Head Light is the large internal coil, 6 volts AC with the yellow wire.
Tail Light is a small internal coil, 6 volts AC with the Gray wire.
HL Bulb is 21 watts
TL bulb is 5 watts
A kitted bike makes the coils put out max. voltage. You can test with a multiimeter set on ac voltage. Make a small wire and install this in with the yellow wire. Using a set of jumpers with clips, connect red to yellow pig tail wire and red on your meter. Black clip to a known good frame ground and the black on your meter. Tape all exposed areas and connections. Go for a ride with WOT, you can glance at your meter to get voltage. Over 6.8 VAC will blow bulbs.