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Kawasaki GPz 1000RX

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Make Model

Kawasaki GPz 1000RX

Year

1987

Engine

Four stroke, transverse four cylinders, 4 valve per cylinder

Capacity

997 cc / 60.8 cu-in
Bore x Stroke 74 x 58 mm
Cooling System Liquid cooled
Compression Ratio 10.2:1
Lubrication Wet sump

Induction

4x Keihin CVK 36 carburetors

Ignition 

TCI (Transistor Controlled Ignition)
Starting Electric

Max Power

125 hp / 91.1 kW @ 9500 rpm  ( 116.2 hp @ 9750 rpm )

Max Power Rear Tyre

 116.2 hp @ 9750 rpm

Max Torque

10.1 kgf-m / 99 Nm @ 8500 rpm
Clutch Wet, multiple discs, cable operated

Transmission 

6 Speed 
Final Drive Chain
Frame Steel, twin spar

Front Suspension

40mm Telescopic forks, air assistance and AVDS
Front Wheel Travel 140 mm / 5.9 in

Rear Suspension

Uni-Trak rising-rate with adjustable rebound damping.
Rear Wheel Travel 115 mm / 4.5 in

Front Brakes

2x 280mm discs  1 piston calipers

Rear Brakes

Single 260mm disc 1 piston caliper

Front Tyre

120/80-16

Rear Tyre

150/80-16
Seat Height 790 mm / 31.1 in

Dry Weight

238 kg / 524 lbs
Wet-weight 267.0 kg / 588.6 lbs

Fuel Capacity 

21 Litres / 5.5 US gal

Consumption Average

14.5 km/lit

Braking 60 - 0 / 100 - 0

13.4 m / 39.1 m

Standing ¼ Mile  

10.7 sec / 206.8 km/h

Top Speed

255.5 km/h / 158.7 mph

Road Test

Motosprint 1987 Group Test

GPZ 1100RX vs GSX-R 1100 vs FJ1200

THE LE MANS CIRCUIT  in February is a strange and eerie place - it's two months before the 24-hour race takes place. The contrast between packed grandstands and the roar of over 50 bikes hour after hour in April, and now with just half a dozen people clustered around three bikes is extreme. But these three bikes are the fastest, meanest production bikes in the world and the Bugatti circuit waits in the cold winter sunshine.

A chance to test the Kawasaki GPZ1000RX, Suzuki GSX-R1100 and the Yamaha FJ1200 back to back had to be grabbed with both hands. So we brought them from around the world and then across Europe to Le Mans and its environs to see how they perform on and off the track.

These bikes are at the peak of the motorcycle's development. But more than that, they represent a culmination of the last two years' progress. In 1984 and'85 there were no dead ends; the turbo had been laid to rest and rigid and light chassis appeared. Engine and frame developments gave us bikes like the GPZ900R in '84 and the GSX-R750 in '85. Now we've got the GPZ1000RX, GSX-R1100 and the FJ1200 - all big brothers of stars from earlier seasons.

The GPZ is a brand new machine. It's an amalgam of Kawasaki's from '84 and '85. The engine is based on the popular 900R, the chassis is based on the GPZ600R. The bike seems sturdier than its antecedents, though its engine sits higher than before. The centre of gravity is therefore higher than before even if the total weight is about the same. The steering is quick due to the 16-inch wheels front and rear, but given enough road the GPZ's aerodynamics begin to work and it's surprisingly stable at speed.

The GSX-R1100 has the looks of its smaller brother; indeed the construction is so similar that it's quite possible that the engineers ran the old program through the computer and multiplied it by 1.4666 recurring, the factor needed to get 1100 out of 750. In fact that's not wide of the mark as both the GSX-R750 and 1100 were mapped out on Hamamatsu's drawing boards at the same time. The 1100's made full use of that extra development time. The result is impressive. A 125hp, oil-cooled engine sits in a chassis that's lighter than the competition's 750s. We expected a race winning ride from the machine but were surprised when we also found good road manners in the package.

Set out with pen and paper the FJ1200's bare specification doesn't impress. The engine is the old 1100 bored out with a few detail changes to the transmission and a lighter, stainless steel exhaust system. To cope with the demand of the long-distance rider, two screens of different heights are delivered with the bike, and there's also an electric fuel tap mounted in the fairing, plus a clock. Although the base lines are sporting the FJ scores by being so uncomplicated and relaxing to ride.

At a standstill the Kawasaki feels unwieldy because of its rather high centre of gravity.  But once it's on the move the 59.25in wheelbase, a rake angle of 28° and a trail of 108mm make a rather compact and sweet handling package.  The engine can feel as raw as the 900R, although the suspension is more compliant, the fairing screen is lower and the riding position more crouched.

