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M21 in a B Frame #776274 06/12/19 11:40 pm
Joined: Sep 2018
Posts: 23
70BSABobby Offline OP
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Hey guys, I'm torn on whether or not I should pull the trigger on purchasing this bike as my next project. It's a bit odd, it's a 1952 M-21 engine in a 1952 or 53 B series plunger frame. I'll just list the good and bad (that I know) and see what you guys think.

The good

1. All new paint
2. New wheels
3. New headlamp
4. New mag
5. Rebuilt carb
6. New tires
7. All parts are there except for speedo and exhaust/silencer.

The bad

1. Owner has never had it running (owner never tried to get it running though)
2. Mismatched engine and frame
3. Needs a title.

The owner is firm at $2,600 USD. If this was a matching frame/engine it would be a no brainer. The other thing that bothers me is it's a weaker engine from a different series in a frame that had a more powerful engine. I'm about ready to just do it, have him title it as a 1952 B33 as he still needs to title it (I won't buy until I see one) and either ride it as is or try and source a B33 engine.

What do you guys think, is this a good deal or should I pass? These bikes are extremely rare in the states as far as I can tell so I'm worried I won't find a more original bike for close to this price.

Thanks in advance for any advice/feedback!





[Linked Image][/url]IMG

[Linked Image]
[url=https://flic.kr/p/2gddrFM]IMG

Last edited by 70BSABobby; 06/13/19 1:58 am.

1970 BSA A65T

2017 Triumph Bonneville T120 Black

2006 Yamaha YZF-R1 Raven Edition
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Re: M21 in a B Frame [Re: 70BSABobby] #776283 06/13/19 1:13 am
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Don P. Offline
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https://www.eBay.com/itm/1949-BSA-B34/254257096536 Take a look at this one.At least it runs and has a title

Re: M21 in a B Frame [Re: 70BSABobby] #776306 06/13/19 8:45 am
Joined: May 2004
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B
BSA_WM20 Online Content
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The B frame is a LIGHTWEIGHT version of the M frame so there is no problems frame wise other than the tabs for muffler & exhaust will not line up.


Bike Beesa
Trevor
Re: M21 in a B Frame [Re: 70BSABobby] #776313 06/13/19 10:46 am
Joined: Feb 2006
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Ginge Offline
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It’ll never break any speed records but it’ll be simple to work on, easy to find parts for and it’s a ‘50’s BSA.

Pull the trigger on it when you see a title.


'51 C11 in a '54 C10L frame..."The Bantam Eater"
'70 Triumph Trophy 500. Bottom end rumble awaiting diagnosis
'72 Triumph Tiger 650. Back on the road...
Re: M21 in a B Frame [Re: BSA_WM20] #776354 06/13/19 9:16 pm
Joined: Sep 2018
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70BSABobby Offline OP
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Originally Posted by BSA_WM20
The B frame is a LIGHTWEIGHT version of the M frame so there is no problems frame wise other than the tabs for muffler & exhaust will not line up.


How would I remedy the exhaust not lining up? Would I buy a different part or would I need to do some cutting/fabricating? Thanks!


1970 BSA A65T

2017 Triumph Bonneville T120 Black

2006 Yamaha YZF-R1 Raven Edition
Re: M21 in a B Frame [Re: 70BSABobby] #776397 06/14/19 9:34 am
Joined: Aug 2015
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Andy Higham Offline
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If you are asking questions like that maybe a special is not for you


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500 sprint/LSR bike "Deofol"
Jawa 500 "Llareggub"
Aprilia RSV Mille "Lo Stregone"
'35 & '36 OK Supreme
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Re: M21 in a B Frame [Re: Andy Higham] #776401 06/14/19 10:49 am
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Ginge Offline
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Quote
How would I remedy the exhaust not lining up? Would I buy a different part or would I need to do some cutting/fabricating? Thanks!


Well, you could cut the frame tabs off and shift them, or you could cut the exhaust tabs off and shift them. Both would require a mock up with the original parts.

You could leave everything standard and build a custom exhaust.

If you’re lucky and the tabs aren’t too far off each other you could fabricate spacers or linking brackets.

Nothing difficult. Just might need to have it all there in the flesh to measure and nut out.


'51 C11 in a '54 C10L frame..."The Bantam Eater"
'70 Triumph Trophy 500. Bottom end rumble awaiting diagnosis
'72 Triumph Tiger 650. Back on the road...
Re: M21 in a B Frame [Re: Ginge] #776403 06/14/19 11:23 am
Joined: Sep 2018
Posts: 23
70BSABobby Offline OP
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Posts: 23
Originally Posted by Ginge
Quote
How would I remedy the exhaust not lining up? Would I buy a different part or would I need to do some cutting/fabricating? Thanks!


Well, you could cut the frame tabs off and shift them, or you could cut the exhaust tabs off and shift them. Both would require a mock up with the original parts.

You could leave everything standard and build a custom exhaust.

If you’re lucky and the tabs aren’t too far off each other you could fabricate spacers or linking brackets.

Nothing difficult. Just might need to have it all there in the flesh to measure and nut out.


Thanks, I appreciate it. This will be a winter project so any snags/learning will be welcomed and enjoyed. I’m waiting on the owner to show a title and if/when he does I’m going to buy it. Again, I appreciate all the feedback. There will be a learning curve with this bike just like my A65 but I appreciate these old bikes and want to learn.

Thanks again everyone.


1970 BSA A65T

2017 Triumph Bonneville T120 Black

2006 Yamaha YZF-R1 Raven Edition

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