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/126818
The Honda V-4 's rear shock is connected to a rocker arm w hich pivot s in the swingarm, and which is connected t o t he frame by rods . (Below) Christian Sarron's works V-4 Yamaha. to n because wh en I went into the . corner the front en d j us t d ug in. If th a t had ha p pen ed o n the th ree cylinder it wo u ld h ave co me back . I kn ow what to do in tha t sit ua tio n a nd I am 95% su re that I co u ld have saved it. . On th e Iour th ere was no way I cou ld , th e fro nt j us t dug in like th e tip of a pole vau lt." The V-fo ur in 1984 was obvious ly not Spencer 's favor ite machine, never comi ng up to th e sta ndard of th e remarka ble '83 cha mpionship-wi nning V: three. The new four seems bett er from the start bu t Spencer still has his reserva tions. "'As I said to someone earl ier, 'If I co ul d get th e fou r to ru n as well as th e three I would be very ha ppy.": P u tting th e petrol tank back on top has made things easier for th e mech anics and now the bank of cylind ricalslide carbs is accessible without removing the exha ust pipes, a lt h oug h a sma ll length of sea t sub-frame must be u n bo lted to get th em out. On last year 's four th e en gine temperature tended to be 500 F higher th an th e th ree but this time they have not enclosed the engi ne with pl astic a nd th e V-shaped radia tor can pass a ir out th rough large hol es in the fairing. At first it is no t easy to see how th e carbs a re a n y better served with air tha n they wer e last year bu t in fact th ere is a scoop just behi nd the bot tom of th e steeri ng head th at ducts air over the to p o f th e radiator. A comple te p lastic pa n keeps this air away from th e up ward-poin ting cylin ders a nd d ucts it to the a irbo x a ro u nd th e car bs. T he underside of th e tank completes th e duct ing system . There a re h oles in th e s ea r/ sidecover uni t that let yo u see 'the carbs a nd ra ther th an th ese bein g ex tra int a kes th ey ma y serve to let excess a ir o ut. T he spark p lu gs p rotrude throug h th e p la sti c tra y, but on ly just. T hey are the la test NG Ks with only abou t IOmm o f ceramic, sho rter even tha n th e special plugs for the three-cylinder Hon das.1.'heir effective leng th is ma de shorte r sti ll by th e fact that the plug cap con nection is ma de down in side the ceramic - th ere is no threaded contact sticki ng u p o n · to p of th e p lug. This no t on ly hel ps with th e ai rflow to the carbs but means that th e ta n k can be very low. T he plumbin g of the ex ha ust pi pe s from the. V-Iour is a real wo rk o f art a nd th e 90 0 cylin de r sp li t mean s that th e p ipes for the low er cylinders have to wend th eir way back a nd forth under th e engine . The upper cyli nders a re not so cra m ped for space as th eir fattest portions come under th e fro nt o f the engine . O ne advantage of the ATAC box es is that the volu me o f the pipes themselves is fractiona ll y. less than it wo u ld o therwise be. T he ATAC cha m bers wh ich are opened a t low rpm are fitt ed to eac h of th e four cylin ders and th e operating fla ps a re co ntro lled by a mechanical centrifuga l system in the same way as on the th ree-cyli nd er 500. The drive is taken off the right hand side o f th e sing le cra n k. In photos o f the right ha n d side of the 'e n gine a sma ll ca p secured by three screws can be seen in front o f th e clutch and benea th th e wat er pump housin g. At 450 fo rward o f the vert ica l a shaft comes ou t o f the engine, runn ing u p and forward to the upper cyli nder exhau sts an d down an d back to the lo wer boxes. The Honda V·4 's two twin-slide carbs feed directly int o the crankcases through reed valves to fuel the four cylinders. Note the plug caps protruding through a plastic tray that ducts air over the upper cylinder heads. (Below) The Honda's NGK spa rk plugs have very short ceramic and recessed lead connections. Wheth er 1985 becomes a nother Yamaha/Honda battle as it ha s o ver th e last two seasons depends on th e pe rfor ma nce of th e latest Suzukis a nd wh ile the factory a n no unc ed th eir withdrawa l fro m G P racin g a t the end o f '83 th ey hav e n ot gone far a way. Thou gh they on ly supp lied engine parts la st year th ere were some com p le te fac tory ma ch in es be ing ra ced a t Kyalam i by the Ga lli na tea m . o f Franco Unci ni a n d Si to Pons. lnstead o f the T G A-l Ga lli na- built specia l which will th is season o n ly be ra ced in - the European -Champion- shi p even ts, th e wor ks Suzu kis have more con vent io na l twin -loo p a lum in iu m frames. They differ from pr evious S uzu ki frames in that th e tubes a re rectangu la r but far from sq uare wi th side faces being a lmost twi ce th e width o f the tubin g. T he side faces a re formed with a ridge to improve the section and stiffness. T he eng ines used by bot h the Iaclo ry team and rhe carbon-Iiber H ero n Suzu ki a re pow er-ch am ber u nits that ha ve a n exha ust cha m ber ca st int o (Co n tin ued to page 1-1) II