GPZ 900 R buyers guide? What to look for?

Hi I might buy a GPZ 900 R this weekend if everything goes to plan.
Does anyone know what I should look out for?
Any weak spots?
The bike in question is from 1984.

Best regards H

As far as I know the very early ones were bullet proof, there were rumours of camshaft issues but my brother (he owned one) never experienced any problems.
You are buying an old bike so check the usual -
Compressions, rust in the fuel tank, anything to do with hydraulics (brakes & clutch ensure fluids were changed regular). swingarm bearings (hard to see but grab the swingarm and push from side to side), bounce the shocks, they do have anti dive on forks.
Check if engine is sludged from short runs, camchain / tensioners were another weak point, if in good condition there should be no rattles. They claim the chain tensioner should not be pulled apart but we always did so the tensioner was still original at over 200K kms.
If its high millage the carby diaghrams can need checking ( the can be costly to replace),
If setup correctly this bike is not only a weapon but also a good tourer, they handle really well.
ENJOY

The 84 GPz900 was the start of a seventeen year run of motors that liked to window the cases with number three rod. GPz900 GPz1000, ZX10B, ZX11/GPz1100, all suffered the same problem. Problem was not corrected until the release of the ZRX1200/ZZR1200 motor. ZX12R was a new design.

Keep the oil level at the top of the sight glass, keep the front end on the ground, and keep your fingers crossed.

Do a search for GPz900 rod, lots of hits.

Valve & valve seat problems are common on all those engines, especially early 900s. Valve faces wore quickly and sometimes the seats chipped badly. If you have that it's expensive to repair. Getting another head would not be any assurance of it being better either. At minimum, check compression and ask about valve adjustment history. If the valve lash has been closing up frequently, walk away.

On the early ones,, they used 10mm thread bolts to hold the head and block on. After a while they went to 11mm thread bolts. If you do buy it and take it apart for any reason and for whatever reason if you needed head bolts, measure the ones you have because there are 2 different sizes available.

Early ones had carb diaphragm twisting problems. By this point in time they should have been replaced under warranty.

Only had blow up cranks on bikes that got thoroughly thrashed and to be honest, they were the 1000 cc units. Never did have a 900 puke a crank when I was at the dealership and by the time I left the 900's were no longer available in the USA.

Cam chain tensioners were the same problem they have always been, even though they were ratcheting type.

Bad ignitor boxes could cause the primary chain on the clutch side to spit through the cover...seen several of those.

Very early models had a transmission issue with 3rd/4th gear. They rode back to back on the same bushing with a thin thrust washer and snap ring on each side. From banging gears the thrust washers would concave. Eventually both gears could engage at the same time....BOOM!....big mess. Again, that issue would likely have happened by now if it was a real early unit. They made updated parts for them.

That's allI can remember at the moment. While they were good runners they were also the first generation of throw away motors after over a decade of super strong motors produced. Buyer Beware on modern 4 valve stuff. It's not like the old press up crank two valve stuff for longevity and durability...not by a long shot.

Thank you all.
But should I consider the GPZ as a no go for a serious performance build?
(Thinking wild street)
Have thoughts about going for broke and installing a turbo. (yes I know that will mean upgrading rods, pistons crank and so forth)
I where thinking about the GPZ as a good starting point because it was water cooled.
But maybe I where wrong?

Best Regards H

Hi! I agree with the comments of fellow forumers. You are buying a old bike so expect a lot of work. If you know who is a mechanic that would be better to help you out in checking the bike it self. No.1 to check is the compression of each cylinder.

I am a car mechanic (got my licence and good grades, then realised that the salary was shit and began working as a welder instead)
The thing is that every vehicle is a different animal, and different things that should be checked.
For example BMW V8 engines drops the oil pump as a whole. (horrific results)
VW 1,8T Is super sensitive whit the oil changes (because they get the so called long life oil)
But will be all right if you chance the oil twice as often.
That's the main reason for this thread .

