2000-2004 Kawasaki ZX12R  undertail
installation instruction


The ZX12R undertail installation is a good job, follow these instructions and take your time, it should take you about 2 hours. 


1. Remove the 2 seats, the tail section, unhook the cable latch for the rear seat, 

2. remove the tail light, the voltage regulator, empty your trunk space and

3. remove the faux glove box, under that box is the computer of the bike, unplug and remove it, keep all this in memory for the re-assembly at the end.

remove everything show with green arrow


4. Also, remove that little sensor:

remove this


5. Watch for any wires in the area where you have to cut, you can cut the under tray with a Dremel, a good utility knife or a saw, you 
can cut it in place.

6. The next 3 pictures show you where to cut (green line):

cut on right side

cut on left side

cut inside the trunk



Note: when cutting, remember that you need to keep the rear part of the stock undertray where the tail light is attached by 3-10mm nuts.


7. Lift the fuel tank to give access for the front middle nut (recent model of undertail, previous ones are still using the 2 sides screws).

use the tank rod to hold it

8. Locate the middle hole (new undertail) and drill the stock undertray in the middle of it when the undertail is at the right place, use a 3/16" drill bit, later you will be using the provided rubber well nut and stainless Phillips screw.


9. Next, Cut 2 rubber tabs under the computer, the 2 located at the thickest place of the computer (the 2 on the side where the connectors are):

cut 2 rubber tabs

10. The computer will now be sitting inside the glove box, but the wires are coming from the outside of the box, so use the computer to mark the back wall of the glove box to cut 2 openings for the connectors, see the 2 pictures below:

you can do better than me but you got the idea:-)

with the computer in place

11. Install the license plate bracket on the undertail, mark and drill the spot as shown on the pictures, (ZX9R shown but it is the same job):

mark the location...


install the bracket

12. Cut about 8" of the stock rear blinker wires to re-use the stock connectors on the undertail blinkers, match these color codes: right side: gray and black with a yellow stripe, left: green and black with a yellow stripe:

right side blinker connection

left side blinker connection


13. To connect the LED license plate light, take the current out near the plug of the tail light connector, connect the + wire of the led to the red wire near the plug, the other wire to the black wire with yellow stripe, test before doing any soldering:

skin the wires without cutting them, solder then tape

blinkers works, license plate LED light work, good job!


14. Protect the live wires with electric tape, please do a good job, make sure there is no risk of connection between the + and - wires or fuses will bust.

15. For a test, install temporarily the undertail and tail section to verify the clearance between the cut and the undertail:


16. Then install the glove box compartment, connect the computer and secure it with the rubber strap:

computor secured and connected


17. Put the tail light lens in place the same as you removed it previously

after shimming, the studs should be flush to the end of the nuts.

18. You can now go backward in the re-installation process, all wires and connectors previously unplugged need to re-plugged, same goes for all the nuts and screws, don't forget any.

19. The last step is the final one, put the tail and undertail in place and secure it with the 2 provided Phillips screws:

install the 2 stainless Phillips screws


Final Result

nice tail hey?


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