Monday, December 23, 2013

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/

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