Cycle News - Archive Issues - 1970's

many millimeters before top dead center sh ould th e ignition tim ing b e set fo r best all around performance ? Th e fa ct ory recommends 1.5 and. Cy cle magaz in e says 2.0. Which is best? _ 3) Have y ou f o und an y modifications to in crease perf ormance via sim ple piston cutting m odifications ? 4) What ad van tages, if an y, would a Wiseco pisto n offer over the sta ndard piston /ring set up ? 5) About how much would it cost to have my top end treated with Kal·Gard ? 6) Which would be better for pr eserving th e transmission life and d e s cre asin g friction. Kal-Gard or Micropla tingt What is the cost of m icro-plating l 7) A s you k now, th e intake , ex haust, and transfer ports are bridged. Would it be to m y ad van tage to bevel the lead ing edges of these brid ges to a knife-like sharpne ss? 8 ) would th ere be an y value t o stuf fing th e crank or having it balan ced I was scheduled for a Saturday afternoon, then zoning would probably require a permit, acco rd ing to McN abb o f Serra High School. O f course, th is c o uld vary greatly according to lo cali ty , but it is something th a t McN abb had to face when he took th e side of students wan tin g a race at Serra, Ho we ver. if a race is called a "st u dent asse mbly ," an d held d urin g school hours, then such permits are not required. Ing lewood High School wo rked it the same way, calling it an assembly. Neighbors That brin gs us t o ano th er thing. Wha t abo u t neighbors? Any o ne livin g near a high schoo l usually learns to expect a lo t of noise, bUI t hey may not ex pect a high sch ool MX . At Serra, McNabb was wo rried that if he n o tifi ed n eigh b ors o f the upcoming race, so meone would get uptigh t and try t o stop it , So he didn't, The only rep ercu ssio n was that so me lady had hung o ut her wet laundry righ t before practi ce and when sh e came b ack o ut some tim e la ter, it w as cover e d wi th du st fr o m th e tr ack abo ut 10 0 yar ds awa y. Sh e was very angry wh en she co n tac ted Serra High o fficia ls lat er. At Inglewo od High School, Bob Hoffman took an other ap pro ac h. He sent out notices to n eighbors that Inglew oo d would be holding an MX, and explained what it was. T he notice than ked the m in advance for putting up with any noise t hey d idn't like . According to Hoffman, they had n o problem with neighbors trying to hall it. ey proved to b e very tolerant of th e idea, even if they didn't understand it. Bo th schools limited practice. Both chools r eq ui red m u ffl ers or silencers on ikes, At Serra, en try was limited to tu den t s , gr aduates, and faculty. (McNabb was the only fa culty mem b er ho actually rode, though.) Inglewood st ricted entry to students. Labor T he labor for ru nn in g the affair after uilding the track was su pplied by the Letterman 's Clu b at Ing lewood and the otorcycle Club a t Serra, along with ol unteers. Volun teers at Inglewood arded the track the night before the ent to prevent -vad alism an d/or early ractice. Get tin g vo lunteers should ro ve no p ro blem, and b o th schoo ls ep o rt converts to motorcycling after thei r races. Spectato r control us ually is set u p so that non -race-in vol ved st udents are ke pt ff th e course an d out of t he infield. At o th Serra and In glew o od st u de nts were kept in b leach ers fo r safety . Gen er al st u de nt body reaction was oo d at bo th schools. As McNabb oin te d ou t, there was probab ly te n ercent that thoug ht it was st u p id, but that's about p ar for any type of high chool assem b ly. Some schools m ay wo rr y abo ut b eing ure that a person who knows wh a t they're do in g runs t heir ra ces. A t Serra igh Russ Darn ell (of MX school fa me) olu n teer ed to ru n the eve nt, with great uccess. Bu t at Inglewood, st udents ran e wh ole show with no probl em. T he re hould be enough students at your .ch o o l who know MX and can train orne non-racers in runn in g a race even f they themselves wa nt to race in the ven t. Inglewood had no problems with it racers with students running