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Kawasaki Ultra 250 X



250 horsepower provides dominating performance

Kawasaki stunned the motorcycling world with the launch of its Ninja® ZX-14 flagship. It didn't take long for the mighty ZX-14 to assume its rightful place as the quickest and fastest stock production motorcycle. Now, Kawasaki extends its high-performance domination into the realm of personal watercraft. As the quickest and most powerful production PWC in history, Kawasaki's new JET SKI® Ultra® 250X serves notice that ULTRA defines the pinnacle of PWC performance.

The supercharged Ultra 250X delivers 250 horsepower for astonishing acceleration that can be felt in the rider's soul. Once up to speed, its precise handling and superb stability are equally impressive, thanks to a brand-new hull specifically designed to capitalize on the engine's awesome performance.

The JET SKI Ultra 250X's new engine, jet drive and hull incorporate racing technology refined through Kawasaki's multiple IJSBA championships. This same technology allows it to deliver the awesome acceleration of a drag racer, and help ensure excellent hook-up - even in rough water.

With a 1,498cc marine engine derived from Kawasaki's astounding JET SKI STX®-15F watercraft, the Ultra 250X produces power comparable to a normally aspirated high-performance three-litre engine, thanks to the addition of a Roots-type supercharger. Unlike centrifugal superchargers or turbochargers, the Ultra 250X's high-volume direct-drive supercharger delivers boost virtually instantly at any engine speed from idle to redline. This results in a linear, smooth torque curve which is ideal for a personal watercraft that needs to accelerate hard all the way from a standstill through astounding top-end speeds.

A common drawback of forced-induction is the heat build-up that occurs when the intake air is compressed. The Ultra 250X overcomes this with the use of a large-capacity intercooler. The 250X's supercharger compresses the air to a maximum boost pressure of 11.4psi. This compression heats the intake charge to extremely-high temperatures, which could limit the engine's power output. However, the 250X's large-capacity intercooler cools the intake charge back down to ambient temperature or even less - ideal for producing maximum power.

The JET SKI Ultra 250X's stunning acceleration is augmented by a huge 155mm jet pump featuring the largest PWC impeller and nozzle Kawasaki has ever produced. Developed based on feedback from Kawasaki's race machines, this pump was specially designed to deliver predictable thrust and good traction, even when riding on rough water. The pump uses eight guide vanes (instead of the six used on previous models) to regulate the flow of water from the impeller for efficient and powerful propulsion. This is a significant factor in the Ultra 250X's mind-boggling acceleration. The new pump incorporates a groove from the center to the rear of the ride plate which makes it easier to hold a stable heading when riding in a straight line.

To suit the 155mm jet pump a new, larger impeller was designed, offering improved bite in the higher speed ranges. The sophisticated three-blade design not only delivers high performance, but also provides smooth and quiet operation.

In addition to more power and acceleration than any other production watercraft on the planet, the Ultra 250X also boasts an all-new race-developed hull. Extensive research and refinement has allowed Kawasaki to design a brand-new hull which is just as comfortable in rough conditions as in calm. Even at high speeds, rough water can do little to deter the Ultra 250X. This combination of unearthly power mated to the latest hull technology allows Kawasaki's flagship to literally cleave through waves that would send lesser machines running for safe harbor.

In addition to its acceleration and top-speed capabilities, the Ultra 250X also offers precise handling and superb stability, thanks to a hull that was specifically designed to compliment the engine's incredible output. This fiberglass reinforced plastic (FRP) hull is loaded with DNA from Kawasaki's IJSBA championship winning machines. This includes carefully designed sponsons and chines for enhanced straight-line stability and precise cornering, combined with a 22.5° deep-V hull for a smoother ride in rough water.

In recognition of the tremendous power on tap, Kawasaki designed the Ultra 250X's hull to lean into corners like a motorcycle. This helps passengers stay centered, and keeps the rider in control during peak cornering g-forces.

The Ultra 250X features a five-step adjustable handlebar position that allows either stand-up or sit-down riding for enhanced comfort and versatility. As Kawasaki's flagship watercraft, the 250X includes thoughtful standard features like an enormous 53 gallon detachable front storage compartment and a 20.6 gallon fuel tank (the largest in its category) for substantial cruising range.

From horsepower to handling and everything in between, once the spray settles after the first ride, one thing will be certain. As the most powerful PWC on the planet, this ultra new JET SKI offers performance and excitement that are unmatched by any other watercraft.



  • Liquid-cooled 1,498cc, in-line four-cylinder engine is fitted with a supercharger and intercooler.
  • Most powerful production PWC engine in the world.
  • The 83.0 x 69.2mm bore and stroke are the same as the JET SKI STX®-15F's powerplant.
  • Compression ratio is lowered to 7.8:1, to minimize detonation at high-boost pressures.
  • Inconel exhaust valves are fitted for superior heat resistance and enhanced reliability (Valve sizes are: 33.4mm intake / 28.3mm exhaust).
  • The engine' over-rev capability has been raised by 700 rpm (redline is 8,900 rpm).
  • Precise power adjustments are easy with a throttle lever that is designed to prevent finger fatigue on longer rides.

