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/125455
ca m foll owe r pivot po int is off-center t o t he s ha f t on whi ch it is ca r r ied , th e r ecom me nde d .001 valve clearance can be acc omplis hed by m erely revolving th e sha ft one way or t he other, thus cha ngin g th e p roximity of the fo llower t o t he ca m lobe. This is don e fro m outside th e eng ine si nce one end of each foll ower shaft ext e nds throu g h it s respective side of t he hea d , adjustment being maintain ed by a lock nu t a t this point. T he t ors ion bar va lv e sp r ings are also tran sv ers ely mounted, just below t he cam foll ower pivot s ha f ts. The outsid e end of ea ch t orsion bar is a spline fit in a locating brack et t ha t is us ed t o preload th e bar and an chor it so lid ly t o th e hend . The remainder, or work ing part of t he bar, is s plined t o t he in si de of a holl ow s haft which , free to turn, is su ppo r te d on it s far e nd in the center of th e head and ca r ries at its mi dp oint a forked a r m whi ch exte nds beneat h a colla r on th e val ve st em. Wh e n t he torsion bar is insta lled, t he forked ar m j us t con tacts the va lve collar, t hen a p r eloa d is c r a nked in to t he t ors ion bar's locatin g bracket wh ic h is locke d in t his posi t ion with a bolt. T h us t he induced twi st in the tor si on ba r exerts pre ssu re (v in it s ou t er slee ve and fo rk) aga inst th e va lve s te m to ke ep it seated again st th e ca m foll ower. W hy t he torsi on bar va lve s pring rather than coils or hai rpi n s p r ings? Sim ply t hat t he torsion bar elim inates su rge at high s pee d, plus ma king a very compact and lig ht ar ra ngement . Two ot her f unctions are associated w ith the ove rhea d ca m mec han is m: s pa rk ti m in g and tachometer driv e. Dual circui t b rea kers are dri ven directly off t he end of th e left exhaust ca m , while th e tach dri ve off th e ri g h t exhaust ca m is convenientl y close to th e in st rumen t it fee ds. Ign iti on is by 12volt ba tte r y a nd A e ge nerato r , ignit ion co ils and co nde nsers. Th e ignit ion is eq ui pped wi t h a ce n t ri f ug a l advancere tard mechanis m. All t hat remain for discu ssion to psid e are t he ca r bu re tors , but t h ese are d a ndie s. Alt hough t hey are s im ila r to conve n ti onal mo torcye1e carbureto r s in that t he y ha ve a vertical slide, wh ich con trols a ir in take, eac h carb a lso ha s t wo bu tterflie s , one fore a nd a f t of th e slide. The rearmost butte rfl y is an ai r choke, but t he fo rwnrd b utterfly is controlled by t he th rottle ca ble, wh ile t he slide is r emo te ly con t ro lled by vac uu m acting above a large pist on a tt a ched to the top of t he sli de. A s the throttle butterfly is pulled ope n by th e throttl e ca ble, ve nt u r i va cuum (o r p ress u re d iffere nti a l wit h outside atmosphe r e ) is by passed t o t he to p of t he slide pi st on, thereby remot ely rai sing the sli de as en g ine needs requir e, The beau ty of it is t hat no m att e r how qui ckl y th e thrott le is ope ned, th e sha f t and the ou t pu t s ide of th e countere ngine will not st all since it alone de- sha f t . The more lightl y loaded opposite te rmine s how much air it ca n i ng es t , en ds of each sha ft r un in pl a in bearNo pe rceptibl e la g is evide n t on r a ni d ings. The bo x is const a n t -mesh type a cceleration, how ev er , so qui ck is the with dog engagement bet ween g ears. transgressi on from butterfly t o sli d e. The ir lateral movemen t is controlled by Throttle effort a t the handl eba r is a s t wo forks attached to sleeves t hat ride light as most sing le ca r bu re to r johs ; on a cam-grooved cyli nder and are the si ng le r eel throttle ca ble being con- keyed to same by loca t in g pins that nected to a mid- way junct ion block slide in t he cam grooves. A s the footwhich ha s a ttache d to it two cables, on e shift lever r ev olves the cyli nde r , it s for each ca r bu retor butterfly. The meth- groove pattern g uides the shifter for k od of ca r bu r eto r attachment is