the lights on my xvs arent standard an to be honest i dont like them

i plan to fit a rear led light

an a old headlight from a honda melody ( onece a have smoothed the casing)

the bulb in the headlight is 6 volt is it possible to swap the bulb for a 12 v

or maybe fit a hid headlight ( i am told they use less current but are poor through clear lenses

The HID bulbs do use a lot less current per unit of light output. Weather you'd find one to fit a medoly headlamp or not I don't know. You need to find out what type of bulb is fitted and look see if there is a HID replacement. The HID units are bulky in comparison, also they do get pretty hot!

The key number in all this is not voltage but how many watts. Headlights are usually 55 watts, and HID lights are usually 35 watts, so simply cannot run as hot as a standard headlights, regardless of how much light they put out. Look at your old 6v bulb and see what cottage it is. Whatever.. 35w from HID is nothing, you'll be fine with it, always assuming you can physically get to fit. Finding a place for the ballast unit might be a challenge!

Jim