Author Topic: Magneto Questions (my first BSA)  (Read 1362 times)

Offline Colt_the_bolt

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Magneto Questions (my first BSA)
« on: 06.12. 2015 05:59 »
Hi everyone,

 I recently became the owner of a 1955 Road Rocket, I've always wanted to build a custom bike around that engine but never wanted to tear down a bike worthy of restoration. This bike sits on a mediocrely made custom hardtail frame, missing numerous parts and the engine painted with what looks like silver barbecue paint, and fitted with a bunch of bolts and screws that aren't correct. Despite this, the engine is still in good shape mechanically and I'm confident I can bring it back to where it should be and give it the respect it deserves. I adore British bikes and own multiple British classic cars and want the engine on this bike to look just like it did rolling off the show floor, everything else will be fabricated and compliment the fantastic functional styling of the engine.

That being said, I have a lot of experience with fabrication and mechanical work and motorcycle restoration but I am TERRIBLE at electrical work. The bike has its Lucas K2F magneto, it does not have auto advance, it has the retard lever, and I have no idea what the "low tension terminal" is on the contact breaker cover. Normally I'd just research online and see where the wire goes but information on its setup is scarce. What is it and where does it go?

I do stuff like bend and weld frames and make springer and leaf spring front ends, gas tanks and fabricate anything out of metal, no idea how the electrical system on this bike works as it came with no wires other than the connections from the mag to the spark plugs, does it involve condensers when there's a magneto? In relation to the battery?  Do I need a battery? I believe the bike is setup for 6v but I have no idea what that means versus 12v. No idea where the kill switch goes either. I'm keeping this bike more of an art piece to putter around town, so headlight and brake light are the only electronics I want so wiring diagrams make my head spin.

Normally I'd just take the bike in and have electrical guys do it for me but I'm sick of that and want to figure it out on my own so I can not be such a dunce about it.  You guys have some fantastic bikes and I'd really appreciate the knowledge and advice you have to offer.

Colton.

Offline terryg

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Re: Magneto Questions (my first BSA)
« Reply #1 on: 06.12. 2015 12:20 »
Got part way through a long reply on my mobile this morning and then lost it before posting.

In the meantime a place to start could be the Service Literature board and the post Magneto Diagram.
Terry
'57 'SR', '59 SR, '63 RGS

Online RichardL

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Re: Magneto Questions (my first BSA)
« Reply #2 on: 06.12. 2015 14:09 »
Colton,

Welcome to the forum and thanks for letting us know a bit about yourself, and how and why you came to have your A10.
 *welcome*

To answer the basic question about the low-tension wire: that's the lead to the kill swicth. The switch is a button that typically mounts on the right side of the handlebars just insde of the throttle grip.

There is no external condenser used with the K2F, but there is one buried inside the rotating armature. That condenser can easily be the cause of some trouble in a 60-year-old armature. Today's easiest fix for a bad condenser is a liitle circuit board with a small condeser mounted to it. The circuit board mounts under the points behind the cover where the kill switch lead emerges. The instructions for installing the condenser are very clear. Check Brightsparkmagnetos.com . (Brightspark's owner is our own member "Groily", who, I suspect, will chime in to add to this discussion.)

If you want lights you need a battery and a dynamo (generator). You didn't mention if you have one. Since originality is not in your program, going 12V probably makes sense for you and is achievable with a stock dynamo. More detailed info on 12V (as in regulators, dynamo belt drives, etc.) can and will follow when you need it from those with actual 12V experience. I run 6V, mostly due to nostalgia, but wouldn't mind the brighter headlight that comes with 12V.

I didn't look to see if you listed where you are located.if it happens to be Chicagoland, I'd be happy to help where I can, and when I can.

Richard L.

Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

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Re: Magneto Questions (my first BSA)
« Reply #3 on: 06.12. 2015 16:47 »
Welcome Colston.
Can't really add a lot without writing half a book, but to get a good look at what the bits are in the magneto, or the dynamo and regulator for that matter, if you press the link Richard kindly referenced and then go to the Library, you'll find a pile of the Lucas workshop booklets for them listed. They're available in a dozen other places too.
As Richard says, the wire off the end of the cover is the engine kill lead - it works by earthing out the low tension circuit in the mag, via a carbon brush which touches the head of the screw that holds the contact breaker assembly on. (The screw is attached to the live end of the low tension or primary winding.)
You have plenty of options when it comes to sorting out the sparks and the rest of the electrics - except the option of Doing Nothing because at the very least  things need checking out - and you'll find there are quite a few people who'd be more than happy to look at any of these mysterious bits. Some might offer a condenser on the contact breaker, others to replace the one in the middle that Richard mentions with a modern equivalent. Some might recommend 12v for the charging side, others might suggest staying at 6v. The question of LED lights will come up too, the jury being sort-of out on them for headlights as they're a bit new-fangled.  (I'm not that impressed with my own ones, but I think they will prove to be the way forward over time.) Most people will recommend a DVR2 regulator if a replacement is needed - because they are universally acknowledged to be very good. (And the chap who invented the thing is also on here.) There are acres of reading on all of these matters on this site, when you've got the hang of roving around. Good luck!
Bill

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Re: Magneto Questions (my first BSA)
« Reply #4 on: 06.12. 2015 17:27 »
 *wave*

Offline Viking

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Re: Magneto Questions (my first BSA)
« Reply #5 on: 06.12. 2015 19:40 »
Magneto ignition works fine, it just need rebuild now and then..

Send it off to a specialist to get is recon....  And it will works for many years...

Kill switch is just a wire from the end cover of the magneto..To a switch on the handle bar

When it comes to electri.  It is easy, get a new wire harness
They are dead cheap, and do the trick.....

