First of all, nothing from a PCX will fit a Nighthawk. A PCX is a plastic CVT scooter with EFI. It's all computer controlled, so the wiring harness is completely different. The problem on your '93 is most likely fairly simple, since it has no computer parts. However, voltage takes a long convoluted route to the spark plugs. This may not be in the right order. I suggest you get a wiring diagram. It goes from the battery to the ignition switch, then through the emergency cutoff switch, through a clutch safety switch, possibly through a sidestand safety switch, then to the CDI, the coil, and finally to the spark plugs. The CDI replaces the simple points, condenser, and mechanical advance system in older models, but it does the same thing with no moving parts. Because there are no points, there has to be a Hall Effect sensor somewhere to tell the CDI when to send voltage to the coil to fire the spark plugs. The problem could be an open circuit somewhere in all that, I would start backtracking until you find voltage. The ignition switch has to be on and the battery has to be fully charged. I have seen so many different designs I don't know exactly what you have. I have never worked on the electrical system of a Nighthawk.