Stock Ultra 250 Avg. Speed 65.5-66 mph @ 7600-7700 RPM
R&D Performer Kit Avg. Speed 72-72.5 mph @ 8050-8100 RPM


Description of Parts RPM Top Speed
R&D Ultra 250X Ride Plate Kit
Part #: 121-25000
7700 68.5-69 mph
R&D Ultra 250X Pro Series Sponson Kit
Part #: 121-25001
7700 69-69.5 mph
R&D Ultra 250X Aquavein Grate Kit
Part #: 111-25000
7750 69-69.5 mph
R&D Ultra 250X Pump Shoe Seal Kit
Part #: 161-25000
7750 69-69.5 mph
R&D Ultra 250X Anti-Cavitation Cone
Part #: 161-25010
7750 69-69.5 mph
R&D Ultra 250 1 Degree Pump Wedge
Part #: 141-25001
7750 69.5-70 mph
R&D Ultra 250X Cool Air Filter Kit
Part #: 215-25000
7800-7850 70-70.5 mph


R&D Ultra 250X Powershot Fuel Controller
Part # 801-25000 (2008 Performance Option)
7800-7850 70-70.5 mph
R&D Ultra 250X Emission Blockoff Kit
Part # 331-25000
7800-7850 70-70.5 mph
R&D Ultra 250X Deep Fuel Pickup
Part # 801-25100
7800-7850 70-70.5 mph
R&D/Solas 16/21 Concord Impeller
Part # 131-01621
7900 70-70.5 mph
R&D Ultra 250X Performer Engine Kit
Part # 611-24349
8050-8100 72-72.5 mph

 Parts/Kit Overview

The R&D 2007-2008 Kawasaki Ultra 250X Performer Kit was developed to improve overall handling, reduce pump cavitation, and increase top speed performance with strictly bolt on performance parts without engine modifications! The entire Performer Kit installs quickly and very easily with basic instructions and hand tools. Each component part in the Performer Kit can be used as a stand alone product delivering the performance gains individually charted above. The new 2007-2008 Kawasaki Ultra 250X engine platform is significantly different over previous Kawasaki models with its new roots type supercharger. The new supercharged Kawasaki engine is a fantastic power plant; however the 950-1000 pound weigh-in without a fuel load has left the engineers at R&D a big challenge to work with. The R&D Performer Kit will add a noticeable 4-5 mph increase in top speed performance with superb handling benefits. The R&D Performer Kit will transform a great boat into “The Perfect Boat”. The R&D Performer Kit parts have been offshore endurance and closed course race tested and have chocked up some impressive wins in the 2007 season as well as world championships in the stock 4-stroke runabout class at the world finals.

  • The R&D Kawasaki Ultra 250X Ride Plate has been fashioned after our dominant and championship winning GP-1200R and Kawasaki 15-F ride plate designs with a few new tricks added. The Ultra 250 ride plate is extended 30mm and re-angled over stock to reduce porpoising while the new R&D stepper concept will add top speed. R&D's Ride Plate concepts are the only aftermarket designs to dominate in Offshore, National, and World Championships, and to be used and endorsed by Factory Yamaha and Kawasaki racing teams for nearly a decade! The new Ultra 250X ride plate from R&D is “The Perfect Ride plate” with a great balance of speed and handling with no compromises!

  • The R&D Kawasaki Ultra 250 Pro Series Sponson Kit will deliver higher top speed performance and a much smoother and more predictable ride over O.E.M. sponsons. Low speed and high-speed turns are a breeze with new found control! The secret to R&D’s new generation concept is in the backing plate design with an aftermarket first, low pressure, low friction concept that breaks up and relieves speed robbing drag within the sponson’s backing plate channel. The new R&D design staggers the sponson blades fins water trapping area to pick up less water in the front and more in the back. The stagger/step-up concept greatly reduces chine walk in high speed corners, while allowing more rear end grip. There is also a higher end recreational/race setting with enough grip for the best of pros! Finally there is an aftermarket sponson kit that really does it all! More top speed due to less drag, less chine walking, racer preferred rear end grip, and unmatched straight line stability.

