The only non-adjustable regulators I've seen have some sort of electronic control built in. If it's got spring-closed points, it can be adjusted by changing the spring tension, either by bending the spring anchor or turning an anchor screw. The points behind the "F" terminal control the voltage, the ones behind the "A" terminal regulate current flow into a low battery. The top voltage should be 14.7 against a fully-charged battery, with a charge current of 10 amps or less. If you can figure out a way to reduce the spring tension on the voltage regulator points, you can lower the voltage. Be sure to do the final check with the cover installed, as the setting will be reduced a little with the cover on due to better magnetic conduction. If the "F" terminal on the generator gets grounded some way, like a frayed wire touching the frame or body metal, the generator will go to full output with no control by the regulator.
Jerry
