Hi,
If the capacitor is bad and you get the engine to run,
Try small plug gaps, and rub the plug points with a pencil (very old trick)
Look at the rotating points, You will see lots of arcing at the contact points if the condenser is bad
I have had magneto's fail in situations like yours after the bike has been sitting for a long time
If the windings are original they can break down like this, one start then no more
John