Really dredging, I don’t have another word for it: The old ignition points with the corresponding ignition coil.
I have tried 3 different configurations of points and coils at 6 Volt and the combination of 6 Volt battery, starter motor and points has always caused me misery, both with cold and warm starting.
So I built in an electronic one, and not a 123 ignition. just an English one, especially for 6 Volt OR 12 Volt.
First built in with the 6 Volt installation and that worked perfectly.
Still working fine today, and now at 12 Volt.