The Suzuki/Kawasaki offering has more low-end grunt than the YZ, but it vibrates more than its counterbalancer-equipped rivals.
On the track, the rider layout just feels right. The KXF/RM-Z has the most bottom-end grunt in the class and pulls longer than the Yamaha between gears because it builds revs just a tad slower. This doesn’t mean that the Yamaha and Honda have better motors, they’re all just different. The Kawasaki actually turned out the best peak horsepower numbers on the dyno at 34.26.
“The Kawasaki felt very powerful explosive for a small-bore bike and revved out to a very sweet high note,” said Rob Barnum, a 38-year-old desert racer and grand prix champion. “On short takeoffs it was awesome, then felt feathery and nimble in the air,” added the former Supercross privateer tuner who has just opened Barnums Pro Products that specializes in 4-stroke motor and suspension work.
One thing riders noticed about the KXF/RM-Z is that it vibrates more than the other two bikes. This can be attributed the lack of a counterbalancer in the motor; the Honda and Yamaha have counterbalancers. The bikes also seem to pop a little between gears on wide-open shifts. We can say that neither our KXF nor RM-Z overheated during the testing, which some magazines have been reporting, which might be caused by leaning out the jetting too much.
The only problems we had with our KXF and RM-Z test bikes were occasional fits of starting woes when the bike was hot. Since none of these bikes have decompression levers, Kawasaki’s technician, Ryan Collins, taught us a valuable trick that will help start any hot or crashed modern, high-performance 4-stroke. After turning the fuel off, you slowly twist open the throttle of the Keihin FCR carburetor. When FCR carbs are twisted open quickly, they squirt fuel into the motor, which makes starting more difficult. When opened slowly, however, no fuel is squirted in, and you’ve just opened the slide to allow another burst of fresh air in to help dissipate some of that extra fuel. After kicking the bike over several times with the throttle open, release the throttle back to closed, pull the hot-start out and give another it another real kick or two. When the bike starts, turn your gas on and ride away.
The Suzuki/Kawasaki proved to be a great first-effort in the class, taking wins in the handling category and the dyno peak power contest.
The suspension and chassis of the KX/RM do a fine job of handling the track irregularities. The faster test riders, however, thought its rear shock was perhaps too soft and bottomed quite often. This didn’t seem to hold it back much in the suspension category of the shootout, as the KXF/RM-Z tied for second with the Honda CRF in overall suspension performance.
Both Kawasaki and Suzuki shortened up their front-brake-line routing like Honda’s and, consequently, the brakes are very good. Not surprisingly, the KXF/RM-Z took first overall in the handling and rider-layout categories. Test riders just love the way the bikes feel underneath them and handle. “The skinny layout made it easy to turn,” commented one test rider. They are very competitive machines, indeed.
2004 XR250 vs DR-Z250 vs KLX300R Conclusion
2008 Superbike Smackdown V “Laptimes”
2008 Superbike Smackdown V “Scoresheet”
2008 Superbike Smackdown V “For My Money”
2004 250cc 4-Stroke MX Shootout
2004 Yamaha YZ250F Comparison