Cycle News - Archive Issues - 1970's

MPRESSIO S (; 11II -= ~ YAMAHA 250MX MONOSHOCKER t l!') rC'l ,.....; l!') ,.....; _. >- BOUNCE&ZAP ;:s ........, By Jeff Peck When Ya maha rolled out th eir Gr and Prix d eveloped rnon oshoc k suspension on their stoc k MX series bikes, rid ers and writers hailed it as a giant te chnical leap forward in long travel suspensions at an affordable price . This sent other manufacturers sc rambling for way s to make their double-shocker bik es handle as well as th e m onoshockers ov er th e rough stuff. Man y companies have co m e very close, bu t for the m oney the monoshock stiII delivers on e of th e sm o o thest rides of any dirt bike. The idea o f the m onoshock is no t new. The Vincent m otorcycle used th e basic idea back in the mi d -fifties. Ya maha has d one a co nsidera b le red esign o f th e product and wr apped it in a neat er pack age . As a m o to cro sse r, t he Yamah a 2 50 MX co me s o ff fa irly wel l. It is very fast, handles well enough a nd m ost people wiII b e h appy wi t h it. The p lac e where the monoshock er re ally sh ines though is in the desert. The rear su sp ension srnoothes o ut the nas ty whoopers and th e po wer · availab le fro m the 24 6cc engi ne ru shes y o u alo ng . Let's take a qu ic k ride and see what it 's lik e. First you tum on th e gas , then yo u sp end tw o m inutes fightin g with the little cho ke rod, th en you kick it over once or twice and with you r sweaty paw twitching nervously on th e th rot tle, it ligh ts o ff with a defiant " Bb br iln n g. " . The e n gine revs fast and gives a feeling of power that is sec o nd o n ly to the feeling y o u ge t o u t on th e tra ck. R ight : The powerPulling out o f corners , the Yamaha is f ul 250 motor has quick, almost sudden . In fact, th e eno ugli pu ckcr for explosiv e power takes so me time to ge t anyon e. used t o . If yo u are not careful the rear tir e will grab a b ig mou thful o f m o ther ear t h a nd se nd the fro n t e n d skyward . Far riglu : Overall This meth o d o f ex iting a co mer is fin e Il arrowll ess of the for d azzling your frie nds an d imp re ssing p it tootsies, but as an e ffect ive mean s of Yam alia adds t v raci ng it leaves a lit tl e bit to be desired. th e co mfo rt w hile S u n s h i ne Yamaha in Orange, riding, California manage d to smoo th o u t th e beast in th e Yamaha 's m otor with so me porti ng trick s th at m ade th e e ng ine wo rkable fro m ar ound 3 0 00 RP:'1. Also addi ng a spacer betwee n the ree d va lve and th e cylinde r a lo ng wi th modifying the reed itsel f help to smoot h o u t th e powerband. In sto c k form th e p o we rband is sho rt yo u alread y kno w th at if you d on ' t an d zap py , b ut co m bi ne d with th e close weigh 23 0 pounds th e n y ou are go ing to ratios in th e tran smission th ey pro pel have to have some wo r k d one to th e you ar ound the trac k q ui ckly . Do n' t shock u n it t o set it up fo r yo u r we ight. expect to cli mb any hill s wi th ou t mo re Sun sh in e Yamaha has all the to ols and than a nor mal amoun t of clutc h know ho w to han d le an y m odificati on slipping. As in th e case with all Yamahas th e t h a t yo u mi ght d esire o n yo u r m ono sh ocker. . tr ansmi ssio n wo rked flawlessly. This is Seeing as ho w I already weigh 230 to say th a t it did no t m iss any gears an d poun d s the bi ke was al re ad y set up for was smoo th as .b u tte r. Th e o n ly thing I me . In ro ugh sections th e rnonos ho ck di d not like was th at at t imes th e close throw tr ans d id not le t you kno w if you reall y shows wha t it is abou t. Mo st of were in a gear un t il yo u had le t th e th e tim e yo u d on 't even kno w th at yo u have just pas sed a series of ho les. cl u tc h out. A little bit mo re room \\~lOo p-de -do o s are wher e yo u get you r betwe e n gears wo uld be a b ig help here. chance to m a ke u p time o n th e re st of T hey h ave thrown a n ew sh ifter on this th e pac k as th e y fight th ei r way year that is so me wha t sho r te r, but b y th rough . You j us t ge t yourse lf wa y bac k the sam e t o ken th e part th at your boo t and kee p the gas o n. Keepin g the gas on h its to sh if t the tra nsmissio n is n ow is the o n ly way th e monoshock wo r ks wid er whic h makes it m uch h arder to th e best. Yo u have to kee p th e rear en d miss. under lo ad or else it 's goi ng to bounce Now th at we h ave