.

Kawasaki GPz 1100 / Z 1100GP

.  

Make Model

Kawasaki GPz 1100-B1 / Z 1100GP

Year

1981

Engine

Four stroke, transverse four cylinder, DOHC, 2 valve per cylinder.

Capacity

1089 cc / 66.4 cu-in
Bore x Stroke 72.5 x 66 mm
Cooling System Air cooled
Compression Ratio 8.9:1

Induction

Bosch electronic fuel injection

Ignition 

Electronic, CDI 
Starting Electric

Max Power

108 hp / 81 kW @ 8000 rpm

Max Torque

95.1 Nm / 70.2 lb-ft @ 7000 rpm

Transmission

5 Speed 
Final Drive Chain
Frame Steel cradle design

Front Suspension

Telescopic coil/air spring forks
Front Wheel Travel 138 mm / 5.4 in

Rear Suspension

Swinging arm with 2 dampers adjustable for preload and damping
Rear Wheel Travel 99 mm / 3.9 in

Front Brakes

2x 270mm discs 1 piston  calipers

Rear Brakes

Single 270mm disc 1 piston  caliper

Front Tyre

3.25-18

Rear Tyre

4.25-18
Wheelbase 1540 mm / 60.6 in
Seat Height 780 mm / 30.8 in

Dry Weight

237.3 kg / 521 lbs
Wet Weight 255 kg / 562 lbs

Fuel Capacity 

21.4 Litres / 5.5 US gal

Consumption Average

38.8 mpg

Standing ¼ Mile  

11.5 sec / 118 mph

Top Speed

137 mph / 220 km/m
.  

With its blight reel paintwork, fancy new initials and high-tech fuel-injection system, the original GPz1100 was the biggest and fastest of a new three-bike range of high-performance fours that brought Kawasaki storming into the 1980s. But once glance confirmed that the big GPz was very much a superbike of the old school, with an air-cooled, two-valves-per-cylinder engine, twin-shock chassis and generous supplies of both power and weight.

 

Even at a standstill, the GPz was an imposing motorcycle. Its angular styling made no attempt to hide the fact that this bike was not built to be messed with. Its seat was high, its wheelbase was a long, and it weighed a substantial 5621b (255kg) with fuel. The engine's capacity of 1089cc was slightly smaller than that of Yamaha's rival XSI100. let alone Kawasaki's own Z1300 six.

But with a peak output of I08bhp at 8500rpm. the GPz was the world's most powerful four in 1981.

Kawasaki needed that credibility boost, because the Big K's reputation for all-conquering performance had slipped since the mid-1970s heyday of the Z1 and Z900. Unlike its rival the 16-valve Suzuki GSX1100. the GPz relied on Kawasaki's age-old format of two valves per cylinder.

 

But the new motor was substantially uprated from that of the Z1000H EFI. which had become the world's first fuel-injected roadster 12 months earlier.

Capacity was increased by boring out the cylinders to give dimensions of 72.5 x 66mm. and the larger pistons had higher domed crowns to increase compression ratio. The new motor had bigger valves and revised timing for its twin cams, the crankshaft was lightened, the five-speed gearbox strengthened and an oil-cooler added between the frame's twin downtubes.

 

Uprated chassis

The GPz's chassis was also based on that of the 1000H. with numerous modifications. Its main frame tubes were made from larger-diameter but thinner-walled steel. Rake and trail dimensions were increased. Front forks were 38mm in diameter and air-assisted. Rear shocks could be tuned for rebound damping as well as the normal preload. All this was state-of-the-art for a Japanese superbike. So too was the bike's large instrument console, with its voltmeter and fuel gauge set between the speedometer and rev-counter.

 

Those dials got to record plenty of action. With its big valves and hot cams the GPz liked to be revved, tugging hard on its rider's arms as it howled through the gears towards the 8500rpm redline and a top speed of around 140mph (225km/h). Acceleration away from the line was ferocious, making the GPz motorcycling's straight-line king in 1981. And its mid-range delivery was excellent, too. The fuel-injection gave a crisp response, sending the bike surging forward even from below 3000rpm in top gear.

Stability at speed was good provided the GPz was pointed in a straight line and the throttle was held open. Competent suspension meant that the big bike could be good fun in corners, too. But braking and changing direction at the same time was more than the chassis could take without complaint. The GPz was slightly lighter than its Z1000H predecessor but there was still a lot of metal to throw around.

 

Kawasaki moved quickly to update the GPz. adding a handlebar fairing in 1982. and a year later revising it further with a larger, solid-mounted fairing plus single-shock rear suspension. In 1984 came a bigger step: the liquid-cooled. 16-valve GPZ900R. That was the bike with which Kawasaki entered the modern era. but its debt to its predecessor of 1981 should not be overlooked. For it was the first big red GPz1100 four that restored Kawasaki's justifiably proud reputation for full-blooded high performance.

