Motorcycle Repair: Is my stator bad?, yamaha venture royale, stator coils

Question
I just bought an 85 Yamaha Venture Royale 1200 cc bike with 55,000 miles .
The battery will only stay charged when the bike is driven on the highway (high rpm).  If I drive around town a lot the battery does not stay charged and the bike will not start.
I bought a new battery and charged it well (several hours on the 10 amp setting and more hours on the 2 amp setting, never letting the battery get hot) before installing it on the bike.  With my voltmeter, the battery read 12.0 volts just before I installed it fully charged.  I put the new battery in the bike and put a volt meter across the battery.  At idle the battery shows 12V, at 3000 rpm the battery is charging with 13.5 V, at 5000 RPM the battery is charging with 14.0 volts  The battery never sees more than 14.0 V at any higher RPM.
My 3 stator (white) wires have been soldered to the regulator wires.  I stripped back some of the tape (kept the regulator hooked up) and put voltmeter leads across all the 3 white stator wires.  At and idle, I get consistently about 13V across all the stator wire pairs.  Putting an ohm meter to each stator wire to ground gives infinite festivity (probably no shorted stator coils.)  The only problem is when I rev the bike to 4000 or 5000 rpm the voltage across the stator wire pairs does not increase above 13V (the book said I should see about 60V-65V across the stator wire pairs at high rpm).  Do I need to disconnect the regulator from the stator before I see high voltage across the stator wire pairs at high rpm...or is my stator shot and just not putting out enough voltage?

Thanks!  

Answer
First of all no 12 volt battery is truly a 12 volt battery, each cell should produce 2.4 volts... meaning a normal 6 cell 12 volt battery should read with a full charge at 14.4 volts. Now, as far as your charging system... it should be able to compensate for a low battery, unless your system draws your battery past 10.2 volts. If you're okay on that then it would probably be your stator.