Somewhat to my surprise, there were many GPzs on offer in MCN. I finally picked up a nice looking bike, from a mature owner with a fistful of service receipts that fully covered the eleven thousand miles on the speedo, paying a grand less than the discounted new price for a bike that was less than a year old.
After the Z1 the Ninja felt like a particularly lithe 750, much more compact and despite flat bars much easier to chuck around. Where the Z1 always felt as if it wasn't sure just which direction it was going to take, the GPz felt very precise.
First time out on a new bike, I found I could take some of my favourite bends at up to 20mph faster. Having spent years coming to terms with soft suspension and weak frame of the Z1, learning when to back off before it went into a speed wobble, all that was necessary on the new 900 was to sit there, lean the thing over and shoot around the corner. Any old wimp coming straight from his Part Two could leap on the GPz900 and burn off a vastly more experienced rider on the older four.
But it wasn't perfect. Nothing ever is. Determined to find a flaw in its character, I left my braking later and later. Braking into a corner on the Z1 would seriously twist the fork, make the damn thing try to sit straight up and if you really persisted get the whole plot bouncing and twisting every which way - it could get very frightening. At first, the Ninja acts neutrally but right on the limit the sixteen inch front wheel will try to flick upwards, the whole bike would twitch and then settle back to its usual sane composure.
You have to be pretty silly to make the bike misbehave like that. Part of the problem, anyway, came from the enormous power of the twin discs. They only need moderate pressure to have the front wheel howling in anguish and the tyre companies shouting with joy (I've gone through a front Metzeler in 3500 miles). Similarly, the rear disc is so powerful that I'm afraid to use it in the wet, as it is very easy to lock up the wheel. When this happens the back wheel slides out from under the bike, but it comes back into line easily once brake pressure is released.
Where the old Z1 would go into a gentle weave at 80mph, and often turn it into a wobble above the ton, the Ninja is stable right up to an indicated 160mph (probably a true 150mph). Only when tyre tread is down to 3mm does a weave intrude into this confidence inspiring eulogy. When I first had the bike this was so mild that I could keep on riding the bike until the tyres were down to the legal limits, but with over 42000 miles on the clock I have to change the tyres at the 3mm mark, any later and high speed runs do degenerate into a fight between the tyre and frame. each of which wants to go off in different directions.
Having spent my youth learning to anticipate Z1 speed wobbles, I could feel the same dangerous tremors building up in the Ninja, although the superior chassis package never did let them emerge. Better safe than sorry. As I weigh fourteen stone I like all the suspension settings turned up high and when the suspension wears and begins to sag a little, I'm not able to improve the situation by using higher settings. The damping on the rear UniTrak shock, in particular, has gone AWOL and on bumpy curves it can do a nice little pogo act - it's nice because the combination of tubular frame and stressed engine don't let the worn out shock worry it.
OK then, the chassis is way ahead of the old stuff and up there with the best of the new exotica. The riding position is only spoilt by the fairing. No, that's a little unfair. The cut down full fairing is better than nothing and neatly covers up the potential styling nightmare of radiator and plumbing, but couldn't Kawasaki have given just a little more thought to keeping hands out of the cold and wet? Also, at really high and very illegal speeds the screen directs a blast of wind right into my neck, which becomes either cold or wet in the winter. The fairing mounted mirrors are often blitzed by vibration and, for some reason, the right hand indicator bulb blows every five thousand miles.
I can take the riding position for about 300 miles before a sore backside and stiff shoulders set in. Around town there's too much weight on the wrists, but this problem disappeared after six months, so I guess I've now_ got stronger wrists than before. Thanks Mr Kawasaki.
Apart from these minor quibbles, the Ninja has been a joy to ride. I'm not quite so happy with the engine. The mechanical integrity and massive strength of the Z1 is somewhat missing from the GPz. I mean you actually have to adjust the valve clearances on the newer bike. On the Z1, the bucket and shims required such infrequent attention that they could be neglected with impunity. Kawasaki use screw and locknut adjusters on each of the 16 Ninja,valves. I now have to spend an afternoon stripping parts of the Kawa to access these valves and slip a set of feeler gauges in between frame tubes and other sharp edges. Worse still, they always need adjusting.
There was one period, with 25000 miles up, when the exhaust valves started going out of adjustment very rapidly and asking around I found out that early bikes suffered cam wear due to insufficient oil feed. The next time I checked the cams there were chunks of metal missing out of the lobes. Fortunately, a mate works in a breakers and was able to swap the cams from a later bike when the boss was out for the afternoon. I also fitted the later oil tube which gives a better oil supply.
With 35000 miles on the clock the camchain started to rattle. Luckily, Kawasaki placed the camchain on the left hand side of the engine, so it was relatively easy to replace, although I actually had to go to buy a new chain and tensioner. I hope the ease of replacement isn't part of the same kind of philosophy as Kawasaki used in their old triples when they came equipped with a second set of plugs...
