Installing a JetKit in the Katana:
The preferred:
Ivan's Performance Products JetKit

OR (2nd choice, IMHO):
the FactoryPro JetKit
OR (last choice, IMHO):
the DynoJet, part number 19-3159, previously also sold as K&N-labelled jetkit part number 81-9382

OK - you want to re-jet your carbs, but have never seen what's under your tank(?) I hope you will find this useful.

disclaimers: I'm not a factory trained katana mechanic - I have a katana, some parts, service manual and a digital camera.
This page has been modified by The CyberPoet from

First off, literally, is the plastic. You can get away with loosening the side fairings to remove the tank. I like them off so I don't scratch them and also give all those bolts a re-torque.

Removing the tank. Unplug the fuel level sensor and remove the two bolts at the rear of the tank. Slide the tank to the rear to unseat it from the front rubber mount. Lift the rear of the tank to expose and remove the three hose.

Now the tank is off !
I installed the new needles with the carbs on the bike.Remove the top caps, then the spring  Lift out the diaphragm assembly.
Using needlenose pliers pull out the jet needle stopper.
The spring, washer, needle and spacer can now be removed.
Stock Needle
Remember you reuse your stock washer and spacer !
The e-clip is place on the third slot from the top per instructions

Place the newly assembled needle into the diaphragm valve (be sure to fully seat the needle stopper), and insert back into the carb. You will see a little hole that the needle will fit into.
Test it's movement then replace the cap.


New Needle

Now it's time to remove the Airbox. Loosen the 4 clamps up front and remove the 2 bolts on the seat rest. Remove the 2 air vent line from the carbs and lift out the airbox


Air vents

starter cable (choke)
Pulling the carbs:
Unplug the throttle position sensor ( don't remove )
Unbolt the 2 throttle cables and the starter cable (choke).
Loosen the 4 clamps that hold the carbs to the head.
Grab the carbs - pulling to the rear rock them up and down

Now that they are loose it will be easier to unseat the cable ends
NOTE: Throttle cable removal-make sure you put these back correctly or the throttle will work backwards. ones a puller the other a returner.

Remove the carb assembly and plug the holes.

throttle cables
First you must drain the bowls ( I used the gas can for the lawn mower ) holding them upright loosen all 4 drain screws one at a time until empty then retighten screw.

Then turn the carbs upside down. Carefully use the 5/32 drill bit supplied in the kit and drill out the air/fuel screw plug. Turn the air/fuel screws clockwise until gently seated, then back out 3 full turns counterclockwise.
Remove the float bowlcover screws (I used a drywall bit -
it's a #2 phillips but sits in the screw better
and install the Main Jet.
D110 - stock setup
D116 - K&N air filter with large donut
D120 - K&N air filter and Full Exhaust

Adjusting the Floats
Turn the carbs upside down.
With your fingers, lift the floats up and measure the top
of the float to the body of the carb when the tongue
(tang) is just touching the needle. Adjust to 13mm +/- .5mm

Adjust all 4 and replace the covers.
(you may want to replace the cover screws with allens or Torx)
cover screw size is
Verified via Arsenic: M4 x .7 turns - 10mm to 12mm length will work

I was asked to post a picture of a good burning plug.
notice that the white insulator has a light brown color.
( this is an Iridium NGK CR9EIX )