2. Tail light bulb
3. Shorts in wiring harness, especially under rear fender where you might not think to look. Bare wires from rubbing on tire, or where wires go in and out of fender.
4. Ceramic resistor in brake light circuit, but only comes into play if bike stalls when you hit the brakes.
5. Corrosion on connectors at motor, switches, light fixtures.
6. Spark plug coil, cap, plug
7. Motor properly grounded to frame.
8. Ground wires connected to spark plug coil.
9. Coils, solder joints underneath flywheel
10 Contacts INSIDE kill switch.