Hi all,

I've been asked to post a few pictures of a WM20 that has the same owner since the early 80-ies;





Frame no is WM20 4037 and engine no is WM20 30848
Does anyone have more info about the history of this bike?

Many thanks,

Sven

email (option): snvosselman@gmail.com

Hi Sven

There are about a dozen M20s in the post war keycard listed with the frame number 4037, there is a theory that someone looking in the wrong place found a frame part number 66-4037 and put that down instead of the proper number.

Could you supply a photo of the frame number from this machine, it might answer this question.

Rob

email (option): robmiller11(a)yahoo.co.uk

Hi Rob, I will ask the owner...

Cheers, Sven

email (option): snvosselman@gmail.com

Here are 2 pictures of the frame no and one of the engine no I got from the owner;







So before drawing any conclusions I would like to point out that this owner has the bike in his posession for over 35 years. In the early 80's there was much less knowledge about originality of WW2 bikes so numbers and places where they should be could have been mixed up easily.

Regards, Sven

email (option): snvosselman@gmail.com

Thanks Sven

Fascinating, I assume it doesn't have a "WM20" in front of the frame number? or any flattening of the down tube where you would normally find a frame number?

Rob

email (option): robmiller11(a)yahoo.co.uk

Isn't that an odd place for the engine number? You can just see the original number where they are normally stamped.

Dave

email (option): jeepfinger@blueyonder.co.uk

When did they move the frame number from the bottom lug ? Are all WM20s marked on the headstock lug ?

The engine number certainly looks like a re-stamp as Dave says. My experience with Nortons suggests that whilst this was not common practice with wartime rebuilds, those rebuilt after the war were often re-stamped.

I'm not sure when the first frame numbers moved from the bottom to the top of the front down tube?

There was a KM20 with the frame KM20 4037 Engine KM20 3037 from WO contract C3655 delivered 17/7/39

But according to the factory ledgers there wasn't a WM20 4037 as far as I can see?

I suspect that this is a replacement front frame section fitted during a late or post war rebuild which had a part number "4037" stamped on in the factory along with an unknown quantity of other similar ones.

Rob

email (option): robmiller11(a)yahoo.co.uk

Hi Rik,

What do you think? I can't see it properly, but the 3 in the frame number, looks like the 3 stamped on the engine breather. I wonder if the original engine number has been ground off?

Dave

email (option): jeepfinger@blueyonder.co.uk

I'm not an expert on BSA numbers (and they are quite haphazard for such a big factory)but the '3' with the serif tail on the top bar looks rather Continental to me.

Enginenumber on breather boss is a restamp for sure I would say. You can see scratches below the (Original) WM20 prefix, I suspect that is where the Original number has stood.

Framenumber is surely not KM as KM20.4469 is still stamped on the bottom lug. If there is not a WM20 prefix in front I would say that chances are great that it is a restamp too. (or been messed with)

(BTW, Rik, the number 3 with the serif tail is on my KM engine, so that fonttype of numbers was used in Britain in that time)

for a few years ago an old man came with his wm20 to me and we discuss about his framenumber...it was exactly the same as this one.only the number without wm20 was stamped in it and also it was not nice done.
he own the bike for about 45 years and drove in whole europe with it,he only replaced the piston and cilinder and swapped the magdyno.
i send a message to henk and he told me that the number was correct also he told me that the front frame was swapped at some point in war.because the mechanics where maybee lazy they leave wm20 and only put the framenumber in.
after 45 years the man now know that his bike was made in 1945 and realy was an wm20

This BSA is now for sale. Anyone who is interested can reply to Wiebe:

w.kunst41@outlook.com

Regards,

Sven

email (option): sn