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/126808
(Above) GSXR crank (front) has smaller journals. t h inner counterweights and a straight-cut output gear - it's much lighter than the GS ·s. The aluminum GSXR frame (right) is much simpler than the steel GS un it. and weighs 19.6 pounds less. complete w ith swingarm. (A bove) Cutaway view exposes the wet sump l u bric at ion system. The lubricating oil also cools t he engine. making a lightweight package. Flat-slide Mikuni carburetors have a 29mm bore. Generator is driven by the crankshaft. and mounted under the carbs for a narrow engine package. The difference in deflection tol erance is important in case a bike is cras he d, th e Suzu ki men say; th ey a lso say th at th eir a lu m i n um frame, coa ted with a n Alurnite p ro cess similar to a nod izing. is as corrosionresistant an d as durabl e as a co n ventiona l steel frame. There are fi ve cas t sec tio ns of th e fram e. One is th e steerin g head sectio n - including steeri ng head. tri angu la red braces, stu bs to accept th e fram e back bon e tu bes a nd downtubes, a nd a tri angulated sec tion tyin g into the backbone tubes a bo ve th e rear o f th e cylinde r head . T he o the r four sections are locat ed in th e rear o f th e chassis. includin g two side cradle plates - wh ich link th e downtubes.'- engi ne crad le tu bes a nd main back bon e tubes and whi ch a lso carry th e swi ngarm pivot . T he side p lat es a re holl ow ed o ut with cas t-in support ridges, a nd th ey're linked by two o ther casti ngs. a brace posi tio ned a bo ve th e swi ngarm that dou bles as an upper shock m ount; a n d another brace, ben eath th e sw ingar m, th at doubles as a rear en gine m ount an d low er shoc k lin kage m oun t. T he cas tings are linked by extrusio ns fit into recei ver stubs and weld ed ; th e rear su b-fra me , wh ich ca rries th e . seat a nd rai lsecti on. is welded to th e side pl at es. An other extr us io n is welded between th e fro nt downtubes as a brace, an d tabs to ca rry th e oil coo ler are welded to th e do wn tu bes o n eac h side. Footpeg ca rr iers bolt i n pl ace; w he rever p o ss ibl e , a i r cra ft -s tyle th rea de d holl ow rivets are used to receive bo lts and screws. T he rivets arc lig ht , easy a nd q ui ck to ins ta ll , and eliminate the need for n uts welded in p la ce o n the frame. The ent ire tai lsen io n a nd scat rear assemb ly attach to threaded rive ts in th e rear subframe. The rear shoc k linka ge sys tem is a new. simplified desig n for Suzuki , . a nd u ses a pivoti ng roc ker linkage to co n nec t th e bouom of th e swinga rm with th e bo tto m of the shock a bsorber. Th e sys tem in cludes any ecce ntric ca m desi gn in th e main linkage p ivot - th at cha nges th e leverage o n th e shock according to travel a nd p rodu ces a p ro g ressive effect: th e goa l is to h ave su p p le suspens io n reacti on a t h ighway spee ds an d firm su spe ns io n a t h igh spee ds, (especia lly wh en corner in g ). with a smooth transition bet ween th e two . The ad va nta ge of th e new system is th at it accom p lishes with a more co m pact, sim p ler lin kage sys tem what previou s Suzuki Full Floa ter sys tems did with larger . more co m p lica ted lin kages. T he bigges t ben efit. besides so me wei g h t savin gs from th e m ore co m pact design , is a rela tivel y-low sea t height o f 30 in ch es. Positi on in g th e rear ~uspension wh ere it is, without requiring a longer wheei base (the GS XR 's is 56.5 inc hes), was possibl e beca use th e airbox/air cleaner is under the gas ta nk a n d th e bat tery is di rectl y u nder th e sea t, where the air box / a ir cle aner go o n o ther Suzu ki st reet bik es. Rear shock spri ng preload is adjustable by turn ing lock ing co llar nuts on th e th readed shock bod y; rebound dampin g ca n be externa lly set to a ny of fo ur posi ti ons with abou t a 20% da m p ing force cha nge across the ra nge o f adj ust rnents, T he front forks ha ve 4l m m sta nchion tubes (the G Si50's were 3i m m ) a nd are ca rried by forged a lu mi n um triple clamps. There's an alu m in um bra ce bo lted between th e for k sliders, above th e front fender, a nd th e fork s inco rporate Suzuki's Po sitive Damping Fork sys tem - wh ich in creases co m pressio n dam p in g as th e rat e of fork co m p ression in creases, with a blow-off valve to deal with bumps hit under full braking . T he system serves as a n on-brake-linked a n ti-d ive, and is adj usta ble with kn obs locat ed o n fillings o n eac h slide r. In th eir officia l presentation, th e en g ine ers said th at a n IS-i nch front wh eel is a n ad vantage wh en using la rger-di ameter front di scs because it 's ea sie r to quickl y rem ov e and replace th e front wh eel - th ere's more space between th e rim a n d th e ca lipers. U nofficia lly, severa l engi n eers later said that from a fu nc tio na l (Con tin ued to p ag e 2i) 13