Cycle News - Archive Issues - 1990's

I increased i n diameter (f ro m 17 to 18mm ) for in creased rigidity , a nd th e beefed-up rea r shock moun ts have be en rel ocated : : 6m m close r to th e cen terline of the bike. Has th e han d ling b een imp roved? We honestl y did n't notic e a d ifferenc e in the handli ng. The bike simply d id a fine job cu tting the inside line or sweeping arou nd the ou tside of a turn with good stability a nd manners. We tho ug ht the bike m igh t s tart to headshake more with th e d ecreased rake and trail, but that was n't the case - the bike remained stable a nd turned well at the same time. Occa sional insta nces of quick headshake still happen, but not a ny more than with last year's mod el. Yamaha reco mmends 95m m of rea r-su sp ension sag w ith th e rider on the bike. The handling pro wess ca n a lso be attributed to the extensive work Yamaha carri ed out on the sus pension units. The 46mm Kayaba fork is all new, featuri ng an increased d iam eter for the damping ca r t ridge (f ro m 28 to 32 m m), a nd recei ved a new o u ter-tu be sh ape. The piston was a lso increased in size in acco rdance with the cartridge, as was the midspeed valve (from 25 to 27mm). The va lving wa s also changed to provide more consis tent damp ing , a nd Yamaha pulled o ut all the stops by going to an elasto m er bo ttoming system m uch like rear shocks ha ve been using for yea rs. Th is "works typ e" bot tomin g system abandons the oil-lock bo tto ming system , in favo r of a plia ble piece of ru bb er in each leg. The end result is improved bo ttoming control, since the elastomer is not I speed-sens itive a nd you d on ' t hea r or feel metal-to-metal co ntact o r cla nking noi ses w he n bottom in g, but rath er a smooth thud . The for k still retains th e .41kg / mm springs used in '97. In the rear, Yamaha op ted to use th e sa m e link th a t the ra ce team used for mo st of the seaso n on its works bikes. Due to the new linkage ratio, the sp ring rat e has bee n decreased from 4.8kg /mm to 4.6kg /mm but, effectively, the rear is not a ny softe r that it w a s last y ea r. Wh ile the overa ll wheel travel remains th e same (12.4 inches ), the shoc k stroke has been len gthened by 6mm to reduce opera ting tem peratu res by lowering the shaft speed . Int ernally, th e p iston seal now has two O-rings instead of o ne to provid e a better seal and preven t blowby, and a high er-qu ality top heim joint was installed for increased d urab ility. O n th e trac k, the YZ has excelle n t sus pensio n perfo rmance, co mbini ng a fairly plush and controlled ride w ith an exce llent resistance to harsh bottoming especially in the front , where yo u could rea lly feel harsh lan dings in you r wrists w ith past fo rks . The YZI25 for ks w ill bottom with so me regula rity, and the occurrence is s ti ll accom pa ni ed by a wei r d so u nd (a lmos t a " t hu d" o r "pop"), but yo u reali ze tha t yo u d on't have to cr inge on those ty pes of landings, as the rubber stop s take away the . (Left) A 1997 race-lea rn-spec se r ious jol t a'n tici pa ted . Th e rear end " never ga ve any sig ns or hints of harsh bo tto ming, either, and actu ally received great revie ws, especially in its ability to sk im through la rge wh oop s withou t a swap or kick to speak of. Faster or heavie r ri d e r s will ne ed to go to s ti ffe r sp rings to get o p ti mu m per for m an ce fro m the su sp ensio n units, as th ey are set up for abo ut a 165-pound intermedia te-level rider. Yama ha dug into the brakes for 1998, hoping to move into the Hon da realm of excellent braki ng perfo rmance, and the YZS took on new bra kes fron t and rear in an effort to get more power with less effort at the leve r. To go along wi th the Akibon o fro nt mast er cylinder im plemen ted a few years ago, the Honda-type Nissin caliper body and su pport bracket are mu ch more rigid this yea r. A sing lepin brake- p a d -r eta in e r system h as replaced the d ual-pin uni t for better feel and increased durability. The rear brake got the sa me treatment , as well as a larger d isc (fro m 220 to 240mm) a nd new pads to improve performance. The YZ brakes are top-notch on the track, offering good feel and po we r wit h a mod era te amount of lever p ressure. M u s h y? Not a hin t. Be lt er than Honda ' s? Not q u ite, but ri g ht th ere . They are g reat brakes, indeed. T he fi na l ch an ges to the YZ125 in cl u ded changing th e plastic to th e bright , almost translu cent blue that th e factory team used last yea r, along with th e factory-in spi red g raphics sc he me. Th e sea t co ver w as in crea sed in th ickness (from 1.0 to 1.4m m) for more durability, and the s ha pe of th e foam was changed to a more rounded and taller pr ofil e (lOm m tall er). Tester s really ap prec ia ted the taller foa m in conju nc tio n wi th the roo mier riding position cre at ed by th e relocat ed handlebar pos ition . It' s sweet. The _ thicker foam is also much nicer to th e post erior , if yo u know w ha t we mean. On the down sid e, th e b lue pla st ic a nd gra phics still ...~_ don't take abuse ve ry well, a nd rather quickly takes on a beatenup look. When it comes rig ht down to it, Yama ha cou ld have left th is bi ke enti re ly alo ne thi s year and still probably ~ould have done very wel l against the other bikes in its class, bu t chose 10 push on by getting more out of the awesome mo to r, co m p le te ly red esign ing and improving th e suspension u nits a nd making the bike more roomy and comfortable. It' s a defin ite wi nne r, and th e pr ice re mains unchan ged at $4799. Th e price alone is wo r thy o f m ak in g you s h o u t "WooHoo!" before you even rid e it. C :\ link, a longer sh ock shaft. a revised sh ock p iston and a rev ised spring ra te round out the changes to the rear suspension. (Rig ht ) Th e t ront end also went th rou gh numerous changes, and the bi ggest was the addition of an ela stomer bottoming system, like that w hic h a rear shock uses. The suspension action Is first·rate. (Be low) The 1998 YZ 125 Is equally comfortable ra il ing a berm o r sweeping through comers, offering stable yet responsive handling eharaeterist ics. 1998 Yamaha YZ125 Specifications U st P rice Displacement En g in e type $4799 Bore x stroke 54 x 54 .5mm Compression r atio _ -10 .4 :1 8.9 36mm Mikuni 124cc L iquid-cooled . singlecyhnder two-stroke w / YPVS exhaust pow er valve Carburetion Ignition Transmission Starting system ~ Fuel capacity Wheelbase Rake / tra il CDI .Stx-speed Kick 2.11 gal. 56.9 in. 27 .2 degrees /1 18mm Seat h eig h t 39 _ in, 1 Front t ire Rear tire 80Al00·21 Dunlop K4901T 1oQ/90- 19 Dunlop K6951T Front suspensi on Kayaba adjustable 46mm inverted fork WIth 11.8 inches of wh eel travel Re ar suspensio n Kayaba adjustable shoc k with 12.4 inches o f wheel travel F ront brake Rear b rak e Claimed d ry weight Disc Disc 196lbs. A 8 ~ ~ r-, 0\ 0\ ,..... gi ;... OJ .g ...., U o 13

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