The aerodynamics are better too; the wider fairing protects the rider more completely and we also noted the highest top speed on the Kawasaki - 158.95mph.

High praise, but the Suzuki was even more enjoyable on the long and winding road as its chassis is even better. The riding position is more relaxed than on its smaller brother, the GSX-R750. The wheelbase is short, 57.48in, the rake somewhat steep at 26.5° and the trail on the long side at 117mm, but the 18-inchers front and rear don't give the pilot an impression of quick, nervous steering. Just easy to control and enjoyable. An hydraulic steering damper mounted across the front of the headstock controls any tendency for the front wheel to wander at high speed, a problem on early GSX-R750s in certain conditions. 'Easy. You just go into a bend, anyway you want', was a typical reaction among our test riders when questioned about the GSX's high speed cornering.

The engine, of course, feels stronger all the way through the revs compared to the 750. If you want to pop a wheelie in the first two gears you just have to crack open the throttle. Low rotating mass at the crank gives good response on the throttle but also nervous behaviour at tickover. Unscheduled stops at traffic lights should be expected.

The Suzuki doesn't feel as stable as the Kawasaki at higher speeds and its top speed is also lower. The rider has to tuck his arms and legs right in to keep the bike steady; it is not instability per se but a racy nervousness.

The FJ1200 stands out from the other two. At lower speeds it handles really easily, in spite of its weight, due to the low centre of gravity and high, wide 'bars. The engine and tank sit low down which is great for slower corners but a limiting factor when it comes to ground clearance. The chassis measurements are very close to those for the GPZ1000 - 58.66in wheelbase, 27.5° rake and 112mm trail. The Kawasaki's better handling in curves comes from its better weight distribution. At higher speeds the front wheel of the Yamaha tends to plough itself through the bends. At 'normal' speeds - whatever that is - this tendency is barely noticeable.

The engine is very torquey so you tend to stay in top gear most of the time. There is always power on hand, although compared to the FJ1100 the engine runs a bit rougher and also vibrates more, but this isn't a serious drawback. The brutal power can cause wheel spin but it is always easy to control. The Yamaha is more of a normal motorcycle and the rider sits more upright with the high bars and low foot pegs. The fairing, however, is not 100 per cent ideal for touring, but more of that later. The chassis is sturdy and stable all the way to the bike's top speed.

Computer-controlled testing equipment was used during testing and as a warming-up exercise we chose to start with the braking test. Several test runs were made and any fading was unmercifully noted. Measurements were taken from 62mph to standstill, without reaction time included. The four-piston calipers of the Suzuki and the one-sided calipers of the Kawasaki were easy to control. Subjective reaction from the rider reported that the Kawasaki was the most controllable as the machine performed very well during the whole manoeuvre. The Suzuki tends to stand on its nose due to its low weight. And it was of course the weight that decided the final results.

The GSX-R1100 stopped a yard before the Kawasaki: 34 yards compared to the Kawa's 35. The Yamaha stopped after 37 yards, also a good result.

Fuel consumption figures revealed the Suzuki as the most frugal with an average of 36.4mpg, the Kawasaki was second with 35.5mpg, and the Yamaha was thirstiest with 33.8mpg.

Average fuel consumption puts the Suzuki at the top of the list although a high speed test run revealed the Kawasaki to be the least thirsty one when it was going really fast. This emphasises the excellent aerodynamic qualities of the Kawasaki which allows the engine to run effortlessly at speeds where it competitors are a bit stressed.

With these figures we have calculated a theoretical range for all three machines. The Yamaha, with its large tank can go for 177miles; the Kawasaki is more economical, but the smaller tank limits the rider to 162 miles; the Suzuki is the best, but also has the smallest tank - 3.95 gallons - so the range is only 144 miles.

The next tests we ran were for top speed and acceleration. With its lighter weight and greater horsepower the Suzuki walked away with the standing quarter-mile award. An impressive 10.71 seconds was the best result from several runs. The rider was a hefty 14 stone, so a lighter rider trying on a warmer day should do something like 10.5. The Yamaha's low-down grunt produced a time of 11.2, and the Kawasaki managed an 11.3.

For motorcycles intended to be ridden in every day traffic, perhaps several hundred miles per day, overtaking capacity is important. At maximum acceleration from 43mph to 80mph - a typical demand when overtaking a lorry, two Metros and a caravan - the Suzuki wins again with 2.97 seconds, the Yamaha second with 3.45 and the Kawasaki last with 3.47 seconds.

For the same acceleration, but in top gear only, the Suzuki still wins with 6.37 seconds, followed by the Yamaha at 6.81 and trailing far behind was the Kawasaki with 8.57 seconds.

Le Mans' closed Bugatti circuit was not much good for deciding top speeds for these three. So it was out onto the Autoroute. The lady in the ticket booth looked surprised the first five times, but cheered us on every time after that when the machines left with the computerised test wheel attached.

