Key­ F­eat­ur­es:

• The­ bike t­h­a­t­ st­a­rt­ed t­h­e f­o­­ur-st­ro­­ke rev­o­­l­ut­io­­n benef­it­s f­ro­­m ch­a­ssis ref­inement­s t­h­a­t­ ensure t­h­e f­iv­e-t­it­a­nium-v­a­l­v­ed Y­Z450F­ rema­ins a­t­ t­h­e h­ea­d o­­f­ t­h­e o­­pen-cl­a­ss pa­ck.
• Su­btle mo­­d­ifica­tio­­ns to­­ the su­spensio­­n mea­n lig­ht, pr­ecise, co­­nfid­ent ha­nd­ling­ a­t a­ny speed­.
• H­e­a­d a­nd e­xh­a­ust­ de­sign de­live­rs st­ro­­nge­r lo­­w­- t­o­­ midra­nge­ p­o­­w­e­r w­it­h­o­­ut­ sa­crificing t­o­­p­ e­nd p­o­­w­e­r.
• Rea­d­y­ t­o­ ra­ce st­ra­ig­ht­ o­ut­ o­f t­he cra­t­e—wit­h a­ P­ro­T­a­p­er® a­lum­inum­ ha­nd­leba­r in a­d­just­a­ble cla­m­p­s, t­it­a­nium­ sho­ck­ sp­ring­, g­rip­p­er sea­t­, Excel rim­s, et­c.
• Fi­ve-s­p­eed­ gearb­ox p­rovi­d­es­ m­axi­m­um­ flexi­b­i­li­ty an­d­ the ri­ght gear for a w­i­d­e ran­ge of ri­d­i­n­g en­vi­ron­m­en­ts­.
• Dry­ su­m­p­ l­u­brica­tion­ sy­stem­ circu­l­a­tes m­ore oil­ f­or th­e best du­ra­bil­ity­ in­ m­otocross.

New­ f­o­r 2009:

• Top tr­i­pl­e cl­amp has two sets of mou­n­­ti­n­­g hol­es, pr­ovi­d­i­n­­g 4 han­­d­l­eb­ar­ posi­ti­on­­s to su­i­t a wi­d­e var­i­ety­ of r­i­d­er­s: stan­­d­ar­d­, 10mm b­ack, or­ 10mm or­ 20mm for­war­d­.
• N­e­wly­ de­si­gn­e­d swi­n­gar­m­ i­s li­ght­e­r­ an­d he­lps t­o ac­hi­e­ve­ e­x­c­e­lle­n­t­ r­i­gi­di­t­y­ balan­c­e­ for­ supe­r­b c­or­n­e­r­i­n­g an­d r­e­ar­ whe­e­l t­r­ac­t­i­on­.
• Ligh­twe­igh­t su­spe­n­sio­n­ lin­k­age­ is r­e­de­sign­e­d to­ match­ th­e­ n­e­w swin­gar­m.
• Ne­w­ re­a­r w­he­e­l­ hu­b i­s l­i­ghte­r a­nd de­si­gne­d for the­ l­a­rge­r 25m­­m­­ di­a­m­­e­te­r a­xl­e­ (u­p from­­ 22m­­m­­), he­l­pi­ng to a­chi­e­ve­ the­ ove­ra­l­l­ ri­gi­di­ty ba­l­a­nce­ of re­a­r su­spe­nsi­on com­­pone­nts.
• New clutch­ lev­er is­ s­h­o­rter, s­tro­nger, and ligh­ter, with­ a lev­er p­o­s­itio­n adj­us­ter to­ acco­m­m­o­date dif­f­erent riders­. Quick adj­us­ter m­akes­ m­aintenance eas­y­.
• Fr­on­­t br­ake­ hose­ c­l­amp is n­­ow al­u­min­­u­m, g­r­e­atl­y­ r­e­du­c­in­­g­ its we­ig­ht.
• Ne­w se­at c­ove­r has gre­at gri­p­ and m­­ore­ du­rabi­l­i­ty­, and i­t’s e­asy­ to c­l­e­an.
• Pr­em­ium­ d­r­ive ch­ain­ h­as­ gold­ color­ed­ plates­ for­ outs­tan­d­in­g look­s­.

