Author Topic: B21 - So what exactly have I got here?  (Read 259 times)

0 Members and 1 Guest are viewing this topic.

Group Leader

  • Star
  • *
  • Posts: 17
    • View Profile
B21 - So what exactly have I got here?
« on: 21 June, 2019, 16:24:16 »
Hi  Everyone,

Some may have spotted I joined the forum a few weeks back and today I have received my BSAOC welcome pack so now I'm a fully paid up member from  the Herts and Beds border.

I've recently acquired a 1939 B21 De luxe which is essentially complete (minus a speedo, see my previous thread) but needs a bit of TLC before it chugs off up the road.    It came with a BSAOC dating certificate that a PO had got along with an age related registration certificate.   It claims to be an Empire Star (by the badge on the tank) and on a previous MoT certificate although from my (very!) limited understanding of BSA model numbering I've not found any official reference to the B21 ever having that title.   I understand that the B21 was made between '37 & '39 and there was the complimentary B22 series which did have the Empire Star name.  It appears that a crude categorisation between the two models might be; the B21 series had a hand-change gearbox and the B22 had a foot-change box although it's not as a simple as that of course. 

My bike seems to be a bit of a hybrid (albeit matching frame and engine) as it is a B21 with a hand-change box adapted for foot-change with an external positive stop mechanism!   This mechanism wasn't working when I got the bike but I've now disassembled, cleaned, lubricated and correctly assembled it  (well at least better than it was) and now all four gears can be selected although you'd be stretching it if you said it was slick!  The mechanism seems to contain all the bits that would normally be found in the box and they look identical to the illustrations in various manuals of the foot change versions (Ratchet plate, 2 pawls, 2 parallel springs etc) so it looks like it was an official mod or upgrade.

From what I've seen there didn't seem to be a 1939 version of the B22 just the B21 standard and B21 de-luxe, so is it that the de-luxe is in essence the B22 / Empire Star or is it more likely that a PO stretched a point and applied Empire Star markings to it just to make it sound a bit more imposing?

I note in the members handbook it says that there are handbooks for the B21 and B22 series in the library but they do not appear in the member's area on the website (It does say on the website that Pre-War are not available) does this just mean they've not yet been uploaded but they could be acquired in the interim by more direct means?

Anyway, I'm sure they'll be loads more questions on girder forks, BSA head bolts, BSA colour schemes and numerous other topics over the following months!

Any advice / guidance gratefully received.

Thanks

Alan

« Last Edit: 21 June, 2019, 16:39:45 by Group Leader »

Group Leader

  • Star
  • *
  • Posts: 17
    • View Profile
Re: B21 - So what exactly have I got here?
« Reply #1 on: 21 June, 2019, 16:32:41 »
Here's the tank badge - is that original?

Oh, and the oil filter has had a bit of a makeover.

Alan

JulianS

  • Empire Star
  • *****
  • Posts: 1441
  • A10
    • View Profile
Re: B21 - So what exactly have I got here?
« Reply #2 on: 21 June, 2019, 17:36:26 »
Below from 1939 catalogue.

This was the year the 250cc C10 and C11 models were introduced.

Group Leader

  • Star
  • *
  • Posts: 17
    • View Profile
Re: B21 - So what exactly have I got here?
« Reply #3 on: 21 June, 2019, 21:05:46 »
Ah ha,  I see that the speedometer was an optional extra ;D  Shame the original purchaser didn't fork out for that option, still never mind!

But has anyone seen such an adaption of hand-change box to foot-change?   So far I've come across no refernces to the device or photographs of it.   And why did my B21 De-Luxe have a hand-change box anyway?   Maybe it was a subsequent replacement for an original foot-change that happened to be convienent (the tank doesn't have any fittings for the hand-change lever)? 

And is it an Empire Star or not?

Julian - In my B21 Speedo thread you kindly included an extract from the parts book.   Is that one of the documents that is available from the BSAOC library?

So many question for this BSA newbie!

Alan
« Last Edit: 21 June, 2019, 21:10:21 by Group Leader »

JulianS

  • Empire Star
  • *****
  • Posts: 1441
  • A10
    • View Profile
Re: B21 - So what exactly have I got here?
« Reply #4 on: 21 June, 2019, 22:40:08 »
No Empire Star models listed in 1939. Last ones were 1938.

I will send you a PM.

Group Leader

  • Star
  • *
  • Posts: 17
    • View Profile
Re: B21 - So what exactly have I got here?
« Reply #5 on: 12 August, 2019, 14:28:02 »
Carrying on the investigations into my B21 confirms, with the help of the information provided by various forumites here:
https://www.bsaownersclub.co.uk/bsaoc_forum/index.php?topic=5905.0

It does appears that the front hub is incorrect.   It has no facility for the speedo grive gear, the backplate is the wrong size, has an unusual aperture complete with mesh guard, a home fabricated torque arm but at least it does benefit from having some rather sporty cooling holes provided no doubt by a previous owner in a rather imprecise arrangement somewhere back in the mists of time.   

Nevertheless it's the only hub I've got and will have to do, at least for now!

The brake shoes have been re-lined by a local company for what I thought was a very reasonable tenner.   The backplate has been cleaned up by grit blasting and re-painting.    The brake drum looks to be in good order but a number of the wheel spokes are bent so they will need looking at.

Alan


Group Leader

  • Star
  • *
  • Posts: 17
    • View Profile
Re: B21 - So what exactly have I got here?
« Reply #6 on: 12 August, 2019, 14:44:39 »
As I mentioned in my other thread, I will need to contrive some sort of speedo.  This will be a home brew, electronic Chronometric job driven by a couple of magnets and a magnetic sensor housed in a dummy speedo gearbox (if anyone's got an appropriate, non-functioning but externally reasonable one please let me know!).  To that end, a brass ring has been turned that is a very good fit on the bearing housing into which a couple of rare earth magnets have been mounted.  The assembly has been loctited into position.

A complete Chrononmetric housing was purchased from a chap at the Banbury Run autojumble.   A prototype of the working bits has been assembled although there's still some software refinement to be done and the production version will have a higher quality needle drive actuator.   The wires from the wheel sensor will eventually pass up a speedo cable outer so as to look the part.  You can just see one of the magnets through the aperture and a temporary sensor mounting has been lashed up as you can see in the video.

Still the basic device seems to work and emulates, as intended, the operation of a proper job.

https://www.youtube.com/watch?v=4tPon8KCs74

Alan

Group Leader

  • Star
  • *
  • Posts: 17
    • View Profile
Re: B21 - So what exactly have I got here?
« Reply #7 on: 15 August, 2019, 21:10:36 »
Aha!  It seems that my B21 De -Luxe masquarading as an Empire Star with a funny front hub has got a Blue Star Gear change on it. 

I wonder if it's actually a Blue Star box too?   Pehaps I shall name it Bitsa.

You don't have to be Inspector Morse to work out what BSA you've got but it would certainly help!  :)

Alan