• Source: Kawasaki Ninja ZX-7R

The Kawasaki Ninja ZX-7R was a 750cc motorcycle in the Ninja sport bike series from the Japanese manufacturer Kawasaki produced from 1989 until 2003
From 1989 through 1995, this motorcycle was marketed as the ZX-7 in the United States. In the European and Asian markets, this motorcycle was sold under the ZXR-750 name.
Beginning in 1991, Kawasaki offered a superbike homologation version of the ZX-7, dubbed the ZX-7R in the US and the ZXR-750R worldwide.
In 1996 Kawasaki dropped the ZXR name worldwide and the former ZX-7 / ZXR-750 became the ZX-7R and the homologation ZX-7R / ZXR-750R became the ZX-7RR.




Overview


The ZX-7R is powered by a liquid cooled, 749cc in-line four-cylinder with double overhead camshafts and 4 valves per cylinder. The engine case, cylinders and cylinder head are made from aluminum. A multi-plate wet clutch transfers power to a 6 speed transmission.
The frame used on the ZX-7R is an aluminum twin-spar design, constructed of several pressed and cast aluminum sections welded together. The rear subframe is made of welded square tube steel sections, providing enough strength for a pillion passenger.
The double sided aluminum swingarm used largely the same fabrication techniques as the frame. The rear suspension used Kawasaki's Uni-Trak rocker arm system, designed to provide a progressively stiffer damping and spring rate under compression.




Production Years






= ZX-7 (H1) 1989

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The first year ZX-7 was launched in 1989 and received mixed reviews from motorcycle journalists. Some criticized its weight; 30lbs heavier than that years Suzuki GSXR750 and 70lbs heavier that Honda's RC30. Overall it was praised for its approachable handling, albeit with a noticeably stiff rear suspension.
The H1 model produces 107 crankshaft horsepower at 10,500 rpm. The engine has a 68mm bore, a 51.5mm stroke and a compression ratio of 10.8:1. The valves are actuated directly by the camshaft via bucket style tappets. Fueling is accomplished via 4x 36mm Kehin CVKD constant velocity carburetors. Intake air is fed to the air-box through the two tubes run from the front cowling through the fuel tank. The oil is cooled via a separate, oil to air heat exchanger mounted below the radiator.
The frame is an aluminum perimeter type. The suspension consists of adjustable 43mm forks at the front and a monoshock at the rear connected to the swingarm with a Unitrak rocker linkage. Front brakes are dual 310mm rotors with 4 piston calipers. The rear brake is a 230mm rotor and two piston caliper. Wheelbase measured 1410mm. Dry weight was measured at 451.9lbs.




= ZX-7 (H2) 1990

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The 1990 model year inherited many of the items in the "race kit" from the prior year. The swingarm, previously a box beam type was updated to be a single cast/welded piece. Engine changes included larger 38mm carburetors, shorter pistons, longer connecting rods, and an increased compression ratio of 11.3:1. The oil filter, previously an external spin on design was moved to an internal paper cartridge style. The exhaust header, radiator and oil cooler were changed as well. Wheelbase was lengthened to 1455mm. Dry weight was measured at 441 lbs (200 kg).




= ZX-7 (J1,J2) 1991-92

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For 1991, the ZX-7 received a host of changes. A new shorter stroke engine was introduced with a bore of 71mm and a stroke of 47.3mm. This new engine retained the 11.3:1 compression ratio and 38mm Kehin carburetors from the H2 model. The valves are actuated via rocker-arm style cam followers instead of the direct actuation on previous models. The oil cooler was changed to be an oil-to-coolant style heat exchanger. The engine is now utilized as a stressed member of the chassis. These models were deliberately restricted by Kawasaki to 100hp due to fear of a potential Europe-wide horsepower limit.
The aluminum perimeter chassis was lightened and equipped with new inverted 43mm forks, and larger 320mm front brakes. The wheelbase was shortened again to 1420mm. This new model weighed roughly 30lbs less than the prior year. The J2 model received a reduced spring rate in the rear in an effort to make the rear suspension less stiff.




= ZX-7R (K1, K2) 1991-92

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The 1991 ZX-7R is the first year of the super bike homologation version of the ZX-7. Many changes were made in order to improve performance and usability on the track. The engine is unrestricted and equipped with 39mm Kehin flat slide carburetors, more aggressive camshafts, a higher 11.5:1 compression ratio and a close ratio transmission. This engine produces 121 horsepower at the crankshaft. The steel tank of the ZX-7 was replaced with an aluminum version to save weight. The front and rear suspension is fully adjustable. The ZX-7R can be quickly identified by its single rear seat and lack of passenger footpads.




