I just bought one and had a similar experience.   owner started it one kick three different times.  I got it home, kicked it,  did pretty much what yours did once or twice,  then nothing.   I put in a new plug and it fired right off.   I think mine floods easy.

Some things to look at or try'

1) apperently in the petcock there is a screen (filter)   check that and clean it out to make sure you got good fuel flow.
2) Check the amount of fuel in the gas tank,   If the level has dropped right to the RES/ON level,   you may get some fuel sloshing around when kicking but not enough to run.   Make sure your switch is in the Reserv position.    ASK ME HOW I KNOW,  LOL   Mine was hard to read and I had to look it up.   Also,  when riding, my bike died and did what yours did.   When I switched to reserve, it started the first kick.
3) Carb could use a cleaning,   Started Jet clogged maybe.

Is plug wet or dry after your attempt?

Hope this helps
 

Behold the seal.
I touched it and it fell out..
literally. 

  Both case covers off.

feeling a little more confident now...probably out of necessity as I live nowhere near a shop.
crank seals, gasket, and replacement cover bolts for the ones i had to mangle to get off...ordered and on the way.  I figure I got a week to read and watch videos.  

The theory to me makes sense.  If those seals were such crap that air moved in and out, it's not funny it messed with how it ran seriously.

 

Oh wow, you win, good find. Seal is in Back to Front as well!! Never seen them come apart like that on those seals. Was never in far enough to seal in the first place. Wonder how it ran before parked up but must've been 'just' rubbing on the crank enough to get by before this happened.

What size are these nuts? 
looks like 1 1/8 but they have to be metric

Think they're 27mm but don't have one handy to double check. What are ya doing in there as those seals survive well. Replace the left one & she'll be good. Don't let me stop you though.

I figured get em both? 
 

I figured they date back to Nixon, its probably time.  The nice dude I bought em from told me they should have been replaced during the  Clinton administration