Make sure the throttle cable has no sharp bends, make sure the cable housing is inserted all the way into the barrel ends. Mount your kill switch where it fits out of the way using the 2 wires attached to the 2 wires coming out of the motor. See where I mounted mine on the eyelet on the left seat stay near the seat.
View attachment 158204
Just realized the honda gx50 has only 1 kill wire from the motor and switch, grounds through the frame. Same install though.