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BSA M20 unusual markings... #495236
06/24/13 2:56 am
06/24/13 2:56 am
Joined: May 2010
Posts: 35
Western NY
O
odballaffliction Offline OP
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odballaffliction  Offline OP
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Joined: May 2010
Posts: 35
Western NY
Hi everyone! I just bought an early (1938) what i think is a civilian model M20. I was told it was a 1938, but the only markings i can find on the frame are M20 4437. It has the girder front end with the gutta percha knobs, as well as the highly valanced fenders, hardtail, and an iron head. My real puzzler though is the timing side cover that is normally stamped B.S.A. instead has an SA monogram cast into it. Twice. One where BSA should be, and another bigger one half way up the cover. It was imported from belgium years ago so maybe that has something to do with it? Thanks!
http://www.flickr.com/photos/97939602@N07/with/9123232224/

Last edited by odballaffliction; 06/24/13 3:08 am.

My god they've procreated in the night!
how many is too many...
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Re: BSA M20 unusual markings... [Re: odballaffliction] #495254
06/24/13 9:20 am
06/24/13 9:20 am
Joined: Aug 2004
Posts: 285
UK
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pachy Offline
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pachy  Offline
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Joined: Aug 2004
Posts: 285
UK
Whatever lettering it has its a 39 onward engine.
37 & 38 M20 have a different design with a completely smooth timing cover that incorporated the cam bushes & most of the major engine components of a 38 are not interchangeable with 39 onward engines.

Here's links to pics of the 37/38 type engine ..



http://japantrip.tripod.com/rides/bsam20.jpg
http://automotiveset.com/Bsa/Bsa-M20/gallery.html?pic=2#gp

Last edited by pachy; 06/24/13 9:47 am.
Re: BSA M20 unusual markings... [Re: odballaffliction] #495261
06/24/13 10:55 am
06/24/13 10:55 am
Joined: May 2004
Posts: 3,859
Sydney Australia
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BSA_WM20 Offline
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Posts: 3,859
Sydney Australia
Where on the frame did you find those numbers ?

I seriously doubt that either the frame or engine ever formed any part of an M20.

I have seen that logo before but can not quite recollect where.

BSA engines were used by a lot of companies other than BSA to power a lot of things other than motorcycles.
During WWII BSA started to produce a series of dedicated stationary engines which carried on til the late 60's when they sold the rights to Villiers.

From 1937 on all BSA frame numbers had 2 letters ie;-ZM20, BM20 etc
The only frames that had a plain M were the 8 Hp V twins from the early 20's but their frame numbers are stamped under the saddle nose.

Some more photos of both the engine & frame will be of great help.

Are you sure that the frame is in fact a BSA one ?


Bike Beesa
Trevor
Re: BSA M20 unusual markings... [Re: odballaffliction] #495262
06/24/13 11:08 am
06/24/13 11:08 am
Joined: Dec 2004
Posts: 9,546
Scotland
kommando Offline
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kommando  Offline
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Joined: Dec 2004
Posts: 9,546
Scotland
This may work


Re: BSA M20 unusual markings... [Re: odballaffliction] #495271
06/24/13 12:20 pm
06/24/13 12:20 pm
Joined: May 2010
Posts: 35
Western NY
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odballaffliction Offline OP
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odballaffliction  Offline OP
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Joined: May 2010
Posts: 35
Western NY
thanks for the help so far. I will be back around the shop later and i will pop off that side cover to see whats going on beneath it or if there are any other markings and take some more pics of the engine. It looks like the numbers on the engine have been ground and restamped and i am sure the frame has too. I can see some file marks on the neck and the new number is under the nose of the seat. I will have to wait a couple weeks for the person i bought it from to send me his import papers but i am curious to see what they say. Note the valanced mud guard in the background.

