Cycle News - Archive Issues - 1990's

WORKBENCH By Brian Catterson Road race prep, part 2: Details, details ... ow that you kn ow every th ing th ere is to kn ow about sa fety wire, let's d iscu ss some o f th e o ther requiremen ts put forth by roa d racing organiz tio ns, Fo r wh en it comes to racea p rep p ing a motorcycle, safety wire is j ust th e tip o f the iceberg ! Wh ile safety wi re does an excelle nt job o f p reventing fasten ers fro m looseni ng, su bseq uen tly spill ing o il, g.as or wa ter o nto th e track , th ere a re ot he r wa ys for fl u ids to esca pe Iro in yo ur en gi ne. Principal amo n g these is the cra n kcase b rea ther, whos e hose typi cally runs to th e bas e o f th e airbox . It' s possible for o il to esca pe here, th erefore most cl u bs require that you vent you r cra n kcase breather into a ca tch ca n or bo ttle, Ca tch ca ns / bo tt les ca n be as sim p le as a n em p ty bottle of fork fluid with rubber hoses, or as exot ic as a n anodized aluminum cyli n d er with welded-on fittin g s to accommodate stainless steel braided lin es '- rule books typ icall y di ctate only th at it be immune to th e effects of gasoline, capable of holding a t least six ounces of fluid , and unlikely to spi ll unless more than two-thirds full. T he most popular locations a re under th e tailpiece o r behind th e fairing. . While most cl ubs requir e o nl y th at yo u vent you r cra n kcase breather into a ca tch can/bo u le, so me require tha t yo u vent you r carbu retors' float bo wls there as well ; you mi gh t likewi se co ns ider ro u ting yo ur battery's breather hose. H yo ur eng ine is liq uid -cooled, you 'll need to provide a radia tor o verflo w N co n tai ner , o ne whic h is qu ite a hit la rger than you r ot her ca tch ca n/ bo tt le. For tunately, most machines come from the fan ory so equip ped. You 'll a lso need to replace the coolant wit h plain wat er, sinee a ntifreeze co nta ins lu bri can ts thai make for poor tra ction. A special note o n the la tter: If you race in a cl ima te wh ere tempera tures a re li kel y to fall.below freezin g at n igh t, rememb er to drai n the wat er o ut o f you r bi ke's cooling sys te m before yo u turn in . Otherwise, you ma y a wa ke to find a n expens ive puddle of oil under your bike's crac ked engine cases. We've even seen th is ha p pen a t so u thern Ca li forn ia 's Will o w Sp rings, so be war y! T he not -so-obvious wa y for o il to find its wa y o nto the tra ck is for it to leak th rough th e motor. In th e ru sh to build ever- lig h ter sport bikes, som e manufacturers hav e begun to fit thin a lu m in u m or ma gnesium engine sid ecases which can b reak in the event of a crash . Therefo re; many clubs now require owners of specific brands/models to fit tub ular case guards or th e increasingl y po pu lar a ftermarket heavy -duty replaceme nt si decases . Some clubs sim p ly dictat e that th ese models must run with th eir fai ri ng low ers in pl ace. pea king o f cras h ing, a few clu bs now sti pu la te th at you remove yo ur bike's steeri ng head lock. Apparentl y, th ere have been cases o f th ese lock in g th em sel ves followi ng a crash. lea ving th e poor co rnerwo rker on the scene pushing the bi ke in circles - perhaps o n the Irack in the pa th o f o nrom ing traffic! Addi tio na lly, you shou ld du ct ta pe cl o sed t he' ca ps o n yo ur h yd rau li c brak ets) a nd /or cl u tch res..rvoi r(s) to p revent brak e flu id leakage, (At the very least, th e liquid will rui n yo u r pa int job if it escapes.) In the int erest o f p revent ing fla t tires a nd rider injuries, you'll be req uired to rem ove or ta pe o ver a n y g lass a nd/or tran slucent p las tic surfaces o n your bike; these include head light s, taill igh ts and reflectors. Wh ile mo st racers si mpl y ch oose to remov e th ese pa n s. so m e (prod uctio n-based) racing classes requ ire tha t yo u retai n you r taillight. Co lorcoord i na