This bike doesnt use a v regulator,only a rectifier. As already stated,battery is supposed to help regulate the system. Ran it with and without battery,no change.This is a 6 volt system. Service manual says ac dynamo is self regulating for voltage,but it also lists rectifier output as 15v. I'm confused.
The old manuals didn't make some things very clear!
The 15 volt output refers to peaks of the AC waveform following rectification, if viewed with an oscilloscope, into a load and not filtered by the battery. This becomes about 10 volts charge rate. The old selenium rectifiers also lost about 2.4 volts when new, 3.8 volts mid-life, and over 4.0 volts when old and leaky, as they also passed AC back-and-forth (hence the heating). They have a half-life of about 15 years, after which they become only 40% rectifiers, letting a lot of the AC voltage pass (boosted 40% above the zero baseline). If yours is getting warm (or hot) when running, it's time to replace it. You can't just plunk in a silicon rectifier in its place, though, as they have very different characteristics and much less loss. They result in higher rectified voltage.
Some have swapped out the old selenium full-wave bridge with a single diode for each of the dynamo coils to help reduce the overvoltage situation, using silicon diodes in place of the selenium parts. This reduces the charge rate of the main coils to about 70% of normal, as compared to a full-wave (silicon) bridge rectifier. That's one way to help slow it down, if yours has lost its selenium rectifier.
Make sure the grounding to the system is dead clean and shiny, too, including where the engine bolts to the frame.
