I have an early 70's Honda SL125 engine and I'm trying to wire it up so that it can run without the battery. I found this guide http://waynescyclegarage.mysite.com/custom.html and I've followed it and done just what it says, but I'm not getting any spark. I used a voltage meter on the stator and there seems to be no issues with that. I also put one wire of the meter on the wire going into the coil and the other on the spark plug and when I use the kick starter it comes up with something on the voltage meter, but despite all that, I still get no spark. What could I be doing wrong?

  • You must have a battery. It smooths out dangerous voltage spikes from the alternator, among other things. Jul 25, 2018 at 12:45
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    @RobertS.Barnes Old motorbikes never used to have batteries, they used a magneto to generate the spark for the ignition.
    – HandyHowie
    Jul 25, 2018 at 14:19
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    Magnetos ( small engines like lawn mowers, etc.) don't use batteries. The magneto generates a low voltage DC pulse which goes through the built in coil which substantially increases the voltage, which then goes in the high voltage wire to the plug. Jul 26, 2018 at 16:54

1 Answer 1


I ended up getting it sparking. I didn't have the pink wire grounded properly.

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