The Keihin Carburettors for the GPz900R - Specs & Differences

Carb Info and Specs for GPz900R Range (1984 to 1991).

The Following Info on the Keihin CVK Carburettors used on the GPz900R Range.
- A1-A7 Specs extracted from the GPz900R Workshop Manual,
- A8 Specs from the Kawasaki Dealer- microfiche.

General Specs. (G) - All Models, (U) - USA, (A) - Australian Model, (Cal) - Californian Model


1984/1985 >>>
ZX900-A1
ZX900-A2

4 Cyl, 4 Stroke, DOHC,
908cc ( 72.5 mm Bore x 55.0 mm Stroke ),
11.0 Compression,
228kg Dry Weight,
22 litre Tank,

84.6 Kw (115 Ps) @ 9500 Rpm.
85.3 Nm (8.7Kgm / 62.9 Ftlb) @ 8500 Rpm.

*** (U) 80.9 Kw (110Ps) @ 9500 Rpm. ***

Keihin CVK34 (x4)
Main Jet 132, (U) 135, (Cal) 138.
Man Air Jet 100.
Jet Needle N27B, (U) N27A.
Pilot Jet 35.
Pilot Air Jet 160.
Starter Jet 42, (Cal) 38.
Pilot Screw 2 1/2 (turns out).
Fuel Level -0.5 mm.
Float Height 17.0 mm.

Cam Timing.
10 deg BTDC @ 1000 Rpm to 35 deg BTDC @ 3500 Rpm.

Inlet.
45 deg BTDC Open, 65 deg ABDC Close.
290 deg Duration.

Outlet.
65 deg BBDC Open, 45 deg ATDC Close.
290 deg Duration.

Idle Speed 1000 Rpm ( +- 50 Rpm ).

Plugs NGK-DR8ES, (A) NGK-D9EA.


1986 >>>
ZX900-A3

Keihin CVK34 (x4)
Main Jet 132, (U) 135.
Man Air Jet 100.
Jet Needle N27B, (U) N27A.
Pilot Jet 35.
Pilot Air Jet 160.
Starter Jet 42.
Pilot Screw 2 1/2 (turns out).
Fuel Level -0.5 mm.
Float Height 17.0 mm.


1987 >>>
ZX900-A4

*** SAME as ZX900-A3 ***


1988/1989 >>>
ZX900-A5
ZX900-A5a
ZX900-A6

Keihin CVK34 (x4)
Main Jet 132, (U) 135.
Man Air Jet 100.
Jet Needle N27B, (U) N27A.
Pilot Jet 35.
Pilot Air Jet 160.
Starter Jet 42.
Pilot Screw 2 1/2 (turns out).
Fuel Level -0.5 mm.
Float Height 17.0 mm.

(U) Plugs NGK-D8EA.

*** (A) For the Australian Model ***
Keihin CVK32 (x4)
Main Jet 95.
Man Air Jet 100.
Jet Needle N27C.
Pilot Jet 35.
Pilot Air Jet 130.
Starter Jet 45.
Pilot Screw 2 (turns out).
Fuel Level -0.5 mm.
Float Height 17.0 mm.

*** (A) 77.2 Kw (105 Ps) @ 9200 Rpm. ***
*** (A) 82.4 Nm (8.4Kgm / 60.8 Ftlb) @ 8800 Rpm. ***


1990 >>>
ZX900-A7

Keihin CVK34 (x4)
Main Jet 100.
Man Air Jet 100.
Jet Needle N27I.
Pilot Jet 35.
Pilot Air Jet 160.
Starter Jet 42.
Pilot Screw 2 1/2 (turns out).
Fuel Level -0.5 mm.
Float Height 17.0 mm.

*** 79.4 Kw (108 Ps) @ 9500 Rpm. ***
*** 83.4 Nm (8.5Kgm / 61.5 Ftlb) @ 8500 Rpm. ***

Plugs NGK-DR8ES.

234kg Dry Weight.

1991 >>>
ZX900-A8

*** SAME as ZX900-A7 ***


This is as far as the Australian Models go.
The Dealer advised that the A8 was the last of the Factory Imports Sold in Aus.
You can see that the 1988(A5) and 1989(A6) models had Smaller Bore CVK32's.

The impact of smaller Carburettors is maybe slightly better or more efficient fuel
metering at lower to mid-range Rpm, however you do lose out with Top-end power.
You need a Bigger Bore carburettor to get maximum power at High rpm.
There is no compromise here.

So, as a suppliment to the section on re-establishing the Power of the GPz900R,
to the original Specs of at least 115 bhp Engine, then you should look at
getting a set of CVK34 mm Carbs if your model has the CVK32's fitted.
As well as the Airbox modification I mentioned.
And of course jetting accordingly, to get the Air/Fuel mix correct.
You may need to adjust the needle height, or get a 'variable' needle.

As a guestimate, with a nice 4-1 pipe and free-flowing muffler,
CVK34's (jetted), and an Open Airbox, and Hi-flow filter,
I would think you could reasonably expect to add about 12-15 Hp (maybe more)
to the Original 115 bhp (Engine).
If so, you would have a 130 bhp GPz900R - which would be no slouch.
Pod filters and a DynoJet Kit, or actual Dyno Tuning your Bike,
could even see you near to a 140 bhp (Engine).
And if you changed the CAM's ... who knows ...

Have fun.

PS: For Keihin Needle Conversion Charts visit the page,

http://keihincvk40.blogspot.com.au/

Ceramic Coats

Have a look at websites,

http://compcoat.com.au/coatings.html

http://compcoat.com/

Same place...

Although I have not had work done here, my neighbour uses these guys for his Race Car exhausts.

There are other places that do Ceramic coatings too.

For your exhaust, less heat transfer, more horsepower, non-corrosive non-rusting finish.
The Ceramic coats inside and outside the pipe.

Looks great too.

Horsepower Math

Just a quick general section on Exhaust Sizes.

See the chart for chossing a diameter for your exhaust, although with bikes
you may not have much choice.

Acknowledgment from website
http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/

Keihin CVK - Needle Conversion Charts

These are just two re-posted Keihin Needle conversion charts that may be useful.

Thanks to the websites,
http://www.motorcyclecarbs.com/ , and,
http://www.jetsrus.com/ , for the charts.
Have a look at the sites for more info.

GPz900R - Keihin Info

Please see  http://gpzrear.blogspot.com.au/  for specific info on the GPz900R Kehin Carbs.

Keihin Tuning CVK - Factory PRO Website

Again, this post is only to point you to the FACTORY PRO Website with regards to tuning the CVK carburettors and Dyno-tuning the CVK Carburettors.

http://www.factorypro.com/tech/tech_tuning_procedures/carbtun.html

All credit goes to the Author - Marc.
His website is very informative and obviously took a lot of work and research to provide the information he has allowed us to use.

Thanks Marc, and your Team.

Keihin Carburettor - CVK40

I am only putting this link up because I was impressed with this explanatory webpage on the workings of the Kawasaki Keihin CVK carburettors.

http://www.gadgetjq.com/keihin_carb.htm

All credit goes to the original Author for his straight forward explanation of CVK carbs.
- In his example the CVK40 from a KLR650.