And this is with everything turned off, AND with the battery-tender hooked up!
It was at 12.5 one day, the next 00.0 - drained every milivolt off!
The battery is only like four months old.
I've never heard of such a thing in my entire life.
Also, (what I'm sure is) a related problem; before this happened, it appears the stator isn't charging the battery. I checked the stator and voltage regulator according to the workshop manual - both appear good. The resistance readings on both are in spec., the output voltage on the stator is about 50v at 5,000 rpm - just as specified.
So, the stator goes straight to the voltage regulator, the vr goes straight to the battery, via a 30amp fuse. The stator is good, the vr is good, the fuse is good - that's the entire circuit, so what's wrong??
Unfortunately, I'm on my own; there's only one Aprilia servicer in the Portland area (Vintage Scooters), and after dealing with them once before, there's NO WAY I'm going back there again.