How does the charging system work?
There are four basic pieces to the charging system. These are the Stator, the Reg/Rec, the Battery, and the wiring that connects the three. The stator is under the left engine cover and turns with the crankshaft. It's made up of 2 pieces: the stator itself, which is a bunch of wire loops, and some magnets. As the wire passes in and out of the magnetic field it generates an AC electrical charge. This charge is fixed, and is a 3-phase in most bikes (meaning the stator has 3 individual wire loops, all making a charge). That AC runs up to the Reg/Rec.... or Regulator/Rectifier. This does just as its name implies: it rectifies the alternating current into DC, and regulates it down to a maximum of about 14.7 volts DC. The reason the AC must be converted to DC is because you can't store AC voltage in a battery, only DC.
As a side note, an alternator works on a similar principle, except the regulator controls an electromagnet (increasing and decreasing its magnetic power) to limit the power output, instead of shunting the excess to ground as heat.
The Reg/Rec then lets the power flow to the battery. If any one item in the system is bad, it can, and eventually will, damage the other items. This is the main reason it's so important to keep the system in good shape - it can be expen$ive to replace everything. Most often, though, the wires take the brunt of the failure and cook themselves. They then gain resistance (heat = resistance) and make everything work that much harder, which is an unnecessary stress.
The most common electrical problem with this bike is a low battery. The other components are quite reliable. If you can't start the bike, the battery is low. Other indications of battery problems include (but aren't limited to) a temp needle swinging all over the place, or an erratic tach. A low battery/electrical charge will present itself with ever-decreasing lights and power, backfiring as the plugs start to fail to ignite all the time, and eventual deadness. It's rare for everything to just cut off (anything's possible, but highly unlikely).
Riding at high RPMs doesn't really make a difference in charge coming out of the charging system. Actually, quite the opposite is usually true on most bikes ~ they show more VDC getting to the battery at idle and up to 3-4000 rpm than past that.