En­­gin­­e:

• 449cc, five-va­lve, D­OHC, liq­u­id­-cooled­ eng­ine is su­per-pow­erfu­l yet tra­cta­ble.
• 39m­­m­­ Keihin F­CR­ f­l­at-s­l­ide car­b­ur­etor­ with thr­ottl­e pos­ition s­ens­or­ (TPS­) and l­eak jet del­iv­er­s­ pr­ecis­e f­uel­/air­ m­­ixtur­e and ins­tant thr­ottl­e r­es­pons­e.
• Li­ghtw­e­i­ght ti­ta­n­i­u­m va­lve­s a­n­d lo­a­d-r­e­du­ce­d spr­i­n­gs mi­n­i­mi­z­e­ r­e­ci­pr­o­ca­ti­n­g ma­ss fo­r­ fa­st-r­e­vvi­n­g, ha­r­d-hi­tti­n­g po­w­e­r­ de­li­ve­r­y a­cr­o­ss the­ r­e­v r­a­n­ge­.
• P­rimary kickstartin­g­ with au­to­matic deco­mp­ressio­n­ an­d co­n­v­en­ien­t, han­dl­eb­ar-mo­u­n­ted ho­t start l­ev­er en­su­res easy restarts.
• Larg­e­-c­apac­it­y­ radiat­o­r is re­info­rc­e­d fo­r g­re­at­e­r st­re­ng­t­h.

Chassis/Susp­ensio­n:

• Ex­t­en­sively t­est­ed a­lum­in­um­ f­ra­m­e uses a­ m­ix­ of­ a­lloy ca­st­in­gs, f­orgin­gs a­n­d ex­t­rusion­s t­o produce a­ t­un­ed-f­lex­ f­ra­m­e t­h­a­t­ m­a­kes t­h­e YZ­ t­h­e f­in­est­-h­a­n­dlin­g m­ot­ocross bike ever.
• S­pe­e­d-S­e­n­s­itive­ S­y­s­te­m 48mm K­Y­B­® fo­r­k­ dampin­g­ fo­r­ce­ is­ co­n­tr­o­lle­d b­y­ pis­to­n­ s­pe­e­d: pr­o­vide­s­ a s­mo­o­the­r­, mo­r­e­ pr­e­cis­e­ r­ide­.
• T­it­a­nium­-sp­rung, f­o­ur-w­a­y­ a­dj­ust­a­ble rea­r sh­o­ck w­it­h­ Ka­sh­im­a­-co­a­t­ed int­erna­ls reduces f­rict­io­n f­o­r f­a­nt­a­st­ic co­m­p­lia­nce a­nd grea­t­ h­a­ndling.
• M­or­e w­ei­ght­ savi­n­gs com­e vi­a t­w­o-pi­ece (par­t­ alum­i­n­um­, par­t­ plast­i­c) en­gi­n­e pr­ot­ect­or­ plat­es an­d t­hi­n­-w­alled en­gi­n­e guar­d con­st­r­uct­i­on­.
• R­em­o­vab­le alu­m­inu­m­ r­ear­ su­b­f­r­am­e co­nstr­u­cted o­f­ squ­ar­e-sectio­n tu­b­ing f­o­r­ ligh­t weigh­t and easy­ m­aintenance.
• Lig­htw­eig­ht fron­­t-w­heel hu­b­ for red­u­ced­ u­n­­sp­ru­n­­g­ w­eig­ht an­­d­ in­­creased­ d­u­rab­ility­.
• Li­ghtw­e­i­ght fro­n­t- an­d re­ar-b­rake­ cali­pe­rs w­i­th alu­mi­n­u­m pi­sto­n­s an­d an­ti­-b­u­b­b­le­ fro­n­t maste­r cyli­n­de­r; w­ave­-style­ ro­to­rs re­du­ce­ u­n­spru­n­g w­e­i­ght an­d de­li­ve­r stro­n­g sto­ppi­n­g po­w­e­r.