Cycle News - Archive Issues - 1970's

Cycle News 1973 03 20

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/141049

Contents of this Issue

Navigation

Page 1 of 47

'" :;; ~ w Z W ..J U >- U Motocrossing th e SCSOO mu st b e something lik e road racing a 903 K awasak i. How would you like • .' < !~ iJD. "T THE WORLD'S LARGEST -.,~~~~~ b v Dave Scho on maker Ph ,;l o s b y Ran d y Dietzel, T om C u ll' a nd S choon ma ker In the age o f on e-upmansh ip , Yam ah a is ou t to fo llo w sui t. T hei r lo ng- rum ored , mu ch co n tro ve rsial, in te nsely feared m o nst er MXer has fina lly arrive d . Strange ly eno ugh , it 's en te ring th e m ar ket w i th o u t to o mu ch "1 0 d o " o n th e p art o f Yam ah a ad vertising. . Th e first hint w e got of its availabil ity w as throu gh a wan t ad in our o wn pape r. \Vhen we read the w ant ad w e began to get this vag ue no tio n wh y the lo w in te ns ity . Th e y are bill ing it as a sc ramb le r. Now again, in this day and age of one-u p m an sh ip eve ry o ne ca lls an y th in g wi th a h igh p ip e a "M X " . Wh al co uld b e go ing o n? We fig-ured it mu st he a to ad . an d the y w e re af raid to call it a m o t o cro sser. I'll h a ve 10 a dm i t th a t ex p ec ta ti o ns fo r th e SC-500 we ren't too hi gh . We pic ked up the bik e from M al c olm Sm ith 's K&N in Riverside and since we we r e in the area de cided to c arry o n to A rro yo. Lo ad in g an d unl o adin g i t announ ced something about i t .,- i r' s he avy . And I don' t mean figu r at ivel y . Ex pe c tations fell e ve n furth er. A flip of the c- o in determ ined wh o - h ad t o ki ck s ta r t it. I lo st. My poor h oots , m y p o or lo ot. I w as j ust ge ll ing o ve r a 36 0 E n d u ro . . S o, o n go es th e gas, d own on th e c h o ke, D on "t be timid n ow. KaWh am ! Huh ? Must n ot of engaged . T ry again . Ka-Wh am! Blut, bl atty, bla t t y , bl at. What ? It's runnin g. That ca n ' t be. My a rc h isn 't even blue . Wow ! Hey, this suc ke r is really d ocile. Hmmm, th ink I 'll kill it and t ry it again . K ick. Blut, bla t. 0 0 · 0 0- 00, ah -h- h- h , MOTORCYCLE PISTON? Wh a t is go ing o n ? F oll o wi n g tr ad i t io n it sh o uld be a leg-e a ting m onst e r. Fir s tly , with an engine th a t is in cred ibl y ove rsq u a re (95 m mx 70 m m ) th in gs don 't hav e t o m o ve to o far , and sec o nd , a littl e c o m p ress io n re le ase . h ol e in the cy linde r helps o ut so rne more . Ge t th is: the comp res sio n rel e ase is o pe n at all times but ven ts in to the e x h au s t p orI to avoi d an y n ast y gr it. Th e co m b in a tio n adds u p to a 496cc si ng le . w h ich ki cks ~ve r p ainle ssly , T he ch o ke c o mes o ff e ar ly in th e ga me an d th e e n gin e doe sn 't mind w a rmin g up w i thoul it. Q uick ly a few th in gs h ec ome ap pa re n t. Blipp in g th e thr ottl e d o es n ot p ro duce a mind shatt er ing screa ch o r an awe so me fe elin g o f powe r. Rev s rise slowly fo r a ra ce r an d tr ail o ff slow ly to o . At -lo we r revs , th e SC -500 ge ts a ki n d o f sha ke to i t, b ut o nce th e revs rise it is, ve ry smoo th . In fa ct vibr a tion is prac tic all y non-e xi stent o nce und e rw ay . T he SC -500 ge ts Y amah a ' s n ew m e ch an ical tric k , th e O rnni -Ph ase Ba lance r. T h is li ttl e dev ice co nsists of tw o coun te rweigh ts wh ich are chain drive-n fro m the cran k . T he ir effect is to ca nc el o ut vibrati on by p roducing a harm onic vibration wh ich is 180 d egrees o pp osed 10 th e e n gin e vibra tio n . It w orks. Wh a t it also d oe s is , in e ffe c t, ad d flyw heel to the engine . Henc e th e slo w r ise a nd fall o f RPM s. Silti ng the re on th e bike I go t this feeli n g of plush ne ss. The sea t w a s comfor table an d co n tro ls arrange d in a manner wh ich p ro mo te dre laxation th ough not ne ce ssaril y e ffici e n cy . Wh en I b o un ced u p a n d d o wn on th e se at , it w a s kind of like le aping on t o a