So my 81 xl500 has 6v AC direct unregulated lighting. Am I correct in thinking Ineed all the correct wattage bulbs to effectively provide some kind of regulation? With just the headlight bulb and tail light the tail glows really bright and soon fails. I see in the wiring diagram there is another bulb in this circuit, the pilot bulb rated at 4w. My guess is this will lower the current to the tail light and even things out?