whoaru, thanks for taking the time. The battery really do seem shot. If I put it in the bike 20 minutes after charging it, it most of the time won't turn over the engine and will immediately resets the dash. Even the headlight seem dim. Most of the time there is just a very loud clicking from the starter relay. I ordered a new relay a few days ago just in case (it was cheap).
I've checked for parasitic draw, it's 11 milliamps when key is off, which is from what I can find considered normal since the dash draws a little. When I pull either the main or decomp. fuse, the draw will drop to 8 milliamps, not sure if *that* is normal. I've verified that the decompression solenoid was not stuck.
When the bike is idling, the voltage across the battery poles reads about 14.1V, when I rev it a bit (not too much), it goes up to 14.4V.
But I finally received, filled and charged my new (lead-acid) battery two days ago, and after installing it in the bike yesterday the bike started immediately. Drove for a couple of hours in three sets during the day, bike started immediately every time.
I think I'll keep this battery for as long as it will last me, take it up to the apartment during winters to maintenance charge it (no electrical outlets in the common garage) and hope that the battery was the *only* electrical problem.
But I would still find it very interesting to get an answer on the AH required for lithium batteries!