classic motorcycle forum
Motorcycle Discussions => British Bikes => Topic started by: robbsa on August 08, 2019, 10:00:19 PM
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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
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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.
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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 (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.
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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...
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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.
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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.
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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
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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?
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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 !
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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
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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
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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
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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.
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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.
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Thanks chaps, will let you know how I get on.
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Good news, I have obtained a split washer, connected up the spark plug and attached the magneto to my drill......and have a spark!
Thanks for the help.
I've built myself a jig to help me work on the engine whilst I work on the frame. and the next step is to get the piston and cylinder head back on. The bore looks okay in the cylinder but since been left in the garage, the piston has got a bit of surface corrosion and also has some carbon build up.
The surface corrosion looks like it could be taken off with a bit of emery paper, but I'm guessing this will possibly ruin my compression?should this be machined? not sure how to get the carbon crust off without damaging the piston. Any further top tips?!
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Yes you have to be cautious using emery cloth ANYWHERE inside an engine or on components,
the particles can remain, and turn into grinding paste !
The corrosion on the side of the piston if machined off would cause the piston
to have more clearance and thus piston slap - but won't affect compression.
I use a well blunted stainless steel wool - give all your saucepans a good clean with it first,
to blunt all the sharp edges. Polish in small circles, so you don't wear grooves in any particular direction.
Watch that it doesn't produce any visible scratches, in which case its not blunt enough.
The carbon on the top of the piston can mostly be scraped off using a blunt instrument - I mostly use a
sharpened wooden stick ! The aforementioned stainless steel wool also works well here.
Again watch that there are no scratches - the piston top is not really a working surface,
although the finish is often less than pristine from previous owners attempts !
Smoothing off any previous scratches is a good plan, you don't want lumps or bumps becoming hot spots,
and possibly causing pre-ignition.
And the reason I mention STAINLESS steel wool is that ordinary stuff leaves tiny bits of steel wool everywhere,
which soon rust if exposed to dampness anytime - the last thing you want inside engines. (or outside for that matter).
Stainless wool mostly breaks into long strands, which are easy to spot - and obviously kept away from inside engines.
have fun !
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P.S. I should have first asked if that piston is iron or alloy ? It looks iron ?
Iron can withstand stronger treatment, including fine filing.
And is less prone to emery particles embedding in the surface.
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Alloy I think, judging by the look of the corrosion. I use a stone lubricated with kerosene (paraffin I think you call it) on cast iron pistons, but only ever a new file on an alloy piston. A used file often has shards of steel that can end up embedded in the soft piston.
R gives excellent advice. Can I add a warning? There is a mistake that many of us have made once - once is enough - that should be avoided at all costs.
With a one-piece cylinder and head be extremely careful if you put the loose piston and rings inside the cylinder. Do not push the piston up to the top! If the rings go over the top of the bore they will pop out into the combustion chamber, and getting the whole thing out again is extremely difficult. It's one of those "oh no" moments.
Have fun.
Leon
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99% sure it’s alloy judging on the weight, colour and corrosion on it. I’ve ordered some stainless wool and will go gently at it with a sharpened lolly stick this weekend to try and remove the carbon. Thanks again for the help guys, although I have plenty of workshop experience doing other things and tinkering with engines and bikes that are less precious, I want to get it right on this one first time due to the age. All the tips and help is appreciated.
Feel like progress is good at the moment.
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Sorry if you've thought of this already but do measure the bore and piston and make sure they are a suitable fit before you spend a lot of time cleaning it up. One of the problems with part dismantled projects like this is that the components that come with it aren't necessarily the right ones. I think we've all made that assumption, I definitely have!
REgards, Mark
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Thanks for the word of caution, I’m 99% sure it’s the right one but I will check as suggested to be on the safe side.
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Stainless steel wool arrived and piston came up nicely.
checked the bore again, and there are a few tiny spots of corrosion in there. may have to get it honed. what do you think?
I still need to double check the bore diameter and piston.
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I still need to double check the bore diameter and piston.
Do that before doing ANYTHING.
Once you hone it and then find the clearance is now excessive, its too late... !!
Which then throws up the problem of finding a new piston, and getting it to a suitable running clearance.
It is permissible to use a bit of emery to polish out slight spots of corrosion in the bore,
as long as it is thoroughly cleaned/washed out afterwards. Use a bit of tissue paper to swirl
around in there, and see if it comes out dirty will tell you when it has been cleaned enough.
The last thing you want is bits of abrasive left on the working surfaces.
A big decider towards needing a rebore or not is if there is a wear ridge up at the top of the bore, at the
top limit of where the piston rings travel to. If you can feel this with your thumbnail, it may be too much.
The danger is the piston rings will catch in there, and break.
Adding a slightly thicker gasket at the base will/may help in this respect, if the rings don't quite reach this region.
Honing just the top reach of the bore likewise, although this has to be done carefully so as to not add to the problems.
have fun.