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#217020 - 10/04/08 9:06 pm Where to start? -- 1941 BSA M20  
Joined: Feb 2006
Posts: 23
Bob T Offline
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Bob T  Offline
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Carol Stream, IL, USA
OK experts...where do I start on this '41 BSA M20:




Right now I'm leaning towards a decent runner, not a show bike.
My thought is to start with the frame, clean it up, fix any damage and work from there.
I'm not rich, but not poor either...
Plus I'm old enough to have gone down this road before and understand the time and cost involved.

My Dad picked this bike up in the mid '70s and never did anything with it. He gave it to me about 10 years ago and it's been sitting since.
I've now got the room and the time to start.
Here is pic of the engine number plate:



So any opinions, tips, ideas would be appreciated...especially from you M20/M21 experts...

Bob T.

Last edited by Bob T; 10/04/08 9:51 pm.
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#217111 - 10/05/08 11:21 am Re: Where to start? -- 1941 BSA M20 [Re: Bob T]  
Joined: May 2004
Posts: 3,548
BSA_WM20 Online content
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BSA_WM20  Online Content
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Sydney Australia
Before you start anything send the maggy off for a rebuild.
There are parts inside that deterioate with age.

I always advise to shot the thing together and get the engine/ gear box sorted out first.
While you are on the road enjoying something that your dad didn't start the search for missing frame bits.
When you have the mechanicals all in good order & all of the parts that you need to get the frame up to scratch, pull it down for the big cosmetic rebuild.
It is a real bummer to have spent a small, fortune on getting the whole bike painted & looking pretty only to find out that the fork bearings or girder bushes are not up to scratch.


Bike Beesa
Trevor
#217113 - 10/05/08 11:40 am Re: Where to start? -- 1941 BSA M20 [Re: BSA_WM20]  
Joined: Aug 2001
Posts: 4,952
Rich B Online happy
Rich B  Online Happy



Joined: Aug 2001
Posts: 4,952
Stone Creek OH USA
Neat bike grin and looks like the major hard to find stuff is there.

Very first thing I would do is get copies of parts & service information for an M20 if you don't have it already. The CD sold by this site has lots of M20 literature on the CD.

Then I would do a dry build. Just assemble it and see what is missing/damaged. Make a list.

Then as Trev sez, I would send the magdyno off for a rebuild while I did the rest of the bike. I would definitely effort to make sure the girders are straight and tight as they should be.

M20's are neat. Not fast, just steady plonkers. Looks like a fun project.

Besides, us "M" series owners need to stick together. Oh wait, did I just give away the identity of my latest "find" grin


Life is too short to drink cheap, bad beer.
#217116 - 10/05/08 12:22 pm Re: Where to start? -- 1941 BSA M20 [Re: Rich B]  
Joined: Sep 2006
Posts: 144
LJ. Offline
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LJ.  Offline
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Peterborough. UK
Looking at your stable... Your M20 is going to be your best bike Bob! I have two very nice A10s but my M21 (very similar to M20) is tops!

There is loads of info on the net and, if the moderators don't mind me pointing, Henks Website is your first stop for info and pictures. Henks Site

Parts are not too difficult to get from what I have observed, unless you want those ultra rare items like brass combination levers, tank top air filters etc. You might already have them?

Although my machine is later, it is not so very different from the earlier ones, so feel free to IM or Email me with requests for pictures if you get stuck.

Good Luck and I hope all goes well.


LJ.
*******
1940 BSA M20 500cc Girder/Rigid- In Bits!
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7 500cc Girder/Plunger Star Twin-Black
1953 BSA B33 500cc Teles/Plunger-Maroon
1961 BSA A10 650cc Golden Flash-Blue
1961 BSA A10 650cc Golden Flash-Red
#217119 - 10/05/08 12:53 pm Re: Where to start? -- 1941 BSA M20 [Re: Bob T]  
Joined: Aug 2008
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Jim Hultman Offline
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Jim Hultman  Offline
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Minnesota, US
Originally Posted By: Bob T
OK experts...where do I start on this '41 BSA M20:
Right now I'm leaning towards a decent runner, not a show bike.
My thought is to start with the frame, clean it up, fix any damage and work from there.


