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#403651 - 11/14/11 1:42 am Positive Ground to Negative Ground  
Joined: Oct 2011
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David V. Offline
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David V.  Offline
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Berkeley, California
Hi All,
I'm new here, and I searched a bit but I did not find a clear answer on how to change from positive ground to negative ground.
My current setup is: Dynamo, 12 volt battery, unknown electronic regulator, and points ignition. I have installed a new electronic ignition system (Ignitech), and I believe the ignition coil requires a plus twelve volt source. So, I just need to go to negative ground.
Not regarding the new (or old) ignition system, could someone please list the changes I need to make?
Thanks,
David

PS: I'm sorry if this is a common topic that I have missed in the archives. In that case if someone could just point me on my way....

BSA Gold Star eBay items

BSA Gold Star forum This board is dedicated to BSA Gold Star motorcycles.

#403702 - 11/14/11 12:25 pm Re: Positive Ground to Negative Ground [Re: David V.]  
Joined: Aug 2001
Posts: 4,952
Rich B Online happy
Rich B  Online Happy



Joined: Aug 2001
Posts: 4,952
Stone Creek OH USA
I did the positive to negative conversion this year. No good reason for the change, other than I think (-) ground since all of my work type electrics and other personal vehicles are all (-) ground.....save confusion for moi grin

But be warned. The Lucas Purity Police will find you and sentence you to a life time in purgatory doing hard labor for having the audacity to alter the perfection of the your stock electrical system by converting to (-) ground. The Lucas Purity Police can go feck themselves laughing

I used a DVR2 From Mike Hutchings in the UK for the electronic regulator. Good product, good guy to do business with. He is also a member of the BSAOC....if that matters.

Follow the instructions to convert the bike to (-) ground on the supplied wiring diagram. Also don't forget to "polarize" your dynamo and you are good to go....


Life is too short to drink cheap, bad beer.
#403705 - 11/14/11 12:56 pm Re: Positive Ground to Negative Ground [Re: David V.]  
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Ger B Offline
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Quote:
No good reason for ... all of my work type electrics ... other personal vehicles ... save confusion for

You only create confusion this way, Rich.
Why not convert the others to pos-ground?

Only because Napoleon Bonaparte concurred mainland Europe, the whole world has pos-ground and metrics exept the UK.
Therefore the proud heritage of Lucas negativism should be kept alive on British bikes, and not be converted to disgusting French habbits.

grin


Ger B

#403748 - 11/14/11 6:25 pm Re: Positive Ground to Negative Ground [Re: Rich B]  
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Magnetoman Online content
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Magnetoman  Online Content

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Originally Posted By: Rich B
I did the positive to negative conversion this year. No good reason for the change, other than I think (-) ground since all of my work type electrics and other personal vehicles are all (-) ground.....save confusion for moi grin

But be warned. The Lucas Purity Police will find you and sentence you to a life time in purgatory doing hard labor for having the audacity to alter the perfection of the your stock electrical system by converting to (-) ground. The Lucas Purity Police can go feck themselves laughing

Actually, the choice of positive vs. negative ground is not arbitrary. If your electrical system is in reasonable condition, it doesn't matter which you have. But, it does matter at the margins. A spark plug works by creating an electrical field near the electrodes of the spark plug high enough to extract electrons from the negative electrode, which then are attracted to the positive electrode, and in being accelerated across the gap striking and igniting the fuel droplets the happen to be in the way. The process is the same whether the ground electrode of the plug is positive or negative (i.e. whether you have a positive or negative ground). However, what is different is that the electric field near a sharp point is significantly higher than that near a flat surface. Even though the center electrode isn't a point, and the ground electrode isn't a flat plane, there is still a signficant difference. Having the center electrode of a spark plug negative (i.e. so electrons are "pushed" out of it, and then "pulled" to the positive ground electrode) requires ~20% lower voltage from the coil.

A battery/coil or magneto system has enough designed-in reserve capacity that this ~20% difference doesn't matter for a properly maintained system. And we all properly maintain our bikes' electrical systems, don't we?...

#403753 - 11/14/11 7:21 pm Re: Positive Ground to Negative Ground [Re: David V.]  
Joined: Apr 2011
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Deadstiffcatt Offline
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Nor. California
David,

Irregardless of whether you choose a positive or negative ground, the single most important item overlooked by newer acolytes to the Lucas system is the pre-start sacrifice required by the Prince of Darkness.

