. I have fitted an external coil on a couple of small 2 stroke motorbike engines and small battery to provide spark. They worked well and were easy to start but this is probably not going to help you.
I've seen a few Victa 18 mowers where the secondary side of the coil has failed being the fine wires but usually
the thicker primary wires still work so you disconnect the points wire and wire it to the external car 6 Volt coil positive side
then negative on the car coil goes to the points and no battery is required.
Cheers
Max.
