Unable to start 1967 Lightning...baffled

Up to two weeks ago my Lightning, with Boyer Mark III analog ignition, was running like a top. I left the bike sit over the two weeks I was away, and now it will not start. I have tried new fuel, new plugs gapped to .025, as per shop manual. I have removed the carbs and thoroughly cleaned them. Cylinder compression on both sides is strong. Both plugs ( Champion N3C) are giving strong spark. I even increased the gap on the old plugs to 3/16 inch and there is good spark. Both cylinders are getting fuel vapor from the carbs. As far as I can tell the engine has everything it needs to fire, but it will not. At best, I have had one backfire from one side, and when kicked over, the left exhaust blows out some smoke. The oil sump has been drained, and oil returned to the reservoir tank. All wiring on ignition appears good. I am thinking this is a timing issue, but how and why would the timing be so off since I garaged the bike two weeks ago, when it ran so well? As a last resort, I am going to remove Boyer rotor and test the magnet strength. If they are too weak to hold the rotor against a steel plate, I will replace it. I had that happen to my Commando when it would not spark advance. It ran terrible, but at least the Commando would fire. Once I replaced the Boyer rotor all was well again. I am completely baffled. Any advice is appreciated.

Put the battery on a trickle charge overnight then test all 6 cells with a hygrometer.

Report back...

Boyer ignitions are, without question, the WORST when it comes to even slight battery undervoltage.

I am using a fully charged battery from my Goldwing, tested at 12.78 volts...going to test that rotor for magnet strength today

Don't get sidetracked by the battery if it checks out at 12V DC then lay the plugs on the head, ignition on, kick hard and look to see if there is good spark. You've got fuel, compression all you need is spark. If that is weak or absent, trace back from the HY lead to the coil connections back to the Boyer box and its power wire. Not any loose earths will fail the Boyer.

I have experienced a good spark on kickover but once screwed in, the plug/s would fail under "pressure".. I dont know why nor do i understand but what i do know is you can take a brand new plug out of the box and its a "Dud".. Therefore changing the plugs would eliminate another issue.. (always keep the other for spares)

I have come across a Boyer trigger plate slipping on the drive taper, this may have happened when you tried to kick start it after the two week break. It will still,produce a good spark but no longer at the right time, do a simple static set up and see if you have better luck.