This is a simple yet highly effective ritual to perform, yet left undone can lead to nagging and sometimes permanent electrical problems within the Lucas system.

Half of the battle is the use of non Lucas components in your system. If you are introducing these into your wiring, care must be taken to perform the proper ritual sacrifice. I've included below the proper system and operating checklist for both adding non Lucas parts and polarity change.

Materiels needed-
1. short length of wire from an old Lucas harness- must be genuine!
2. short lengthh of modern wire left over from new non-Lucas unit.
3. Zippo lighter.
4. can of beer.
5. cigarette

Lightly entwine both Lucas and non Lucas wire together, and curl into a rounded shape. Place this unit in front of the motorcycle, leaving a space of about 4 feet between the wire and the front wheel.
Now stand in front of the wire, and open the can of beer. Take a short swig, and rinse it around your mouth. Swallow. If you are retaining a positive ground system, place the beer to the right of the wiring, about 3 inches away. (If switching to a negative ground system, place can of beer to the left.)
Pull out your Zippo and the cigarette, and light up. After you have taken a couple of drags, use the Zippo to light the wire unit on fire. If you are retaining the positive ground, circle the burning mess three times in a clockwise walk. (For a negative ground change-up, circle three times counter clockwise.)
At no point disturb the burning mess of wires at your feet. After a couple of minutes burning, the fire should extinguish itself for lack of any more plastic or cloth covering to burn. However, if it continues to burn after there is no more plastic or cloth covering, use the beer to put out the fire you have just started on your wooden floor. If you did not light your floor on fire, finish off the beer internally using drags off of the cigarette to occaisionally add the proper flavor that beer requires.
When unit is well cooled, place newly made mess of molten plastic and wire in the shop up on a windowsill near the box marked, 'Wiring Accessories."
Return to motorcycle, perform AMAL Starting Ritual*, and go for a test ride. Things should be just great!

*AMAL Starting Ritual not included in this missive. Please seek out proper AMAL Guide for this ritual, or needed psychiatric help if you believed a word of this crap.

Best to you! Joe


#403763 - 11/14/11 8:55 pm Re: Positive Ground to Negative Ground [Re: David V.]  
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John Healy Online content
John Healy  Online Content


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Boston, Massachusetts
Rich: I have only one thing to say, "Just wait for your first battery "Senior Moment."" They do wonders for our regulator sales.!!

Last edited by John Healy; 11/14/11 10:38 pm.

#403778 - 11/14/11 10:12 pm Re: Positive Ground to Negative Ground [Re: David V.]  
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Magnetoman Online content
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Magnetoman  Online Content

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Originally Posted By: David V.
how to change from positive ground to negative ground. My current setup is: Dynamo, 12 volt battery, unknown electronic regulator, and points ignition. I have installed a new electronic ignition system (Ignitech), and I believe the ignition coil requires a plus twelve volt source. So, I just need to go to negative ground.

You haven't given us enough information to answer your question. Your Gold Star came with a 6V dynamo, so someone already has made significant changes. Are you sure it isn't already negative ground? Also, I googled Ignitech and the only ignition systems they sell for 1-cylinder bikes list a range of (modern) machines they go on, all of which I suspect are negative ground (I didn't check each of the bikes listed to be sure). Although I only spent a few minutes on their web site, I couldn't tell if the products they sell can be used with either polarity (it certainly is possible to make such a product, although it would be more expensive, so I doubt if a company would do so if they expected 99% of their installations to be made on modern bikes).

This may sound harsh, but I don't mean it to. They way you've asked your question makes me concerned you do not have sufficient grasp of electricity to do a pos.>neg. conversion without way too many tears being shed.

#403790 - 11/14/11 11:02 pm Re: Positive Ground to Negative Ground [Re: David V.]  
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John Healy Online content
John Healy  Online Content


Joined: Mar 2005
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Boston, Massachusetts
There are two ways of changing a Lucas generator to 12 volts:

a. Use a 6v to 12v regulator. These come in positive ground and negative ground versions. This conversion is the least desirable and requires you to turn the generator nearly twice the rpm to get enough out of it to keep the battery charged.

b. Use a 12 volt armature and 12 volt field coil. These are used in conjunction with 12 volt positive or 12 volt negative ground regulators.

The regulators for both of these set-ups are ground sensitive. For examples: Put a positive ground regulator on a negative ground system and you will "let-out-all-of-the-smoke."

