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/127119
.- .. ~ ~ . I . ... . .' - -: " . .' ' '. .. ' _ ~ :" _,f • ,' .. . . • • > .' /0, J , '. 00 00 ~ ,.....; -". .., '. ~ 0 ,.....; >- -, l-< ro ;j l-< ,. , ..0 (1) ~ .. , . .' ' .- Test: Kawasaki KX2S0-Fl . t's not·easy I being~mean By Kit Pal m er Every year Kaw asaki 's KX250 keeps getting better and better, an d every year it falls short of being th e very best 250cc MXer from Japan. L as t year it was extremely close to being number one, but wimpy forks kept it from excelling over the Honda CR250. . . About ~he on ly dung ~hat the 1987 ~X had m com mon . with -the 198 .6 KX ,:"a~ th e color , and. the same IS true in 88. The latest KX IS a ll-ne w fro~ th e 1Sro und up: new eng-me cas ti ng . different frame geom ~try , mor e progressive rear sus pe ns io n, a ll-n ew fork s, carb u re to r a nd a red esigri ed ex ha u st power -valv e (KIPS). . _ T he two biggest cha nges to the mo to r is th e new 391I? m Keihin carbu retor a nd th e redesigned KIPS po wer- valve. T ? e Keihin car.b rep.lace~ l a~t year s R-bot tom slide Mikuni, It s ca lled a ~W~39 a nd features a new conce p t in a ir flow design. A new . flu sh a i r i nta ke tr a ct a ll o ws turbulent-free airflow Ih roug~ t~e carb, and a crescent-shaped slide IS now used ena bling th e slo w-speed jet . ~o be -po siti oned closer t th e .m ai n Jet. The intended result IS quicker, sm oother throttle response th rougho u t th e power range. . Although the power-valv e is bas icall y the same d~lgn as past KIPS power-valves, a thud va lve has been added to the center of th e mam exhau st port. The new valv e regulates main exha ust port timing, adds power and produ ces a smo o the r transition from mid- to hi gh-rpm. The 67.4 x 70.0mm bo re and stro ke remains the same for 1988, but th e co m p ress io n rat io is c ha nged slig h tly. The cylinder head is sligh tly sm aller thi s year , and the head gas ket is slig h tly slimmer, wh ich gi ves th e KX slig h tly mor e compressio n at low er rpm. To g ive th e KX smoother pull o ff th e bottom th e cra n ksha ft's co u n terweights a;e . slightly hea vier. Modifica ti ons to th e cl u tc h incl ude relocating the needl e bearin gs on th e release sha ft for lighter clutch lever pull, and there are now dimples on th e su rface of the a lu minurn plates to improve grabbi ng and reduce the cha nce o f sli p p ing. T he new pl astic a irbox has two tric k rotary sh u tter val ves o n each side o f th e box. The val ves ca n be easily and quickl y o pe ned for more air intake a nd closed in muddy or extremely dusty riding conditions. T here are a n u m ber of changes to the KX's chassis, and the bi ggest is the switch to .the proven . cartridge fork design. The 43mm KYB cartridge set up replaces la st year's harsh Kayaba TCV (Travel Control Valve ) u ni t. The new fork has II.8 in ches of travel, and at the bottom of each for k leg ar e external compression damping adjusters with 16 sett ings. There are no rebound or preload damping adjustm ents. The KYB piggyback reservoir shock has some damping changes, and th e compression darnpi ng adjustm ent knob used la st year has been changed to a screw type to elim ina te th e cha nce of changing th e damping setting with th e rider' s leg. T here a re al so 16 rebo und damping se tt i ngs a n d th e u sual screw l th rea ded -type preload adjustment. Cla ime d wh eel travel is 13.0 inch es. -T he Uni-Trak lin kage ratios are slig h tly altered to produce a slightly mor e progressive ri sing rate, and the swi ngarm is all new. An additional cross sectio n has been added to th e swingarm's cen ter ri b, a nd the com plete . unit is now taller and wid er. The chain adjusters are nicely recessed into th e sw inga rm , and ·the plastic chai n guide now has an a lu m in u m guard. The o lder cha in gui des ca me without the alumi n u m guard a nd would break orr whe n ridin g on roc ky tracks or through deep-groo ved turns, usu ally resu lting in derailed cha ins. Th e n ew fram e, now p a inted green, has a 28° degree rake a nd a 5.1 in ch trail , and gusseti ng is beefed. up arou nd th e steering head and swi ngarm pivot. The rear sub-fra me is detachable. Both front and rear dis cs have slo tted , cas t-iro n rotors, with twin- · pi ston calipers. Composi te h ydraulic brak e hoses ar e used rather than more ex pe ns ive-to -p rod uce stee l-braided hoses. Last year 's KX was ex trem ely slim . T oo slim . Many riders felt it was so narrow. that th e bik e was tough to con tro l, especia lly in th e turns. So th e 1988 KX has a sligh tly wid er seat a nd gas tank. The tank holds more fuel a t 2.6 gallons. What does it all me an? First impressions say a lo t. When you hop on th e KX for the first time, horsep ower is what comes to mind ' first. Not the lack o f it, not by a long sho t. The new KX has o ne of the most powerful 250cc motors we've ever ri dden. Most of the trench -digging power is in the middle of the powerband, wi th decent lo w-end an d topend p ull. The . Kawasaki almost wants to jump out of your hands when the th ro ttle is suddenly wicked o pe n, and if yo u're not payi ng attention, yo u can easily find yourself with the fro nt wheel hi gh in the air. It's that powerful. Bottom end is a lmost overs hadowed by the a weso me mid-range, but it's there, and it 's enough to pull th e KX out of turns quickly. Clicking the six-speed transmission through th e gears, th e KX feels a lit tle mellow, but hits hard in th e middle of th e powerband and continues to pull hard on top. Although the KX isn 't the fastest 250cc around, it is clos e. Even with its brute power, th e Kawasaki is relatively easy to ride, although it takes a little getting used to if you j ust stepped off a Yamaha or a Suzuki. P ower is defin itely different, but certainly isn 't lacking. The KX isn 't a revver, but it do esn't rea lly like to be shortsh ifted , 'either. It 's best to shift the KX right in the middle of the powerband - not too soon; not too late. When it's shifted correctly the KX is awesome. We had no problems with carbu reti on whatsoever. The KX co mes jetted spo t on, and th e cresce n tshaped slide does its job quite well. . Throttle response is instantaneous, no hesita tion, and th ere's no coughing when landing off jumps. Blasting out o f iurns is quick and sim p le on th e KX. With the help of th e clutch , th e-KX ca n sometimes be left in a gear higher than usual wh en going into turns. But half the time,

