Cycle News - Archive Issues - 1970's

bike off the showroom floor that's rac e-ready. \ I'ell , alm ost rea dy. Ma ybe all yo u have to do is ch an ge the tires, shocks , b ar s. ca rb , do a little p ortin g and h ead w o rk, an d h ave a pipe b u ilt for it; but at least you w on ' t have. to take th e ligh ts off it. Hodaka fig ured o u t ye ar s ago th a t most b ike riders will le ave a bik e as it is, o r else c h an ge it com p le te ly . SUI LDING A RACER The I :?5cc Womb a t w ill cost y ou 66 5 and the y left al l the fun in it for you . Y o u ca n d o just li ke we did with th e 90c c Hodaka in th e Ol d Days. Tak e " our n ew Wo m b a t ho me; break o ut you~ n ew 1001 kit that comes wi th th e bike and pull all the street ga rb age off. N o w it looks some thing like a ra cer, anvwav, Ho d aka knows th ey can 't pl e ase 'e ve ry rac e r with th e same tires o r sh o c ks, so th e y jus t pu t the righ t size wh eel s on it : :?I" up fro nt , 18 " on th e rear, tires that are ju st fin e fo r th e ride r. that wa n ts a plun ker an d shocks th at w o rk fin e fo r trail ri di n g a nd bi rd wa tching. But yo u h av e $35 0 t o spen d b ef o re y o u get th at $ 10 0 0 m oto cr o ss-ready ra ce r plus a $2 0 0 cu sh io n o n t op o f that. S o let's buil d a ra cer . We have quite a wa y s to go before w e rea ch ou r $35 0 lim it , and we will u sc the o th e r $2 0 0 to buy the little wife o r Mom a tent and cam p s to ve so we c an go to th e ra ces the night b efore. We need fo r k kit , shoc ks , and tir es. =-: ow, o n o ur d e sert b ik e tha t Je ff J effries rides (w hic h is th e b ike we us c for research an d d evel opment for T iger Di st .}, I usc a \\'e b c o fo r k ki t, Curnutt sh o c ks, 3.0 0 x2 1 Ba ru m fro n t tire an d 3.50x 18 Nitta rear tire. =-:0 need to do an y thing else; as far as h andlin g goes, it w orks fine . We use the stock tank for th e d esert. (N ee d the ex tra gas .] Our m 010 cr055 bike is o wn ed an d sponsored b y Kal -G a rd (I ' m just the c o n trac ted tuner.}, an d Tony R oge rs rides this o ne. I usc the sa me Iork k it, C urnu tt shocks and a plas ti c Pacific C u st oms tan k. It holds enough ga s for a motocross an d is lighter than the stock tan k. T h e bike weighs abou t 18 0 lbs. race -rea dy with a 2 .i 5 x 21 Ba rum tire up front anda -I.00x I8 Cheng-Shin rear tire . For th e li llie S teens 10 0cc, like we d id fo r V al Kim bro ugh , you take out th e 10 0 cc " B" engme , go d own to yo ur local H od a ka d ea le r, plunk d own your $ 25 0 an d Ret a 1:?5 c c Womb a t engine, b olt it in a n d h an g o n . If it ' s "built " li ke Val's, h an g on d ouble h ard an d point it . We ll, n ow w e h av e a s up e r tigh t bike th at lo oks, fe els , and h andle s as good as th e b e st o f th em ; bu t i t has on e problem. It 's slo w . H odaka d idn ' t build th e Womb at fo r racin g, th o ugh. T hey buil t it to d o j us t wh at it does : produce good b ottom end torque th a t will ta ke you any pl ac e yo u wan t to go an d b e d epe ndable neough to pump water for 20 years w it h o ut b re akin g. We know it ' s n ot a racing engi ne, so lc r' s buil d o ne . GO TO WORK We h ave a stock port liming with th e ex ha us t o pen 10 0 d e gr ee A .T.D .C . : transfe rs, 12 0 d egr ee A .T.D .C. an d int ake closing ; I d egre e A .T .D.C . - big d eal. Wh a t d o th ese figures me an to yo u? Si n ce th is is for th e Father-tuner and th e rider who wa n ts to do hi s ow n th ing , I'll try to expla in it and keep it sim ple. o There a rc 3 60 de grees in a circle , which is the d is tanc e the c ran ks ha f t (u rns in one revo lu tion. and th e amo un t of tim e we kee p the ports closed or o p en d e t e r m i n e s "..h a t kind of horse power we get out of the eng ine . X ow v o u can see there are a mill ion com bi n aiions tha t ca n be had o u t of this 36 0 d e gre e ci rcle . Y ou coul d spe n d the nex t 10 y e ars and a b o xcar-load o f cylin de rs tryin g all th e com b in atio n s you cou ld thin k of. We build all o u r racing e n Rin es in th ousandths o f an in ch d ime n sions. I t ' s m ore accurate than using th e millimeter sca le for me , bu t I will usc bo th f igu res, and you c an use whichever y o u lik e. Pull th e cy lin d e r o ff, ge l o u t y our grinding to ols, and let's go to work. -< o r m Z m :E (/l .c:l '.....' " w -e " '" " w HOW ' Take a can of Ma chin is r' s Dvkernan , red or bl ue , w h ich e ve r colo r turns you on , an d paint the surface of the cy lin der. Pain t the top of th e exhaust port. Transfer p orts a re le ft Slack, so no need t o p aint th ese, but pain t th e bo tto m of the in ta ke p o rt. Measu re from th e to p o f th e c y li n d er d own 1.1 5 0 th ou sand th s (o r 29 .209 ; .m m ) . S cribe a lin e across th e t op of the exha us t p o rt. Now me asu re aga in fro m to p of cy lin de r to b ottom o f intak e p ort : 3 .35 0 th ousandth s or 85. 0H92 m m and scribe another lin e. Now file an d grind awa y this metal th a t yo u have ma r ked off, be ing very ca re fu l not to go past the line s. Blend a ll edges in to smooth port an gles fo r th e bes t now pattern. Re fe r to Diagram -No. 1. Be su re an d main rain radi us in the ex haust port comers. T his gives yo u a port ti ming th a t w ill give you an engine for go o d all 'rou nd mo to cr o ss a nd desert racing. For th e Expert m oto c ro ss, d esert and 1"1' rider, raise the exhaust p ort an o th er .0393;0 th ousandths (O r one m illime te r.) and lo we r th e in take . .0393;0 thousan d ths (one m illi m e te r). Th is will give m ore t op en d with so me loss o f low end to rque . The fir st set o f port timing, figures is what I used in th e Steen's bike for V al. Both o f these port figure sets can be use d with th e installation o f the re ed valve . The re ed valve asse mbly can be purchased fro m yo ur lo cal H oda ka deale r. In st all ation of a ree d valve on your cy lin d e r will give yo u a broader power b an d w it h gobs of low end to rq ue . But it m ust be installe d properly 10 work right an d, on th e Womb a t , it's not an easy job to do. The rin g pins ( to keep the rin gs from turning) are righ t in the way. Some tuners will say that o n pistons like the \\·o m ba t. it makes no d ifferen ce : yo u can run the open ends o f th e ring in the port with no problem, but 1 d on' t buy th at id ea b ecause after a while the tip s o f th e rin gs wi ll we ar enough so th a t th ey may break and ruin the cv lin d e r. If ' you us e a stock piston, I adv ise tha t you have the re ed p o rt mach ine d into the back of the cy lin d er , between the ring pins , bein g c a refu l not to b rea k the bridge. Refer to Diagram N o . 2. Hodaka will be com ing o ut soon wi th a kit for t he Wo mbat c alle d the Co mbat (Co n t inu ed on Page 4 6 ) 800) ? < .{;;R. }R.!- kJ RaloN boos! ?oRI c.C>A-1 s;f «: f -- ../- # O R. ? / sfD;v s f oe.k c!'1l. .f?c. 0.-//0'( k:.J. ()tJ "- -s, . 2~lJ i .... . .... ... .. . . . . . . . . . . . . . .... . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . , ... , '" 30 "

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