the vent. Of co urse, neither did Serra wi th arnell in c o mman d. alf t ime Yo u m igh t want to have an adde d u tractio n fo r a so r t o f " half ti me " .how . At Serra High this ca me in th e orm of the e ditors o f Moto cross A ction Iagaz jne d emonstra tin g some hot shoe iction. Local d ealer or d istribu tor racin g earns or ho t shoe cl ub s co uld provide he same th ing at yo ur even t, and pass n a few go- fast t ips t o the attendees. a! II doesn 't matter if you atten d a »rivat e o r a pu bl ic sc hool, you can still ut o n a h igh sch oo l MX. Oth er schools n b oth c ate go ries have d o ne it (Serra is I par o ch ial school, Inglew ood a pub lic .chool), and your h igh school can d o it 00. It will tak e about two or three onths to ge t it all t o gether if you ustle. Start today by ge tt ing to geth er a oup o f your frien ds, an d go see th e . DIll .. DIll ..,; ... g g -,r r- - C'> C'J >- - 1-0 . ~ ::l 1-0 ...D ~ t:.t.. Paul G. R eins inger Sylvania, Ohio ASKE.C. E.C., A friend of m in e recently purchased a 1970 OSSA Stillet o. He was warned agains t using any kind of a kill button. He didn't and consequently blew it up numerous times when th e thro ttle stu ck. Are th ei « bikes that shouldn't be eq uip ped with a kill button. If so , which ones ? Why ? What is th e solution ? Nameless Denver, Colo. Nam eless, Wha ts the ma tter? Afraid your buddies will give y o u a hard time , or cal l y o u st u p id because you ask a q uestion? No q uestio n is stupid if you don ' t kn ow t he answer. I don't know of any bike that you can't hook u p a kill button t o. T he OSSA has a Moto plat ignition. Hook yo ur button up to th e bl u e colored wire. I would advise t hat you also rep lace th e th ro ttle cable so it won 't stick , no ma tter wh at kind o f kill button you use. If an en gin e fre e winds on y ou long enough, th e electricity wi ll be more t han t he kil l bu tto n can handle, so you wind u p with an engine in pie ces. E.C., I have a Hodaka Super Rat and I'm very happ y with it ex cep t fo r th e shif tin g. The sprin gs o n th e long shaft k eep untwisting and th en it won't go in low gear. I've tried th e Web co springs and th ey are b ett er than st ock but still only last ab out th ree races. I'll bet I can change shifter springs faster than any on e in the wo rld. It sure ma k es me mad when the d umb thing quits shifting in the mid dle of a race. Are there an y other. kind of sp rings that I can use? J im Williams Oakland, Calif. Sou nds to me like yo u're jum pi ng on th e sh ift lever a little too h ar d . Hodak a springs go away pretty fast but I've never heard of an yo n e eating them up that fast. T he re may be a solution for you, th ough . The Hodaka di stri b u to r for the Sou th ern Ca lif. and Arizona, Tiger d istribu tin g Co ., 653 West Broadway , Glendale , Cali f. 9 1204, has j us t co me ou t with a new sp ring. The part number is T ·322 and th ey ca ll th em " Tiger Su p er Sh if te r Spring s." T h is sp ring has o ne less wind an d is m ad e o ut of he avi e r gauge wire, Y our lo ca l Hod ak a deale r can o rd er t he m fro m 'l'iger o r yo ur ca n ge t th em from us at Precision Cycle. T iger put a set in a test bike about a ye ar ago and it's st ill shifting . Th ey o nly cost S 1.4 5 a se t, so wh at have yo u got t o lo se ? rd m in is tr a tio n abou t your own race . o u co uld be racin g wh ere th e girl s are o w practicin g ar ch ery befo re th e end f the school year ! • II E.C., I have a 125 Hoda ka Wombat tha t I have b een trail riding one year. Last wee ke nd my buddy talk ed m e into going to th e moto cross races and giving it a try. It was great, bu t everbod y ran away from me on th e straightawa ys. How mu ch increase would I get if I went to a highcompressionheadanda larger carb ? Min e has a 24mm and m ost of th e MX bikes I have looked at hav e a 2lfmm . A ny help you can give me on getting better perf orman ce fro m my bik e will b e appreciated but I don't have much money to spend. Thanks very mu ch, R . Lang Big Springs, Tex. My first suggestion to