That's the great thing about M-20's - Once you do the preliminary assembly, and happen to find out things work fine, you can paint them with a brush and just ride! The military was quite crude that way, but these bikes look great with just a simple military style stencil on the tank.

Looks like you have most of the parts, but you can sill have fun trying to find lots of detail things like the original bag mounts, the big frame mounted side stand and most of all the correct Vokes air filter. I think you can get repro filter packs, which are very cool.

This looks like a GREAT project! Have fun!

#217127 - 10/05/08 1:43 pm Re: Where to start? -- 1941 BSA M20 [Re: Bob T]  
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Jim Hultman Offline
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Jim Hultman  Offline
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Joined: Aug 2008
Posts: 1,429
Minnesota, US
Originally Posted By: Bob T
So any opinions, tips, ideas would be appreciated...


This is kind of an interesting web site on M20's..... M20 site

#217128 - 10/05/08 1:45 pm Re: Where to start? -- 1941 BSA M20 [Re: Jim Hultman]  
Joined: Feb 2006
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Bob T Offline
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Bob T  Offline
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Carol Stream, IL, USA
Wow...I knew this was the place to be...Thanks Guys!

OK...If I'm reading your posts correctly...

First I need to strip the frame down as I found a cracked weld on the small cross piece, at the rear down tubes. Fix that and coat it with something so it don't rust.
I have access to a sandblaster and experianced welders)

Second...do a dry assembly to check for missing/worn/broken parts.

Third, if all looks doable, send off the mag for rebuild whilst locating/repairing/rebuilding the rest of the bike.
And whom does mag rebuilds? (And at what cost?)

Thanks again for the tips and links...

Bob T.

#217129 - 10/05/08 1:55 pm Re: Where to start? -- 1941 BSA M20 [Re: Jim Hultman]  
Joined: Feb 2006
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Bob T Offline
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Bob T  Offline
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Carol Stream, IL, USA
Originally Posted By: Jim Hultman
Originally Posted By: Bob T
So any opinions, tips, ideas would be appreciated...


This is kind of an interesting web site on M20's..... M20 site


Thanks Jim...I had the one LJ posted above, but not this one.
I have a file where I put every picture of an M20 I can find...figured they would help in the rebuild.

(Man...it's kind of exhausting having to log in two or three times just to make a few posts)

Bob T.

Last edited by Bob T; 10/05/08 1:59 pm.
#217152 - 10/05/08 3:54 pm Re: Where to start? -- 1941 BSA M20 [Re: Bob T]  
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Jim Hultman Offline
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Jim Hultman  Offline
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Minnesota, US
Originally Posted By: Bob T
And whom does mag rebuilds? (And at what cost?)

Good question, that. My magneto expert here in Minnesota died a few years back, and I haven't found anyone to replace him yet. I'm sure someone here probably knows of a Lucas specialist, but the guy I brought my mags to did mostly old tractor and airplane mags.

Kind of scary that we are losing those irreplaceable treasure troves of knowledge. Plus he was a really cool guy! (Neil at Electro Mag in Minneapolis)

#217157 - 10/05/08 4:21 pm Re: Where to start? -- 1941 BSA M20 [Re: Jim Hultman]  
Joined: Feb 2006
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Bob T Offline
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Bob T  Offline
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Carol Stream, IL, USA
Originally Posted By: Jim Hultman


Kind of scary that we are losing those irreplaceable treasure troves of knowledge. Plus he was a really cool guy! (Neil at Electro Mag in Minneapolis)


Sadly we live in a throw away and replace era...

On another note...I threw together a quick web page this morning to record my adventures with this bike...
Nothing much yet, but if I keep it up it might become something.

My 1941 BSA M20 Page

Later,
Bob T.

#217171 - 10/05/08 5:34 pm Re: Where to start? -- 1941 BSA M20 [Re: Bob T]  
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LJ. Offline
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Peterborough. UK
Thats a good start to doing a personal blogg on your M20 Bob, I have done the same... LJ's M21 Blogg

Getting your Armature re-would in the UK be no problem, however for you in the U.S. if there were re-winders in short supply, you could send just the Armature itself to the UK and do the rest yourself at home, it is not a difficult job to do, replacing bearings and possibly insulation gaskets, and would keep weight down for posting.