ted duct ta pe wo rks wo nd ers here. T he re ar e a few parts tha t you 'll be required to rem ove from yo ur motorcycle. These include the mirrors and turn sig na ls, licens e plate and its bracket , ce nter- and/or sidestands, a nd ki c k starter (if applicable). You 'll be required to have brakes and , tir es in good cond itio n (a nd we can 't ima g ine wh y yo u'd want not to !), that th e throttle sp ri ngs back to th e off position, and that the kill switc h is funct ional. Aircraft-t ype met al val ve ste m ca ps must be u sed to prevent blo wouts, and we'd recommend replacing yo u r bike' s stoc k rubber valv e stems wit h metal o nes - we've seen ru bber o nes pull o u t o f the rims u n de r racing co nditio ns. After seei ng a number of bi kes ingest d irt through their ca rbu retors a t the recent WER A Pro Series ro u nd a t Willow Sp ri ngs , we wo nder why mor e riders don't use airfilte rs. However , if yo u m us t ru n wi th open carburetors or veloci ty stac ks, yo u ma y want to co ns ider fitt in g a ,te the r-type kill swi tc h like th os e co m mo n ly used by Speedway racers, a nd by the Bimo ta Wo rld Superbike team . Yo u 'll likely a lso enc o u nter rul es pertai ning to strea m lin i ng, th e size, mo u nting a nd location o f n um ber pl a tes, a nd permissible no ise levels. One new ru le to emerge since th e advent of ru n-wha t-ya-bru ng Formula USA racing is th e proh ibition o f fuels ot he r th an gasoline . Mot or cycle roa d racing is dangerous enoug h withou t the added hazard of fir e, particularly fire yo u ca n' t see such as that associated with _metha no l. Sti ck to hi gh-octane pump o r raci ng gas . Ru les var y from club to club, so get a hold of your club's ru le book (the sooner th e better !) and read it thoroughly. Being prepared in advance beats th e pants o ff having to rush through so me o verloo ked requirement in o rde r 10 make yo ur practice sessio n , a nd th e respect yo u 'll gain from th e technical inspector might go a lon g wa y o ne da y when yo u're protested! Wonbcnch is a Wftkl,. column daling with motorcycle ma inu~Danu. pcrformanu .nd ~uipment. H."e sollWlhing that WorkbnJch can ..ddttSS1 Drop .. line 10 Workbmch. C,ek Nruts. P.O . los 498. Long kach., CA 9080 to4M9&. e 1990RM 125 1990YZ250 Hp 1990 SUZUKI RM 125 PIPE SHOOT·OUT 1990 YAMAHA YZ250 PIPE SHOOT·OUT ~~~~~~~~~~:.:.:..:.:~~~;.;.~ 55.0 ............ . t::::.: : :~:: ::-:::: :::-:..::: ::: : : ::: :::.: :: :' . ...., _-.-._ . - 40.0 50.0 .. .. .... - - . - 35.0 ..., . , ~._.- .._ClltCUrT 45.0 ;"';';'!::I.==l:!= .ntCK . .. . . . : : : : : : :". " GOI.O 30.0 ".,GOUJ 40.0 .;: ::::1 . NO CIRCUIT .:;::::1 35.0 _:: : : : : : : : :: :::: : : : ::: : : ::. STOCK 25.0 20.0 30.0 15.0 25.0 10.0 . 20.0 5 .00 :: :: : ::: : : : ::: ::::::::: ::::::::::::::::::::::::., 5000 6000 7000 800 0 9000 10000 Eng lnoRpm 5000 6000 7000 8000 9000 10000 nooo 12000 Engin e Rp m PSI 52.3 HP STOCK 47.6 HP PSI 36.8 HP STOCK 34.5 HP FMF 48~4 HP PRO CIRCUIT 48.2 HP FMF 33.7 HP PRO CIRCUIT 34.6 HP Yankily yankily yank. You've heard iI all before. Som pipes lugat the truth about howmuchtheyactually increase horsepower, Butonly one pipe remains the champion e of performance bycomparison. PSI. . , In yel another dynoshootout, we saddledup a boxstock '90 yz 250and • '90 RJ\I 125; with the threeleading pipesyoucan buy ollthe dealer shell, tofind out who has harnessed the horses-or who's pulling yourleg. Andthe lestcoocludes. On the yz 250, PSI', pipe pull, an incredible ~.7 Horsepower overstock, while PSI's RM 125 pipe produced. healthy 2.2 additional Horsepower overthe competition. FMF and PRO CIRCUIT onceagainchut and tug way below. PSI Pipesproduce more tractable, useable horsepower than anyother brandon the market. Guaranteed. So, what's iI goin to be. Hones Dr legs? g PSI. INC.• ItT 2. BOX 309 0 \\1LD ROSE, WI 5-1984 0 14141787-2430 0 fAX 14141787-3764 25

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