A pro tip for restorers: Print your in color. Laminated copies survive grease and rain in the garage.
Are you working on a points system or a 12-volt CDI model? Anyone got a wiring diagram for a '74 C70? - Facebook Honda C70 Wiring Diagram
Looking at the diagram, you can predict where a 40-year-old bike will fail. A pro tip for restorers: Print your in color
The handlebar kill switch (red button) interrupts the black/white wire to the CDI (on 12V models) or points (6V models). On a , this is a tiny loop. If this switch fails internally, you have spark zero. Always check continuity on the black/white wire to green when the switch is in "Run." Honda C70 Wiring Diagram