If you have a dynamo fittet, get it recon, and it will last long time.

To get 12 volt power and trouble free electric, fit a Alton generator ( cost loads of $ ) but last a life time.
http://www.alton-france.com/generators.html

Wire harness: (sure you can get that near you)

http://www.feked.com/bsa-a7-a10-wiring-harness.html


Offline Colt_the_bolt

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Re: Magneto Questions (my first BSA)
« Reply #6 on: 07.12. 2015 00:51 »
Thank you guys for your help! The links and leads you guys posted are helping a lot, the bike is fitted with a Lucas 6v generator that is apparently new as per the last owner. i'll do some research into that mag circuit board. Also im posting a link to a button switch, can it be used a a kill switch? with the two wires, one going to the mag, where does the other lead?

I live just north of Seattle and as far as ive found the only place with experience with British bikes near me is a place called European Motorcycles. I haven't given them a call yet as the motor's paint job is kind of embarrassing. x)

Im sure ill have more questions and continue to use this great forum as a reference, and ill start posting pictures of the bike when its a little more photo worthy.

Offline Tomcat

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Re: Magneto Questions (my first BSA)
« Reply #7 on: 07.12. 2015 05:50 »
Welcome aboard Colt, glad to hear of another BSA being saved.
OK, so you don't like electrics? The best place to start is with the basics.
1/  A Magneto is driven by the engine and generates high voltage electricity for the spark plugs. There are two big wires (High tension) that go to the spark plugs and a small wire (Low tension) on the magneto end cap that is shorted to earth to shut down the magneto.
2/  A Generator (also driven by the engine), regulator and battery supply the electricity for the lights, horn and to re charge the battery.
As stated above, if the magneto is doubtful, remove it and find a reputable repairer and have it fully reconditioned. As the Magneto is self contained, the engine will run without a generator, regulator and battery. I hope this help. Cheers Tomcat *smile*
'48 A7 '59 SR '74 850 Commando TDM900

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Re: Magneto Questions (my first BSA)
« Reply #8 on: 07.12. 2015 08:04 »
G'day Colton, welcome to the forum.
Electrickery isn't one of my favourites either. Many more knowledgeable people here.
We have another member in/near Seattle, RGS-Bill, although I haven't heard from him for 5 months.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
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Offline bobandbec

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Re: Magneto Questions (my first BSA)
« Reply #9 on: 07.12. 2015 09:36 »
Hi
I've just finished wiring up a new loom for my A65. Knew nothing about wiring before I started so bought from this seller on Ebay(UK) who labels up all the wires and provides any sub-looms as part of the package.
http://www.ebay.co.uk/itm/252188242595
When you get stuck into it it is surprisingly straight forward.

Peter

Ps no connection with the seller

Offline duTch

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Re: Magneto Questions (my first BSA)
« Reply #10 on: 07.12. 2015 10:55 »


 Hi there Bolt-on, I'm no electric guru either, but the electrics as stated are quite simple (well they were 'til I came along)...you can elect for positive earth(standard for these) or negative earth which is less confusing and daead easy, and you can use still also use a mechanical regulator(which I kinda like for no reason)
Quote
.......Also im posting a link to a button switch, can it be used a a kill switch? with the two wires, one going to the mag, where does the other lead?.....

 no link I could see, but- Yep 'a' button will work, the second lead earths on the handlebar/frame/engine case. Usually the kill switch only has a wire from the maggie to the switch/button which earths out on the handlebar. With a button, you'll just have to hold it until engine stops, or elect for an actual button switch that stays connected to earth until reset(oldest trick in the book).

Quote
......... ill start posting pictures of the bike when its a little more photo worthy.

  We wanna see before and after... *fight*

Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Offline Colt_the_bolt

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Re: Magneto Questions (my first BSA)
« Reply #11 on: 08.12. 2015 02:43 »
More leads from you guys, thanks for that, i'll look into that wiring harness thats labelled. sorry the link didnt post but if you say buttons work ill just assume it does as most of the stuff from Lowbrow Customs is pretty legit.

And dont worry im photo documenting the whole project, it probably wont be finished until april but ill keep you guys posted.

What is the conversion to negative earth entail? pros and cons.

Offline terryg

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Re: Magneto Questions (my first BSA)
« Reply #12 on: 08.12. 2015 07:45 »
The standard electrical components (dynamo, electromechanical regulator, lights, horn, battery) will all work in either a +ve or -ve earth system. Changing over means reversing the battery connections and 'flashing' the dynamo. As noted above, magneto ignition is separate and not affected by system polarity. The ammeter connections will require reversing to preserve the charging indication direction of deflection.

Use the forum search function to find several descriptions of how to 'flash dynamo'.

Solid state regulators (eg DVR2) and LED lights are not reversible, they have a defined and fixed polarity. Since the vast majority of automotive electrical systems are -ve earth  electronic ignition, LED lights and electronic speedos and tachos are normally designed to operate in -ve earth systems, which is probably why most people change.

The origins of which polarity to use relate to galvanic corrosion issues and protection.
Terry
'57 'SR', '59 SR, '63 RGS

Offline duTch

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Re: Magneto Questions (my first BSA)
« Reply #13 on: 02.08. 2016 09:37 »

 Was looking for something else, and came across this and wondering if you (Colt-the bolt) is still on board and how the project is progressing *????*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Offline cyclobutch

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Re: Magneto Questions (my first BSA)
« Reply #14 on: 02.08. 2016 12:34 »
Last active 27th December it seems.
Various, including ...
'58 Iron Head Flash Bitza