The Kawasaki Ninja ZX-11 Is A 90s Legend That Will Eat Up Modern Sports Bikes

Summary

• The Kawasaki ZX-11 was a game-changer in the world of superbikes, setting new standards for high-performance motorcycles.
• Its groundbreaking design and technological innovations, such as the Ram Air system, paved the way for future generations of motorcycles.
• The ZX-11’s enduring legacy can still be felt today, as many of its innovations have been incorporated into newer Kawasaki models.

The Kawasaki Ninja ZX-11 was a game-changer in the world of superbikes, paving the way for future generations of high-performance motorcycles like the GPX and GPZ did in the Eighties. It spent some time on the drawing board, but the only thing on Kawasaki’s mind was horsepower and speed – everything else was secondary. When it was introduced in 1990, for $7,599, it was the fastest production motorcycle that you could buy at the time.

From an engineering standpoint, it was a continuation of the development of the old ZX-10 that followed the path set by the GPz900R back in 1984. Though slightly similar to the ZX-10, little was interchangeable between both in terms of parts. The engine was impressive and featured a crank with 1mm larger crankpins, molybdenum connecting rods, and lighter 11:1 ratio pistons with accurately detailed valve relief cutouts. The valve train was similar to that of the ZX-10 with larger intake and exhaust valves of 31.5 mm and 27 mm respectively.

In order to give you the most up-to-date and accurate information possible, the data used to compile this article was sourced from Kawasaki, as well as other authoritative sources like CycleWorld.com, and Motorcyclespecs.co.za.

Technology From Formula One Racing

One of the ZX-11’s most significant features is the ground-breaking development and design of its Ram Air system (normally aspirated induction), a first on a production motorcycle, and is what gives it the extra push to hit its terminal velocity. With an airtight, fifteen-liter airbox, without Ram Air, the ZX-11 makes close to approximately 120 bhp before the induction system kicks in to max out at 147 bhp at 10,500 rpm.

The system works on the same principle of Formula 1 racing cars – the faster it ran, the more powerful the engine would become with cold air being thrust into its induction system through a snorkel opening built into the front fairing. With the airbox pressurized, the air-fuel mixture routes through a single bank of four, 40 mm CVKD semi-flat slide Keihin carburetors to be ignited in the combustion chambers.

Because of the space taken up by the airbox and the long snorkel coming from the front of the fairing, Kawasaki engineers tilted the engine 2 degrees forward (17 degrees from vertical) to make way for a large capacity fuel tank. With this adjustment, the Ninja benefits from a lower center of gravity as well as increased front-end weight that improved handling. The Ram Air system has become a standard feature on most high-performance motorcycles, and its influence can be seen in the designs of today’s superbikes.

Engineered To Go Fast

Technologically well-engineered, the Ninja features a liquid-cooled, inline-four, 1052cc, 16-valve DOHC engine that produces 83 foot-pounds of torque, thanks to its larger 2mm liners pressed into the old ZX-10’s bore that gives the ZX-11’s motor 55 cc more displacement over its predecessor. Its cylinder head lineage continues through the ZX line, with the only change being rocker arms given up for a shim bucket system where deemed necessary.

Its camshaft/valve train system is extremely efficient and robust with only extremely high mileage machines ever requiring valve clearance, which is easily adjusted if you’re mechanically inclined. Each of its 16 valves is operated by individual rocker arms that are laterally kept in place by a horizontally mounted spring that can be slid over to one side to change shims during valve clearance while the camshafts are still in place. Its Keihin CV four-bank carburetor also requires little maintenance with the occasional synchronization, which, when required to be done, is not out of sync by much.

Kawasaki Ninja ZX-11 Stock Highlights

• Aluminum twin-beam frame that’s as strong as steel
• Ram Air system based on an old hot-rodder’s trick and Formula One technology
• Self-adjusting cam chain tensioner keeps the ZX-11’s cam chain taut
• The slippery bodywork has been designed by aerodynamic experts
• The European version, the ZZR1100, is restricted to approximately 126 horsepower by a differently designed carburetor cap

Engine Specifications

Chassis

To match the increase in the motor’s power, Kawasaki reinforced the chassis with a new frame and swingarm to handle the acceleration and improve the handling. The ZX-11’s new aluminum frame may look similar to that of the ZX-10 featuring a twin beam frame, but the E-box main beams have been increased by a thickness of 4 mm while the rectangular swingarm box section is 90 mm by 30 mm thick, which may account for the 8 lb rise in weight over the 1989 ZX-10.

Suspension

On the suspension front, the ZX-11 has 43mm conventional front forks, 2 mm up from its predecessor’s 41 mm, providing approximately 4.9 inches of travel, while the rear features a nitrogen-charged shock absorber with a separate reservoir paired to a bottom-link Uni-Trak system. Both units are preload and rebound adjustable – with no scope for adjusting compression. Both components do their duties well, soaking up bumps and potholes and any other inconsistencies that the ZX-11 may find in the road.

