Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/127864
-------- RIDING IMPRESSION 1998 Yamaha YZ125 been made lighter, and the exhaust silencer has been made significantly lon ger (fro m 234mm to 314mm) to increase resp onse in the lower rpm rang e. To deal with the potential increase in power, the shift cam in the six-speed gearbox gets the addition of a new bearing to enhance shifting, and new frict ion material is used in the clutch. Finally, the water-pump impeller was changed frum resin to aluminum , the impeller s ha ft was ch an ged fro m resin to s teel, and the single water / oil sea l was replaced with two separate seals- all for increased durability. Yamaha was successful again (thankfully) because this bike barks with even more authority this year, improving the bike' s ex cellent bottom-end a nd midrange power and slightly increasing the amount of usable power after the peak (ov er rev ). Basically, the power is about as seamless as you can get out of a 125cc mo tor, and it pulls well into the upper revs. The low -end gru nt and the smooth transitio n in power makes the bike a breeze to blast out of turns for riders of a ll abili ty le vels , and p ro s will appreciate the slight inc rease in peak power and overrev. The motor is very good - period . On ly a few of our pro· level testers felt the bike cou ld use a few mo re ponies at the very top of the powerba nd - an d that's ge tt ing pretty picky, considering how good the motor is over all, but125cc pros rarely let off the gas. The clutch and transmission action is good, but some testers did occasionall y hav e to take a few extra stabs at the shift lever to get the .bike to shift under full load. Some riders also did not like the shape of the clu tch lever or the sligh tly heavy pull (compared to others in the class ). In the chassis department, Yamaha's changes to the frame included bringing the rake in a half of a degree (from 27.7 to 27.2 degrees) a nd reducing the trail by 4mm (from 122 to 118mm) . This was done in an effort to quicken up the handling and create a roomier riding area, since the geometry change has moved the handlebars 4mm higher a nd IOmm forwa rd. The swi ngarm-p ivo t bolt was (Lett) Pro test rider Tim "Bonk" Sha rp airs out the Improved 1998 Yamaha YZ125. (Below) You wouldn' t think Yam aha would mess with the best 125cc motor of all time. but they did. Don't worry, the new By Camero n Coatney Photos by Kit Palmer R a ~ ~ , 0\ N ..... Q) .0 o ..... u o 12 lLl ~/ tl1 wha tthift title all probab ly hat~, abou t?" is / you're I\. thi n kin g righ t now. Don't fret, just say it: Woo-Hoo! Let it fly out of you r mouth with g usto, with no regard for how stu pid you might sound . You' ve sa id it befo re, and yo u'll say it agai n if you have any plans on bu ying a 1998 YZl 25, because that' s what yo u'll be saying as soon as you throw a leg over it. It was the best 125 las t yea r perhaps the best morocro sser outright and early indications show that it will probably win the 1998 Cycle Neue IPcc Motocross Shootout. Yes, it's that good. The 1997 Ya m a h a YZ12 5. w as a potent pa ck age, combining a so li d , seam less and fast m ot or with a good handling and su spended chassis. You would hope that Yamaha wouldn't mess too much with a good thing, but they d id - and the results we re ve ry good . Th ey're lu cky, bec ause w e wo u ld' ve b a gg ed them unmercifull y had they messed up wha t we consider to be the best 125cc m o tor o f all time. Since most ride rs loved la st yea r's mot or, Yam ah a has attempted to keep the same po wer characteris tics (g rea t lo w -e nd and midrange wit h good top- end overru n), but jus t provide more of it. The cornbu s tion cha m be r is sl ightl y cha ng ed in s ha pe and vol um e, result ing in a higher com pression ratio (from 8.5:1 to 8.9:1). Last year, the power-valve tips were moved closer to the piston for better sealing characteristics when fullv closed, and the results were so good 'th a t th ey were moved even closer th is yea r. Fo r quicker revv ing, the piston and wrist pin have head wit h Increased compression, revise d exhaust power valve, lighter piston and ,}"'i-~. wrist pin and longer silencer have made a great motor even _. . bette r.