kawasaki Ultra 250X Details
Engine
- 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’s 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
Exhaust
- 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
Impeller
- 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
Hull
- 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
Sponsons
- 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