The fuse install detailed here http://www.mzriders.com/viewtopic.php?f=20&t=3967&p=21280&hilit=rectifier#p21280 does a good job of protecting the regulator/rectifier module, but it does nothing to indicate if your battery is charging to specs while riding. A good way to fix this problem is wire in an aftermarket LED charge monitor that indicates the voltage input to the battery.
I chose the Signal Dynamics 1050 battery monitor found here: http://www.signaldynamics.com/products/Modules/huvm.asp and it works great. It's easy to hook up (only requires IGN-switched 12V and ground). The multicolored indicating LED is external, so it can be mounted anywhere it's visible. I picked up the 12V and ground inside the headlamp shell, and mounted the module in there also with tie wraps. I mounted the LED on the fork next to the ignition switch into a drilled 1/4" hole. The mounting bezel for the LED is included with the kit. The LED colors indicate the voltage applied to the battery as below:
Flashing GREEN - Voltage above 15.25 VDC
Steady GREEN - Voltage above 12.9 VDC
Steady AMBER- Voltage above 12.6 VDC
Steady Red - Voltage above 12.1 VDC
Flashing Red - Voltage below 12 VDC
I got a nice steady GREEN while driving. A good modification, inexpensive, will work with all 12V motorcycles, and it's nice to know your battery is charging as it should be before it's too late. In the picture below the LED looks like it's YELLOW but it is GREEN.