waterbed. T h e seat absorb ed a little, th en th e shocks , an d even th e tire a little . E ve ry thi ng ret u rn ed and w as re ady to gree t m e lo r my ne x t bo un ce . Le an in g i t o n th e sides ta nd sh o wed th e fo ot c o n tro ls to b e n icely p o siti o n ed also. T h e grips are n orm al Yamah a h ard a n d the b ars an gle hac k wh ich d oesn 't w o rk for m e w h en I' m o n th e pe gs. Le vers are Yamah a . T h a t m e an ,s th ey will b reak , but the y a re n ' t o u trage o usly e xp ensive . T h e th ro ttle is a fu rthe r d e velo p m en t of what ha s be en on e of the be tte r th ro ttl e s aro un d. A h ose cla m pe d rubb er b o ot c o vers the e xi t I o f th e cah le Ir orn th e assem b ly . T h ro t tle p ull is ge n t le and h a s a welcome h alf-turn . '. (Wo e be un to th e 500 owne r with a qu arter-turn th ro ule. ] The pegs ar e Yamah a m e ta l an d ca n p ac k wi th mud, but th ey a re n' t bad . In co mes th e cl u t ch . IImmm, I re ck on I co uld do th a t m o st all d ay . A d ab d own I I fo r fi rs t and aw ay w e go. Phlutt. Darn n e ar s ta lle d it. I th ought 5 0 0 sin gles were su ppos ed to pull fr om idl e. G ue ss t his on e lik e s a c o u p le o f R PM a t least. S ure am glad it's ea sy to start. Now a few rev s and awa y we RO . Sh azam ! Sh e su re is gea re d tall . Idl e ge ls y o u b o o gey in g right al on g. Be lter not d o an y th ing but b ab y it in fir st with all th a t powe r. D ro p h er in to sec ond an d grab a han d ful. Wo w ! C lu tc h mu st be slipping. O oops . Th at guy c o ve red with dir t ba c k the re seems to think it wasn ' t th e d ut c h . Let's try that again . V aro om . . Ca ri m in y, i t just j us t b us ts th e re ar wh eel lo o se a nd d igs a d i tc h. How abo u t o ver h ere o n this h ard st uff. Grab a ha n dfu l. ..a rg h, w h o a , oo p s, o ops, c lu tch , gr ab th e cl ut ch . \Vh t~\\· . tha t w as dose . Sure did hl ow my co o l. Yessir e eSob , she sure do es have so me b ean s. No w we 'll go u p th rough th e ge ars he re . M y Lord, it 's ge ared 50 - 0 · 0 hi gh . Every ti ng is goi ng b y h o rrib le blu rr y , an d w o w , sh u t o f f. We di d n ' t ge t a chanc e t o get th e SC -5 0 0 o n th e d yn o b ut a fair e s ti ma te mi gh t be th at it is pro du cin g: so me thing in e xc es s of 3 0 rear-w hee l h o rsep ower on the Pa trac o d yn e . T orque wo u ld probab ly b e a n ew re c ord fo r a 5 0 0 c lass m or oc rosser, to o. With ge a ring a s d elivered th e real t o p sp eed for th e Y amaha wo rks o ut to b etween 75 an d 9 0 M PII , o n p ap er. Mo stl y we j u s t c h ic ke n ed o u t a l top en d . I t pull s ve ry s tro ng in fou rth ge a r a nd taller ge arin g c o u ld be pulled. (Hey, a ll y o u guys lo okin g for 110 l'.IPII Grand Pri x moun ts.) T he powe r is so su bs ta n tia l that fourth ge ar (o n ly a fo u r speed) is an o verd ri ve a t .807 : I. T h ird is s t ra igh t through , an d firs t looks like a road racer a t 2: I. It is one su m b ichey fast m oty cycle. Gra b som e brakes h e re n ow. T h e Iron t is r eally nic e. It j u s t pulls things do w n an d n ow for a Hr tl e rear grab be r. Kl unk. Sideway s huh ? M aybe a bi t gra b b y . We 'll try i t a lillie m ore eas ily this lim e . Kl unk. Well, m a ybe it will loo sen up after some time. S ure h ope so . It's a good thi n g th e fr ont w orks so well . AI least th e rear is full fl oating an d ge ts a lo n g with the bum ps OK . No w w e re turn to the van fo r ..1 litt le in ten se turling se ss io n . T he po or beas t had b egun p ingi ng in a d eathl y m anne r an d w as eve n a lillie ti ght by the tim e th e return journey w as c o m p le te d. S ome experime n ta tio n rev ealed tha t abou t 4 0 m ore on the I Vi sually you will be able to tell the 500 fro m th e 3 60 by black stripes and a bigger silencer. 0.

Articles in this issue

Archives of this issue

view archives of Cycle News - Archive Issues - 1970's - Cycle News 1973 03 20