Cycle News - Archive Issues - 1970's

unmatchable (in class) power. T he ex haus t p orts are separa te d b y suc h a th ick bridge th at th ey are just barely in th e category o f being Siamesed, T he p orts are cu t way back into th e cy lin de r at their to ps fo r ma ximum scavengi ng of exhaust gases. T he re are two pu ~ge p o rt s in addition to th e very lar ge vo lu me tri c capacity trans fer ports that d irec t th e gases toward the exhaust. T hose b ig tran sfers throw a t re mend ous ch ar ge u p fro m th e tig ht cra nk area. T he real min d-blo wer, th ough , is the widely separated intake po rts. T hey're offset. And one is slightly smaller th an t he othe r. Figure that one out, wor kshop tu ne rs. Some ' com p uter already d id, it see ms . A comp letely new design Keih in 34m m carburet o r co ntrols the gas-air mi x ture in to those po rts and d oes a hell of a job o f it. T he Keih in h as a co m p le tely guarde d main jet to keep fue l fro m ei the r surging in to or vib rating away from it in th e ro ug h. Floats are solid foam th at can ' t be punctured o r leak. A ttention to minute in ternal d etail s th roughout th e engine is overw helming. T he engin e, carb, an d .ci " u. ~ w z · w ..J ' U > U • . en tire p ower train are re all y buil t. On e o the r n ice fea ture in th e o u tp u t department is th e p iston . It is trea te d in su ch a wa y as to develop a distressed surface wh ich mak es o il cling to it. Two unbreakable rin gs are used: the kind tha t will bend in three di fferent d ire ctions with out sn ap p in g. Th e co n rod rotates o n so me really massive lower en d be arin gs an d ne edle bearings at th e t op end . t ha t pull s t he T he c a b l e chro me-p lated no-sti ck brass slide u p an d d ow n is rou ted o u t or th e carb at th e co rrect angle by a little rubb er air tigh t n ipple to the q uarter turn th rottle on t he han d lebar s. It ac tually p er fo rms abo ut like a 3/ 16 tu m throttle. T he air to make th is tri cky en gine wo rk comes from a good-sized st ill air box under the seat filtered through a large surface area oiled foam air cleaner th a t has lit tle hairs allover it to trap water before it gets to th e fo am . Neat , hu h? T he air to co o l this h o t 24 8c c n umber is waft ed through rath er co nve nt io nal loo king but e xt en sive finn ing wh ich ex te nds o ver. around and under the head . The cy lin der has fins , to o . Wh at d oes th is engine really d o fo r you - th e rider an d purch aser ? Well, for openers it d evel ops a lot o f horsepower.. We co nsisten tl y got readings o f over 2 1 horses to th e ground with a bike in n o particular state of tune. The effective torque is also pretty impressive with over 50 ft -Ibs. ( ta kin g in to account the overall gearing effect) a ver y common figure . In practical terms, there was no 250 that could beat it in a drag race off the start line. The CR250M also waxed every production 400 or 360 it was pitted against. The gear rati os are that tight and the engine is that responsive . If you're not first into the comer in your motos, it is definitely not th e bike 's fault. We discovered that, even with sloppy shi fting , as soon as the trans was in fo urth gear it would pull out ahead of ab o ut an ything and just keep goin g. You co uld be in fifth gear and and pulling stron g 3 0 o r 40 yards off the star t lin e, if y ou were really sharp in your shi fting . There was on e bike/rider combination that th e 25 0 Honda hasn't T his dirt rider was very impressed by the Honda detail ing, light weight and pull ing po wer. - K .C. Br intnall pho to . bea t o rr the lin e an d on ly one. I t is, a p parently , th e fas te st produ ction scooter o ut of th e h ole that ex ists . T here 's o ne th ing th e en gine d oes for you. I Some o r th e o the r things it does is not load up (Thanks, Keihin) , continue . to run strong when hot and flogged and produce h ill-flattenin g gobs or torque an ywhere in it s power band. That power band, surp rising ly , was proved on the dyno to be a lot smaller than it felt in riding. One of the reasons the 250 Honda was so easy to keep on the pipe was the Japanese 4 .00 X 18 Dunlop fitted on the rear. A slight tum of the quick throttle, the tire would break loose, th e RPM would climb like a ro ck et, the engine would come into its high torque band and the motorcycle would move out like the proverbial je t. It was very easy to go very fast on the 250. It was scary fast to some people at first . You don 't lack for beans with this scooter, but the best part is that y o u' can ge t the machine to ap p ly all tha t power in the .d irectio n y o u want to go . HANDLING You can pretty well forget all yo ur I" impro mptu drag races off the start line , t he 250 Ho nda co uld o utrun all 250's and eve ry 4 00 but on e . establishe d ideas abo u t the handlin g of Japanese prod uc t io n rn otocrossers, T he bo u ncy, squirrell y , fro n t wh eel sideways , " Loo k o u t here comes the rear end !" feel isn't there . Th e Honda front en d is light but the long 5 7-in ch wh eelbase keeps it on the ground an d tracking unless y o u really . intend to get it up . The Honda-designed rear shocks are very good. They have wide diameter springs, which help to ke ep sid e flex and co il bind to a minimum, and are o f two . well thought out rates. The shocks have dual cy linder ' construction w ith the internal cylinder acting as an auxiliary dampener in the oil bath. They do th e job . T he shocks absorb jo lts and they kee p th e rear end tra cking straig ht ove r the rough st uff getting power to the ground . The rear end of the Honda jus t doesn't hop around. A fai r amo unt of the boun ce docs ge t p assed on to th e rider, probably due to the low relative mass of the bike. A machine o f ma ybe 2 2 0 pounds wet won 't absorb as much of the jolt as a heavier bike. On a works machine, this is called "feel" and the Honda 250 is closer to a works machine than anything else y o u are likely to ride, at least in terms of weight, power, and detailing. Cornering actually requires that you tum the bike. Don ' t laugh, it works lik e

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