[lee]

There's a wiring diagram at Vulcan Wiring Diagrams that might help.

Normally, your bike would have running lights that flashed brighter for the turn signals. Hence two positive and one negative wire on each side. Your aftermarket ones apparently don't have the dual-intensity (1157 type) but the single-intensity (1156) ones. These are normal for your rear signals.

Black/yellow is ground and blue (or blue with red stripe) is the running light that you won't use. There should be a grey wire on the right and green on the left that goes to the flashing bulb, or in your case the red wire.

 

[lee]

Yes, the blue is just the running light.

FYI: 2002-2008 Kawasaki MeanStreak VN1500 VN1600 FRONT TURN SIGNAL LEFT RIGHT SET | eBay

 

[lee]

Looks sharp, very clean