What year are these numbers?

[Frenchy]

Engine: CA7 4239
Frame: BA7 7978

I've found a link to a tech sheet that lists a lot of BSA engine/frame numbers, but it is not complete.  Can anyone help?

[trevinoz]

I reckon the frame might be 1953 but should have an "S" suffix.
The engine looks like 1956/7.
They definitely don't belong together as the frame is plunger and the engine is swinging arm, if the numbers are original.
Trev.

[brackenfel]

This is what I've used in the past when looking at bikes on Ebay etc.. Also helped me check mine out before I bought it!!:-

http://www.britishonly.com/tech/tips/framenumbers.asp

Hope this helps..

Adrian

[Frenchy]

I misread my frame number...  It begins with "E" not "B".  

I found that same link, Adrian, but it is incomplete and doesn't account for my numbers. I found another link online last night that has a better, more complete, BSA serial number listing.  According to it my frame and engine both appear to be '57's.  http://www.bsaownersclub.co.uk/Engine_Frame_Listing.html#1950  

My numbers are slightly lower than what's listed, but I'm going to assume they're both from '57.

[dpaddock]

Roy Bacon's "BSA Twin Restoration" has both numbers as 1957.

David

[Bender]

Are you sure you haven't got a "56" engine in a "57" frame? The "57" year started with CA7 4269.

Maybe they came out of the factory assembled together, after they found the engine laying in the corner somewhere after the end of year clean-up?