= ZX-7 (L1, L2, L3) 1993-95

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The 1993 ZX-7 is the first model to have Ram-Air, an engine air intake positioned next to the headlights on the front fairing. The ram air intake is ducted from the front of the motorcycle, through the frame and into the bottom side of the engine air-box. This system is designed to take advantage of the motorcycle's velocity, allowing for the stagnation pressure of air at the front to provide a positive pressure to the engine intake. Another advantage is the cooler air temperature seen at the front of the motorcycles as compared to next to the engine.
The 1993 ZX-7 inherited the ZX-7R motor from the previous year, minus the flat slide carburetors and close ratio transmission. The engine has a bore of 71mm, stroke of 41.7mm, compression ratio of 11.5:1 and breathes through 4x Kehin 38mm CVKD carburetors. The engine produces 118hp at the crank and 54.3 lb-ft of torque.
Chassis improvements include smaller diameter, 41mm inverted front forks, and a revised, more linear Uni-track linkage at the rear. These updates addressed many of the handling problems with the previous models, specifically regarding rear suspension stiffness. The wheelbase was lengthened to 1430mm. Dry weight was measured at 452 lbs (205 kg).




= ZX-7R (M1, M2) 1993-94

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The 1993 ZX-7R received the same major updates as the ZX-7, benefiting from the addition of Ram-air. The ZX-7R engine is equipped with 39mm Kehin FVKD flat slide carburetors and a close ratio 6-speed transmission, producing 121 horsepower at the crankshaft.
One update not received by the ZX-7R was the revised rear shock and linkage, instead the older, stiffer setup was carried over. The front forks have additional adjustability, with 13 way rebound and 8 way compression adjustment. This ZX-7R introduced an adjustable swingarm pivot allowing for further adjustment of the bikes handling characteristics. Like the previous ZX-7R, this model received an aluminum fuel tank for weight savings. The subframe is also smaller to save weight without the need to support a passenger. Dry weight was measured at 431 lbs (200 kg).




= ZX-7R (P1-P7) 1996-2003

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In 1996, Kawasaki changed the U.S. naming convention for its 750cc sport bikes. The ZX-7 was now to be known as the ZX-7R and the ZX-7R became the ZX-7RR.
This model year was a large update to the 750cc Kawasaki, receiving an entirely new engine and dual Ram-air inlets. The engine has a bore of 73mm and a stroke of 44.7mm. The rocker-arm style cam followers of previous years was replaced with a direct actuation bucket style, reducing valve-train inertia and allowing for higher engine RPM. The throttle pulley was moved from the far right side of the engine to the middle, reducing free play in the throttle butterflies in an effort to stabilize idle RPM. The cylinder head received a wider, 25 degree valve angle compared to the previous years 20 degrees. The larger cylinder bore necessitated the move to a closed deck cylinder, and the cylinder head received oiling and cooling improvements. The exhaust header was updated to be a 4-2-1 style instead of the previous year's 4-1. This engine produced 123 crankshaft horsepower.
The chassis was updated with a stiffer frame and larger 43mm forks with added adjustment for rebound. The rear shock also gained additional adjustability with 20 way compression adjustment and 4 way rebound adjustment. Braking was improved with new 6-piston Tokiko front calipers. Total dry weight was 448 lbs (203kg).




= ZX-7RR (N1) 1996

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The 1996 ZX-7RR received track focused improvements such as; larger Kehin FVKD 41mm flat slide carburetors, and a stronger paper based clutch lining. Additional changes were; a quick-change camshaft sprocket, close ratio transmission and a heavier flywheel to prevent rear wheel spin while cornering.
The chassis was stiffened with gusseting near the rear of the engine. The suspension received additional adjustability; 28 way compression and 13 way rebound on the front forks, 20 way compression and 18 way rebound on the rear shock. The 6-piston Tokiko calipers on the standard model were swapped out for 6-piston Nissin units. A smaller 8AH battery is fitted for weight savings.
1996 was the only year the ZX-7RR was sold.




Racing



Many variants of the ZX-7 were raced by both factory Kawasaki and privateer teams. During its production run, racing variants of the ZX-7R and ZX-7RR enjoyed success in a variety of motorcycle racing events:

Kawasaki returned to the FIM Endurance World Championship in 1988 fielding the then new ZXR-7, variations of the bike went on to win the championship in 1991, 1992, 1993, 1994, 1996.
In 1990, Doug Chandler won the AMA Superbike Championship riding on a Team Muzzy race prepped ZX-7.
In 1990, 1991 and 1992, Scott Russell won the AMA 750 Supersport championship riding on a Team Muzzy race prepped ZX-7. Russel went undefeateted in 1991 riding the ZX-7, winning all 9 rounds of the series.
In 1992, Scott Russell won the AMA Superbike Championship riding on a Team Muzzy race prepped ZX-7R.
In 1993, again riding on a Team Muzzy race prepped ZXR-750R, Scott Russel won the Superbike World Championship, giving Kawasaki their first WSBK championship.
Riding a race prepped version of the then new 1996 ZX-7RR, Team Muzzy and Doug Chandler came back to win the AMA Superbike Championship again in 1996 and 1997.




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