So your first job is confirming the polarity of the output of the generator. We can make an assumption here. If the bike's battery is wired positive ground, and the bike keeps the battery charged, we can assume that the generator output is positive ground.

To make this negative you will have to "flash" the field coil with a battery. Ground the negative side of the battery to the generator body. Flash the positive side of the battery to the field coil wire. (be sure to disconnect the field wire from the regulator when you do this). When you get to this stage get back to us and someone will walk you through Flashing a generator.

You will have to buy a negative ground regulator of one of the two types described above. This is where identifying the regulator you have now will help making this decision a whole lot easier. Are there any markings on it at all?????

http://www.podtronics.net/DC_regulator.htm

Now wire the battery negative ground and to prevent a senior moment from ruining things, buy a negative ground decal and place it near the battery so that it is easily seen.


#403803 - 11/14/11 11:44 pm Re: Positive Ground to Negative Ground [Re: Magnetoman]  
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David V. Offline
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David V.  Offline
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Berkeley, California
Originally Posted By: Magnetoman
Originally Posted By: David V.
how to change from positive ground to negative ground. My current setup is: Dynamo, 12 volt battery, unknown electronic regulator, and points ignition. I have installed a new electronic ignition system (Ignitech), and I believe the ignition coil requires a plus twelve volt source. So, I just need to go to negative ground.

You haven't given us enough information to answer your question. Your Gold Star came with a 6V dynamo, so someone already has made significant changes. Are you sure it isn't already negative ground? Also, I googled Ignitech and the only ignition systems they sell for 1-cylinder bikes list a range of (modern) machines they go on, all of which I suspect are negative ground (I didn't check each of the bikes listed to be sure). Although I only spent a few minutes on their web site, I couldn't tell if the products they sell can be used with either polarity (it certainly is possible to make such a product, although it would be more expensive, so I doubt if a company would do so if they expected 99% of their installations to be made on modern bikes).

This may sound harsh, but I don't mean it to. They way you've asked your question makes me concerned you do not have sufficient grasp of electricity to do a pos.>neg. conversion without way too many tears being shed.


John,
Thanks for the concern. I didn't want to bore everyone with all the details but to make sure I get the right answer I will.
To start with, the bike's electrical system was working fine before I disturbed anything. The setup was: Dynamo, modern regulator (still unknown, will investigate), 12V battery, with positive terminal tied into frame ==> positive ground system (confirmed with voltmeter)

The reason for any change to the system was to move away from points and to a programmable ignition.

After wiring the Ignitech system into the electrical system (having assumed a negative ground; yes, silly mistake, no frying done), and being surprised by the lack of response from the system, I investigated voltages, and found that I was working with a positive ground system. This does not present a problem for powering the controller, as it is simply connected to terminals, and it does not present a problem for my crankshaft sensor, as is simply uses a reference ground, which can be easily changed. According to the Ignitech website, however,


" Attention !!!

If capacitive ignition is connected in the way that inductive ignitions use (coil to +12V), ignition can function some time but it is danger of damage of ignition coil and ignition. Damage is caused by permanent current from +12V through ignition reverse diode in ignition to ground.

If inductive ignition is connected in the way that capacitive ignitions use (coil to ground), ignition doesn’t work but there is no danger of damage."

Now did they simply mean that if the powered input of the coil is connected to ground and the spark plug is also grounded at the head nothing will happen? I took it to mean that the coil needs a positive (relative to ground) power source, but I have sent an email to Ignitech to ask if the inductive coil will work with a negative power source and thus work with a positive ground. Also, I had heard that sparking systems work better when the spark arcs from the coil to the ground rather than from the ground to the coil. In any case, I thought it might be simpler to change to negative ground than to rework some of the new wiring, and that the system might work better as well.

#403804 - 11/14/11 11:47 pm Re: Positive Ground to Negative Ground [Re: John Healy]  
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David V. Offline
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David V.  Offline
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Posts: 12
Berkeley, California
John,
The regulator looks like the 6-12-PE, 6-12-NE on the podtronics website, and since the bike is wired as PE, it is probably the 6-12-PE.
-David

#403890 - 11/15/11 1:23 pm Re: Positive Ground to Negative Ground [Re: John Healy]  
Joined: Aug 2001
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Rich B Online happy
Rich B  Online Happy



Joined: Aug 2001
Posts: 4,952
Stone Creek OH USA
David,

Some others have elaborated over a few things I glossed over. The dynamo on my GS was converted to 12V before I got the bike. You can convert using the standard dynamo, but as John pointed out, a 6V dynamo doesn't work too well converted, unless you rev the snot out of you bike...which isn't a bad thing grin

The DVR2 is available as (+) or (-) earth when you order.