ta lked abou t yo u aro un d li ke an old DT-1. This is getting the bike m o ving in a forward definitely no t a b ike fo r t he fa int direction, wh at happens whe n yo u wa nt heart ed or t imid to ride . to stop? The answer is, all k inds of neat Acting as a fo il to the ex ce llen t re ar th ings. For o ne th in g the front b ra ke w o r k s ex tr emely we ll. It s o n ly suspens ion is the p o o r fro nt e nd. Most shortco mi ng is th at ove r rough terrain of th e p ro bl e m s lie in the triple clamps th e leve r pressu re ch anges because of which al lo w th e fro nt end to flex q ui te p ull put o n it by th e cab le gui des. The a bit and give o ff a good d eal o f hi gh rear br a ke works fine, as long as y ou speed wo b ble . An other d ra wback in th e ta ke th e ro d o ff and be n d it so t hat you fro n t en d dep a rtment was th e tenden cy don 't ha ve as much leverage o n it . When t o wash o ut. Playing around wit h t ire th e brakes get we t th e y ar e a little pressure helped a bit , as di d c han gin g sp o tty b u t th ey dr y ou t quic kly , th e fork o il a nd th rowing in some Bey ond all this st o p p ing an d go ing , Bel-Ray 20w. h ow w ell d o es the sus pe n sio n work? Abou t th e best thin g you co uld do Let's star t a t th e rear en d. If you have wo ul d be to in ve st in eit he r a Bob re ad any o f th e te st s o n t he Monosh oc k Ottow Gas /Oil fo r k kit ($ 14 .95) or a " '" u Q. U. U. .., '" >- III Vl o o I- I 0. "--,,,-==:.s.;,;~ Terry Ki t , ava ilab le th rough Su ns hi ne Yamah a. Both will ge t th e bugs o ut of the fro nt e nd and add m uch -need ed for k travel. Thro wing away the sto c k ti res will also help yo ur ridi ng sty le im me nsely. We op ted for Ch en g Shi n s on b oth en ds with a 4 .5 0 x 18 (SOT model o n th e rear an d a 3.5 0 x 2 1 o n th e front. This combination h as p ro ven ver y effective for m o st desert racers and w e fo und it wo rked well o n o ur te st bik es. With the addition o f th e bette r tires th e bike handled very well , especially in deep sand. At low speeds t he Ya maha turns well and do es no t figh t yo u as you gu ide it aro und th e bends. As we said ea rlie r the high speed handling leaves a little bit to be desired b ut you lea rn to live with it . Rid er co mfort has always been very good on Yamah as and the m o no cro sser is n o differe nt. If you are sit ting down th e exce lle n t sea t assists in ad d ing c ush over the rough par t s of th e trac k. And if yo u lik e to spe nd m o st o f your ti me stan d ing up , the foot p eg position is jus t rig h t so th at yo u don ' t feel like you are bendin g over and grab b ing at the b ar s so mewhere down aro u nd yo u r ankles. C rafts ma ns h ip o n t h e 250 m on o cro sser is ve ry good . So me of the n ice little touches like t hreads in the for k legs for the fro nt ax le or go od so lid elec t rics m a ke the Yam ah a wo r th t he m o n ey yo u are lay in g ou t for it. Some things you mi ght want to do to the Ya mah a t o make it a little more livea ble mi gh t be : drilli ng out t he m o un ti n g ho les in th e c ases and putt in g in aircraft quali ty bo lts will take a way that annoying b uzz tha t yo u feel in th e handle ba rs. Also th rowin g a pair o f Inter -Am bars o n m ight m ak e yo u r arms last lo n ge r in tho se 40 minute m oto s. Ad d th at little ta b o nto th e cho ke so th at you do n 't have to w age t he battle o f th e gri p every t im e yo u want 't o start from co ld. Buy a better silen cer so tha t yo ur ne ighbo rs will ta lk t o yo u again. Lit tl e th ings like th is are all yo u need to d o to m a ke the Yamaha 25 0 M o n o more fu n than it alr ea dy is to rid e. • Spec ifications Engi ne Ty pe . . . . . 2-str o ke, T orq u e In d u ct io n, Single D isplacem en t 246cc (15 .01 cu . in .] Bor e & Stroke 2 .75 6 X 2 .52 0 in . Co m pressio n rat io 7 .69 : 1 Max . lo rq ue Lubr icat ion sy stem Start i ng syste m Ignition sy ste m Transmission 22 .5 ft .-lb . @ 6 .500 rpm Pre-mi x Pri ma ry kick st art er C. D.! . 5 -speed gearbox Dim e nsio ns Overa ll le ngth 8 3.3 in. Overall widt h Overall he ight _ Wheelbase Mi n . ground cl ear an ce 38 .8 in. 45 .9 in. 66 .1 in , _ 9 .3 in . Fuel tank Capacitv 2 .1 U.S. ga l. T ires Front Rear 3 .00 -2 1-4PR 4 .60 -18 -4P R Specif icatio ns subj ect to chan ge w ithout no t ice. 37

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