You could diagnose that by disconnecting the kill switch's wires way back in the wiring harness near the engine. (?? i dont have an Express and am going by the diagram.. im not sure exactly where the connector is)
There are a couple Express manuals HERE and they have wiring diagrams near the end ..
I took a quick look at it and it seems you can disconnect both the ignition and kill switches by just unpluging one connector.
Trace the kill wire. The kill switch wire is connected to the points/condenser wire. (The kill switch grounds the points and kills ignition.) After a short study time the wiring diagram will make sense.
If that kill switch was miswired it may be killing the spark all the time. If the bike gets spark with it disconnected you've found the trouble.