John,

Senior moment on hooking up batteries? Not hardly....my brain is so wired to think (-) ground the idea of (+) ground is banished forever.

Writing tech manuals in my spare eek time reinforces the (-) ground thing....I have only had to do 3 eletrical manuals this year eek mA, .25 - 5V sensor circuitry, processors, switches, 11 page schematics, 12V, 24V, proportional solenoids, etc....and they all use (-) ground grin


Life is too short to drink cheap, bad beer.
#403893 - 11/15/11 2:18 pm Re: Positive Ground to Negative Ground [Re: David V.]  
Joined: Mar 2005
Posts: 9,967
John Healy Online content
John Healy  Online Content


Joined: Mar 2005
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Boston, Massachusetts
Quote:
Senior moment on hooking up batteries? Not hardly


Where have I heard that before smile You must travel with a younger crowd...


#403899 - 11/15/11 2:28 pm Re: Positive Ground to Negative Ground [Re: David V.]  
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Ger B Offline
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Ger B  Offline
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Quote:
You must travel with a younger crowd


And every year that crowd grows larger... grin


Ger B

#403904 - 11/15/11 3:02 pm Re: Positive Ground to Negative Ground [Re: David V.]  
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Magnetoman Online content
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Magnetoman  Online Content

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Originally Posted By: David V.
After wiring the Ignitech system into the electrical system (having assumed a negative ground; yes, silly mistake, no frying done),
Now did they simply mean that if the powered input of the coil is connected to ground and the spark plug is also grounded at the head nothing will happen?


Why are you sure hooking it up backwards didn't fry some internal component? Lack of popping sounds or smoke doesn't mean it survived. What measurements did you make that indicated no internal damage was done?

If the spark plug is grounded? If a unit is in operation, the spark plug always is grounded, so I don't understand what you mean by "if" in this sentence. Can you clarify?

#403931 - 11/15/11 5:24 pm Re: Positive Ground to Negative Ground [Re: Magnetoman]  
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David V. Offline
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David V.  Offline
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Berkeley, California
Magnetron,
There are only 3 elements to the system: Coil, sensor (inductive), and box. I checked the function of the box after my mistake. The coil was connected to the spark plug (grounded) and the positive terminal (grounded), so no possibility of damage. The sensor was connected to the frame (grounded) and the box (sensing input, should not allow current flow).

As far as the spark plug being grounded, yes, it must always be grounded. But the coil does have a choice of connection, and if it is connected to ground as well, there is no possibility for a voltage differential across the two terminals of the coil, and so it would be quite difficult to get power.

#403949 - 11/15/11 6:40 pm Re: Positive Ground to Negative Ground [Re: David V.]  
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Magnetoman Online content
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Magnetoman  Online Content

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Originally Posted By: David V.
I checked the function of the box after my mistake.

The sensor was connected to the frame (grounded) and the box (sensing input, should not allow current flow).

But the coil does have a choice of connection, and if it is connected to ground as well, there is no possibility for a voltage differential across the two terminals of the coil, and so it would be quite difficult to get power.

When you say you "checked" the box, does this mean the instructions that came with it give you a proceedure for testing it, and it passed those tests?

While it is possible an inductive pickup uses the frame (ground) as one leg of the circuit, it is highly unlikely. Because of this, I strongly suspect the wire running to your sensor has two pins. The resistance between either of them and the body of the sensor should be very high (i.e. megohms). The fact you had the body of the sensor bolted to the frame isn't relevant, since current will never flow via that path unless the sensor is toast (and, even then, there are several ways of toasting it, only one of which will result in the internal leads being shorted to the housing).

What you wrote about the coil needs clarification. It is possible one side of the primary is connected directly to a metallic housing, which in turn is connected to your frame. Possible, but not likely. More likely is that there are two terminals for the primary, neither of which is connected to the housing. I am not very concerned that you damaged your coil by having connected your battery backwards to the electronics box for a few seconds, but what you wrote makes me concerned about your wiring in general.


Moderated by  Rich B 


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