Swapped advancers from the TEC 333 that was on it (this ain't right for a CB750 - no idea what the PO was thinking) with a 300 I acquired. Static timed using a probe light.
Reinstalled 3 spark plugs.
Learned my new 18mm socket CANNOT be removed after you've tightened down the plug on #2. Ground down the socket. Put plug in. Took plug out. Ground the socket some more. Put plug in. Took plug out. REALLY GROUND DOWN THE SOCKET.
Reinstalled 1 spark plug.
Remounted 1 carb I had pulled to measure the rubber boot holding it to the manifolds (this has dual VM34s on CycleX manifolds).
Attempted to start. Got a little cough, and then the battery died.
Observed I forgot to replace the leads on the battery maintainer sometime last week, and my periodic attempts to check timing and various electricals over the last week have drained the battery too low to get it started.
Dug out the 10A battery charger and put it on.
Fiddled with some stuff while it charged.
Attempted to start... cranking, no starting. Waited a bit longer to gather more battery charge. Attempted to start... cranking, no starting.
Observed I had the kill switch flipped.
Fiddle with some stuff while it charged.
Started... with only cylinders 3 and 4 firing. Well, that can't be coils. OK... bright idea - maybe I have a carb problem (1 carb feeds #1 and #2, the other carb feeds #3 and #4). Quick test? Swap the carbs.
Rerouted fuel lines and cables to swap carbs.
Started on all 4 cylinders! (huh?)
Best I can figure I had a stuck float on one carb... bumping them around swapping them must have freed it up.
Too late for the neighbors to mess with completing dynamic timing tonight...
Clean up tools.