Garage Queen - 1978 KZ650

So....I finally got around to checking.
Pulled the plugs. No spark.
So what could have went wrong right in the middle of driving it that would make me loose spark?

The main fuse still good?

Probably a bad connection somewhere.
You need to start testing with a multi meter (MM), or even a 12 volt light tester.

There is a red/yellow wire that feeds power to both coils.
Should get close to 12 volts there when checking with a MM, bike turned ON.
If not, then you will have to go backwards along that circuit and test again.

Should be a write up here somewhere, or in a Service Manual, how to check the ignition system.