Motorcycle Repair: Battery discharges while being ridden, battery discharge, old battery

Question
Mike; Frank Hames here. I am writing to you in the
hope you might help me with a problem with my wife's 94 FXR.
Several weeks ago we were at an HD dealership after a hundred or so mile ride and her bike wouldn't turn over. We left it there. After several days they couldn't find anything wrong with it. I brought it home and put it on a Battery Tender. It took 3 hours to bring the almost two year old battery back to charge. We went out riding again only to find the battery needing a charge when we were through. I put a new HD battery in it last week. Same results. I then took it to the best and most expierenced wrench around North Texas and he returned it without finding a problem.
We rode it home and it needed a 30 minute charge to bring it back to full charge. My VM reads 14.2 volts DC across the battery at about 2200 rpm so the stator and voltage regulator seem to be working but the battery is being drained while being charged when riding it seems.
I'd greatly appreciate any advice you might have for us. My wife's bike is  1340cc with a mild (.510 lift) cam and an S&S super E.It has 45,000 trouble free miles and is a one owner.The engine has not been rebuilt and has the stock starter, stator and voltage regulator. Thanks much.  Frank Hames fhames@flash.net 972-625-7517

Answer
Here is somthing I need you to do. First, see if you can hook the volt meter up to the battery so that you can see it while you are riding. If not, then go for a  ride for around 30 minutes and keep stoping and checking the voltage on the battery.
The reason i am asking you to do this is the stator might not be working properly when the bike gets hot or the regulator might be working off and on and letting the battery discharge.
Let me know what you find.
Mike