is definatelt a plunger clutch complete with top hat, not a A65. Must have the optional primary drive. Mine is not a Superflash, unfortunately. Numbers are BA10.....with HC beneath.
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It seems to have been an American market thing, I read somewhere many years ago that the Yanks were destroying the duplex drives so a triplex was made available.
I also have found one on a BA10/HC set of cases which were brought here from the U.S.