GPZ900R Carburettor Jetting

In my case I de-restricted an Australian 1990 (A7) model:

Original CVK34 Main: 100, Pilot: 35, Needle N27I, half airbox port
Replacement CVK34 Main: 135, Pilot: 35, Needle N27B, full airbox ports
Fuel level: The top of bottom bowl

Full airbox port photo. On the original A7 airbox the opening is only half.

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

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/

Best motorcycle oil

I use this Valvoline XLD Premium 15W-40 on all my bikes since 12 years ago. Very cheap $16 for 5L when on discount... no clutch slip whatsoever. Classification is SL/CF so over the top already. Change religiously every 5000km

Dual Sport Shinko E705 on GPZ900R Sportsbike

Fitted Shinko E705 dual-sport tyres on the GPZ. The handling felt 'interesting' at first. I felt like someone had installed a gimbal on the forks. But by 2 hours and halfway to Reefton it felt normal/great!

Front: Shinko E705 150/70-H18 (1507018)--$175
Rear: Shinko E705 120/70-17 (1207017)---$155

I fitted them for longetivity as they have very deep thread (1cm). My last Dunlop Tyres only lasted 3,500km on this heavy bike.

Replace rear Tyre

Dunlop RoadSmart 180/55-17
Ebay $180



Tips to replace low-pofile rear tyre:

When installing, avoid beading by stepping on the tyre. Push down to the middle part of the rim.

http://www.clarity.net/adam/tire-changing-doc.html

It'll usually be enough to push the beads at the opposite end into the center well of the wheels just once. But if you're mounting low-profile tires like those found on the back of modern sportbikes, the forces you're applying to the end that you're levering over will probably keep seating the beads on the opposite side. Which is what you want -- eventually -- but for now you need slack, so you don't want the beads seated yet. This just means that you'll need to push the opposite-end's beads (top and bottom) into the middle well of the rim a couple of times. This ranges from "no big deal" to something like your own personal reenactment of Sisyphus' little rock game. If you're getting frustrated here, review the diagram above and make sure you have helpers.