Cycle News - Archive Issues - 1980's

- Even though the Kawasaki has an adjustable rear shock strut, it's best to leave it in the stock position. TIres are M -37 and M -38 Bridgestones. Excellent suspension and a powerful motor make the new Kawasaki KX250 a tough contender i n the very competitive 250cc 'ctass. Test: 1985 Kawasaki KX250 D-1 More than just improved By Kit Palmer How m an y times in the past has Ka wa saki been so close to clai m in g best p roductio n 250cc m o torosser only to be edged ou t by eith er Su zuki, H onda or Ya m aha ? It's happ ened more times th an Ka wasaki likes to th ink about; they're q u ite fam iliar with th e old say ing, close but no cigar. 24 Kawasaki is o u t to cha n ge all th at in 1985 with the new KX250 Works Repl ica th at features an all-new eng ine . sus pens io n . frame a nd st yling. Last vears KX250 co u ld n' t mat ch th e H onda C R250and th e Yamaha YZ250 in either th e motor or suspension dep artment. This co u ld be th e year. th ough , that the Kawasaki takes the lead. Th e most o bvio us change to th e m otor is the add i tio n of a power va lve de sign . called the Kaw a saki I n tegra ted P o w e r-va l ve Sy st em (K,J.P. S,) . in tended to give th e KX stro nger lo w-end a nd top-end power: Th e K.J.P .S. system includes an exhaust reso na lOr. two a ux il iarv exha ust sub-ports, two valves to o pen a nd close th e resona tor a n d sub- ports. a nd . a cra n ksha ft-d riven ball-ramp governor. . At low rpm , th e d ua l va lves si m ultaneously open th e resonator a nd close th e sub-ports to boost p ower o rr th e bonorn. At high rpm, th e va lves close th e resonator and open the su bports to gain power o n top. The system sha res a little bit of both Yama h a ' s YP\,S a n d H o n d a ' s AT A C p ower-va lve systems. T h e single cylinder. tw o-stroke. 70x64.9mm bore a nd stro ke , 249cc motor is liquid-cool ed. but th e dual radiators are now longer and narrower tha n befo re a nd are mou nted 2.12 inches lo wer to improve th e center o f gravity. En gine cooli n g has !>cen improved by redesigning th e cylin der h ead for bett er wa ter flow. Th e radiator still hold 1.1 lit ers of coo la n t. The KX now ha s a cen ter-p ort ex ha ust system to go along with ihe new power-va lve . A redesigned exhaust pi pe ro u tes to the right side o f th e bike and be nds radi ca ll y (bu t n o t a s radi callv a s th e KX500 ) around th e rad ia to r: a t th e end o f th e pipe is a new . rebuildable a lu m in u m silenc er. T o reduce g rabbing and ch a tterin g . the wet cl u tch has been rede sig ned so the clutch gear is not mounted so lid lv to th e clutch hub: . - ins tea d. it' s a float in g type m aking e n g a ge m ent a n d disengagement smoother. The five -speed, co ns ta nt mesh tran sm ission h as th e sa me gea r ra tios . T he fol ding sh iftlever, th ough. is now a lu mi n u m -a lloy. as is th e (p ri mary) ki ckstarter lever, to reduce weig h t. . T he KX has a large 40m m (u p from 38m m) Miku ni ro u n d-slide ca rbu retor. which fea tu res a Ilat -Rvborrorn slide with a radiused cuta way aro u nd th e needl e to improv e lo w-spe ed autorni zation a nd ai r flow . It ha s a choke pu ll -ty pe kn o b loca ted o n th e right side of the body. T he new carb feeds fue l into a n eight-peta l dua l-stage reed -va lve tha t u ses h ighl y-th rottlesensitive carbon-Ii her reeds. Ins ide the reed-valve intake cha m ber are n ew reed -valve a ir guides designed to reduce intake fuel turbulence for smoother and quicker th ro ttle response. The ca rbu retor sucks air through Kaw as aki 's new Fr esh Air Int a ke System (F. A.LS.). Air now enters th e airbox from a chamber m ounted directly underneath ' the gas tank . Air flows around the front number plate a nd into a d uct (u nder the ta n k ) that fu nnel s th e ai r to th e ca rb, after bei ng filtered by a sing le. o iled -foa m air filter elemen t. T he fi lter can be reached without having to take orr th e seat or the right side panel . after removing four airbox cover screws. For additional breat hing: the re are 10 sma ll. circular hol es in th e a irbox cover. Because o f igni ti on sta tor fai lures la st vea r, the lead wire termina l ha s been' reinforced . a nd th e cra n ksha ft co n tac t area ha s been en larged. The CD l's ignition cu rve is no w the sa me as th e 1983 KXs, bu t full advan ce ha s been cha n ged to 20° BTD C. All o f these things are tu cked in side a n a ll -ne w h igh-ten sil e steel frame which is no w p ainted silver in stead of tr aditional black . T o accom modate th e ce nter-port exhaus t system. the si ngle fro nt downtube spl its into a dou ble crad le rig ht where th e pipe mates wi th th e cylinder. The largedi am et er-tubin g fr ame is slig h tly lighter th is yea r but is h eavil y g u ssetted. R ake is 28°. tra il 4.7-i nch es. Wh eelb ase is 57.7 inches. seat heigh t 34 inc hes a nd ground cleara nce 14.8 i nch es. T he front, a ir-a dj ustable. telescopic fork isn ' t ra d ica lly cha nged for 1985. but it does have a three-w a v mech anica l prel o ad a dj us te r ex te rna lly mou nted at th e top of th e for k legs . The l O-way compression da m pi ng adjus ter. 43mm di ameter stanchion tu bes. and 11.8-in ch wheel tra vel are a ll un changed: however. the steeri n g stem is now a lumin um-alloy to reduce weight. Fork gaiters are no lo nger used. The revamped , single-shock, Un iT ra k rear suspension system is full y adjusta bl e: The rocker-arm st rut, co m p ressio n a nd rebo und damping and preload adj ustmen ts ca n a ll be tinkered with to sa tisfy riders' preferences; but Kawa sa ki recommen ds leavi ng the stru t adj ustment a lo ne . If the strut is adjus ted any shorter to lower seat heigh t. the back end will bo tto m hars h ly. crea ti ng trem endous stress o n th e adj ust er bo lt and ca using it to snap i n ha lf. New th is year is th e d ua l-ra nge co m p ressio n da mpi ng system , with . two four-wa y adj us ters : o ne co ntrols da mp ing rates in low -speed si tuations, a nd the o the r co ntro ls damping ra tes i n h igh-speed sit ua tions . Wh en th e shock is loaded slo w lv, th e low-speed damping co ntrol keeps th e rear wheel from ho pping. and whe n the shock is loaded q u ickl y, the h ig hspeed damping co ntrol h elps red uce bottomi ng. The KX is th e o n ly rnotocrosser of fering this kind of adj ust-

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