Well we're only getting 3.5vdc at the battery on a 6v system.  It stays constant through out the RPM range.  Only system this is affecting are the blinkers and brake light, which is making it hard to pass inspection.  I'm getting about 33vac off the stator before the R/R but I cannot find specs to confirm if that is proper voltage or not.

I have tried installing a different stator and got pretty similar results, whcih doesn't particularly prove anything but I want to rule out other systems before I talk my guy into dropping $250 on a new stator.

Would the regulator or rectifier possibly cause this?

Does it use a 3ph generator or does it use sperate lighting and charging/ignition coils, does the headlamp work normally and can you post or link to the schematic?

I can't find any schematics online, and have no manual.

The healdight works great...seperate charging and lighting circuts.  No 3-phase...it just has two big coils.

My vote would be R/R.  

Found a schematic:
http://zorch.maow.myip.org/bikes/wiring/XL250S_XL500S_1979-1981.jpg

I need to clarify...I'm getting less than 12vac at idle, but it quickly picks up to the 30+vac area.

Anyone know how to test the regulator and rectifier?  They're seperate pieces on this bike.

Not sure what kind of rectifier is on that one, but maybe it is a bridge rectifier?  The schematic of one of those :

R would be the regulator.

I don't know how you would test the regulator, but you can probably check the rectifier.
If you have a digital multimeter with diode check, it's fairly simple.  Place red wire at point a (negative terminal) and the black wire at point c (one of the connections to the stator).  The meter should beep and may display a small voltage.  Swap leads, and the meter should not beep (may display OL, or OPEN, or something else).  Then place the red wire at point a and the black wire at point d (the other connection to the stator).  Beep again, swap leads, no beep.  Then place the red wire at point c, and the black wire at point b (positive terminal).  Again beep, swap no beep. Then place the red wire at point d and black at point b.  Beep or no beep accordingly.

I vote your battery is no good.  If it checks out ok, then go after the R/R.  That's one ancient Honda with a 6-volt system.

What states have vehicle inspections? I know that all I had to do to get my bike tagged is make sure the VIN on the frame matches VIN on the title....  Maybe KS is just awesome!

charge voltage never makes it to 6v...not a battery problem.

TX requires yearly inspection, and requires operable turn signals on any bike made after 196X.  Google "ama motorcycle laws" and you'll find a chart that lists your requirements per state.

I'm leaning toward the regulator and/or rectifier as well.  Here's a pretty good writeup on checking the system out, but I'm not sure how it would relate to your setup.  From all the random crap I remember reading about you doing with bikes and other stuff, I think you can figure out where the parallels are 

http://eviltwinsbk.com/forumz/index.php?topic=276.0