As already stated, how simple the bike is. I'd even fit the un restored (iffy) magneto and see how it runs, likely it will be difficult to re start when hot but likely easy to start when cold. Some may see this as a complete waste of time but it's good experience to understanding a magneto. Taking off and refitting and timing it is not a long job at all. bigt


LJ.
*******
1940 BSA M20 500cc Girder/Rigid- In Bits!
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7 500cc Girder/Plunger Star Twin-Black
1953 BSA B33 500cc Teles/Plunger-Maroon
1961 BSA A10 650cc Golden Flash-Blue
1961 BSA A10 650cc Golden Flash-Red
#217250 - 10/06/08 4:09 am Re: Where to start? -- 1941 BSA M20 [Re: LJ.]  
Joined: Oct 2007
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jeep44 Offline
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jeep44  Offline
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Detroit,Mich.
You have found Henk Joore's WD M20 site,haven't you? There is also a yahoo group for M20s- both very informative. i have bought many tools and parts from Henk with no problems at all.
I have two restored M20s-a '40 and a '44. Are you intending to restore yours to WW2 configuration?
One hint: mine were painted with several layers of paint,and there were quite a few original markings under the top layer of paint-carefully sand the tank, toolbox and fenders instead of just having them stripped-you just may discover what unit your bike may have served with.
There is a book out about WW2 motorcycles, written by Chris Orchard. He gives lists of contract numbers that will allow you to determine the correct "C" registration number that your bike carried painted on the sides of the tank in WW2. If you cannot get this book, I can look it up, based on your frame serial number (engines almost never match the frame due to Army rebuilding).
After I got mine I had to get all the proper uniform bits,too. There are quite a few items specific to Dispatch (despatch?) riders,such as the three-strap boots, helmet,and DR mac. The Yahoo site has a lot of photos of the gear (a lot of it is mine)
I also went totally obsessive on gathering all the correct tools for the toolbox-an extensive set of tools was supplied with the bike. Henk has been a good source for these.
Good luck on your restoration!


2007 Royal Enfield Bullet
'67 triumph T100R
'40,'44 BSA M20s
'97 Ural Tourist
'80 HD XLS Roadster
a few others
#217324 - 10/06/08 5:46 pm Re: Where to start? -- 1941 BSA M20 [Re: jeep44]  
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Bob T Offline
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Bob T  Offline
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Joined: Feb 2006
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Carol Stream, IL, USA
Originally Posted By: jeep44
You have found Henk Joore's WD M20 site,haven't you? There is also a yahoo group for M20s- both very informative.

Yes I have and I'm already a member of the yahoo group...

Quote:
Are you intending to restore yours to WW2 configuration?

That's the question, isn't it...Problem is, I hate the color green with a passion, except in nature.
Don't like green cars, bikes, clothes, wall paint...you name it.

So what to do? Haven't decided yet.

Last edited by Bob T; 10/06/08 5:50 pm.
#217332 - 10/06/08 6:09 pm Re: Where to start? -- 1941 BSA M20 [Re: Bob T]  
Joined: Oct 2007
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jeep44 Offline
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jeep44  Offline
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Detroit,Mich.
Well ,I did one of my M20s in desert tan color-that looks good,too.


2007 Royal Enfield Bullet
'67 triumph T100R
'40,'44 BSA M20s
'97 Ural Tourist
'80 HD XLS Roadster
a few others
#217650 - 10/08/08 12:03 pm Re: Where to start? -- 1941 BSA M20 [Re: jeep44]  
Joined: Feb 2006
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Bob T Offline
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Bob T  Offline
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Posts: 23
Carol Stream, IL, USA
Originally Posted By: jeep44
One hint: mine were painted with several layers of paint,and there were quite a few original markings under the top layer of paint-carefully sand the tank, toolbox and fenders instead of just having them stripped-you just may discover what unit your bike may have served with.


Well Jeep, I started doing what you recommended with the paint and I did find something last night...don't know what it...



There seems to be more layers to go yet...

Bob T.

