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The Z1 set a new bar in style and performance. 50 years on and the Z900RS captures the essence of the old and blends it with the new.
Throughout the 1960s, ‘big-bore’ British motorcycles like the Triumph Trident and BSA Rocket were among the fastest machines on the road, delivering smooth, four-stroke power and torque with superior handling, thanks to their strong chassis. The Japanese manufacturers took note. After years of successfully racing two-stroke sportbikes, new FIM rules introduced in 1967 led Honda to pull out of GP racing and direct its well-funded research team to develop a road-going four-stroke to take on the Brits. Released in 1969, the four-cylinder, four-stroke Honda CB750 would blaze a trail through US and European sportbike markets. Within a few years, BSA was bankrupt, and Triumph was struggling. The CB750 also presented Kawasaki with a problem. They had been secretly-developing the “N600” concept, a new 750 four-stroke sportbike of their own.
Kawasaki, like Honda, had previously focused on two-stroke powertrains. Their latest machine, the ferocious 500cc H1 Mach III, was very fast, but its handling was manic. The chassis wasn’t up to the job, and the two-stroke’s power delivery was almost binary. Kawasaki also had their eye on the lucrative US market, but after getting beaten to the 750 class, they returned to the drawing board and developed a new strategy. The Kawasaki Z1 900 made its US debut in 1972 and changed the game forever. If the CB750 had opened the door, the Z1 kicked it in and stomped on it. Arguably the first ever superbike, a review in the November 1972 issue of Cycle said, “The Z1 is the most modern motorcycle in the world. It is also the fastest. The first of a new generation of bikes capable of nattering down quiet country roads one minute and rotating the Earth with incomprehensible acceleration the next.”
The modern retro motorcycle market has been steadily evolving ever since Triumph released the Bonneville 800 “Modern Classic” in 2001. Ducati and BMW soon jumped on the bandwagon, and belatedly, Honda and Kawasaki have begun to tap their own rich heritage for inspiring retros. In honor of the fifty years since its launch, Kawasaki has released a special anniversary edition of their reimagined Z1, the Z900RS, finished in the distinctive “Fireball” Candy Diamond Brown color scheme to match the 1972 model. Kawasaki released the Z900RS in 2018, a retro super-naked for the 21st Century, with styling to mirror the original Z1, including a teardrop fuel tank, large round (LED) headlight, and bullet analog dials. Yet, hiding below the retro skin was a thoroughly modern sportbike with adjustable suspension, traction control, ABS, and beefy disc brakes. The RS also benefited from the same engine as the Z900, providing plenty of grunt.
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Although the Z900RS and aggressively-styled Z900 share the same 948cc, liquid-cooled, inline four-cylinder engine, it received several modifications for the RS, smoothing out its edges and combining manageable performance with a dignified delivery befitting its neutral ergonomics. Reduced valve timing and compression ratios, coupled with a heavier flywheel and 36mm throttle bodies, sacrifice top-end power for improved mid-range torque and smoother throttle response. Kawasaki’s dual-valve technology also helps handle the 109 horses straining at the bit. Cooling fins added to the cylinder heads to elicit a classic air-cooled appearance look the part. But, a 17-inch radiator up front (the only eyesore on an otherwise beautiful machine) tends to defeat the purpose.
The Z900RS trades the original twin-stacked exhaust pipe configuration for a gleaming 4-into1 stainless steel system with a shorter can. Kawasaki claims their chunky dual-wall header pipes help resist bluing and the centralized pre-chamber reduces weight. A slipper clutch makes for easy two-finger lever operation and helps to regulate clumsy downshifts, preventing rear tire chatter. Kawasaki has given the RS a shorter first gear, giving back some off-the-line punch, and a taller final gear for easy cruising.
The RS gets a redesigned-trellis frame chassis and twin-tube subframe, using the engine as a structural component to reduce weight. Unlike the combative, nose-down attitude of the Z900, the RS takes on a laid-back stance for less frantic handling characteristics. The top triple-clamp is 1.5-inches higher, while added steering offset reduces trail and maintains agility, promising relaxed ergonomics in a sporty but stable package. Suspending cast alloy wheels are a 41mm inverted front fork, with 10-way compression and 12-way rebound damping adjustment, and an aluminum swingarm and monoshock, which are adjustable for preload and rebound and mounted horizontally for improved mass centralization. Twin 300mm front discs, clamped by dual-piston monobloc calipers, and a 250mm disc at the rear give the RS serious anchors.
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The Z900RS’ high, wide handlebar position evokes the Z1 and provides a comfortable, neutral seating position. Rubber-mounted bar-ends dampen vibrations, and control levers are adjustable. The old-school teardrop tank provides excellent knee support for getting into the corners, and the stepped one-piece seat is supremely comfy and accessible, at just 32-inches from the ground. Compared to the Z900, the footpegs are slightly lower and farther forward and feature rubber pads with rubber-mounted weights to dampen vibrations. The 4.5-gallon fuel tank extends below the side covers to maintain its classic styling aesthetic while bestowing the RS with practical range.
