i bought this undertail. But it came with no wiring instruction. Each bulb has 4 wires. Blue, Red, Black, and Yellow. How would i wire this into my bike. Currently the bike(03 F4i) has no changes to the wiring.

 

im gonna say :
Black - GND (green)
RED - BRAKE (Green yellow stripe)
Yellow - Running lt (black/brown)
Blue - signal( orange or blue)

thats close, either that or brake and running light are swapped..either way try it, wont hurt anything