Hi my name is Brian 54 years old, live in Aberdeenshire and new to the site.
I have a BSA M21 1958, owned it for 3 years now, it's on a A prefix reg which a
Has never bothered me but I'd like to know if it was a matching frame and engine numbers bike.
I've had a look at the dating numbers section and found that the frame number is correct for 1958 but the Engine number is 1957, is this proof that it's a non matching numbers bike?
Or is it possible the bike was assembled with an engine that had sat on the shelf for some time? the bike was registered in the first week of July 1958
Thanks in advance for any help
Brian