Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/127870
kiRM250W RIDING IMP E SIO 1 R S N 998Suzu (Left) Suzuki made a lot of benefic ial changes to t he 1998 RM2SO's suspens io n. (Below) New rearshock lin kages raise the bac k of the RM, giving it a better, more balanced feelin g. By Kit Palmer Photos by Kinney Jon es or a motorcycle that was late getting here, you' d assu me tha t the '98 Suz uki RM250 would be rad ically cha nged fro m th e previous model - bu t it is no t, r ea ll y . Su zuki openly admitted they got a late start on their testing program, w hich resulted in the p roducti on RM250 .ar riving in the United States abou t a mont h or so after th e o ther ma nu facturers had al ready released their mod els. Hey, better lat e I than never. An ywa y, whil e th e n e w RM2 50 might no t boast a ny obvious changes, besides gr aphics, it has taken on a few significant modifications to keep thin gs in teres ting, suc h as following Honda's (and Kawa sa ki' s, for tha t matter) lead by equip ping the RM w ith a power-jet carburetor system. Th e Keihin PWK38 carbu retor is now equ ipped wi th a solenoid-controlled p ow er-jet syste m for impro vin g, Su zuki cla ims, th e RM' s power at high er rpm. The power-jet system con tro ls a n ad ditiona l fuel circu it that sp rays fuel directly in the carburetor venturi w ithin ' a certain rpm range. Suzuki claims this system allows mor eaccurate main-system jetting needed for optimum high-rpm power. In another a tte mp t to improve topend power (as w ell as midrange), th e exhaus t-port timing, as well as the scave ng ing -port timing and s ha pe, h av e been modified , and so ha s the Suzu kiPower Chamber exhaust power- val ve sy s tem, which ha s gone from a clamorous two-stage system to a quieter and [F 48 mo re efficie n t sing le-stage de sig n. The power valve itself has been reshaped to achieve a better exhau st-p ort seal, and the exha us t rou ting to the Power Chamber ha s been modifi ed for im prove d flow. Oth er performance-enhancin g engine changes include a lar ger int ake tract, a new exhaus t pipe, and a flat-top piston, which Suzuki claims give the RM a better "hit." The intake-port shape also has be en modified to wor k w it h a lar ger re ed b lock for im proved e ngin e response, Suzuki claims. In recent years, the RM250 has been crit icized fo r its noisy mot ors, so not only d id Suzu ki go to a si ngle-s tage power va lve , th ey also reinforced the a r e a a ro u n d th e c r a n ks ha ft's m ain be a rin g , which Su z uki a lle ges w as p a rtially to bl am e . While th ey 'w ere d own th ere , Su zuki e ngi nee rs increased the weig ht of the cranksh aft to increase iner tia , thu s impro vin g po w er d eli very a nd rear-wheel tr a ction con tro l. To imp rove durability, the clutch has been beefed up and the Daido 520 chain is mad e ou t of a stronger material. So what did all these changes mean? Simply, mor e power on top and a more linear powerband . Run th e bike th rough th e gea rs for the first time and it becom es quite obvious that Suzuki shifted the bu lk of the RM's pow,:r more tow ard the top of the rpm rang e, and it managed this without sacrificing too mu ch power off the bottom . The bik e pulls nicelyoff the bottom, runs strong in the middle and revs out well on top . Overall power is good s tro ng and healthy, but so me o f our testers felt the RM just didn't quite have the "hi t" the y wanted wh en slamming. into a soft or powdery berm, especially