"..>>>> The battery and plugs are fresh <<<<and>>>> The Carbs have been cleaned too <<<< This clues me to then check the Ignitor pick-up pulser trigger coil?
I can move the ONE functioning/working spark from the up cylinder to the down cylinder by moving the iginitor/pulser/pick-up/signal generator coil leads/wires plug-in connectors from one CDI box circuit to the other CDI box, from the left one to the right one and vice versa to-and-fro to move the good spark at will while there is always one BAD/ no Spark too.
To remove any un-known concern about the carbies, next, i will just inject the dead-cyclinder with carb cleaner and see if it lights-up/pops better, just very occasionally on start-up attempts the dead-cylinder will hot-fart or backfire, maybe. That trick did work momentarilly once before when their was an orange spark to that cyclinder.
Compression, Spark, Fuel.... My first priority is to see Two blue/strong sparks, this is where i am stuck. I am seeking a Ohm-age number quote [I.E.: 50~350] for the expressed value of the ignition pick-up coils or even a relative Voltage produced-per-kick so that i can go the next-step beyond simply looking for an open-or-shorted condition of the pulse generator coils, as one of them has been regularly exposed to the incessant dripping of the leaky pet-cock/fuel valve, which is also a suspect situation for a possible faulty signal.