Flying Horse 2-Stroke/4-Stroke Motorized Bicycle Kill Switch &ndash; Gas Bike Engine Shut off Switch This Kill Switch works to kill the spark for your 2-stroke 48cc or 66/80cc bike engine kit and stop the motor Installation will vary from kit to kit, but is simple. Take the black wires from the CDI and magneto and wire the black wire from the kill switch to those wires and ground all three. Take the yellow/red wire and connect it with the blue wires on your magneto and CDI. Secure the wires so they do not free hang, and you're ready to go