Before jetting a ZX7R be aware that Kawasaki uses ram air induction (pressurized airbox) to deliver air and equalize pressure needed to draw fuel through the intake. Coupled with the vacuum system is a fresh air induction system that allows air into the exhaust system giving you that fun popping during heavy decceleration. These factors, of which I don't claim to understand fully, result in the factory main jets to be larger than most aftermarket kits. For example; on my 2003 7R I had 170 and 180 main jets as stock equipment, and the DynoJet Stage 1 kit had DJ-136 and DJ-138 mains (the numbers are not fully comparable in sizing).

Installing an aftermarket kit including main jets, slide springs, and needles without changing anything else will cause your bike to starve for proper fuel delivery. So do the following:

1) Remove the screen support bracket and mirrors
2) Remove the fuel tank
3) Remove the airbox (taking off the ram air rubber duct joints will make removal and installation easier)

When removing the airbox notice that the two tubes at the front are hooked up to two silver things as in the attached picture (taken from http://homepage.ntlworld.com/webzxr/.../ventbowl.html ).

4) Take out those two silver things!!!
5) The silver thing at the front of the bike has the carburetor bowl vent tubes hooked up to in. It is CRUCIAL that you route that hose from the carb DIRECTLY into the airbox. I used the existing port on the left side of the airbox cover.

6) Take the two big tube that come out of the valve cover and connect them together.
7) Plug the two remaining little vacuum tubes (one on the right side of the bike near the front, and the other on the left by the carb body).

8) You will now need to seal the remaining hole in the airbox cover with a good seal of some kind.
9) Install the jet kit per the instructions.
10) Button it all back up and test it out.

You should now have a good baseline to work with and changes should be predictable and make sense. Without making the above modifications first, you will be going back and forth wondering what the hell is going on. I didn't come up with this stuff myself of course, I was lucky to find the following webpage that really helped out; http://homepage.ntlworld.com/webzxr/.../ventbowl.html

DynoJet was also helpful in providing good instructions in their kit that basically hinted at what needed to be done, but due to the specific nature of the problem other sources of information was needed.

Good luck.



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I have a question for you. If someone gave you a set of zx9 carbs, and said they were stage III jetted, how could you tell?