You want hi voltage fine stranded wire. It can be bought at your local neon shop, called G.T.O. wire good for 15,000 volts. Get hi flex GTO if they have it. It’s for moving signs & works great with magnetos, all I ever used on my mags.
What is the resistance on your secondary wibding from ground to spark plug terminal? Too high, look for a blow out on the coil, tiny burn mark caused byleaving the plug wire loose while spinning, The coil makes electrical energy & if disconnected it may blast a hole in the insulation & may have only a carbon connection in the windings.
Another overlooked item is the condenser, actually capacitor, the other is slang term & incorrect. Dielectrics fail in old caps, that is the insulating value correctly called dielectric value or how well it insulates, anyway old (condensers) caps go bad from insulation failure. It should be replaced but must know how many microfarads is used with your motor. HELP GUYS
look at the points using a magnifieing glass at the contact area. Look for build up or pitting, sure sign your cap has failed.
Check all connections with a ohmeter for non resistive connections.
I had problems with a mercury magneto, drove me nuts. I added a ground wire from the mag plate to engine block & it fixed it. A losse fitting mag plate to block does not have a good electrical connection.
& know I’m long winded.
Jeff