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/127157
Test: 1989 Suzuki RM12SK Moving a step closer to the top By Nate Rauba Photos by Kinney Jones Sometimes, as the old saying goes, the more things ch an ge, the m ore they stay the same. And th a t old saying just abou t fits the 1989 Suzuki RM125: Wh ile last year's R M250 go t all the a tte ntion, th e R M125 wen t basically unchanged and, alt hough it had enough power 14 to keep most riders happ y, it didn 't have enough horsepower to pu t it at the top of the h ighl y-com pe titive 12Scc class. This year Suz u ki to tall y revamped t he R M 125 but, o nce agai n, it shares so me of the same traits as previous RM s. It is a goodhan dl in g , well suspended bike but no t ex tremely fas t. Q uite q u ick, but no t fast. So wha t's new? I r'sal m ost better, as Suzuki says, to descr ibe what"isn ' t new on the RM 125. T ha t leaves o nly th e wh eels, co lor an d maybe a few o ther items since most every thi ng else has been changed in so me way. The new motor in the RMI 2S features a n a ll- new case reed -va lve system . Suzu ki switched to the case reed from th e piston-port reed design found on last year's model, a nd mat ed wi th th e 35mm Mikuni TMX carb ure to r with crescent-sha ped slide ยท in trod uced on the '88 mach in e, the com bina tio n is designed to increase low- end and midrange power. While th e case-reed and carburetor help g ive th e RM a potent low -end, Suzuki's Automatic Exhaust T iming Co ntrol (AETC) is retained to boost to p-end power. The design rem ains , the same wi th a pair o f valves th at s li de ba ck a nd expose a higher exhaus t pan as the revs rise. Once the gasses escape from the cyli nder they are rou ted th rou g h a n ew. exhaust pipe a nd out an a ll- new, repackable, quieter ova l muffler. An additio na l cylinder head bracket has been added to help redu ce vibra tio n. Wi th in th e six -speed transmission th e d iam eter of the shift fork sha ft has been increased from 10 to 12mm, a nd bearings no w su p port th e gea r s h ift ca m fo r eas ie r s hi ft i ng. Alt ho ug h there have bee n n o . cha nges to the clutch , the pu ll is now m uch easie r than befor e, thanks in pan to a redesigned lever. Unfortu na tely, Suzuki still hasn 't gone to a quic k-c ha n ge clutc h cove r, t he wh o le rig ht sid e cover sti ll ha s to come off in order to get to the cl ut ch. Severa l chassis cha nges were made, pr imari ly du e to s us pe n s io n cha nges. T he front suspens io n now features 46m m Kayaba forks, up 3m m over last year's, a nd with the increased forks th e frame's rigidity al so had to be in creased to handle th e greater loads placed on the fram e. ' In order to reduce weight, th e left side sub frame has been cha nged from steel to aluminum. Not o nly has the fram e beco me more rigid, bu t it a lso carries a low er center of gravi ty. With the p ipe swept bac k a nd u p to th e bo ttom o f the gas tank at a lo wer a ng le, the radiators cou ld be lowered 50mm, a nd the left side o f th e fuel tank dips 130mm lo wer tha n last year's to ge t the weigh t o f the fue l down farther. Fuel capacity has a lso been increased fro m 1.8 ga llo ns 10 2.1, a nd the to p surface of th e fuel ta n k has a lso been lo wered 3Sm m . Inside the 46mm KYB fork lowfri ction bearing s are u tilized for im p ro ved dampin g cha rac teristics, and the damping is still full y adjustabl e with 21 co m p ress io n a n d rebound settings . Although th e forks are la rger th an last year's th ey are a lso sligh tly lighter du e to thinner wall s. The Full Float er rea r suspe ns io n ha s al so lost so me weight. The sh ock" has been lighten ed al ong with the - Fron t b rake action has been impro ved by a larg er disc. new brake pads and reshaped lever. Massive 46mm forks increase front-end rigidity and help make the RM125 turn quickly.