SPECIAL FEATURE
2004 SUZUKI RM-Z 250 IT’S PRETTY SURREAL TO THINK IT’S ALREADY BEEN TWENTY-YEARS SINCE THE BIRTH OF THE MX2 CLASS IN THE FIM MOTOCROSS WORLD CHAMPIONSHIP, AND WITH IT, THE EVENTUAL DEMISE OF THE 125CC 2-STROKE ERA AND THE 125CC CLASS AT WORLD CHAMPIONSHIP LEVEL.
Whilst Yamaha had led the way with the new, innovative 4-strokes with the introduction of the production YZ400-F in 1998 and YZ250-F in 2001, the pressure from the other brands to jump on board and offer up some resistance was increased, in time for the 2004 MX2 era, and for Kawasaki and Suzuki, that meant joining forces in order to come up with a plan. So, in this issue of MXGP Magazine, we take a look at Suzuki’s contribution to the dual-effort and how the RM-Z 250 came to be. Designing and developing new products is never easy, nor is it cheap, and as a response to what Yamaha was already doing with its YZ250-F, Suzuki and Kawasaki announced in August 2001 that they were forming a ‘Strategic Alliance’ with the intention of producing a joint 250-F effort, in readiness for the new era of the ‘baby boomer’ 4-stroke machines. Of course, it goes without saying that the obvious benefit from this exercise was based around money, and how much they could save, and so from that side, the intriguing question was which side of Japan would be designing what, and how different or similar would the bikes look when they rolled off the production line? And which production line would that even be; Kawasaki or Suzuki? As it turned out, both machines would eventually roll off the Kawasaki production line in Akashi, Japan. When push came to shove, we later learned that the engine side of things would be designed by Suzuki, with Kawasaki responsible for the chassis, and actually, when all was said and done, the only difference between the two was the colour and the design of the plastics, and by the end of 2003, both bikes broke cover for ‘Media Tests’ ahead of what would be an important 2004 debut season. With no previous 4-stroke experience to draw upon, Kawasaki’s reference point regarding the frame was the KX125, which from a chassis
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perspective, had been using a twin-spar steel perimeter frame since 1990, and since that side of things wasn’t ‘broke’ so to speak, there was no obvious reason to try and fix it. One thing that Kawasaki did introduce though, was a new D-section where the perimeter frame tubes were designed to ‘allow the bodywork to hug the frame more closely, thus offering a slimmer design and better riding position.’ In fact, everything to do with the chassis came out of KHI (Kawasaki Heavy Industries), and so from that standpoint, that also included the 48mm KYB cartridge fork and KYB rear shock. Why was this so relevant? Well, for as long as most people could remember, Yamaha and Kawasaki bikes came with KYB, whereas Suzuki and Honda always utilised Showa, and so this was seen as a massive shift for Suzuki – especially since the 2004 RM range of 125cc and 250cc 2-strokes still came with Showa suspension! The forks were new and ran check valves on the bladders to help improve damping, offering an overall smoother action through the stroke. The rear shock was also new and so too was the new-link Uni-Trak system which was designed to transmit suspension input via the swingarm, which therefore allowed the frame to be lighter. With a much simpler rear shock motion, the suspension action was therefore smoother, which according to the technicians at the time, helped to increase traction at the rear wheel by 35%. As far as the motor, Suzuki’s reference point was already out there. Okay, it might have been dressed in blue plastics, but as a starting point to where you can see what the competition had already been doing, then why not see what can be done differently, right? Right! At that time, Yamaha’s engine ran five valves, so Suzuki’s response was not only to