You need at least three wires, high beam, low beam and ground. Open it up and see if the socket is grounded inside the light. If so, I would run a ground wire from the light to the frame.
Take a test light and check to see which wire on the bike is high beam and which is low beam. Pretty sure one is white and the other yellow, I don't have it in front of me right now.
Ground the new light to a battery and check which wires are high and low and you have your answer. Good luck.