  • The R&D Kawasaki Ultra 250X/LX Aquavein Intake Grate Kit will substantially reduce impeller/pump cavitation, dramatically increases overall handling, and adds a 3 to 4 mph average top speed in choppy water conditions by keeping the pump loaded and hooked up!

  • The R&D Kawasaki Ultra 250X/LX Pump Shoe Sealer Kit was developed to quickly and easily fill the large casting pockets in the O.E.M. Kawasaki Ultra 250 pump shoe inlet. Installing the R&D pump shoe sealer kit and resealing the pump shoe and intake grate will reduce low and high-speed cavitation, which will increase overall pump efficiency and performance!

  • The R&D Kawasaki Ultra 250X/LX Anti-Cavitation Pump Cone Kit will reduce overall internal pump cavitation within the Kawasaki Ultra 250’s offset reduction/compression nozzle design. The O.E.M. Ultra 250 reduction/compression nozzle is offset 5 degrees, while the O.E.M. pump cone/bearing cap remains straight which causes uneven pressures within the pump and reduction nozzle. The R&D Anti-Cavitation Pump Cone is offset 5 degrees and reshaped to match the O.E.M. reduction nozzle offset promoting even pressures, which will substantially reduce cavitation, increase pump hook up, boost acceleration, and increase top speed performance.

  • The R&D Kawasaki Ultra 250X 1 Degree Reduction Nozzle Wedge Kit for the new Kawasaki Ultra 250 will add quicker acceleration and top speed performance as well as allow the Ultra 250’s bow to ride slightly higher, which will significantly reduce annoying bow spray promoting a much dryer ride. Extensive testing has led our development team to wedge the reduction nozzle up 1 full degree, which will inexpensively give the Ultra 250 better handling everywhere and provide a boost of up to 1 mph in top speed performance. In fact, a much smoother and more predictable ride will be noticed, along with the reduction of annoying bow spray! The billet aluminum CNC machined 1 degree reduction nozzle wedge kit was specifically designed to work without compromising or removing the O.E.M. reverse gate. The R&D Pump Wedge Kit comes complete with all the necessary hardware and instructions for easy installation. A smoother, more enjoyable, dryer, faster ride! Only from R&D!

  • The R&D Kawasaki Ultra 250X/LX High Performance Air Filter Kit will improve acceleration and top speed performance by increasing air flow and reducing air temperatures that enter directly into the Ultra 250’s air plenum box area. The O.E.M. air plenum box on the Ultra 250 is a great design that will flow plenty of air, however, the air that feeds the plenum box is heated by the engine. R&D has created an easy to install “flat filter” that installs directly in place of the large center access inspection cover located directly under the main glove box. The R&D Flat Air Filter insert will allow unrestricted fresh and cool air to enter the air plenum box area, which will add power you can feel and a nice high performance tone. The R&D Performance Filter Kit also features two filters, one for each of the surge and blowoff protection valves. The O.E.M. surge valve recycles compressed hot air back into the air box plenum at idle and under deceleration conditions. The R&D surge and blowoff valve filter kit removes the air recycling hoses, which will keep the hot air from entering the air plenum box reducing the engines intake air temperatures. The R&D Ultra 250 Air Filter Kit offers great performance tips on how to remove the restrictive air vent hoses which will further reduce the under hood/under seat ambient air temperatures. The R&D Filter system does not remove or alter the O.E.M. plenum box in any way; therefore there are no questions to be answered regarding water ingestion! The R&D Filter Kit is easy to install with no modifications required to the O.E.M. parts.

  • The R&D Kawasaki Ultra 250X/LX Exhaust Emission Blockoff Kit was developed to block off the O.E.M. exhaust emission ports located in the valve cover that connects to the exhaust ports. The Kawasaki labeled “air suction valve” operated effectively under low speed and cruise RPM ranges allowing air to be pulled from the main air box plenum and into the exhaust ports, which will result in a lower measured emission ratio (cleaner). The air suction valves fiber reed pedals can become heat damaged over time, which can cause the valves to leak or back flow hot exhaust gases back out of the valve at sustained W.O.T. (wide open throttle) operations. Leaking air suction valves can result in a melted PVC connector T and poor top speed performance. The R&D Air Suction Blockoff Plate Kit will reduce exhaust gas temperatures, reduce exhaust back pressures, improve low and top speed performance, and deliver a more accurate and precise air to fuel ratio for precision high performance tuning accuracy. The R&D Air Suction Blockoff Plates are a great addition to any recreational application to remove expensive prematurely worn valves that can cause poor performance. The addition of an R&D Blockoff Kit will be strongly suggested on any stage level of performance modifications on the Ultra 250X.

