Moto or KZ ? As far as I remember, there’s spare wire coming off the coil, you run a wire from that to a switch, and then from switch to ground. Get a push button switch that closes when pushed and open when released.
It’s a early 90s Rotax 128..and there is not an extra wire… So should I splice it into the ground wire so when I push the normally closed button it opens up and disconnects the ground? Or should it be done another way?
Which type of ignition is on that engine. Is it Selettra or PVL ?
Go to their website, and you should be able to find the best way to wire up the kill switch. If you can’t find any info, contact Riley Will at BRC Engineering in Calgary Alberta, he knows more about those engines than anybody else.