Wheels, Brakes And Tires

The rims are new, as are the tires and brakes. The front and rear cast aluminum rims are 17″ in size to reduce rotational forces and are coated with a toughened clear coat to protect the surfaces and ride on 17″ Dunlop low-profile radial tires. In the braking department, upfront, the ZX-11 gains a new pair of Tokico four-piston calipers that grip semi-floating rotors 310 mm (borrowed from the ZX-7). At the same time, the rear duties are performed by a two-piston caliper gripping 310 mm rotors.

Ergonomics, Handling And Rideability

The Ninja’s a big bike, coming in at 577 lbs wet, and it looks opposing in Kawasaki H8 ebony black, but once you’ve slung your leg over it and have got it going, it feels light and easy to manage. It turns and handles well, though, on high-speed runs through corners, the 11 could do with an increase in preload if you’re pushing it.

Other than that, all you have to do is point the front and the rear follows, and if you get into a sticky situation, the ZX-11 will get you out of trouble. The rider triangle connection is brilliant with no leg discomfort at all between seat and foot-pegs. The handlebar relationship is decent too, with the handlebar fairly positioned in terms of height, though some riders may feel that handlebar risers are in order to prevent weight being transferred to the wrists when leaning forward.

The engine is extremely refined thanks to the balancer shaft that counters any vibration from the four-cylinder motorcycle, and the multi-plate wet clutch system mated to a six-speed transmission transfers power to the rear wheel smoothly. The transmission is identical to the old ZX-10 with second through fourth gears made stronger to handle brute-force acceleration, while the clutch has been revised with thicker, larger diameter plates with radial grooves to help improve oil flow and increase cooling along its surfaces. Early ZX-11s did see gear-shifters popping out of second gear, but this was more on account of abuse and poor maintenance rather than manufacturing issues.

Hard first-gear pulls quickly see 60 miles per hour, but as you get into second and open the throttle hard, you’re thrown back like you’re pulling a couple of Gs with your hands almost ripped from the handlebar grips. As you move through the gears and get past the 4,500 rpm flat spot, to 5,000 rpm, the ZX-11 goes ballistic and the engine gets stronger as it keeps accelerating up to its 11,500 rpm redline.

t’s hard to describe its acceleration if you haven’t ridden one, but it’s almost akin to an F-14 Tomcat taking off down a runway! Its smooth, curved aerodynamic front with flush-mounted indicators and streamlined lower and side fairings reduce drag and improve stability at high speeds, and are what allow it to attain its record-breaking terminal velocity of 176 MPH (283 km/h) – Cycle World clocked 174 MPH on their ZX-11 with a standing quarter-mile run of 135.54 miles per hour in 10.46 seconds.

Taking The Kawasaki ZX-11 To The Next Level; Natural Induction.

Even at 175 miles per hour, (which is still quick when compared to some of today’s liter-class motorcycles), for some people its existing performance was not enough, with engine builders and racers hell-bent on taking the Ninja ZX-11 to the next level. In 1990, Doug Meyer, formerly of Dublin Kawasaki set three records in three days on a modified naturally aspirated Kawasaki ZX-11 Ninja “C1” running a 1109 cc Wiseco piston kit with a 190.49 MPH run and then re-set the record with 191.797 miles per hour.

In 1991, he ran a one-off modified ZX-11 with electronic fuel injected developed and provided by Mark Dobeck, founder of DynoJet Research in a modified 1300 class with a 186+ run, but melted the pistons in the process.

A Record Setting Machine

In 1992, Doug’s ZX-11 turned up at Motorcyclist Magazine’s “Superbikes from Hell” competition with fuel injection and set the second-fastest quarter-mile and top speed run with a time of 9.99 seconds and 188 miles per hour respectively, only to be beaten by 2 miles per hour by Lee Sheirt’s nitrous Suzuki GSX-R 1350 with a 190 MPH pass. In the article, Lance Holst said:

Meyer’s ZX-11 pulled on the top-end with a vengeance I’ve never felt on any other normally aspirated bike.

The same bike was entered that year in Sport Rider’s magazine UFO shootout running a 1,080 cc engine, 41 mm carburetors and all carbon-fiber bodywork, Marchesini wheels, and a bunch of other modifications, but that’s a story for another time.

The Kawasaki Ninja ZX-11 would eventually lose its crown after being on top for six years, beaten by Honda’s Super Blackbird 1100XX. However, it was so popular that Kawasaki continued its production run with just one iteration of its design in 1993, the “D” model, till 2001. Its legacy lives on in the Kawasaki line, with many of its innovations incorporated into newer models, such as the ZX-12R which was produced from 2000 to 2006, and the ZX-14R, which continues to be Kawasaki’s flagship motorcycle.

In conclusion, the Kawasaki ZX-11 was a true pioneer in the world of superbikes, paving the way for future generations of high-performance motorcycles. Its groundbreaking design, engineering, and technological innovations set a new standard for the industry, and its influence can still be felt today. The ZX-11’s success and enduring legacy make it one of the most significant motorcycles in history.

Additional Specifications