Did this engine have a much different frame from the WM20 or even the JM21? i know the oil tnk was the narrower type. Most likely the rear section had castings at the front junction.
The 1937 & 38 m19 m20 m21 m22 M23 all used the M19 frame .. still stamped M19 but Km20 had desert lug & no sidecar lugs & WM20 ive noticed has even a different seat pivot bracket casting.
It's strange they have changes the models with the great oil tank in 1939 only the M22 with the old small oil tank was stil avaliabel 1939 and may be olso in 1940. Bud most M22 are from 1937 and 38 never seen a M22 engine 1939 or 40 Gr Theo
M22 standard. Last year of selling was 1939
Engine KJM22 Frame KJM19.
These were 1938 Jm22 machines that BSA had left over from 38 & stamped the extra "K" in front.
The factory registers show that the WM23s were installed in WM20 frames taken from the line between M20s and M21s, mostly during February, March and April 1940. Generally for export but with a number of UK dealers scattered between them.
I can't see that any WM23s were produced during 1939 - presumably too busy with WD production until the time was found to use up remaining engine stocks ?
A quick glance suggests that with the exception of one solitary KM23 delivery in August 1939, there seem to have been no M23s assembled between June 1939 and February 1940.
