BSA L29

[robbsa]

Hi there,

anyone out there got any knowledge of 1920's BSA side valves. I have a BSA l29 that I have had for a few years and haven't touched it for a while. now trying to get my teeth into it again.

One of my first questions is around the ignition, magneto and then lighting setup. The bike I assume needs no battery to start and run, but what does the lighting require? I have no setup for this. I'm assuming some sort of 6v supply (it has a Lucas headlight, not a acetylene headlight).

Sorry if this is a naive question.

thanks
Rob

[Bear640]

Hi Rob, I don’t know where you live but in Aust pre 1930 lights were an optional extra. A pic of the maggy setup would be nice.
Cheers.

[R]

Yes, the L29 was sold in 3 models - no lights, for extra with acetylene lights, and for extra extra it had a magdyno
(and electric headlamp etc).  The magdyno had a generator piggybacked on top of the magneto.

No lights on the one shown in the brochure view, so no magdyno view - nor acetylene setup.
https://cybermotorcycle.com/gallery/bsa-1929/images/BSA-1929-L29.jpg

You'd have to consult the parts list for your bike to study what all the extras were, but a battery
and battery carrier and electric switch(es) in the headlamp were likely part of the deal.
Watch that what you have may not be the same as what was BSA supplied, if it was added
later - as was commonly done, as the new fad of 'electrics' became accepted by a dubious buying public.

[R]

P.S. Unless you intend to ride a lot after dark, it is quite possible to run 'total loss electrics'.
A decent sized battery gives you a good hour or so of lighting, if there is no generator to recharge it.
And the MOT etc doesn't test for this ?. But don't be more than an hour from home after dark !
And don't forget to charge the battery before you leave...

[antoni]

And don't forget to charge the battery before you leave...

I am not being pedantic here. It would be necessary to charge the battery at your return, possibly also before you leave.

A lot of grief with yer usual lead-acid battery would be avoided if it's always kept in a charged state. They discharge themselves slowly over time - even without any load at all. And they really don't like being left flat.

[robbsa]

Great thanks all, I’ll try and post some photos. Believe it is either the option that came with the battery or a mag/Dyno with electrics has been retro fitted. I’ll post a photo of the parts I have.

[cardan]

This is the Lucas magdyno as used by BSA in 1929. This particular example dates from November 1929, but looks to be in pretty poor order.

https://www.ebay.co.uk/itm/193036690843

Leon

[robbsa]

this is the setup I have the old original one is too corroded. the previous owner seems to have had this refurbed.

I also seem to have some sort of votage regulator?

[R]

Yes, you have a later setup - the magdyno with removable generator piggybacked on top,
which ran from somewhere in the 1930s to late 1950s.
If you look closely the date is stamped into the circular generator, and the tag with 2 little screws
has the date of the magneto part - its not visible in your pic.

The voltage regulator is required with this setup - earlier versions of preventing your battery from boiling
involved adjustable 3rd brushes, half charge resistance wires, manually switching off boiling your battery,
and other such pleasures !  Hopefully the gubbins inside is cleaner than the outside !

[cardan]

If you look closely the date is stamped into the circular generator, and the tag with 2 little screws
has the date of the magneto part - its not visible in your pic.

If it doesn't have the tag, the date is stamped into the vertical face of the magneto base. 632 = June 1932 and so on.

The generator became detachable from 1931. The worst part of the one-piece three-brush design was that there was no slipping clutch between the magneto and dynamo, so if the bike backfired the gears would strip.

Leon

[robbsa]

Great stuff guys thanks  - I did some investigating over the weekend and concluded the same, but good to know about the date stamps - I will check.

Also, thanks for confirming the voltage regulator. I'm feeling like it might be best to source a replacement for this. I'm also assuming that this bike would be running a 6V system?!

Thanks
Rob

[robbsa]

this will probably seem like a really basic question too, but I could do with an image of the HT lead assembly (the end that plugs into the magneto)  - I need to make one up. It has a flat pin type terminal that makes a face on face contact. if anyone could share an image or part to show how its held in place and assure a good contact that would be a great help, but I'll probably work it out if not.

cheers
Rob

[john.k]

Doesnt plug ,it screws in .....black bakelite acorn thingy with coarse threads.......the wires end in a flat contact washer,doesnt need to be soldered..........BSA maggies generally have dedicated base arrangements,but 1929 may be earlier ,and just use four screws........other thing is check your new mag has correct rotation(easily altered if necessary),correct advance direction,and the correct base mounting.The taper is standard across(nearly) all mags ,due to Robert Bosch.

[iansoady]

The flast contact washer is a brass affair with a small central hole (1/16" or so) and a radial slit linking this to the periphery. You strip the HT cable (use only copper cored stuff) then poke the stripped end through the hole and splay out under the washer then the screwed sleeve holds this in contact.

Yes it will be a 6 volt system as standard but if you want is easy enough to "upgrade" - not everyone thinks this a good idea - to 12 volt.

[robbsa]

Thanks chaps, will let you know how I get on.