In addition to contemporary components, the Z900RS also gets all-around ABS and traction control. The latter uses wheel speed sensors and an ECU to offer two levels of intervention. Mode 1 features a less obtrusive algorithm allowing a degree of wheel slip for spirited riding in the twisties. Mode 2 is more sensitive and controls ignition timing, fueling, and air induction to ensure reliably smooth engine response and optimal traction regardless of rider inputs. The large-diameter headlamp and chromed lens ring add to the retro credentials, but as with all its lights, modern LEDs, designed to look like the originals, adorn the RS. Nestled between the bullet shaped analog tachometer and speedometer dials, a subtle white-on-black multi-function LCD provides a fuel gauge, coolant temperature, trip computer, and all the basic information expected on a modern machine.
If you love classic bikes but prefer to go riding on Sunday rather than play at being a mechanic, a modern retro is a great solution. Triumph did a commendable job evoking their storied history to capitalize on the demand for retro machines; they also understood that looks are not a substitute for handling and character. Based on those criteria, the Z900RS deserves to be a serious contender in the big-bore, retro market. As the Brits would say, the RS is drop-dead gorgeous and, just as importantly, it is exceptionally-fun to ride. When you hit the starter button and the inline-four rumbles to life, the first thing you notice is the exhaust note, which is as '70s as flared pants, and settles into a deep purr. A sound so full of promise that it will have you grinning like an idiot. The seat is almost too comfy, and I wonder if it will feel precarious in the corners, it doesn’t. The bars are high and wide, and, for my 6-foot-2 frame, the seating position is entirely neutral with a comfortable bend at the knee and arm.
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When you find an open stretch of road, engage first gear, find the initial bite on the clutch, and feed in all the RS' throttle–bam! Despite everything I just said about a less frantic engine and dual throttle valves, the inline-four explodes into life. With traction control set to Mode 1, the front wheel lifts an inch off the ground over the first 100-yards, and the exhaust emits a deep booming wail, as smooth as the power delivery and far removed from the familiar 270-degree growl that has become the soundtrack to the modern motorcycle. Heading to the mountain roads along the highway, the RS wafts along in 6th gear. I can slide back into the stepped seat, lean into the wind, and take the weight of my arms, and although the blast would eventually be tiring, it is a comfortable place to be, making the RS a credible mile-muncher.
Getting into the open mountain roads and the Z900RS is exactly what it should be, just slow enough that a confident rider can truly test its performance envelope on the street. Like all modern 900cc motorcycles, it is still quick, but you can use all of its power, and for that reason, it is fantastic fun to blast around the canyon roads. Steering is quick and precise, and although taller in stance than its sportier sibling, it carries its weight well. Unlike the new Ninja 6 we tested that stuck to the steering line like glue, the RS does allow for a little rear-wheel slip at street-speeds when you push it. I suspect this has more to do with the Dunlop GP-300 tires fitted to the RS than the traction control setup. Fortunately, the front tire is reasonably assured, and any slides were the predictable type that make you feel like Casey Stoner rather than heading home for a stiff drink. Two fingers on the brake lever provide adequate progressive stopping power, although the Brembo brakes fitted to the SE version are better suited to more aggressive riders.
The Z900RS is an outstanding performer on the road, but perhaps its most remarkable attribute is its finishing. Kawasaki paid uncommon attention to the aesthetics enriching the 50th Anniversary RS. It claims a special technique developed to apply the candy flecked paint in layers brings out the distinctive, deep, glossy finish, rich in color. The duck-bill tail cowling and oval taillight match the original Z1's design, and surface-emitting LEDs in the tail and headlight maintain the retro look during operation by filling each lens with light, mimicking traditional bulb lamps. The three-piece front fender uses lightweight die-cast aluminum supports, and the two-tone seat utilizes different materials for the top and sides, double-stitched in the old built-to-last style. Even the graphics, applied using an advanced immersion method, leave no unsightly raised surfaces. Gold, flat-spoked wheels, add the final touch, and when the sun catches the RS, they complement the sparkle from the candy flecked paintwork.
The 50th Anniversary Z900RS model we tested has an MSRP of $12,049, and a base model, available in Candy Tone Blue, is $11,749. The $300 premium for the paint is well worth it. In the same family, an upgraded SE model with an MSRP of $13,449 is available in the classic “Yellow Ball” dark green and gold paint scheme, which benefits from Brembo brakes and an Öhlins monoshock, and a Cafe version, with a vintage rounded cowling, is also available for $12,199. Of course, the Z900RS is not the cutting-edge, global game-changer that inspired it. Nevertheless, it excels in all the ways a great modern retro should and is a worthy inheritor of the Z badge. Beautiful to behold, equipped with modern components, and, above all, pure joy to ride.
Guy started riding motorcycles aged 21 and bought a Kawasaki ZX-6R the day after passing his road test. He was a sportbike enthusiast for many years until, in 2010, the Long Way Round television series inspired him to organize an adventure moto-tour. Since then, he has traveled thousands of miles across the US, Chile, Argentina, Canada, and the UK on various adventure bikes. He attended adventure bike school with the BMW Performance Academy, completed enduro training with Off-Road Skills in the UK, and recently brushed up his sportbike skills at the renowned California Superbike School. He spent a year in amateur endurance car racing and has attended Skip Barber and Dirtfish driving schools. Guy has previously been the Road Test Editor at Rider Magazine, and his stories were also published in Adventure Bike Rider, ADVMoto, and DRIVETRIBE. In 2020, Guy was one of three winners of Moto Guzzi's "Spirit of the Eagle Rideaway" competition.