Last edited by Bob T; 10/08/08 12:05 pm.
#217693 - 10/08/08 3:28 pm Re: Where to start? -- 1941 BSA M20 [Re: Bob T]  
Joined: Oct 2007
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jeep44 Offline
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jeep44  Offline
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Posts: 76
Detroit,Mich.
I had Royal Artillery formation signs on the sides of the gas tank on one of my M20s. I've seen formation signs on the front or rear fenders of other M20s. There should be tire pressure markings on the front and rear fenders,too.
One of mine also had "Drive on the right" painted in red letters on the top of the tank-its rebuild tag on the engine showed that it was rebuilt by a REME unit that was stationed in Germany.


2007 Royal Enfield Bullet
'67 triumph T100R
'40,'44 BSA M20s
'97 Ural Tourist
'80 HD XLS Roadster
a few others
#217841 - 10/09/08 3:33 am Re: Where to start? -- 1941 BSA M20 [Re: Bob T]  
Joined: Oct 2003
Posts: 11,108
RF Whatley Offline
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RF Whatley  Offline
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Posts: 11,108
North Georgia, USA
Originally Posted By: Bob T
OK experts... where do I start on this '41 BSA M20?
Right now I'm leaning towards a decent runner...


Bob -
The Land World Speed Record for an M20 is only something like 65 MPH. You could be the next Burt Munro....
with a blistering 67 MPH.

laughing


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
#217868 - 10/09/08 10:56 am Re: Where to start? -- 1941 BSA M20 [Re: RF Whatley]  
Joined: Aug 2001
Posts: 4,952
Rich B Online happy
Rich B  Online Happy



Joined: Aug 2001
Posts: 4,952
Stone Creek OH USA
Actually Whatley...if I remember right, one of the board members set the LSR for a flathead 500cc single several years ago at Bonneville. It was a bit more than 65 mph..... I seem to remember low 3 digits.....and teh 3 digits were left of the decimal point laugh


Life is too short to drink cheap, bad beer.
#217869 - 10/09/08 11:12 am Re: Where to start? -- 1941 BSA M20 [Re: Rich B]  
Joined: Feb 2006
Posts: 23
Bob T Offline
BritBike Forum member
Bob T  Offline
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Joined: Feb 2006
Posts: 23
Carol Stream, IL, USA
Originally Posted By: Rich B
Actually Whatley...if I remember right, one of the board members set the LSR for a flathead 500cc single several years ago at Bonneville. It was a bit more than 65 mph..... I seem to remember low 3 digits.....and teh 3 digits were left of the decimal point laugh


Yes...it was Bill Jenkins who set several records, (multiple classes), from 82mph to 108.213. Because it's a side valve motor, they run in the 350 class. Believe me, I actually looked into doing this a couple of years ago.
Here's a pic of Bill's bike:



Later,
Bob

#217871 - 10/09/08 11:39 am Re: Where to start? -- 1941 BSA M20 [Re: Bob T]  
Joined: May 2004
Posts: 3,548
BSA_WM20 Online content
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BSA_WM20  Online Content
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Sydney Australia
There is an interesting article on the Victory library about how to make an M20 get up & go. And they are talking about 102mph.
Mine is geared up to give about 80 mph ( in theory).
It actually gets to about 75 because I can just keep pace with expressway traffic @ 110 kph but it gets really really hot so when you finally stop, you have to make it a long one.
At 60 mph it will run all day & night if my bum can take the punishment.
With the 930 Concentric it would do the 80 mph but the fuel consumption made A75's look fuel efficient


Bike Beesa
Trevor
#218097 - 10/10/08 6:20 pm Re: Where to start? -- 1941 BSA M20 [Re: BSA_WM20]  
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Ray Smith Offline
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Ray Smith  Offline
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Wales
Congratulations Bob you have a great bike.They are solid and easy to work on and very forgiving to ride.One thing no one has mentioned
once you have the frame clear of everything and before blasting and painting check that the frame and forks are true and that the wheels will run in line.If its together and running with a good magneto it will run for as long as you keep it supplied with fuel and oil.Many years with M20/M21s the only problems encountered were the occasional failed head gasket even this is unlikely to fail if fitted properly.
I see you don"t like green as a colour my favourite M20 colour is sand if you don"t like that the Air Force and Royal Navy also had M20s painted appropriately Air Force or Navy blue
Good luck with it.


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