Zephyr 750 and K&N + jetkit

Hi
I'm new at this Forum.
And first of all, sorry my bad English.

I'm thinking about changing the airbox to pods, because I have bought a 4 in 1 cobra speed pro exhauster.
The question is which K&n filter + jet kitt - shall I buy?

The bike is from 1995.

Br.
Jens
Denmark

Welcome to the forum. I have always liked the Zephyrs, and I especially like the custom touches you have added.
If it were mine, I would keep the air box and add a K&N filter and Dynojet Stage One jet kit. If you must have the individual filters, then the Dynojet Stage Three is the way to go.

Oops. My mistake. Evidently, Dynojet does not make a Stage Three kit for the 750 Zephyr. Their Stage Two is for a low restriction filter in the air box, with the top of the box removed. That would be my choice.

www.dynojet.com/jetkits/motorcycle/jetki...torcycle&vm=kawasaki

Thanks for reply texasKZ
My plan is to port it and change the cylinder at Winther.
I have bought wiseco 810 pistons, and later on bore a used cylinder up from Germany.
I think also to mill the head, and maybe put some gpz cams in it.

Is it still best to use the airbox ?

Br.
Jens

Even with those modifications, I would probably keep the box, but that is your call. I suspect the Stage Two jet kit might not be enough for your build. You might check with Factory Pro or Ivan's to see if they have a setup that will work with your plan. If you know somebody else with a similar build, ask them what they are using.

Hi Jens,

Glad to see you here, and glad to see your Zephyr with kit installed!

I agree with TexasKZ . On my Zephyr I have 810 piston kit for long time and for approximately 70000 km. I changed couple of exhausts until I ended up with 4in4 and I always stick to original air box and filter. However I replaced main jets several times and I also changed pilot jets for bigger ones. As for air filter, I may suggest KA-0850 K&N replacement filter as alternative to pod filters.

In the mid 80's motorcycle companies figured out that if they designed the factory airbox to work with the CV carbs as a system they could get more usable power.. Kawasaki designed the box to provide the optimal airflow for maximum performance. By pulling it and putting on pods you mess up the user friendly power that Kawasaki designed into it and then transfer the power higher up in the rpm range where the bike is not used as much. The result is you go from a nice torquey user friendly engine to an engine that you have to keep the rpm's up. And no matter what jet kit and how much jetting you do you will never recover that nice smooth torquey user friendly power you once had. Keep the box, install the K&N air filter, put on your pipe then jet the catbs.

Thanks Gazzz

Yes it looks nice great job you have done there

I think I will go after the air boxs solution, what type of jetkit did you use?

Jens

I do not use jet kit, I actually only changed main and pilot jets. I looked in my service book to check what sizes of jets I used and found that I somehow missed to write down their numbers. However next week I am planning carburettors maintenance on my Zephyr so I could check what jets I used and write their number here.

A friend of me is riding a Zephyr 750 and had a power loss @6000 rpm. After a lot of maintance like cleaning the carbs, valve clearance, ignition check, we discover the stock man jets ( stock air box/filter) are a little bit to lean on higher revs.
Stock main jetting on #1 and 4 carb is 88 / #2 and #3 is 92. We install 98 main jets on # 1 and #4 carb and 102 main jets on # 3 and 4 carb.
The bike now try to rip off your arms at full acceleration and he very happy with his 20 Euro Investment. Just for the records if anyone has the same Problem.

I checked what I installed in my carburetors.

Main jets:108 for #1 and #4 carbs and 110 for #2 and #3
Pilot jets: 40 for #1 and #4 carbs and 42 for #2 and #3

P.S. Same setup of jets we used in ZR7 (successor of Zephyr 750) with 4in1 downpipes and some quite free flow muffler.