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Author Topic: A10 Plunger Primary  (Read 703 times)

Offline manxman

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A10 Plunger Primary
« on: 14.11. 2017 17:49 »
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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Online Rex

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Re: A10 Plunger Primary
« Reply #1 on: 14.11. 2017 18:37 »
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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Offline manxman

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Re: A10 Plunger Primary
« Reply #2 on: 14.11. 2017 18:43 »
I wondered if the triplex was standard across the range or what year the change was made?
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Offline a10 gf

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Re: A10 Plunger Primary
« Reply #3 on: 14.11. 2017 18:43 »
Twin chain on my plunger...
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Online muskrat

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Re: A10 Plunger Primary
« Reply #4 on: 14.11. 2017 19:02 »
Triplex was introduced in the A50/65, so someone has done a conversion.
Cheers
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'51 A7 plunger, '57 A7SS racer now a A10CR, '78 XT500, '83 CB1100F, 88 HD FXST, 2000 CBR929RR ex Honda Australia Superbike .
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Online JulianS

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Re: A10 Plunger Primary
« Reply #5 on: 14.11. 2017 19:11 »
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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Online muskrat

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Re: A10 Plunger Primary
« Reply #6 on: 14.11. 2017 19:20 »
Well there you go. A day doesn't go by that I don't learn something.
Cheers
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'51 A7 plunger, '57 A7SS racer now a A10CR, '78 XT500, '83 CB1100F, 88 HD FXST, 2000 CBR929RR ex Honda Australia Superbike .
Australia
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Offline manxman

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Re: A10 Plunger Primary
« Reply #7 on: 14.11. 2017 20:05 »
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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Offline trevinoz

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Re: A10 Plunger Primary
« Reply #8 on: 14.11. 2017 20:21 »
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.
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