al so slee ves in t heir la t eral movem e n t. The s ig nificant; the ir mou ths fit insi de , and clutc h is wet type with seve n plates; it a re cla m ped to, rubber ex te ns ion hoses withstood t he ri g or s of t he test w it ho ut whi ch a re bond ed to s te el flan ges that slip 0 1' overheating, and leve r operation bolt to t he engi ne m anifold s. T he ca r - a t the bars was qu ite ea sy. buretnr bodie s a re t he re fore very flexT he chassis t hat carries t he 450 en ih ' e in rela tion to the eng ine. a bso rbinggi ne is we ll co nstructed but conven li ttl e of it s vi bration. I ndividua l paper tional in most respects exc ep t t ha t th e pa ck air cle an er s of g ene rous properframe is heavily gusseted at points of t ions filt e r e ng ine brea t hing; a cle ve r tube in tersec t ion an d includes two tan k 'ouch here be in g th at the filters a re inbars, th e lower on e of w hic h a lso se r ve s te rconn ec te d, so that each ca r bu re to r as a t op mot or mo un l. T el escopic coil lak in!: it s t u rn feed s from both filt ers spring suspension is used fron t and re a r rat her than j us t one , thus doubling' with oil damping. Generous t ra vel is filte r capacity a nd kee ping th em clea ne r ev ide n t and t he bike r id es lik e the d ue to t he re duced a ir tlow s pee d p rove r bia l cloud, a t s peed , or a t a t h -o ugh the eleme nt s. cr awl ove r sm a ll ir r egula r iti es (i n and out of d ri vew ays , etc .) . S urp risingly, the three-way adjustable r ear shocks a ppea red t o be da m ped on r ecoil only (or at best very lightly on counterr ecoil) ; a quick bounce on t he sadd le, with t he bike at rest, and it pops r ight back u p w it ho ut per cep t ible sign of snnbbing. Thus, a lt hough th e 450's r ide appeared above r eproa ch on t he r oad, I wonder what a set of truly d oubleda m pe d r ear shock s would make. Granted, it would be d ifficult to improve on the ride it presently ha s. E ither wa y, hang on to th os e Honda rear shock du st cove rs ; they're made ou t of plastic rather t han steel, doing away with th e irksom e sc r a pi ng noises t ha t accom pany th e conve nt iona l metal cov ers - just on e Like th e M ississ ippi, t he Honda 450's of the many, ma ny sma ll r efinem ents. lower enel should roll 0 11 f or ever , w ith P ar t of t ha t plush carriage is due to [our ro lla lII"illS held in pill ow block s th e dual spring setup within ea ch a lloy f ro nt fork leg; two different rate springs bolt ed to "pp er half of case. Th reads pr ov id e for li ght a s well a s heavy loa d s , nre all met r ic ami to ols are itrcluclcd. giving t wo-st a g e prog r ess ion. The most W i th a pisto n sp eed of 33 75 f eet per . outstanding fea t ure of th e chassis is th e 'minute at lW OO rpm, the H onda pistons brake syst em. The du al lea d ing b rake T" n a [u ll 100 0 f eet per m illll te below shoes u p f ro nt (two ca ms) are impr esma xi mu", speed of f actory-hot stoc k ca r sively powerful, yet so p r ogressi ve and eng illes bu ilt [or st ree t, R eall y safe! true that eve n a nov ice ca n use th em r athe r heav ily w it h safe ty - an incr ed So compa ct t hat it s ma in sh aft is a l- ible devi ce. T he r ear shoes a re opera te d most du e sou t h of th e rear ca m lobe, by a s ing le cam and a re m ost adeq uate t he four-s peed gearbox is sho r t fron t to for t he back. The wh eel s a re 18-inch ers ba ck prima rily because t he ma ins haft wi th 3.2 5 ru bbe r f r on l, 3.5 0 r ea r. Wheeland countershaft are ca r ried in double ba se is 53 inc he s. row rathe r t ha n s ing le ro w hall bearBut it is th e appointments - sheeting s , all owing smaller diame te r bear- metal, fittings , con trols, etc . - t hat add in g s a nd thu s close r spac ing between frosting to the ca ke, and the Honda t he shafts and smalle r di am et er gea r s. 450 is d r ip ping with such refineme n t s. T he dou bl e r ow ball bearin gs men ti oned The biggest con ve rs a ti on pi ece is t hat are used on th e inp u t si de of the m ain- 4.2-gallon g a s tank. I wasn't qu it e s u re • • • •