The latest member to join Kawasaki's Z gang comes in stark contrast with the family's futuristic and aggressive streetfighter looks. Acting as a tribute to the 1972 Z1 patriarch, it is a meticulously styled modern classic variant of the current Z900 with some targeted mechanical modifications.

Kawasaki may have been one of the first manufacturers to compete against Triumph's Bonneville with the W650 and W800 since the early 2000s, but recent trends have moved to giving contemporary sportbikes some classic styling. So it was no surprise that Kawasaki's central novelty at the 45th Tokyo Motor Show came in the shape of a modern clone of the legendary Z1, a motorcycle that along with Honda's CB ushered the motorcycle industry into the superbike era by force at the dawn of the 1970s.

The Z900RS is built around the current Z900 naked bike that was launched last year. The easy thing would have been to just fork out a new fuel tank, round headlight and tail unit, and print new RS stickers, but Kawasaki delved a bit deeper into developing its new model.

In keeping with the classical design of the era it wants to revive, the main lines of the new model couldn't be as downward sweeping and aggressive as those of the Z900. The backbone of every motorcycle designed to imitate the 1970s and 80s roadster and café racer themes is a horizontal straight line that links the tail to the headlight, passing below the fuel tank.

In order to satisfy this rule of thumb, Kawasaki redesigned the frame to lower the tail, made the central part narrower to accommodate the teardrop tank and raised the front a bit for a more relaxed and upright riding position.

Then, focus turned to the 948 cc in-line four-cylinder engine that's been retuned for more low and mid-level power and torque. In peak values it makes 111 hp (83 kW), which is quite a bit less that the 125 hp (93 kW) of the Z900, but it maxes out 1,000 rpm earlier at 8,500, and Kawasaki suggests that up until 7,000 the RS is actually stronger than the standard Z900.

Torque figures are identical in the two engine versions as far as maximum values are concerned, but once again the Z900RS reaches the 98.5 Nm (72.6 lb-ft) peak at 6,500 rpm, sooner than the 7,700 of the Z900.

Kawasaki achieved this by modifying much more than just the software of the engine control unit. In the Z900RS we find a reshaped airbox and ducts, shorter duration camshaft profiles, lower compression rate (10.8:1, down from 11.8:1 in the Z900), and a heavier flywheel. The assist and slipper clutch kit remains in the standard equipment list.

The gearbox has been converted as well, with a shorter first gear, a longer sixth, and a longer final reduction ratio that uses a 42-tooth rear sprocket, in place of the Z900's 45 teeth.

Suspension wise, the RS is almost identical to the Z900, with a small surprising twist; the 41 mm inverted forks feature full adjustability, including compression damping, while on the Z900 one can tamper only with rebound damping and spring preload. These unexpected upgrades continue to the braking department, with the RS featuring radially mounted calipers up front.

In terms of styling, Kawasaki paid careful attention to detail, so much that it even considered the exhaust note – admittedly, a first for this manufacturer. Unavoidably, the eye will first fall on the teardrop fuel tank, still accommodating 17 l of gas, just like its Z900 counterpart. But it's the little things that make the difference, like the new engine side covers and finned cylinder cases, the cast wheels that look like they're spoked, even the foot levers that are redesigned to mimic the original Z1 parts instead of just transferring the Z900's more modern, sculptured levers.

The electronic gadgetry of the Z900 is transferred directly to the RS, with the standard ABS and the K-Tric traction control system that can be configured to two levels of intervention, or be completely switched off.

The 2018 Kawasaki Z900RS tips the scales at 215 kg (474 lb), and will be produced in three color options; dark brown and orange, matte green and black, and solid black. Pricing and availability have not been released yet, so check with your local dealer for relevant information.

Source: Kawasaki

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