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BSA frame identification.


samwisemcg
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I was wondering if anyone could help me identify a bsa frame.

The engine is a b40 and I was told the frame is a b25.

There are a couple of things that seem strange. The log book has it down as a March 65 bike, but I am pretty sure the earliest b25’s were 68. I have the frame number in the log book, but I can’t find it on the frame, does anyone know where it should be.

Also it seems like the frame has been modified. There should be 2 center posts, from the foot pegs up to the front of the seat. It seems like these have been modified to one center post. After having a look on google I can see a couple of b40 trials bikes that look the same. 

Does this look like a modified b25 frame, or maybe a c15 frame?

 

Any help would be much appreciated.

Thanks

Sam

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WhatsApp Image 2018-07-16 at 19.52.39(1).jpeg

WhatsApp Image 2018-07-16 at 19.52.39.jpeg

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I think you may have a modified WD BSA B40 frame.

The two tubes from the rear of the tank to swing arm pivot have been reshaped attaching much lower so as not to rub the ridrrs legs also I think the head angle has been altered, look at the down tube above the engine mount.

You have a good looking bike which ought to work rather well.

Edited by trialsrfun
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17 hours ago, windlestone1 said:

That's nice. Try the BSA Otter site, Charlie the site owner is very helpful and has a wealth of knowledge and archives he refers to

 

It's funny you should mention that. I have spent a lot of time on that site this week, it's a great read.

 

16 hours ago, b40rt said:

My B40 has the frame no on the left (as your sitting on it) front engine mount.

I did check here and can't locate it. i wonder if the paint on the frame is so think it has covered it up.

 

12 hours ago, trialsrfun said:

I think you may have a modified WD BSA B40 frame.

The two tubes from the rear of the tank to swing arm pivot have been reshaped attaching much lower so as not to rub the ridrrs legs also I think the head angle has been altered, look at the down tube above the engine mount.

You have a good looking bike which ought to work rather well.

Thanks, I did look into the b40 frame, but they have a removable rear subframe and my bike doesn't.

I haven't had the chance to ride it in anger yet as it still needs running in. I'm looking forward to getting out on it.

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1 hour ago, samwisemcg said:

 

1 hour ago, samwisemcg said:

Thanks, I did look into the b40 frame, but they have a removable rear subframe and my bike doesn't.

I haven't had the chance to ride it in anger yet as it still needs running in. I'm looking forward to getting out on it.

The earlier road bike B40 like the C15 had a detachable rear subframe.

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4 minutes ago, trialsrfun said:

The WD B40 frame which was all welded was based on the Victor scrambler this frame was used on the later BSA works trials bikes.

Jim Susans of Bikecraft modified many WD frames in the way that yours has been done.

http://www.bsaotter.com/jim_susans_bikecraft.html

Thanks, thats really helpful.I will definitely have a read through this page when I get a chance.

There is something else different about my bike. It has an alloy barrel and it was said that it could be a works barrel/engine. I can find aftermarket alloy barrels, but they all have 10 fins. My bike has a 9 fin alloy barrel. Strange...

I guess it doesn't really matter what it is, as I couldn't be happier with the bike.

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If you haven’t already done so, have a look at Brittania Motorcycles where you find and see a very knowledgable person carrying out modifications and alterations to frame, engine and everything else virtually. But again I must say that your bike looks the real business?

Edited by section swept
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  • 2 years later...
 

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