BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: Old Biker on 05 March, 2017, 11:38:06

Title: Engine numbers
Post by: Old Biker on 05 March, 2017, 11:38:06
Being new to the forum I'm not certain of the way this should be approached but here goes.

I recently purchased an A65 which came from Denmark, the paperwork shows it was registered in 1965 but I do not know if it was originally registered in Denmark or whether it just finished up there. I am also uncertain as to the actual model, it was described in the advert as a Star Twin. The engine number is A65B412 and I was wondering if anyone out there could help me pin down the precise model and year. I did look in the owners club library for anything A65 however it appears to skip 1965 just showing 1964 and 1966.
Title: Re: Engine numbers
Post by: Bess on 05 March, 2017, 11:51:41
Hi,

     The Roy Bacon Twin restoration books gives engine numbers starting from A65B-334 as 1965 model A65R.

Hope this helps...
Title: Re: Engine numbers
Post by: Arthur on 05 March, 2017, 13:30:06
The engine number appears to signify that it is either an A65R or an A65T from the 1964 season, ie Aug 1964 - Jul 1965. The frame number prefix looks to be a bit more confusing with one list signifying that a prefix of A50B makes it an A65R while a plain A50 prefix makes it an A65T. Other lists don't seem to make this distinction with the frame number.
Title: Re: Engine numbers
Post by: Bess on 05 March, 2017, 13:59:30
Hi,
     Just found the attachment whilst trying to date my A65 engines.

Bizarrely I have one engine with the old system (A65LC *****) which is dated 1969 and the other with the new system NC***** A65L which is dated 1968, I wasn't expecting that.

The Roy Bacon publication does not give the full new system year codes only D,E and G so I was struggling to date the NC***** A65L engine. The attachment gives all the year prefixes C, D, E, G and H.

Hopefully this attachment is correct...
Title: Re: Engine numbers
Post by: Old Biker on 05 March, 2017, 19:57:21
Thanks for the assistance in this at least I can now be fairly confident of the year and also a little nearer the model as either an R or a T
Title: Re: Engine numbers
Post by: JulianS on 05 March, 2017, 20:47:04
Bess

 The 1969 season engines started in August 1968  with  old number system numbers, but from September 1968 the new system was introduced.

Your first engine will be early 1969 season - probably August/September 1968.

Your engine with NC  is also 1969 season and decodes N for October and C for 1969 season so October 1968.
Title: Re: Engine numbers
Post by: Bess on 06 March, 2017, 08:09:53
Hi JulianS,
                 It sort of made sense until BSA'S own example at the bottom of page 2 of your attachment. That example dates my NC engine as October 1969 not 1968.
Title: Re: Engine numbers
Post by: JulianS on 06 March, 2017, 08:51:43
Its the seasons which can confuse. The service sheet not too well worded.

1969 season ran August 1968 til July 1969.

C means 1969 season so NC is October of 1969 season or October 1968.
Title: Re: Engine numbers
Post by: JulianS on 06 March, 2017, 09:33:56
Oldbiker

Your engine is an A65 Rocket from the late part of the 1965 season (August 1964 - July 1965). See below from Glass's Motorcycle check book, which puts the last engine number for the Rocket at A65B 436.

The versions equiped with the optional tachometer had engines starting A65C.

As it came from Denmark it was possibly imported there by Hansens of Copenhagen.

Also added a brochure photo of the Rocket from the 1965 BSA export catalogue.
Title: Re: Engine numbers
Post by: Bess on 06 March, 2017, 11:28:01
Hi JulianS,
                 I agree very confusing.

Roy Bacon explaining the new coding was introduced in 1969, the seasons starting July 1969 for 1970 and August for 1971 and 1972. The other attachment stating it started in 1969, C being Aug 1968 to July 1969.

The 1969 bikes started with A65LC-101 but there wasn't any 1969 bikes built, it seems only built in August/September 1968.

Lucky for me they dropped the close ratio gearbox otherwise my engine number would have been NCC 01701, very similar to Star Trek Starship Enterprise designation. :)

[attachment deleted by admin]
Title: Re: Engine numbers
Post by: JulianS on 06 March, 2017, 12:57:46
Unfortunately the numbers Bacon gives for 1969 are not correct. The letters are OK. The numbers did not start at 101, they ran on from the 1968 numbers, starting around number 11101 and ending around 23000.

There were about 12000 A series twins made in the 1969 season August 1968 - July 1969, the last ones with date code GC for June 1969.

Photo is from front of 1969 parts book which shows start engine numbers.
Title: Re: Engine numbers
Post by: JulianS on 06 March, 2017, 16:01:06
This is the parts book photo I missed off
Title: Re: Engine numbers
Post by: Bess on 06 March, 2017, 16:18:18
Thanks JulianS, much appriciated.....