BSA motor cycle dating and specifications

[yjr32]

I have a BSA, post war model Bike with Engine Number: BB3D 17770, Frame Number: CB31 8558.
1) Which year mode is this? 2) What is the recommended spark plug for this? 3) What is the size of footrest rubbers both for the driver and pillion rider and what is the type of hole in these rubbers?

Janardhana Rao.

[VintageBike]

Hi,

your frame number is a 1955 B31 or B33 swinging arm frame.
Your engine number doesn't quite sound correct.  I would have expected BB31 17770 (I don't know why the D is there).  This would make the bike and frame 1955 B31.

I believe the correct spark plus is a Champion N7 (L82C), NGK B6HS.

You can buy the footrest rubbers on this very site at http://www.vintagebike.co.uk/Spares/Footrests/Footrest-Rubbers.htm.  Your bike should use the Oval rubbers.  I am not sure on whether your bike has the long or short pillion footrests, but both are also available there..

Regards

Nigel.