Cycle News - Archive Issues - 1980's

(Above) Only the Kawasaki has a rear disc brake . (Below ) Hardly anyth ing was left unchanged on the Yamaha. Most attention went to the motor. (Above) At 2071bs. wet, the Honda is the lightest of the four. (Below) The Suzuki's seat, gas tank and frame are much narrower for '86. 12 - th e more th e fork is co m p ressed, improve accelera tio n, a nd unsprung weight is reduced lO impro ve suspenth e hi gher th e damping rat e. The air/oi l for k sti ll has external spri ng sio n action. O th er cha nges incl ude a sma ller, p reload adj us tme n ts a nd eig h t-way co m p ress io n dampin g settings , The 2.0-gall on gas la n k th at a llows a 43 m m sta nc h io n tubes h ave no promore for ward seati ng p ositi on for rective boo ts o r fork leg guards. turn in g: a stronger chai n gu ide th at Th e 8.7-inch ' from di sc brak e isn ' t mounts in three pl aces in st ead o f two new , bu t th e rea r di sc brak e, which and enclosed cha in adjusters . Cer rirepl aces th e shoe/ dru m design , is. fied wet weight (wit h a full ta nk o f gas) is 211 pounds, T he ca liper mounts solid ly to th e swi nga rm, and th e effective disc dia Yamaha Y Z125S: II's been a num meter is 7.5 inc hes . ber o f years since Yam aha prod uced a Th e #520 chai n is 13% na rro wer, rea lly co mpetitive l25ccmot oc ro sser , wh ich makes it 0.5-pounds ligh ter. so it's n ot su rp risi ng that th e lat est YZI 25 is a n a ll -ne w mo torcycl e. Acco rd ing to Kawasak i, besides reducing overa ll weig h t wi th th e light- . . :' We'rem aking th e YZl2 5 0ur num ber•• er cha in, ro tatin g mass is reduced 10 ' . . o ne p rio rit y th is sea r," says Yarn a0 0 ha 's P roduct Eva lua tio n Supervisor Ed Sch ied ler, and fro m th e look s o f th in gs. th at 's exact ly wh at th ey'r e do in g. Motorwise, th e 1984 and '85 YZl 25s were ex tremely underpowered co m pa red 10 th e H onda , Kawa sak i a nd Suzu ki. so Yamaha designed a co m "p letely new mot or for '86. Al th ough the, cyli nder ret ai n~ th e sa me basic port a rra ngeme n t with seven transfer pons a n d o ne cent ra l exha us t with two su b-ex ha us t ports, p ort tim in g' ha s been radica lly cha nged lO use a new 3-lm m Mikuni Oat -slid e (formerly , ro u nd -slide) ca rbu reto r a nd reshaped exha us t' pipe; th e steel silence r is re~u p ~bl e. I ncluded in t!ten e~," port tim in g cha nges are lar ger su b-exha us t ports, whi ch are pa rt of a new Yamaha Pow er Valve System (YP VS) now d riv en o ff th e righ t side (ins tead o f th e left side) . Bore a n d stro ke is th e sa me a t 56x50m m; disp la cem ent is unchanged at I23cc d isp la cement. The YZ n ow ha s a C"dSC reed induction . whi ch feeds fuel directl y' to th e cra n kcase th rou g h six fib er reed p etal s. The cylinder head now uses IwO . rubber a-rin gs as a gasket; th at's su p posed lO improve heat di ssipation because o f th e metal -to-metal co ntact between th e head and th e cyli nde r; th e a-rings a re a lso supo posed .lOpcm ·ide beue r sea ling than a

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