Hello Chaps...

I've recently acquired a WM21 2735 engine in a reasonably good condition. Barrel, Iron head, timing cover with magneto access hole all in good condition.

Looking on Henks website at Frames & Engine numbers I notice very few WM21 engines, doe's this mean they are scarce? What sort of value does this larger engine hold? I'd be interested if anyone could put a date on the engine please. There is another marking under the engine number 'RB' what is this indicating?

There were inevitably less WM21 engines made than WM20 and most were originally Dutch orders.

WM21 2735 was installed in frame number 2735 and despatched originally to the Dutch "Staatsbedrijf Der Artillerie", Delft on 27/4/40 and then again on 30/5/40 to the War Office, London.

This double despatch occurs quite frequently around this period (the fall of the Netherlands). The implication is that they were still at the factory or perhaps a port awaiting shipment and were then returned and allocated to the War Office.

Allow me some nitpicking: "Staatsbedrijf der Artillerie Inrichtingen"; main arsenal at Zaandam but also activities in Delft at the site of the old "Patroonfabriek" (ammo works)

email (option): viaconsu#planet 'dot'nl

Hans, I assume that Delft was the 'adres voor facturatie' as it appears consistently in the BSA records, in the same way as London is always given for the War Office even though most were delivered to Ordnance, Chilwell.

To my opinion it's about time that the motorcycles or parts from this Dutch contract arrive in Holland, after 70 years it's about time. Please put that engine and any other part from that contract in a box and send all these to:

Vijfhuizerdijk 177
2141BJ Vijfhuizen
Holland

email (option): hum@quicknet.nl

the only thing i can say about R B that they are my initials also did the dutch government pay for the BSA motorcycle and if they didnt receive them then they should get their money back or delivery of said bikes if its the bikes the new address is depot henk

The Dutch government received quite a few BSA's just before the war what made the Germans very happy it seems.

Henk

email (option): hum@quicknet.nl

Hi .LJ.

To your question about the differences:
The difference between the M20-M21 engines is Mainly
A slightly longer stroke of 105mm VS 94mm, which gives an extra 95cc and some higher compression retio.
The difference is about 2 more HP.(Depends where you check..) and a bit more torque.

Many of the 500cc motors converted into 600cc,
but also the other way round, as there is some opinion, which I do not know if really truth,
That the bigger engines tend to "Burn" the exhaust valve much faster.

Noam.

email (option): noam10@gmail.com

Thank you for that interesting info!

Henk I'd gladly send over the engine if you can find the original frame and it's wheels in which to roll it over to you.

Do you mean an or the original frame? I have an original frame it would fit in nicely

email (option): hum@quicknet.nl

Ermm ermmm the original numbered frame same as engine number...

Phew! have I got out of that? Anyway you Dutch fellas have all the M21s. We Brits need to hang on to what little we have left. lol ;-) Actually I do have a 1940 frame, it's just finding the time to build it. I have a Super Rocket I need to get rid of first.

I was lucky enough to find frame WM20 2415 and engine WM21 2473 which both were to go to Holland in may 1940 each as part of an WM21. Not as one unit but two separated bikes. The front frame was found in the Middle East, while the engine comes from France mounted in a frame to be used as a stationary engine. They are joined as one motorcycle now for many years already with me having lots of fun with it. I really love that bike.

Henk.

email (option): hum@quicknet.nl