Cycle News - Archive Issues - 1980's

(A bo ve) Disconnecting th is hose will enable the Ninja to run when the charcoa l canister is plugged . (Below) A length of all -thread and a piece of pipe w ill extend the mirrors. Pilot sc rews are accessible after removing the aluminum pl ugs (above). A .0 2 5- inch- t hick brass washer will lift and correct the jet needl e. Life ~ith Ninja Some easy mods improve Kawasaki's sports flagship at little or no cost By Jim Wolcott O ver 9000 miles have rolled on th e clock of my 1984 ZX900-Al Kawasaki Ni nja; the bike has proven to be re liable and mostly troublefree. H o wever, unlike test bikes run in stock trim a nd re tu rned to th e manufactu rer, th e titl e to th is mach ine was in m v name. U n like shan- ter m test h ikes, I viewed th is as an invitati on to fiddle with some of th e N inja 's detai ls. My idea was to improve performa nce, co mfa n or rel iab ilit y - whi le working wi th the stock components, and without spend ing a lot of mone y. Carb ureto rs As delivered. the Ca lifornia-model Ni nja ha s - to p u t it politely - poor thro ttle response. Prot o type N injas su p p lied for th e motorcycle press a t Laguna Seca raceway in Decem ber , 1983, had none o f th e ca r bur etio n problems of the models that rea ched th e showroom floor. T han ks to em issions reg u la tio ns , sudden ly o pe nin g th e th rottle of a stoc k N inja wou ld ca use a co ugh a nd stu m ble from th e ca rbs, foll ow ed by a grad ua l cha n ge in engine speed. Son in g o ut the ca rburerio n trou bles is a n eas y afternoon 's work . First , remove the fou r car buretors ac co rding to th e Kaw asa ki shop ma nual. As delivered, th e float heigh t is typica lly set too low - ens u ring that eac h and every production Ninj a wi ll pass th e various emissions tests. • •' ~ ' \'F. Q ' '" W ," Pll eJ..W'.. · '6 2 floa t h eight to l7mm , as specified in sectio n 2-8 o f th e Kawa sak i shop manual. T he next ste p s will enrich th e fu el m ixture to ge t rid o f th e stu m ble. You wi ll need 10 adjust th e pi lot screws, located o n th e un derside of the carbs ben eat h the bu tterfly valv es. T he pi lot screws are co nceal ed by pressed-in plugs, whi ch must be rem oved for adj ustment. Drill a 3/32-inc h hol e in th e center o f eac h o f th e plugs. Be carefu l no t to drill too deep; j ust dri ll through the shallow a lu min um plugs. This is important: shou ld th e dri ll bit co ntact the pi lot screw ben eath th e p lug, it wi ll tight en the pi lot scr ew a nd disrupt the facto ry settings . T hread an ea sy- out (a big wo od-screw will work in a pinch ) into th e ho le, a nd twist th e plugs o ut o f the car bs. Since th e adjustment of the pi lot jets is set a t the fac to ry and is fairl y cr i tica l, ma ke a no te o f w here ea ch ca r b is set before adj us ting it. To do th is, carefu lly tigh ten eac h pilo t screw aga in st its seat, co u n ting the tu rns required. Write th is n umber down for futu re referen ce. Unscrew the pi lo t screw 10 i ts' exact starting posit ion, and then u nscrew it a half-turn more. Th at's it - since o n ly U.S. -mode l Ninj as a re eq u ipped with th e plugs, ' l bc:r ;. no ~~ 9)"l:,j n ~«.a lllh ~ •• • ". _• Next, move th e jet needl e up o ne notch . Of co urse, new moto rcycl es don 't h ave no tch es o n th e needl es (to prevent adj ustment ) - so th e so lu tion is to sh im the needl e. A well- stock ed hard wa re sto re wi ll have brass was hers with a 7/ 64-inch hol e, a nd a 5/ 16inc h o utside di ameter. Best bet is to take th e needl e a lo ng for sizing. Find a was he r (or co m bina