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/127362
GRIDING IMPRESSION1991 Suzuki RM 125/250 By Nate R au ba eW hen Suzuki first unveil ed th e new RM 125 and 250. they began with a little speech explaining how high-fashion was th e way to market a product in th e '90s. They want th e RM line to appeal to a yo ung audi en ce. the Suzuki P R gu y explained. to help attract young bu yers into the market, With th at sa id to th e ve tera n members of the press. he then seemed to beg us to please excu se th e looks of th e RM s when making evaluations. T he covers were th en lifted to reveal th e no w-fam ilia r new RM look ; yellow ta nk, [enders and fram e with whi te radiator sh rouds an d side p anel s, brown and yello w-sp lotched seat and wild pink/ yell ow paint strea k gra ph ics. Whoa! Even if you hate the new look , don 't disregard either machine. Except for th e graphic Iacelift, there is little to distinguish the new RMs from their predecessors. Hidden undern eath are a host of sim ilar changes to both machi nes that significant ly improve their performance. Underneath the p lastic Aside from the new gra phics. th e most obvious cha nge is th e suspe nsion. Big 45mm inverted forks gra ce th e fro nt ends of both bik es. and now Never mind the colors they're made by Showa. Suzu ki had used Kayaba components for years, bu t switched becau se they felt that the Showas offered a better bal ance of low and h igh speed da mp ing. pl us the extra rigidity of 45mm stanch ion tub es allows the wheel to move up when a side load is encountered instead of creating for k £lex. New triple clamps have more clamp area for added rigidity. Showa shocks are also at the rear of both ma chines and ha ve 40% more oil capacity over last year's Kayaba units. Both the fork and shock have adjus- table compression and rebound damping adjustments. Bigger forks. rough tra cks and large supercross jumps transmit a greater' load to the fra me. so its strength is increased by using a sq uare crosssectio n front down tube. The steering geometry on both mach ines has been reduced for quicker response 'and to place mo re weig ht on the front wheel for 'added traction. The lower steeri ng head bearing and adjustment nut were also altered to allow more accurate bearing preload adjustment. which has a direct effect on how the bike steers. The R MI 25 and 250 share m a ny sim ilar internal refinem en ts. but the most striking change to the '91 RM line is the wild new graphics and color scheme. The new swingarms are similar to those introduced on Suzuki's dualsport DR machines and feature a solid cast aluminum pivot body welded to larger cross-section extruded aluminum arms. Lin kage ra tes a re unchanged. but higher quality bearings and d ust seals he lp ens ure smoother movement. Both brakes have been improved with sintered metal pads, and wider Iootpegs provide better support for the rider's feet, Both the RMI25 and 250 powe rp lants have been improved by altering th e exhaust pow er valves. The valve guides have been changed so they aren't exposed to the cylinder wall for more precise exhaust po rt timing. New pistons are made with more silicon to improve durability. and the RM250 has a stronger con necting rod . En gine coo ling was im proved by movin g the cylinder head outlet to the rear which allows coolant to £low more evenl y th rou ghout the head and draws combustion chamber heat away more eHiciently. Coolant flow was also redirected in both mod els so that th e liquid £lows through both radiators simultaneously to provide more efficient engine cooling. The RM250 motor received a few more refinements than the' RM 125. Last year Suzuki fitted the 125 wit h an O-ring head gasket, and in '91 the 250 has th e same feature to provide better heat transfer . The R M250's intake manifold was shortened and a less restrictive. four-petal ' reed valve fitted to improve midrange power. Exh au st pi pe tuning was al so cha nged to improve low-end po wer and deli v. ery, and the shape altered to increase ground clearance. A resha ped. lighter silencer, a lso fou nd on the 125. is fitted to the end. Both transmissions were beefed up with strengthe ned engagrnen t dogs on the upper gears , and th e gear shift cam stopper plate was modified for improved shifting. Spin n ing w heels Suzuki makes it easy ' to race two classes on the RMs. Both machines share many of th e same characteristics on the track. and there's little trouble ju mping 0(( one machine and onto the other. The RMI25 starts in a snap, and after a short warmup is ready to hit the track. A ligh t pull on the clu tch and sligh t touch to the shi fter puts it into gear and you're ready to go . Past RM I25 mo tors have had great low-end power that q uick ly faded as the engi ne reached high rpm . This year the RM 125 is once again blessed wi th a strong pull from down low. J ust a slight turn of the thottle results in a sharp burst of power. The engine continues to get stronger u p tltro ugh the midrange and lasts longer than any