Yes just like old cars old bikes will need some extra love

Thanks again for all the answers

Hemmek wrote: I am a car mechanic (got my licence and good grades, then realised that the salary was shit and began working as a welder instead)
The thing is that every vehicle is a different animal, and different things that should be checked.
For example BMW V8 engines drops the oil pump as a whole. (horrific results)
VW 1,8T Is super sensitive whit the oil changes (because they get the so called long life oil)
But will be all right if you chance the oil twice as often.
That's the main reason for this thread .

Yes just like old cars old bikes will need some extra love


Thanks again for all the answers

Anything is possible....we thought you were asking what's feasible This is what I tell everybody that asks me about building an old Kawasaki. You do it NOT because it makes one bit of sense financially....BUT because you love the bike.

Hemmek wrote: Thank you all.
But should I consider the GPZ as a no go for a serious performance build?
(Thinking wild street) ... thinking about the GPZ as a good starting point because it was water cooled....

The stock Kawasaki Ninja 900 had reported issues with over-heating, at least regularly running in the high end of the temp range. Owners replaced thermostats and water pumps, and used various coolant additives. But I don't recall there ever being a perfect fix. Would suspect that adding performance mods would exacerbate the already existing cooling problems.

Good Fortune!

Patton wrote:

Hemmek wrote: Thank you all.
But should I consider the GPZ as a no go for a serious performance build?
(Thinking wild street) ... thinking about the GPZ as a good starting point because it was water cooled....

The stock Kawasaki Ninja 900 had reported issues with over-heating, at least regularly running in the high end of the temp range. Owners replaced thermostats and water pumps, and used various coolant additives. But I don't recall there ever being a perfect fix. Would suspect that adding performance mods would exacerbate the already existing cooling problems.

Good Fortune!

I agree with your suggestion. They also tried replacing the Radiator with a larger rad from zzr and they said it worked well.

Thank you all I am now a owner of a GPZ 900R as well (good to have one bike to tinker whit and drive the other)
Allthough I must have a curse on me or something.
Guess what?
Carb trouble again and some weird as fuck symptoms.
(the buyer lived in a city where I couldn't open her up completely anywhere because of traffic)
But I noticed the engine was kinda of ruff but not so bad that I thought of it as a big deal then.
on my ride home (250 kilometres my ass is still numb)
I finaly got away from traffic and could open her up completely.
Well I can feel that she lacks power (bogs a litte on full throttle) but when you hit 6.000rpm at WOT.
She does not quite accelerate but actually slows down like the engine is dying.
Let of the throttle and she starts up again.

Except the time she actually died on me completely for no reason.
And nearly ran out of battery after a break (she wouldn't start)

But tomorrow I she will get some new oil (I always chance oil and plugs on everything I buy)
And I will do some troubleshooting.
I will start a new thread on it so this one stays on topic for the future if anyone else is thinking of buying a GPZ.

Thanks again for everything.
Best regards H

croxway wrote:

Patton wrote:

Hemmek wrote: Thank you all.
But should I consider the GPZ as a no go for a serious performance build?
(Thinking wild street) ... thinking about the GPZ as a good starting point because it was water cooled....

The stock Kawasaki Ninja 900 had reported issues with over-heating, at least regularly running in the high end of the temp range. Owners replaced thermostats and water pumps, and used various coolant additives. But I don't recall there ever being a perfect fix. Would suspect that adding performance mods would exacerbate the already existing cooling problems.

Good Fortune!

I agree with your suggestion. They also tried replacing the Radiator with a larger rad from zzr and they said it worked well.

Yea..well here's what Kawasaki did..... They sent us a box full of resistors to install between the temp gauge wire and the temp sensor.....gauge read much closer to the middle after that and that cured 99% of the complaints immediately.... :woohoo:

If it doesn't spit coolant out of the tank overflow it's not overheating. But they dam well did pour the heat back on the rider and felt like they were overheating. In severe use, on a racetrack with nothing but water in the system, they would boil over though...