Roots Type Supercharger

  • The Roots type supercharger design produces large amounts of boost even at low rpm, for instant and powerful acceleration right off of idle
  • Force-feeds the engine two liters of air with every revolution, providing a stable supply of high-pressure intake air at all rpm
  • Provides a very flat and meaty torque curve with step-free power across the rev range and none of the lag associated with turbochargers
  • Produces a maximum of 11.4psi of boost pressure
  • Produces more low RPM boost than competitive or aftermarket systems
  • To prevent over boosting at low and medium rpm, two different air bypass valves are used
  • The smaller air bypass valves releases low amounts of excess pressure build-up, for precise boost management
  • The larger air bypass valves is used when excessive boost pressure is accumulated, to maintain an even intake pressure even when giving full-throttle from idle

Air-to-Water Intercooler

  • Efficiently cools the high-pressure intake air
  • Cooler air results in higher combustion efficiency and high engine output
  • Liquid-cooling allows the intercooler to maintain consistent thermal performance

Fuel Injection

  • New, high-flow fuel injectors with four orifices are fitted to complement the increased power output and improve combustion efficiency
  • Single throttle body features a large 60mm bore diameter


  • The Ultra 250X features a 4-into-2-into-1 powerboat-style exhaust system, which routes the exhaust pipe upwards.
  • Allows the smoothest path for exhaust gases, maximizing exhaust efficiency

Jet Pump

  • To efficiently convert the Ultra 250X's massive horsepower into thrust, an all-new, large-diameter 155mm jet pump was designed.
  • Developed based on feedback from Kawasaki's race machines, this pump was specially designed to deliver stable output and good bite, even when riding on rough water.
  • The reverse lever has been moved from the right side to the left side for easier operation


  • To suit the new 155mm jet pump, a larger impeller was designed, offering improved thrust in the higher speed ranges.
  • The sophisticated three-blade unit delivers both high performance and quiet operation.

Guide Vanes

  • To suit the new jet pump, a new eight-vane intake guide is used. These guide vanes smooth and regulate the flow of water from the impeller for efficient and powerful propulsion.
  • Eight guide vanes provide superior traction compared to the older six-vane system

Ride Plate

  • Features a groove from the center to the rear of the ride plate, to enhance straight-line stability


  • The new hull was designed based on feedback from Kawasaki's IJSBA championship winning racing machines.
  • Specially designed to cope with the engine's horsepower.
  • Offers a combination of high stability and responsive handling in both calm and rough-water conditions.
  • Delivers the neutral handling and turning characteristics that made Kawasaki JET SKI watercraft famous.
  • The new super-strong hull is 250mm longer, to ensure stable handling performance with the larger, more powerful engine.
  • The lower hull is specially designed to distribute the engine and power delivery loads over a wide area.
  • Although it has a similar V-shape to the JET SKI STX-15F, the Ultra 250X's hull enables a high bank angle, for motorcycle-like turning performance. This reduces the side G-loads imposed on riders during turns.
  • The V-angle at the bottom of the hull has been changed to 22.5° to help prevent spinouts during sharp turns and to provide a smoother ride in rough water.
  • To avoid concentrating heavy components towards the rear, the battery is located inside the front storage area near the center of the machine. This remote location also frees up space inside the engine bay.

Bond Flange & Bumper

  • The bottom of the hull slants upwards steeply from the center section to the bow, allowing the Ultra 250X to penetrate swells and waves with less shock. At low speeds the result is extreme stability; at higher speeds the Ultra 250X's massive thrust enables the hull to push through waves rather than bounce over top of them.


  • Newly developed sponsons extend further from the hull, providing stable straight-line performance while helping to retain the narrow hull design. They also contribute significantly to the Ultra 250X's excellent maneuverability when changing direction (particularly at higher speeds).

Quattro KSD

  • Ridges across the bottom of the bow, Kawasaki Splash Deflectors deflect water splashing forward from under the hull. To reduce spray during high-speed turns, the earlier triple splash deflector now has one more deflector mounted at the top. Whether turning or blasting straight ahead, at high speeds or low, the Quattro KSD minimizes spray, allowing greater rider concentration and a drier ride.

Kawasaki Smart Steering®/SLO-Mode

  • Kawasaki Smart Steering (KSS®) is equipped to help new riders better enjoy the performance of this remarkable machine.
  • Smart Learning Operation (SLO)-Mode function allows newer riders to become familiar with the handling and response of this JET SKI watercraft at a more relaxed pace before unleashing the full power of the Ultra 250X. Two separate keys (one for SLO-mode, one for full-power operation) help prevent confusion over which setting is in use.

Comfort and Convenience

  • Five-way adjustable handlebars allow operation while standing or sitting and are designed to suit a wide range of riders.
  • Relatively narrow seat is comfortable for either stand-up or seated riding, or when riding with passengers.
  • Ergonomic deck design gives plenty of legroom without necessitating a high seat, for rider-friendly seating accommodations.
  • A long rear boarding step makes it easy to climb on board, and the step retracts inside the bumper to prevent damage.
  • A quick and easy under hood hose connection allows nearly silent cleaning system to flush sea water out of the engine.
  • Mirrors are mounted to the upper deck to facilitate opening of the hatch cover.

Capacious Storage

  • The large-capacity, fully sealed 53 gallon storage area has plenty of room for recreational equipment. A detachable storage tray is also fitted.
  • Mounted on the center console is a detachable drink holder with space for two drink bottles.
  • A compact storage area is integrated with the under-seat rear grip and ideal for small items.

Increased Fuel Capacity

  • Offering more fuel capacity than any machine in its class, the Ultra 250X's 20.6 gallon fuel tank holds 3.7 gallons more than the JET SKI STX-15F watercraft