Source of review: Fast Bikes by Roland Brown

Model History

The 1981 GPz1100 was the first 1,100 cc motorcycle released by Kawasaki. It was officially marketed as the GPz1100 B1. Its frame design was a typical cradle design and the engine was based on the earlier Mk2 engines of the z1000H and z1000J, but the engine capacity was increased to 1,089 cc.
Rather than featuring carburetors, the B1 was fitted with electronic fuel injection (EFI) as used on the earlier 1980 Z1000G/H models. The key cosmetic change was the paint scheme and the return to a painted black engine similar to the original Z1 released in 1973.

Suspension and braking was similar to earlier models; the front forks featured 38 mm tubes, the frame design, based on the z1000H and J models was made from larger diameter steel in the section between the steering head to rear of the tank. To reduce weight, the tube walls were thinner. It weighed 255 kg (562 lb) with a full tank of fuel, and the power output was claimed to be 108 bhp (81 kW)

The B1 was followed the following year by the GPz1100 B2; the B2 featured a cockpit fairing, the use of LCD warning lights and improved engine coating using a black chrome finish instead of the previous black paint. Kawasaki was serious about having the best Superbike, and the B2 was changed in several significant ways over its predecessor.

The engine output was increased by increasing the valve lift from 8.3 mm to 8.7 mm, and valve duration was increased from 280 degrees to 288 degrees to boost upper-end horsepower. The early BOSCH-type analog fuel injection was scrapped, and a new digital fuel injection (DFI) was used in its place. The new system did not use the 'flapper' to measure airflow, but a digital microprocessor, a series of sensors, and a throttle position sensor to meter the fuel much more accurately, eliminate throttle lag, and decrease emissions.

The suspension calibration was all-new for 1982, to make the big GPz an even better handler both on the track and on the street. The fork had slightly stiffer springs, and compression and rebound damping were increased approximately 10%. In the rear, the Kayaba shocks used the same springs, but with greater pre-load, and the compression damping was effectively doubled. And each of the rebound adjustments offered 30% more damping than its '81 counterpart. Wider, Dunlop K300 tires replaced the Bridgestone tires used on the B1 to improve handling and steering response. The B2 was also offered in a gold colour finish called "Sonic Gold".

The B1 and B2 were the last of the large-capacity dual-shock motorcycles from Kawasaki.

In 1983 a new GPz1100 design was released that featured Unitrack single suspension, anti-dive units on the forks and a major styling overhaul often called the "swish" look. Known as the ZX1100A1 model, the 1983 model featured a larger fairing (with a lower fairing section as an option to give a full race fairing), different instrumentation and a warning panel mounted on the redesigned petrol tank. This model contained many features that were to appear on the GPz900R model leading to the suspicion that it was used to test the acceptability of newer technology such as Unitrack and Anti-Dive forks and the newer styling. The 1983 model featured the same EFI design with a few small modifications, such as the inclusion of a warning light that flashed service codes when the DFI system was having a problem, a rev-limiter, and a 'limp' mode that would allow the engine to keep running if one of the sensors failed.

The engine design changed in the 1983 model to use underbucket shims similar to the z650 and the camshaft duration was increased from 288 degrees to 300 degrees, and the valve lift increased from 8.7mm to 9.5mm. To flow more air, the head was revised extensively from the earlier model, featuring new ports, a 'bathtub' combustion chamber borrowed from their own S2 racer, and a 1mm larger intake valve recessed into the head slightly for valve clearance. The power output was now claimed to be 120 bhp (89 kW) at 8,750 rpm.[2] CYCLE magazine recorded 104 rear-wheel horsepower on their dynamometer, and Kawasaki was hoping to have a solid 10-second quarter-mile machine, but the increase in power at the upper RPM ranges lowered the torque at lower RPM's, so taking advantage of that power anywhere but on a racetrack was difficult. This model was released in a Red paint scheme with Blue and Silver stripes. Fundamentally the engine was still the same as earlier air-cooled engines.

1984 ZX1100-A2
The 1984 model deviated little from the 1983 model but featured a new paint scheme called "Galaxy Silver"; the original Firecracker Red scheme was still available. Revisions were minor and include a revised exhaust system and the addition of panels under the instrument cluster. Sales were now in direct competiotion to the smaller, lighter, water-cooled GPz900R model, which by the end of 1984 would win first, second and third place in the Isle of Man TT races.

1985 ZX1100-A3
In 1985 the last GPz1100 was released, competition from sales of the GPz900R released in 1984 had surpassed the GPz1100, so the 1100 was discontinued. All specifications from previous models were retained. This was also the final year for the GPz750 Turbo, which used much of the technology from this series of motorcycles.
Later models
Main article: Kawasaki GPZ1100 Sport Touring

In 1995, Kawasaki re-released the GPz brand, basing the motor on the ZX-9R/ZX-10/ZX-11/ZZR-1100 water-cooled engines. There is no similarity between the later models (officially designated as ZX1100E) and any earlier models. This carbureted model was available from 1995 through 1997 in red or black and some came with rare factory ABS and/or saddlebags options.

Source Wikipedia