by Fast n Furious » Mon Apr 23, 2018 3:53 pm
These are shunt type regulators. They either use a very heavy Zener diode to dump the excess voltage or or a zener controlled thyristor. Either way, the excess power is shunted to earth.
With powerful magneto's, this excess can overload the regulator and burn it out, usually resulting in an open circuit. Therefore, no more regulation, which leads to your bulbs blowing.
The simplest way around this is to always make sure you run with your main lights on, so the regulator isn't having to dump all the power from the magneto to ground. It then just needs to dump the excess after your lights have taken their fill.
Its a good idea to always have your lights on anyway. So..... Win Win.