The civilian M20 1945 - 1947 all have XM20 frame numbers. I recently bought XM20-771 with the engine number WM20-771. A little tatty, but hopefully will soon look better.
I guess this is either a 1945 or 1946 model. Can anyone help confirm the year?
While the number 771 matches both the frame and engine, the frame is XM and the engine is WM. Has anyone come across this before?
email (option): pvlietstra@gmail.com
Hi Peter..Your frame has the sidecar lugs as most XM20s do and the number stamping looks original.
However, this would not be matched to a WM stamped engine. That should carry XM stampings as well.
An engine change in the past seems the most likely scenario..though quite how the engine number ended up matching is anyones guess.
Frame and engine numbers for XM models did match, starting at XM20~101 in late 1945. Unfortunately the records I have, which include BSA literature, show this 'starting figure' for 45,46 and 47, the last year for girder fork models. So, I can't tell you in which of those three years yours was made...an educated guess would be 1946.
WM and XM engines are physically identical apart from the numbers. The bikes themselves were to a military specification but finished in a civilian colour scheme.
All painted parts were black, including the wheel rims, with the exception of the petrol tank which was finished in 'semi matt' silver with black lining and BSA logo.
The usual parts were bright chromed.
The field stand, pannier support tubes, bag carriers and bags, military type lights and pillion seat were removed but other components remained to military spec. I think the small rear carrier that is fitted was in the 'options' list.
This began to change in the last year (47) as stocks of military parts ran out and the riders footrests and speedo bracket were replaced mid season with civvy parts. The M20 was comprehensively altered for 1948 with the introduction of tele forks and numerous other changes..The bike looks nice and solid..The one glaring fault is the headlamp assembly, which is from a plunger model...the 'underslung' pilot light only being fitted for one season and the headlight brackets should be tubular and different lengths...the rest of it is detail stuff....Ian
email (option): ian@wright52.plus.com