minimum wiring to make the plug spark

Hey guys, I'm trying to wire a dirtbike (i know its not a moped, but same rules apply, i think), its a 74 Yamaha GT80 and i basicly ripped the old harness out because it had a lot of stuff i didnt need, like blinkers, headlight, tailight, battery...

I'm trying to rewire it, all i want is a handlebar mounted switch for the ignition. I have 4 wires coming out of the magneto, a coil with the plug wire, and black wire comming out, and what appears to be a rectifier. how do i wire this? any ideas? links? sugestions? I'm sort of lost when it comes to wiring, so any direction to websites or things like that would help a lot!

Re: minimum wiring to make the plug spark

a magneto might have a black (?) wire coming out.. it would be the ignition coil wire. It will be connected to the points and ignition coil. The other wires would be lighting coil wires.

This ignition wire would somehow, somewhere eventually be connected to the condenser to allow the engine to run.

It may only be connected when the ignition switch is ON and any kill switch is OFF. These two switches can 'ground' the ignition and kill it. Or, the wire might be directly connected to the condenser as well as to the ignition/kill switches. This might be the case if the condenser is mounted inside the flywheel/ magneto assembly. The switches can still ground the circuit. Or, the condenser wire - to - magneto coil path might go through a silicon rectifier before being connected to (kill) switches. There a a lot of variations.

If you bypass all switches and other stuff that could possibly ground the ingition and connected that magneto-ignition-coil-wire directly to the condenser, the engine should fire up.

Too bad you already ripped out the wiring.. it would be a lot easier to trace ignition wiring and to be more confident about what goes where if you hadn't.

Re: minimum wiring to make the plug spark

well, what i have left, goes through the battery, and i dont think it ever makes a complete circut from magneto to condenser, to coil, etc, it goes around in circles.

Re: minimum wiring to make the plug spark

take a look at this attachment.. its a basic battery-magneto circuit.

Substitute the 'trip switch' for the cam that opens the points.

Imagine a magneto/generator spliced between the + side of the battery and the (primary/secondary) ignition coil.

(The illustrated coil is the spark plug coil, not a magneto coil)


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