http://i108.photobucket.com/albums/n25/fanny_pants/KIMG0364.jpg


My god they've procreated in the night!
how many is too many...
Re: BSA M20 unusual markings... [Re: odballaffliction] #495290
06/24/13 4:14 pm
06/24/13 4:14 pm
Joined: Aug 2004
Posts: 285
UK
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pachy Offline
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Joined: Aug 2004
Posts: 285
UK
OK i checked all your pics (including someone with a bite mark) shocked
Its fairly obviously a WM20 frame & engine looks all good for post 1939 WM20 the timing cover has probably been disguised after the war (or swapped for one off a BSA made industrial motor) at the same time the numbers were removed.
This was sometimes done when civilians "found" bikes & wanted to remove its identity .. there's alot in north Africa also privately owned with made up numbers, its quite common for people in those days to assume "M20" would be a legit looking frame number.
Also any M20 coming from Belgium has a huge chance of being a WM20.
Top end looks all good for a WM20 (some industrial variants had different fins) a BSA marked timing cover will go on but it must be 39-on type.

Don't listen to too many scaremongerers ... its 99% sure to be a WM20 that's been a bit messed around with.... ; )

Re: BSA M20 unusual markings... [Re: odballaffliction] #495375
06/25/13 11:32 am
06/25/13 11:32 am
Joined: May 2010
Posts: 35
Western NY
O
odballaffliction Offline OP
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odballaffliction  Offline OP
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Joined: May 2010
Posts: 35
Western NY
Why cant i find WW2 beesas! Hell i would even take a free messerschmidt! I would disguise it very well! Thanks for the info. Now i need to decide what direction to take with this thing...


My god they've procreated in the night!
how many is too many...
Re: BSA M20 unusual markings... [Re: odballaffliction] #495389
06/25/13 4:20 pm
06/25/13 4:20 pm
Joined: Aug 2004
Posts: 285
UK
P
pachy Offline
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pachy  Offline
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Joined: Aug 2004
Posts: 285
UK
Nice thing about the wm20's is they are plentiful & there are more than enough full restored ones about, you can use your imagination on one without fear of reprisals. laugh
If i was you (i have original & non original BSA's myself) i would put together what you have there including the unusual timing cover.
don't do any paint or over restore anything, just wipe everything with oily rag or wax the paintwork & assemble it & see how she looks.

Re: BSA M20 unusual markings... [Re: odballaffliction] #509161
10/05/13 7:17 pm
10/05/13 7:17 pm
Joined: Dec 2009
Posts: 83
SCarolina
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BSAonAnyDay Offline
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Joined: Dec 2009
Posts: 83
SCarolina
So i ended up prying this find from my brother (original poster). I asked our english uncle about the sa insignias and he agrees its sturmey archer. The middle badge on the timing cover has been pinned and tacked/soldered. Im not really concerned with why it was done. Like pachy said theres enough m20s about, no need for another concours example to be sealed in a time capsule and go unused.I was really hoping that someone here in the states knew of a person/place that could rewind armatures/overhaul the maggy? Also, are the later alloy heads available? Mine has the iron head but given the temperatures down here in scarolina it might be best to look into such an upgrade.


They don't flatter you; they educate you.
1939 BSA M20
1948 BSA C10
1953 BSA C11
1970 BSA A65T
1973 Triumph TR7RV
Re: BSA M20 unusual markings... [Re: BSAonAnyDay] #509645
10/08/13 9:17 pm
10/08/13 9:17 pm
Joined: Feb 2003
Posts: 2,951
Ohio
R
Rickman Offline
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Joined: Feb 2003
Posts: 2,951
Ohio
DCF?
I suggest you look to Doug Wood to rewind/rebuild your mag.
He has done four for me so far.
And one magdyno.

He posts here from time to time.

Others will post their suggestions...

Re: BSA M20 unusual markings... [Re: odballaffliction] #509809
10/10/13 6:51 am
10/10/13 6:51 am
Joined: Aug 2001
Posts: 4,100
argyll. scotland, uk
gavin eisler Offline
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gavin eisler  Offline
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Joined: Aug 2001
Posts: 4,100
argyll. scotland, uk
The SA logo looks like Sturmy Archer to me, they were a big firm and may have bought motors from BSA for their own use, or possibly its AS for Arney Sackneusen and your motor has journeyed to the centre of the earth.
http://cybermotorcycle.com/gallery/classics_s/Sturmey_Archer_198CC.htm

Last edited by gavin eisler; 10/10/13 1:10 pm.

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