  • The R&D Ultra 250X Deep Fuel Pickup is designed to maximize fuel volume. The stock fuel pickup is located housed in the gas tank three inches above the bottom of the tank. This leaves approximately 5 gallons of lost fuel in the bottom of the tank. The R&D Deep Fuel Pickup relocates the stock fuel pickup to the bottom tank in a vertical position. The new positioning allows for 24 percent more riding time per tank of gas. An absolute must for long recreational rides or offshore racing.

  • The R&D Kawasaki Ultra 250X Solas 16/21 Concord Impeller replaces the O.E.M. standard 3-blade impeller with a sleeker, better performing high-performance blade design. Precision polished blade surfaces will improve low-end response and increased top speed performance of up to 1 mph!

  • The R&D Kawasaki Ultra 250X Performer Engine Kit Option will add a great boost in overall power. Increased low end and mid range response and acceleration, as well as a solid 2 MPH gain in top speed performance. The R&D Performer Engine Kit consists of an R&D 1-1 Supercharger Booster Wheel, R&D Powershot Fuel Control Unit, and an R&D High Performance Fuel Pump Kit. The R&D Performer Engine Kit will deliver more horsepower reliably with the properly matched fuel control component parts only available through R&D. The R&D Performer Engine Kit will perform excellent in all recreational riding conditions using 91 octane pump gasoline.

NOTE: R&D Performance suggests that the O.E.M. blowoff valve be serviced and inspected to verify that the O.E.M. boost pressure of 10 P.S.I. is set properly. R&D Performance offers a blowoff valve adjustment kit, which will be necessary to check and verify the valves pressure setting. If poor performance and low peak RPMs are noticed, use the R&D Blowoff Valve Pressure Adjustor Kit to check and properly adjust the valves blowoff pressure. Some O.E.M. valve settings blowoff prematurely, leaking off and robbing valuable horsepower with low 6-8 P.S.I. settings. The R&D Kit is a necessary tool kit to readjust the blowoff valves pressure settings up to 14 P.S.I. when using R&D Booster Wheel Pulley Kits. The R&D Blowoff Valve Pressure Adjustor Kit has helped many top dealers service departments reset the O.E.M. valve system to O.E.M. valve specifications to keep the Ultra 250X performing properly. R&D Part # 611-26005. R&D also offers a completely adjustable high performance blowoff valve that will be a much better upgrade over the prone to fail or break O.E.M. plastic valve. R&D Part # 611-25210.

NOTE: R&D Performance has tested, data logged, and documented that the 2008 Ultra 250X has an overall leaner fuel map installed in the E.C.U. over the previous 2007 Ultra 250X. R&D suggests that the R&D Powershot Fuel Control Unit should be installed on all 2008 Ultra 250s using the R&D Performer Kit. R&D in house and Independent tests on 2008 Ultra 250X have proven that with the internal changes Kawasaki has made to both fuel and ignition timing maps, and the addition of the R&D Performer Kit with Powershot to have overall quicker acceleration and better top speed averages over the 2007 Ultra 250. R&D suggests that the Powershot Fuel Controller should be installed on all Ultra 250Xs as a great performance power adder. R&D Part # 801-25000

NOTE: R&D Performance suggests that high quality 91-92 octane fuel be used exclusively in the Ultra 250X. R&D Performance testing on the Ultra 250 was done using Chevron Techron 91 Octane.

NOTE: R&D Performance offers a unique supercharger air temp sensor interfacer which may be necessary on some Ultra 250X units. There have been some Ultra 250X models that will default into “limp home mode” if the charger temperature sensor is peaked prematurely. Any Ultra 250 which has this default occur on long rides on hot (115 degree) days should install the R&D Supercharger Temp Interfacer Kit. The Interfacer is an inexpensive fix for this randomly occurring problem on random boats. R&D Part # 801-25008


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