The other problem with the engine was overheating. In traffic jams the temperature went into the red. The official explanation for this is that the gauge is calibrated incorrectly and the motor is really running at a safe temperature. As I know someone who claims to have boiled the radiator dry, I don't altogether believe this, but I've never actually experienced engine seizure or anything, so it can't be too serious.
Where the Z1 had a built up crankshaft with roller bearings, the Ninja has a one piece crank with plain bearings. While this makes the crank that much stronger and lighter, it also means that the new bike needs very regular oil changes where the Z1 could be neglected until the gearbox started acting nasty. While plain bearings have been used for many years in car engines, they don't rev to eleven grand and knock out 127hp/litre...
Because the engine is used as a stressed member a small gear driven balance shaft is used to keep the bike smooth. It works very well, making the old 900 feel decidedly ratty. With over forty thousand miles on the clock, the original ultra smoothness of the bike has been replaced with a few brief periods of secondary vibes, but they never intrude far enough to leave tingling fingers. The engine can become a little more vibratory if the four 34mm CV Keihin carbs go out of balance - they need to be set up every 3000 miles.
Primary drive is by gear to a hydraulic clutch that is lacking in feel but can be operated with a couple of fingers. The same friend who boiled the radiator dry also fried his clutch, but I haven't had any problems. The gearbox started out slick but is now down to Honda level (clunky and jerky) but I rarely miss a change so no problem.
Given that the four valve head and short stroke design gives a lot more low speed stomp than the Z1, six gears are really rather excessive; I would have been more than happy with four. Indeed, I found it quite easy to start off in second, there was still very little than could hope to keep up with the bike's rapid acceleration. With six grand on the tacho the bike really takes off, although the steering geometry and weight distribution means you really have to torture the clutch to lift the front wheel off the ground.
At low revs on cold days the bike splutters a little and it also takes five minutes to warm up. Other than that, power delivery, is very sweet, doubtless helped by the maintenance free electronic ignition. Cruising speed is determined by the ability of the rider to hang on and road conditions. It's quite happy at 120mph or even more. Cruising motorways at the legal limit the bike isn't really trying. It's so easy to break the law that it's a very quick way to lose a licence.
Fuel economy varies greatly. The bike can do as much as 60mpg if used very mildly (i.e. 70mph cruising) or as little as 25mpg if really thrashed something that is rarely possible on UK roads. I usually average around 45mpg against 52mpg on the Z1, but the Ninja does do all my journeys that much faster so I can't really complain about the consumption. It uses about a pint of oil every 500 miles and I change engine oil every 2000 miles just to be on the safe side - as mentioned the combination of high revs and plain main bearings.
A new set of tyres is needed every 4000 miles, which is the major expense in running the GPz, the Z1 had at least double the tyre life, but then the Ninja sticks at least twice as well to the road. The O-ring chain needs adjusting every 500 miles and lasts for at least ten grand. A worn out chain wrecks the usual smoothness of the transmission and I know someone who's had one snap with interesting consequences for the oil bearing capacity of the crankcase covers.
The price of highly efficient disc brakes is rapid pad wear, 5000 miles being the most I've achieved, although, I dare say, if you're foolish enough to take them down to the metal that mileage can be improved upon by a couple of grand. But with this kind of mass and power it's really a very silly idea. I haven't bothered to change the hydraulic fluid for either the brakes or the clutch and it doesn't seem to make all that much difference. I don't put in much elbow grease to keep the beast clean and it's ridden in all kinds of weather. Thus, it's not all that surprising that the black engine paint looks grotty, the alloy wheels are speckled with lumps of white corrosion, the paintwork is flaking off in parts and the odd bit of chrome is more rust than anything else.
The four into two exhaust system was in trouble by 30000 miles but hung on for another ten grand until the holes and burnt out baffles affected low speed engine running and was replaced with a nearly new system off a crashed bike from a breakers. The only time I've fallen off the bike has been when trying to park the thing in my back yard when I have to push it backwards up a steep slope and turn it through a 90 degree bend. But I've done that more often on the Z1...
Would I buy another one? Probably not, but only because my finances aren't what they were and I find the Ninja rather more expensive to run than the Z1. What I would really like is a more compact Z1 engine clone in the Ninja chassis. This would give all the handling advantages of the Ninja and the toughness, simplicity and longevity of the older four (after all, the engine was really all the Z1 ever had going for it). The lack of water cooling would also save some weight and get the bike under the 500lb barrier.
I'll probably keep on with the Ninja until I detect some engine noises indicating that the mains are on the way out, then I'll off load the thing and buy one of Kawasaki's new 500 twins, which go almost as fast as the Z1 and weighs little more than a 250.
When that will happen I wouldn't like to say; my Z1 has done 85000 miles without any major strip-downs and still runs pretty well - cosmetically it's in better shape than the GPz. I won't ever sell the Z1.
Richard Shell