After a mile there was a very slight left before the next straight, and even that is noticeable at speeds over 150mph! Our first reading for the Suzuki gave us a very good 156.65 mph. But the Kawasaki is still the winner. The Suzuki rider can just stay with the Kawa, but if he loses a few yards he's hopelessly lost.

The GPZ1000RX pulled 158.95 mph flat out, with its speedo reading an optimistic 168mph. At this point the Yamaha is far behind, doing a mere 148.38mph. The Yamaha's speedo shows the most error as it indicates a full 161mph at a true 148. The Suzuki is the most truthful with an indicated 161mph at a true 156, which is very good at these speeds as the percentage error tends to increase the faster you go.

Yes, we definitely crown the Suzuki GSX-R1100 as the winner of the performance round; it leads in all areas except top speed. When it comes to second place it is more a question of what the rider wants. The FJ1200 has stronger acceleration than the Kawasaki but the Kawa has a higher top speed and better brakes.

But all this performance is useless if the power does not reach ground properly and cannot be controlled. Another session at the race track again with endurance racer Vesa Kultalahti riding, put the Suzuki on top. The Kawasaki, of course, came second and the Yamaha third. The GSX-R1100 has the lowest weight of the three and this means the chassis is not as stressed as heavier machines in braking and in the bends. The GSX-R is also better balanced and handles beautifully in situations where other machines feel clumsy.

Ground clearance is almost unlimited on the Suzuki and inspired riding is needed to get anything to touch down. The suspension components get high marks and are perfect, both on and off the track. The electronically controlled anti-dive is effective and the amount of anti-dive can be chosen by the rider. The Suzuki has uncompromising racing feel and works best on the track but some points also make it surprisingly suitable for road work. More about that later.

The Kawasaki is overweight compared to the Suzuki. This is most noticeable on the track as the tyres break away much earlier than on the Suzuki. Quick steering results in good handling despite its greater weight, and ground clearance is good thanks to the engine's position in the frame. Suspension is very capable, though not as compliant as that on the Suzuki. Only when hard pressed will the pegs deck out. The brakes are sensitive and the AVDS anti-dive performs well. The Suzuki's better acceleration and better performance in twisty sections is what makes it the winner.

The Yamaha doesn't even come close in the handling stakes. It's a machine better suited for high-speed touring. We tried it just the same, and got the front wheel sliding entering bends and rear wheel sliding coming out. The weight is its limiting factor, as well as bad ground clearance.

The transmission and chassis once again give Suzuki top honours. The majority of these machines will be used for high-speed touring, regardless of what the PR people will have you believe. Few of them will set wheels on a race track. For that reason we decided to put in a minimum of eight hours in the saddle to see how they fared under more normal riding conditions - vibrations, cramped riding positions and small fairings notwithstanding.

Surprisingly, our favourite in the sports department actually turned out to be alright over longer distances. Its riding position is much better than that of the GSX-R750. You sit 'in' the machine with the handle bars rather high, and this relaxed position allows the rider to stay in the saddle for hours on end without too much discomfort. Sitting in the bike also enables the rider to duck out of the wind behind the fairing. Vibrations at certain revs were noticeable, but not painful or tiring.

The rider sits more upright on the Kawasaki which means he can't escape from the wind blast. The engine works almost without vibrations of any kind and the fairing protects the rider well - up to chest level, anyway.

The Yamaha has the most upright riding position. This should mean that it's more comfortable than the other two, and this might be true at moderate speeds, but the large engine produces vibrations at high speeds and the suspension is a bit rough. Nor does the half fairing give as much protection as the full fairings of the other two - with the lower screen there is less turbulence, but there is also less weather protection.

Instruments and controls once again put Suzuki on top as the instruments are easy to read, even if they do look a bit on the spartan side - function and looks may not be the same thing. When it comes to instruments, both the Kawasaki and the Yamaha have more to offer for those who like fancy gizzmos. The Kawasaki has fuel, temperature and voltage gauges, whereas the Yamaha has fuel gauge, clock and electric fuel tap controlled from the fairing as extra gimmicks.

At the end of the day the Suzuki GSX-R1100 comes up the winner. It has no weaknesses, only strong points. It's superb on the track, performance is staggering and despite its obvious sporting intent it makes a lovely road bike.

In second place came the Kawasaki as it definitely has a handling advantage over the Yamaha. It can be pressed hard without letting its rider down and at motorway speeds, the Kawasaki leaves the opposition far behind in its not so good mirrors.

The FJ1200 is a very good motorcycle but in company such as this it doesn't stand a chance. It should seek its followers in the touring crowd, but even here it drops points with vibrations, harsh suspension and a thirsty engine.

Source MOTORCYCLE International 1986