tio n of wash ers) betw een .020 a nd .025-inch thick , slide it o nto th e need le, a n d re-install th e needl e in th e vacuum pi ston . Rep lace the carbu retors o n th e engine , and th e bike is ready 10 rid e: no o the r adj us tme nts a re necessary. T h e Ninja wi ll warm -up faster. respond precisely to throttle cha nges , a nd sho u ld ge t sligh tly bett er gas mi leage. It sho u ld be no ted th at these carbureto r cha nges are not stree t legal ; shou ld the bike be rid den o n a p ub lic highway, tighten th e pilot scre ws a half-turn and remove th e shi m wash ers from th e needl es. C harcoal system Ninj as so ld in Ca lifo rnia are eq u ip ped with the state-m anda ted evapora rive em issio n s svs tern. T his svs rem vents th e fuel tank and th e car bu reto r floa t bow ls through a can ister o f ac tiva ted cha rcoa l, loca ted in the tail section behi nd th e sea t. T he problem occu rs wh en th e gas ta nk is Ii lled to th e brim , th e bike is ridde n a shor t d istan ce a nd th en par ked o n th e sidesta nd , H eat from th e engine ca uses th e gaso line to expa nd , whi ch sends ga s through th e vent into th e ch arcoa l ca n ister. Once th e ca n ister is Iill ed with gaso line, it p lugs up tight, prevent ing a ir Irorn ent ering th e Iuel ta n k and ca r bu retor float bo wl s. Wh en this h appen s, th e Ninja wi ll sp u tter to a halt . As a roads ide fix , u n plug the vent ho ses a t th e j unctio n under th e rear o f th e gas tank. To revive a p lugged cha rcoa l ca n ister, remove it C rom th e bike a nd drain th ' g~ o u t of it. Ne I V\; lJ il,l,lr th e charcoa l; o ne technique is to hook th e a ir p ump from a n aq ua rium to the input side of th e ca n is ter, a n d let it ci rcu la te air th rough th e cha rcoal for a da y. Repl ace th e ca nister, reco n nec t a ll th e hoses, and yo u 're ready for the nex t tim e th e sys tem p lugs up . OC co urse if th e ca n ister is left un plu gged , th ere's no harm to th e motorcycle - thi s sys tem m erely provid es a vent C r the gas tank a nd o ca r buret ors. Mirrors The N in ja 's stock m irrors must have been police-approved . , . th ey're pos itione d for a perfect view of yo ur elbow. Since vou ca n' t see what 's beh in d you, it '~ easy to receiv e a red li ght surp ris e. O ne so lution is to len gth en th e stock mirro rs. T h e stock mirror stems are ma de o f so lid steel with a black p lastic coa ting. Using a ha cksaw , carefu ll y cu t through th e m idway po int of th e stem. C lamp th e ends o f th e stem in a vise, a nd d ri ll a nd tap th em for a 3-32 thread. Cu t a pi ece o f 3-32 a ll -thread a bo u t 2,75 inches long , and th read i t into o ne o f th e mi rror pi eces. Fi nd a section of 5/8-i nch pipe (I u sed elect rica l co nd uit ) and cu t a four-i nc h piece. S lide th e pi pe over the a ll thread , a nd tigh ten th e wh ol e asse m bl y together. W ith a bla st o f flat black spray pai nt, th e leng th en ed mirro r will look like it carn e fro m Kawa saki 's pa ns bin. Of co urse the mirrors co u ld be ma de longer o r shorter using th e sa me technique. I Fork seals T he C sea ls popped a t a bo u t th e ork -IOO O-m ile ma rk - not an uncommon occura nce on a Ninj a. Severa l o wne rs ha ve had good results by replacing th e stoc k sea ls with Leak Proof Sea ls. T he Leak Pro o f Sea ls a re T eflon-im pregn at ed, have less slid ing resista nce th a n the stock sea ls, a nd a re g ua ra n teed fo r th e lif e of the mot orcvcle. Also , Lea k Proof Sea ls ca n be fi lle d by hand - with out ~h~ spe cia l

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