The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: Strana on 22.03. 2022 21:37
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Hello everybody.
I am new to this forum and this is my first time posting. I would greatly appreciate if you could help me with the following issue please.
I recently purchased a BSA 1954. The bike will start and run, but the headlight and brake light will not work at all.
Neither is the kill switch for the bike. The only way i can stop the bike is to stall it. I was wondering is that a battery problem, a dynamo or the magneto? Also is the battery located under the seat?. Be most grateful for any help/advice.
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What exact model BSA?
If you can’t find the battery, you may not be the easiest person to help.
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Sorry forgot to say A10
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The magneto is independent so is not affected by battery or charging issues. If you can't stop the bike this is a magneto problem, probably the cover over the points. This should have a wire coming from it which, if earthed will stop the bike. If you earth the wire and the bike doesn't stop then the cover over the points isn't working properly....you need a new points cover. Regarding the lighting problems, the first thing to do is charge the battery and see if the lights work. Then report back to the forum and we'll take it from there. Happy to help.
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It should have a battery under the seat.. is it there *????* if so charge it then try the lights again.. *smile*
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also note if the battery has 3 cells its 6 volt so charge at 2 amp on 6 volts after checking the fluid level in the cells....if the battery is dead probably why your lights dont work the generator cant charge a dead battery .
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also note if the battery has 3 cells its 6 volt so charge at 2 amp on 6 volts after checking the fluid level in the cells....if the battery is dead probably why your lights dont work the generator cant charge a dead battery .
Can't charge it if it's dead as the proverbial parrot - but with the engine running the lights should normally come on with a few revs, even with no battery in the system at all.
If the lights work with a charged battery, engine stopped, then you're part way there - and then need to look at whether the dynamo and regulator are functioning.
If the lights don't work with a charged battery or with the engine running, then it's going to be 'have a look at the wiring' time.
Lots of threads on here about most of this - and this link is a good layman's guide to sorting out dynamos and so on. They all work pretty much the same, regardless of what bike they're on: https://www.matchlessclueless.com/electrical/lucas/testing-lucas-dynamo/
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Thanks, all of you. I will check that tonight after work
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In 1954 BSA were still running the Plunger frame as the Swing Arm models were introduced. The battery mountings are different, so to define the actual model would be useful. If a Plunger model, has it still got the air filter housing and battery mounting? They are rare and quite pricey to replace with original parts. S/A models have a battery tray under the seat, between toolbox and oiltank.
Usual wiring scheme was to have the brake light on it's own little circuit. Getting this to work should be simple, but poor bulbs, failed switch, dirty contacts, rotted wiring, corroded connectors and a poor earth return all gang up. Start with a good charged battery, a circuit diagram and a multimeter and be prepared for non-standard bodges.
Yes, the head and tail lights will work without a battery, powered directly by the dynamo output. My guess is that the bike will be hiding a few surprises. One of which is a good magneto that won't stop sparking....now that is a GOOD surprise. The cure is simple, by following CB's advice. I'm sure a personal message will help sort this one.
Welcome to the Forum. Tell us how you fell into this bottomless maelstrom, over in the intro section. We love pictures.
Swarfy.
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The magneto is independent so is not affected by battery or charging issues. If you can't stop the bike this is a magneto problem, probably the cover over the points. This should have a wire coming from it which, if earthed will stop the bike. If you earth the wire and the bike doesn't stop then the cover over the points isn't working properly....you need a new points cover. Regarding the lighting problems, the first thing to do is charge the battery and see if the lights work. Then report back to the forum and we'll take it from there. Happy to help.
G'day Strana.
To further John's comment. Not being able to stop the motor with the kill wire, there is an earth brush under the brass screw at the flange end of the mag. If this is missing or broken the points can't be earthed and kill the motor.
Just one of the first problems I had as a new BSA owner 40 odd years ago.
Cheers
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Hi Strana,
Where are you located on this "Fair Isle" ?
Local owners might be able to help ?
John
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Hi all.
Thanks for all the replies.
I took out the battery last night. Its completely dead. I will buy a new one during the week .
Any suggestions in which one to get ,or any 6V battery that fits the box will do.
Tomorrow i will check the earth brush. Thanks for that tip muskrat.
Strana
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I would go for the biggest 6v battery you can fit in the box personally. Either AGM or plain wet cell lead/acid. Keep clear of lithium ion or any new fangled stuff like that. Then you can start playing with the charge rate…if there is any *smile*