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/127857
RIDING IMPRESSION (Left) Ricky Carm ichae l loved the motor on his '97 KX125, bul he had a lillie help from a guy named Mitch Payton_The 1998 Kawasa ki KX125 now has a competitive motor to go along with Its excellent-handling chassis. By Cameron Coatney Photos by Kinney Jones n its mod ified format, it's no secret tha t the 1997 Kawasaki KX125 is a po tent race wea pon. In the hand s of Pro Circu it /Spli tFi re / Kawasa ki' s Ricky Carmic hae l, the KXI 25 wo n three 125cc East Reg ion Supercross main events and won eight ou t of 13 AMA 125cc Nationals, lockin g up the champions hip wit h two ro unds still remaining. Throw in Team Kawasaki rider Damon Huffman's T ro y , O hio , win and tha t gives the KXI25 a win ratio of .692 in the Natio nals this yea r. Now, that isn't too shabby. In its st ock format in "97, however, r-, 0\ the KXI25 had a great-handling chas sis0\ and-su spension package that was held r-' back by a mot or that jus t wasn't as powt'-.,' erful o r as easv to ride as m ost of th e r-' other bikes in ihe d ass . Kawasaki rea l.... ized this, and co ncentrated its efforts on ClJ ,.D improving the motor for the 1998 model year wi th massive changes, indu di ng an ClJ all-new cylinder and the use of a Keihin 0... 36mm Pow er Jet carbu reto r. After riding ClJ the b ik e for se ve ral w eeks, w e ca me U'l aw ay qu ite impressed with the ne w mot or package, as we ll as the revised suspension components . IT 6 .... 8 According to Kaw asaki, the all-new cy li n de r o n the ' 98 KX125 u ses tw o exhaus t port s ins tead of four for better lo w-en d and mid ran ge performance. Kawasaki' s exhaus t power-valve system , or KIPS (Kawa sa k i In te g rate d Pow er Valve Syste m), is sa id to be more effective, with a sp lit guilloti ne va lve regula ting th e Iwo la rge exhaus t ports instead of the old rota ting-drum sys tem used in the past. The new KIPS valves a r e shaped s m oo th ly o n th e bottom edge for increased exha us t flow when fully retracted for a d aimed incr ease in midrange and top-end power. The crankshaft was also changed , and the mass is now concentrated closer to the center of the shaft for less vibration , smoo ther overrev and longer-last ing ma in bearings. As a result, a much smaller flywh eel ro tor is now used. The connect ing rod is 2nun shorter for mo re p rimary compression and is sa id to resu lt in bett er thrott le res pon se. The piston attached to the connecti ng rod is seven g ra ms lig hter (B Og to 123g) fo r qu icker revs, and fea tu res an in take wi ndow for improved top-end power. A new in take ma nifo ld tha t ha s a sma ller intake area for quicker response no w co nn ec ts a Ke i h i n PWK 36 m m Power Jet carburetor to the new cylin- d er , replaci ng last yea r' s PWK 35m m carburetor. The air- ve locity w ings o n the airbox side of the ven turi were still retained on the newer crescent-slide carburc to r, Kaw as aki 's Po w er Jet ca rbs (bo th the KX125 an d KX250 received them for '98) have the act ua l power jet pos itioned mu ch lower in the carb compared to the Honda version that comes s to ck o n th e C R250. Kawasa ki claims that this gi ves the bi ke better p ower throu ghout th e powerband, since the power jet starts releasing fue l sooner as the s lid e o pe ns and the venturi effect pulls th e fuel into the cyl inder. The power jet stays open on the KXI25 until 9600 rpm, wh en it effectively leans out the jettin g by 10 percent for better topend power and more overrev, A longer protective tube has been added 10 the throttle cable, which also ha s a 3mmlon ger inner cable for improved durability. The digital capa citor-d ischa rge ignition is now programmed to work with the Keihin Power Jet carb, and the magneto feature s a s mall er rotor w ith increased power output to provide juice for th e opera tion of the power-jet sole- (Above) Kawasaki cas! an all-new cylinder with two exhaust ports instead of four and gUillot Ine exhaust powe r valves instead of the old drum va lves. A lighter piston. new crankshaft. more compression , new Intake manifold and a 36mm Keihin PWK Power Jet carburetor gave the KX125 the boost in power It needed in '97. (Left) A bolt-on exhaust flange now connects the head pipe to the cylinder.