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It didn’t take long after the introduction of Kawasaki’s Ultra 250X for the aftermarket companies to produce an engine performance kit for the craft. Some companies were advertising their kits, but they were not readily available in the marketplace.
The only well-known company that actually designed, developed and manufactured an engine performance kit for the Ultra 250X is R&D Performance Products USA of Santa Fe Springs, Calif. This is the same company that has cooperated in the past with well-known athletes and pioneers of the sport in order to produce precision aftermarket accessories and engine performance packages. The result has been a boatload of National and World titles.
Tuner Bill Chapin and his partner Glenn Dickinson are the most important people in the R&D factory. Chapin is based in Lake Havasu City, Ariz., where he is responsible for the research and development of all R&D’s accessories. Dickinson, on the other hand, is based in the suburbs of Los Angeles where the plant is located. In the past he has supported riders such as ChristyCarlson, JeffJacobs, NicolasRiusand ChrisMacClugage.
After having met with Chapin, we decided to test out the ‘kited’ Kawasaki Ultra in Havasu after the World Finals wrapped up. This particular craft was tested extensively by Chapin and MacClugage, so it was certainly operated under some hard working hours. We set up a meeting in Body Beach and Chapin showed up with the Ultra equipped not only with the engine performance Stage 1 kit, but also with the R&D handling kit, the one-degree wedge and the pump cone.
After spending time on the modified Kawi, there is no question that the kit-equipped Ultra 250X performs much better than the stock version. The most crucial element is the good throttle response from idle and the instant acceleration it provides under all circumstances. Additionally, the engine power is live through the whole power band and there is no hesitation on engine response when you instantly close the throttle.
The kit-equipped Kawasaki accelerates sharply in tight turns without bogging off. This unique engine performance verifies the fact that Chapin has done an excellent job on the fuel-delivery system as well updating the cooling system – two facts that play a key role in the enhanced performance of the Kawasaki power plant. The engine response is sharp and accurate under any sudden glimpse of the trigger throttle. The acceleration keeps surprising you even at mid rpm where the craft pulls hard, and not linearly like the stock craft.
Multi-time Greek national champion Akis Malouchos was surprised with the performance of the kit-equipped Kawasaki.
“The engine response is great from very low rpm and it accelerates harder through the whole rpm scale. It is a great package for racers (since the level of engine tuning is medium) as well as for the weekend warriors,” says Malouchos.
According to Chapin, in addition to the engine performance kit, the Ultra 250X was also used extensively for testing the handling kit (intake grate, plate and sponsons). With so many hours of use, the engine was warned out and the cylinder/piston clearance was out of shape. A craft would have pulled even harder if a new set of pistons and rings had sealed the cylinders.
We tried to get a speed reading of the kit-equipped Kawasaki; however, we did not get any signal from our two GPS units so we were out of luck. This is a common phenomenon in Arizona and it has happened to us several times in the past. The next day, however, Chapin himself tested the boat and clocked 71-71.8 mph consistently with the engine rpm level somewhere between 8,150-8,200 rpm. Those are the same figures MacClugage saw during the summer in Havasu.
When I tested the stock Kawasaki Ultra in France I saw a top speed of 70mph on the GPS screen and two other riders confirmed that reading. That craft was a preproduction unit and the test was carried out on flat water under seven degrees Celsius (about 44 degrees Fahrenheit). Since the production units were clocking a top speed somewhere between 65-67 mph this leads me to believe that the numbers reported by Chapin for R&D kit-equipped Kawasaki are accurate.
The R&D kit comes complete with detailed instructions for its installation. R&D also offers special tools, AFR gauges, boost gauges and fuel pressure gauges. Tools and gauges are sold separately.
The kit design is based on the fine tuning of air/fuel rate and the intercooler temperature, as well as the rpm of the supercharger. R&D’s kit is the answer for anybody looking for a complete, reliable, tested horsepower package.
Outfitting a Kawasaki Ultra 250X with the Stage 1 performance kit will set you back US$3,616.
Ultra 250X Supercharger Engine Performance Stage 1 Kit:
R&D 1 to 1 Supercharger Booster Wheel
R&D Tensioner Wheel
R&D Powershot Fuel Control Unit
R&D 625cc High Flow Fuel Injector Kit
R&D Fuel Pressure Regulator w/Mounting Bracket
R&D Fuel Pressure Gauge Adaptor
#4 AN style Fuel Rail Fitting
#4 AN Return Line Fitting
preassembled SAE Coast Guard Approved Fuel Lines with #4 AN fittings.
Additional equipment on the craft:
R&D crank vent
R&D surge block off air filter>
R&D pump cone
R&D carbon ride plate
R&D intake grate
R&D air/fuel ratio gauge
R&D boost pressure gauge
R&D Pressure gauge
Catching up with R&D Performance Products
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