Voltage at cranking - less than 12V

[Luce]

If it's running (although slow and rough) I'm assuming you've let go of the starter and the voltage has returned to 12v+ yet it still stumbles and dies.

Unless you want to carry around double batteries like a heavy duty diesel pickup, voltage will sag into the 9's while cranking.

If you've only eyeballed and guessed at the timing rather than having a light on it, my bet is you're a little retarded (not you personally, your timing) You'll do no harm pushing it up 5 degrees sitting at an idle and seeing if it'll run there.


edit- add

The spark happens when the points open, not when they close.