Looking for 1937 B20 or M20 side of center stand. Or anything that will fit the same dimension if the stands are the same for other models. This bike which I have just got appears to have a non M20 OHC engine correct for BSA at the time. The number on the engine is 463810 11 36 AC20 M01/0 It has foot gears not side gear stick.
Frame no. HB20 64528 which I take to be a 1937 B20.
Thank you Jeremy in Sydney
The HB20 frame prefix was used on the 250cc B20 side valve, the 250cc B21 Sports OHV, the 250cc B22 Empire Star OHV, and the 350cc B23 side valve.
HB20 64528 is much too high a number, there was less than 9000 total production of these models 250cc bikes in 1937 season.
The engine number is not a BSA number. Could be a workshop or fleet number. For these models it would have prefix HB20 HB21 HB22 or HB23.
Photos from the 1937 catalogue showing the B21 Sprts and B22 Empire Star.
Thanks Julian. The bike is right now in a bike shippers truck traveling the 900km's from Coulandra on the Sunshine Coast north of Brisbane to Sydney and will be here this afternoon. Then I will be able to unravel the secrets of this mystery bike. Could be a bitzer, not sure yet but I am leaning towards a B22 250cc Empire Star. Regards Jeremy Havard
Had another look at the engine number given.
I think it is actually the number from the magdyno specification plate -
463810 the part number
11 36 date of manufature of the magdyno November 1936
AC - anticlockwise rotation
MO1 the model of magdyno.
Hopefully if you look on the left side of crankcase immediateky below the cylinder base you will see the engine number.