Help us simple people understand the electrical system

sofasurferlinux · #1 07-19-2009, 02:05 AM

In order to gradually build my understanding of how the electrical system works, I have a couple questions.
Because of my interest in appying a lighting system to my bike I would like to more fully understand the electrical system so that I can feel comfortable about tinkering around without ruining something. I'm pretty proud of my little bike and I would feel terrible if I did it some serious harm. So, I would like to ask some questions to verify whether I have a good understanding of how things work.

Three wires come from my magneto. Black, blue and white.
The black and blue wires feed the coil, which in turn feeds the spark plug, from what I understand. The white wire is normally hooked to the kill switch and when shorted out will drain current from the spark plug to kill the engine.
1) Does the white wire divert current from the black or blue wire to weaken the spark, thus causing a stall?
2) Can you give me any more details about these three wires and how they operate?

The white wire contains voltage at a low amperage (or wattage?), which to me means a very weak current.
3) Do I understand this correctly?

From what I've read, the white wire has also been used to power lighting but many people do not yet understand how to hook a lighting system up to it properly and safely.
4) Can any damage be done by hooking electrical devices up to the white wire, or will the only negative effect be that the engine stalls because electricity has been diverted from the spark plug?

I read that the kill switch, instead of being connected to the white wire, can be connected to the blue or black wire (or is it blue AND black), which, because of the higher current involved will result in a faster, more dependable "kill".
5) Is this true?

Please answer as many or as few as you want. I'm not looking for lighting system details right now, just answers to some basic questions.
Thanks.

matt167 · #2 07-19-2009, 09:10 AM

it all works off induction... the fly magnet on the flywheel induces a current into the bue winding on the magneto. black is just a ground so that power has a return path.. the white wire is also a winding on the mag. when used it can steal power from the blue winding.. if you hook the kill up to it, you effectivly short out the blue wire to ground

because it's all induction the currents are low.. less than 1 amp generally.. if you hook a light more than 3 watt to the white wire it will die but theres no adverse effect other than a non running engine
you can kill it by crossing the blue and black with the kill switch. black is just a ground.

the CDI also works off induction.. electricity comes into the primary windings then when it's shut off, the feild collapses and induces the current into the secondary wiring

**2door** · #3 07-19-2009, 11:14 AM

Matt,
My compliments on a well versed answer to Sofa's question. Thanks for taking the time to accurately explain the Motorized Bicycle electrical system in a way that anyone should be able to understand it.
Tom

sofasurferlinux · #4 07-19-2009, 11:39 AM

>you can kill it by crossing the blue and black with the kill switch. black is just a ground.

So, would I be correct to leave the blue and black as they are but splice into them with the kill switch?

matt167 · #5 07-19-2009, 12:07 PM

Quote:

Originally Posted by sofasurferlinux

>you can kill it by crossing the blue and black with the kill switch. black is just a ground.

So, would I be correct to leave the blue and black as they are but splice into them with the kill switch?

yes... actully the best thing to do would be to get rid of the bullet connectors and solder and shrink everything togther.

matt167 · #6 07-19-2009, 12:09 PM

Quote:

Originally Posted by 2door

Matt,
My compliments on a well versed answer to Sofa's question. Thanks for taking the time to accurately explain the Motorized Bicycle electrical system in a way that anyone should be able to understand it.
Tom

your welcome.. thanks for the compliment

**2door** · #7 07-19-2009, 12:15 PM

Quote:

Originally Posted by sofasurferlinux

>you can kill it by crossing the blue and black with the kill switch. black is just a ground.

So, would I be correct to leave the blue and black as they are but splice into them with the kill switch?

Sofa,
Here is a tried and true wiring diagram that should make it simple for you. One item you should also know is that the kill button is a simple, normally open contact. Therfore wire color is unimportant. Either wire from the kill switch will do the same thing when the button is pushed.
Tom

sofasurferlinux · #8 07-19-2009, 12:32 PM

I have read about the inferiority of the kill button and I had the thought that it would probably make a nice horn button, with a new kill button under the seat.

silverbear · #9 07-19-2009, 01:35 PM

I don't know about the quality of the stock kill button, but I would think twice about putting a kill button under the seat. If you need to kill the motor in a hurry... you don't want to let go of the hand grip and be fumbling around with your hand trying to find the kill switch. Even if you use the stock kill switch for a horn, make the real kill switch handy.
In my opinion anyway.
Silverbear

Cabinfever1977 · #10 07-19-2009, 02:47 PM

you will want the kill switch handy and maybe on the right side of handle bars.
if something like your chain breaks and gets stuck or goes into your wheel,you will need your left hand to pull in clutch and your right to hit the kill switch and also you will be hitting the breaks to stop right away to see what broke.