Like Marco says, you need the wiring diagram for your bike. The wiring diagram for my 1990 CBR1000 (completely different from the 900) says the orange, green, and orange/white wires go to the left bulb. The orange wire is power, the green is ground, and the orange/white wire goes to the turn signal switch. On my bike, the blue/white wire goes from the dimmer switch to the starter switch. I think it switches off the headlights when I crank the starter motor.