Cycle News - Archive Issues - 1990's

GTest: ~ 19~0 KT~ 250 EjXC Enduro Zeroing In on perfection By Kit Palmer Photos by Kinney Jones is serio us abo ut offroa di n g . Th is is obvio us wh en eyein g th e 1990 KTM 250 E/XC. Aside fro m a few minor parts. the KTM KTM 250 E/ XC is a n all- new mo torcycle from th e gro und up. It has a newfledged engine. wh ich now inclu des a right-side kicksta rter and a two val ve power-valve system. a redesigned frame wit h a remo vable bo xsection aluminu m rear su bframe and revam ped sus pens ion components . The E/XC is the fini shed product of in- depth race a nd develo pm ent wor k by multi-time Na tional MX : Cha mpion Bro c Gl o ver - R &D work conduc ted -wh ile he was in Eu rope contesting th e 1989 250cc World Championsh ip MX Series a n d 1989 Euro pea n Two -Day End uro Series Champ ion arid former ISDE overall winner Dick Wicksell of. Sweden. For mer U.S . National Enduro Cham pions Kevin Hines and Dick Burleson also had input in th e fin al development stages of th e E/ XC. Internall y, exce p t for a sligh tly lower comp ressio n ratio, a n d d ifferent ign i tion a nd gear ratios. the E/ X C is pretty m uc h the same as the bi ke G lover rode on the G P circu it. Last year, th e KTM 250 Enduro was a top cont ender in th e competitive race for best. produc tio n 250cc (o r overall) e n duro motorcycle hon ors. Withou t a do ubt it was t he best ou t-of-the-crate performer, but with minor modifications to th e deb utant Su zuki R MX 250 a n d Yama ha YZ250WR. and the com p letely revamped Kawasaki KDX200. th e race for the numb er-one position was neck-a nd-neck. Taking a closer look 10 • The KTM 's water-cooled. 248.6cc engine features ma ny changes such as a ne w power-val ve system th a t KTM ca lls the T win Val ve Con trol. . With co n ven tio nal po wer- va lve . design s, th e valve (or valves) adj ust o nly th e exhaus t port hei ght, accord- in g to rp m . The KTM, on th e o the r hand, has two separa te power-valves - one for the exha ust ports and a nother for th e two boost po rt s located next to the main ports. The additio n of the second power-valv e system is to further broad en th e po werba nd over the conve n tiona l single power-valve design . Au stri an-based co mpany has reversed that for 1990. The kicks tarter lever now exi ts th e engine cases on th e right, while th e drive chain is now o n the left, instead of the right. To co mpe nsa te for th e "back wards" mot or, the frame is basically redesigned, alt hough its geometry remains th e sa me as before. An d not For bett er hea t diss ipat io n. th e cylinder head is now sea led by two Ovrings, instead of a single O -ring and a fiber gas ket. Plu s. th e cylinder lining has a Nikasil coati ng. Another big change this year is th e switch to a case-reed-valve inducti on sys te m from th e p isto n-po rt, cylinder -reed-valve design . H owever, an inherent problem wit h this design is the loss of some comp ression in the cra nkcase area. so to compensate for th is prob lem , nylon inserts were put into th e cran ksha ft to ra ise com pressio n back u p to the necessary o perating level. A new low -boy exha ust pipe has different specificatio ns to ma tch th e new cylinder. Attached to the back of the pipe is a ra ther large alumin um silencer with a U.S. Forestry- . approved Sparky spark arrester. H andling the fuellair mixture is th e sa me 38m m fla t-sli de Keihin carb uretor tha t was used last year. However, it has all -new jetting to match the new cylinder and exha ust pIpe. . T he wet, multi-d isc clutch has been beefed u p by in creasing th e clu tch plate sur face dia meter by 20%. plus a hard coa ting has been applied to th e pl ates to keep th em from di ggin g into the fingers of the clu tch basket. T he entire clutch assem bly is no w covered by a two-pi ece magnesium clutch case. The p lat es can now be servi ced without having to remove the entire clu tch case. T he five-speed, wide-ratio tra nsm issio n now has straight-cut sp ur gears ins tead of undercu t gear s for better shi fting action whi le und er a load. Stu rdy a n d lo n g -l as tin g s teel sprockets are used, as is a durable O-rin g fin al dri ve chai n. KTMs in th e past have always had left- side ki ck sta rt er s, bu t th e The KTM 250cc E/XC (above) is pure off-road. It's race -ready right out of the crate (below), which is how we rode it at the Tecate 250K Enduro in Baja California, Mexico . on ly is th e .frame changed, but it's been bu ilt sign ificantly stro nger and lighter. According to KTM , the ch romem o ly s teel frame is two pounds lighter th an last year's frame, but rigidi ty has bee n increased by angling the tubes more efficien tly and beefing up th e piv ot areas. The rear subframe is now constructed out of 'alu min um with sq ua re, rather than round, tubing. The upside-down Wh it e Power 4054 Multi-Adjuster for k is ba sically th e sa me as last year's fork excep t that the hydraulic sto p at the bottom has been modified a nd th e spring rate is sligh tly diff erent. The fork sports 11.8 inc hes of wheel travel. Valving changes and new spring rates have been made to th e singleshock rear suspension system . The shock linkages ha ve been beefed u p and the re's a new ratio to achieve a flatter curve th an befo re. Wh ee l tra vel is 12.6 in ch es. The sa me di sc bra kes are found on the new KTM, but th e rea r di sc has new mounts to help di ssipat e heat a little better. The fron t disc brak e mas ter cylinder is bigg er as well. Met zel er Motocr oss tires co me stock o n the KTM. wrap ped aro und 21 -inch fr ont and 18-inch rea r wh eels. T he new gas tank holds 2.6 gall ons but an optiona l 3.3-ga llon ta nk will be ava ilab le for what KTM cla ims will be a " special" p rice. Other feat ures incl ude a mec hanica l odo meter, head light and tai lligh t. Arrow handl ebars. pl astic boot guards around the swingarm pivo t area , sides tand, a lu mi n u m front fender brace and a usabl e tool kit. Unfort u nately, the bik e does n' t come w ith a ny kind of hand g uards. Hmmm . . .

• Cover