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/126042
.... . 0.. < By John Huetter and Gary Hymes IT'S ALM OST LIKE the powers that be a t Hamamatsu were sitting ba ck wai ting to see if the motorcycle-buying public really wanted production replicas of the Suzuki works racers. Could there really be an y doubt in their minds t ha t they could sell lots of production bikes p atterned after the light, powerful mac hines tha t car ried Roger DeCoster, Joel Robert , and Gaston Rahier to a total of eigh t wo rld titles? They got their feet wet in serious production motocross racing last year with the first of the RM series bikes : the 12 5 " M" model. Then th e surp ri ses of the RM250 and RM370 quickly followed. With their first 125cc World Championship in pocke t, Suzuki de cided not to wait several years to build a production vers ion of Gaston Rahier 's R A75 123c c te rror . At th e end of March, repres entat ives o f th e U.S. mote-press were invited to come ra ce this n ew 125 o n th e Am erican Grand Prix co urse at Car lsb ad, Calif ornia. The machine revealed there, des ignated RM 125 A, just impressed the he ll ou t of every body . Essentially , Suzuki has taken several pages from the design no tebook of th e RM works bike and us ed many of the same, or same type, he avier and be tt er quality cornponen15 from th e bigger RMs to build th e all-new RMI25 A. It has lit tl e in co mm o n with either previous TM Suzukis or the prior RM except name and color. The fr am e ma terial has be en transformed from mild steel to th in wall chrome moly steel wh ich results in a lighter, more rigid ch assis. The front suspension now has a full 200mm of tr avel (nearly eight inc he s) with larger diameter forks similar in tube size to the RM2 50 . The offset front ax le is not necess ary with this length fork . At the rear there is a new swin garm and Kayaba ni trogen /fluid dampers ca nted to the lower mounts at 4 5 degrees. Rear axle t ravel now goes a shade ove r eigh t inch es (2 12m m) . The engi ne re tain s six transfer ports but gains th e cran kcas e reed valve fou nd on the big RMs. The intake co n figurat io n of t he t ransfers h as been altered, however. There is now only on e b rid ge o n each side at th e lower Look twice (t op rt.] , Very little on engine unit interchanges with earlier RM Below, fea rless tester checks rear traveL Chassis diagram(opp.} has 1975 specs in parenth eses f or comparison . And- YaHOO ! Forgiving Iii ' de vil... end wh ich allows a greater uninterrupted are a to suc k up th e cha rge. Suzuki claims th is design imp roves lo w- and mid-range to rq ue characteristics. Rid ing th e"A" model bears this out as it has a mid-range that will be the en vy of an y 125 owner without such an en gine. The cylinder head has been redesigned with th e sparkplug offset to the squish dome and thereby angled into the cool air stream. There is a larger 3 2mm Mikuni carb with a bigger oiled foam aircleaner to m at ch . Other engine changes : The piston crown has been relieved slightly around the edges for better transfer port flow; piston pin size is increased from a nominal 14mm to 16mm. The "A" piston also use s th inner rings th an the "M" series. It all comes togethe r on the co urse . The new RM handles very well , with a feel and st ability over the ro ug h m ore charac teris tic of a 25 0. It turns qu icker tha n the ol d RM without ever be in g twi tchy, On top of tha t, it seems to be more sta ble in a slid e aro und a smooth sweeper . Most 125s have to be bulld ogged through a slide be caus e of p owe r fluctuations as the attitu de and rear wh eel traction ch ange . T he RM "A" didn 't . It feels li ke a big bike, not a toy, with surprising solidi ty. Some of th is is attrib utable to the rigid chro me mol y chassis and longer 55-inch wheel base. So me o f it is no doub t d ue to the smoothed out power delivery of the en gine. The engine see ms to hav e two powerbands. It had mo re m id-ran ge pow er t han any 125 ridden to date . When it carn e on the pipe , it p ulled righ t away in each gear and very strongly . You co uld ac tua lly sho rt shi ft it fo r th e mo st rapid exi t fro m turns, wh ich is a neat tric k with a 125 - often an impossible one. It is peak y in th e sense that t he to p end power co mes ....rith ano ther..;: noticeable surge and the RM will ma ke horsepower up to 11,000 RP~I. They do recomm end new rin gs aft er every"" two race meets and a new pis to n af ter every five. The:~ powerband m ad e it easy to ride even if yo u . don '\ " norma lly go. for 12 5 ra cers all that mu ch. • Th e six-spe ed gearbox is well-match ed to the power output and ano ther new item on the UA " model f (Inci den ta lly , th e works RA 76 is also running a six-sp eed bo x now.) f, The on ly han dlin g problem en countered was a tenden cy of th e fro n t for k to p ump up and hyd rauli c h loc k u nde r extreme' load , su ch as the series of bu mps at th e botto m of t he Carl sbad down hil l. Fro nt end / behavior in turns and virtu ally all o th er co ur se co ndi tio ns was hard to fau lt , ho wever. Quick an d effec tive fork fix es have already been developed for the big ' R~l s . :-;0 doub t the same approach will re solve the f'" 14