Stock K bike tail lighting isn't very good. Here's an easy inexpensive way to upgrade it by adding waterproof LED marker lights to the sides of the tail light lens.  Here's the end result:

 

You'll need two of these: 6 LED red thin marker lights

 

And some double-sided tape.  I use 3M 3615 which you can get at an auto parts store.

Trim the ends off of each marker light so that they will fit into the sides of the tail light lens.

Clean the inside of each side of the tail light lens and then mount a marker light in each side with the double-sided tape.(I used clear plastic red LEDs in this example.)

Then tap the wires for them into the power (gray/black) and ground (brown) wires for the tail light bulb.  This will not "upset" the bulb monitor unit as you'll still have power going through the incandescent tail light bulb.

© 2013 Drake Smith - Please do not use or reproduce this elsewhere.  Feel free to link to it though.