Here's my first question, there is red wire going from the battery to the fuse box. Does power go out and come into recharge the battery on that wire? I know the battery is DC power so I didn't think the power could go both ways (out and in) on a single wire.
I love this topic, (out of necessity) On this site, with a couple searches, you will find out that you can reduce your battery down to a cigarette pack, and also another thread where you can use a Capacitor to store enough energy for the brake lights. To the question. The battery is just a Storage device. It stores energy for the next time you need to start up the bike. Since our bikes need the Field coil to be charged to 12 volts (roughly) ((less than 7 volts will not support the engine for any sort of forward motion.)) 12 volts for the electro-magnetic s to work. So Once you get the engine running, the spinning magnetic and field coil creates just enough energy which happens to be A/C (Alternating Current) So that brings us to the AC to DC part of the the equation. When you look at the different wire diagrams, my bike is a 400SH, and has a diode under the seat pan, and the rectifier. What do they have in common? Diodes. The secret of the diode, (I found it on this website) It does not allow energy to reverse path backwards. So the AC Alternating current means that energy is flipping forward, and backward umpteen times in a second (long forgotten the number of times it switches directions in a time frame)
so how does the rectifier / voltage regulator deal with that? The Stator has 3 white wires coming out, to the Rectifier, the one wire on the 81, the white wire Tee's off and connects up to the Wire to the Headlight, to give the head light the extra juice. The Rectifier allows the 3 wires to allow 14 volts of electricity to the system, so it just keeps pumping the juice into the rectifier/Voltage regulator, one keeps it from going over 14.5 voltage regulator. , the other keeps the power up to 14.5 via the 3 paths of alternating electricity. so once your throttle hits 2500 rpm or more, and everything is in working order, The juice/ is at 14.2 or so, which means the wire is 2 way as far as your question.
previous to your starting the bike. the battery should be near 12 volts/high 11s, then once you kick it over, should still be a 12 volts or so, then once you hit 2500 rpms and more, the stator, rectifier, Voltage reg, are working to allow 14.5 (or so)
Next question, when power leaves the rectifier its now DC and it goes to the fuse box. So what happens in the fuse box with the power from the rectifier? Does it let this power out into general use for the bike?
Yes, absolutely, you hit the brakes, Lights turn on, the Headlight High beam or low beam. Remember that the fuse box contains fuses that only allow certain amount of amps though it. Which is suppose to leave the most power for what it needs, and still permit some power to get to the brakes/ lights/Coil etc...
It hasn't been regulated yet so this seems like it could be a problem. Does it let the power go directly to the battery? Seems like it would destroy the battery at high RPM when the stator is putting out a lot of power and it hasn't been regulated yet.
Not true my friend, power leaves the stator, it goes to an diode and the recitfier. and its at its most powerful, unless there is a failure with any of the above devices. ((So yes it lets the power go directly to the battery via red wire, via ignition relay))
Does the power go directly to the regulator? If so then this would appear to be a closed loop because I don't see how power gets from the regulator back into the battery for charging purposes.
The Regulator goes to the field coil. The first test we try to remember to tell people to do is the magnetic test. hold something that is attrative to magnetic near the stator, and power on the system. something like a wrench, or feeler gauges will slap the side of the motor, and not hurt anything. So the Mechanical Voltage Regulator (VR) Powers up from the battery, if the energy is less than 14.5 it send current to the field coil, and the field coil excites the stator, the starts pumping more power (2500 rpms or greater) to a grand value of 14.5, (unless something is broken) So on bikes that haven't been converted to kick only, The circuit from stator to all the fuses, relays, lights, and ignition is hot (There is nothing protecting the battery from the system.) As long as the system is keeping the volts under 14.5, the battery will be charged, and not getting hot enough to boil out the electrolytes. The battery is there to provide the needed incidental powers that could drop the bike under the 7 volts. For instances, your in town (anytown)and you start the bike and due to noise ordinances, or whatever reason, you don't rev you engine to charging mode, You pull out of your parking spot, and pull up to the very first traffic light, 20 feet from where you started, (5 metes) Your still not charging, your bike is going to use battery power for brake lights/Headlights. then if you turn on your turn signal. so the battery is there help out till your able to hit it. (light turning green) My bike (my Wife has had this bike since 1996) till she garaged it in 2003 she had 2 batteries she would alternate them daily, cause the stator wires were shot. she didn't know, her friends at the time didnt know/wanna help her fix it. For what she did one days of traveling, with the potential of being stranded was always something that could happen to her.
Does the power go directly to the regulator? If so then this would appear to be a closed loop because I don't see how power gets from the regulator back into the battery for charging purposes.
Closed Loop? Yup, The loop is closed where the battery is connected to the Ground on the engine. Just like you car, The alternator/stator generates just enough juice (power) to maintain 14 volts. anything that uses the power has to open a switch, and that will all the amps to do what it was designed to do, High beam/ turn signal, (Car radio) the used Amps/Volts retire to the ground system, allowing the loop to be complete. So you need to loop just so that there is movement of electricity, (does that make sense?) Other wise think of and double AA battery for your Television remote control. with out the + side hitting the piece of metal, and the spring hitting the - side, there is no loop, so a AA battery is potential energy, just waiting for you to plug it somewhere, (unless its dead) so our bikes are the same. Since our bikes are 30 years older, and counting, the same failure is happening to everyone, (with exceptions)
Did that answer your questions? happy riding, (its winter, 1 Degrees F here this AM, planning my repair jobs still)
in them.
.Thanks for explaining all this valuable info.
(It is winter time now, but it will be nice soon!!!!)
Okay, the difference of the solid state VR verses the mechanical. does anyone have a part number for a Solid state voltage reg? I know I have supported the one I got, I want to believe there is a skinner one out there. 
