Author Topic: BSA engine from September 1974  (Read 490 times)

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Daniel

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BSA engine from September 1974
« on: 10 January, 2018, 21:15:12 »
Dear all,

I do own a B50 engine with the number B50 KJ 75682, so it should be from September 1974. The number matches to the Triumph numbers used fro their B50 derivatives.
The cylinder is stamped 71-1215 and the cylinder head is stamped 71-1644 so they are right for a B50.
The unusual thing is the cylinder and cylinder head are round and not rectengular.

Is there anyone who has a good idea what i do own there?

Cheers Daniel

Daniel

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Re: BSA engine from September 1974
« Reply #1 on: 14 January, 2018, 21:29:02 »
I just found a very late Triumph TR5MX engine in Ebay. The number is HH (July 1973) and 75556. My engine is KJ (September 19749 and 75682 (so just 126 engines later). Also the numbers and letters at both engines look to made in the same way.
Have a look to the picture attached.

AWJDThumper

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Re: BSA engine from September 1974
« Reply #2 on: 15 January, 2018, 08:12:10 »
A round barrelled B50 is very interesting - will need to look into it. I see from the other forum that even MIDGIE didn't know the answer to the question other than suggesting it was a conversion. As said, why would anyone want to go from square barrel to a round barrel B50 ::)

JulianS

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Re: BSA engine from September 1974
« Reply #3 on: 15 January, 2018, 09:30:34 »
"KJ" actually decodes as September 1973;

K = September

J = 1974 season model. (the season running August 1973-July 1974) so year is 1973.

AWJDThumper

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Re: BSA engine from September 1974
« Reply #4 on: 15 January, 2018, 11:59:58 »
From what I can see, both of the round heads and barrels relate to the later Triumph derived TR5MX version of the B50. The standard BSA B50 parts (71-1219 & 71-1732) were all square finned. As said, your part numbers equate to the Triumph versions some of them were round finned. Unfortunately, I don't have access to the Triumph parts book to confirm which years had square and which had round fins.

beesa71

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Re: BSA engine from September 1974
« Reply #5 on: 15 January, 2018, 20:52:29 »
AWJDT; have you other images of round barrel TR5MX motors please? You've authenticated them for Daniel and we (on the B50 forum too) are keen to see other items to the same pattern.

Regards to all BSAOC members,


Paul (here (there, with BSAOC) since 1965).

Daniel

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Re: BSA engine from September 1974
« Reply #6 on: 15 January, 2018, 22:20:24 »
Dea rall,

Please find some more pictures showing the casting, the barrel and the head. I hope this give us any more hint.

Cheers Daniel

Daniel

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Re: BSA engine from September 1974
« Reply #7 on: 15 January, 2018, 22:23:31 »
And one more. For me the number it is 30 5 73