I promised to let you know how the homemade voltage regulator worked and how to make one. I´m sending pictures and a schematic.I built the thing on the largest heat sink I had, and fitted it into the air cleaner box,sacrificing the air filter. I put a fine screen on the outside.The purpose of the zener diode is to protect the 7815 regulator which cannot handle an input voltage in excess of 35V.I have noted that under no load the alternator with rectifier can put out 100 VDC! Now the two transistors just repeat the voltage of the 7815 [15 volts] and you can adjust it down by adding a small diode in between,but mine is delivering a constant voltage of about 13 and that´s about right.So far this unit hasn´t shorted out or blown open,hopefully it´ll be as reliable as the original.