you wo uld b e to get the "Com bat Kit " to p end fo r your Wombat. T hey ar e reason ab ly p riced and w o uld give a good increase in horsepower . If that is t oo expens ive for you but yo u can do t he grind ing yourself, di g up a January 16, 19 73 issue o f Cy cle News West. I had a te ch article in th er e wi th so me p orting specs that sh ould work we ll fo r y ou. There is also considera b ly more in fo on Combats and Wom bats that you may fin d interest in g and h elp fu l. Write to Pacific Basin Trading Co ., Bo x 327 , Athena, Oregon, 9 7813. E.C., Keeping the present fu el shortage in mind, can y ou te ll me what I can do to my street bik e (gearing, jetting, tire pressures, etc.] and my driving habits t o get better mileage. Than ks , Chuck McFadden San Diego, Calif. Ch uc k. at leas t you have the right ide a : rid e yo ur b ike an d leave your van at ho me. Gear your bike so that it just kin d o f settles in a t 5 5 MPH for cru isin g. Don ' t overgear. If you geared for 8 0 , it will be lugging th e engine al 5 5 which will ca u se it to usc m o re gas . As for jetting , don 't lean it down to save gas beca use you mig ht stick it . Ti re pr essu re : I would n 't run any more than the facto ry re co mmends because for what you w ou ld gain with harder tires , it wo n 't b e worth wh at yo u sac rifice in safety t h ro ugh trac tion loss. Dr ivin g habits, ju st be cool. The free ways and s treets are: n o t rac e track s. F..C" I w ould lik e yo ur opinion regarding modifi cation to impr o ve the perfo rma nce of the Hond a Elsin ore 125. I ) Th ere are a numb er of new high -performa n ce two -stroke oils on the mar ket. such as BelRa y and Klo tz; to men tio n a cou ple. Whic h have yo u had exp erience with and which wo uld you recommend ? 2 ) For m oto cross co mpe titio n, h ow I ) Reco mmending o ils is a touch y problem. I've never used Bel Ray or Klotz , but I've heard they're both good oil 's. I use Blendzall for my high winders or BTTW rid ers; Poly-O sid e or High Poin t for the other 8 5% of racing and tr a ilri ding. 2) T he CR engine is made to re v, so set the timing at 1.5mm fo r in cre ased top end. If you want a little mo re torque, set it at 2.0. A rule of thumb is- For more torque, advance the timing; for more revs, retard it just a lillie. 3) take .040", or 1.5m m off the exhaust side, crown edge, an d the same off the intake skirt. 4) A Wiseco migh t offer so me advantage n ow t hat they have a new ring that won't break. T his has b een t he weak . point of their pist o n . Bore with .0 03 " to .0035 " clearance for racing. 5 ) $19 .00 , and it's well worth it. Se nd your cylinder, head , and pist on to Kal-Gard, 7118 Gerald Ave ., Van Nuys, Calif. 91 4 06. 6 ) Both Kal-Gard an d micro pia ting work. As to perserv ing th e life, I d on't know abou t tha t. I've never w o rn o ut a gearbox in a racin g b ik e, they always bra ke fir st . Bu t any time yo u decrease friction , it has to mak e it last longer. Mic ro plating costs about $5 0. 00, dep ending on how man y pieces yo u have. 7) T h is a lways helps. 8) I've never really n oticed a big adv an ta ge to st u ffing a cra n k. It ' s a lo t of wbrk, SO it makes yo u feel lik e it mu st be be tter. Dyno tests th at I've run didn't sh ow it was worth it . E.C., I 've been fooling around with expansio n chamb ers: different length front con es, center sections, and rear cones. I've been told that the rear cones should be abo ut twice th e angle (in degrees ) of th e front. Also, that too short a rear cone will blow up your bik e. (N o, it won 't blow up your bik e... E. C.) I am curio us to kno w y our fo rmu la for fi gu ring ou t how long th e co nes should b e. Ho w do y ou co mpu te center section length, /lead p ipe length and dia meter? I'm also very curio us abo ut stinger diam eter and lengt h, and how a fat stinger gives you mid range com pared to high RPM achie ved with a smaller dia m eter stinger. What formula would I use to fi nd the size and length stinger to use? What part does volume piny in th e performance of the ' p 'pe ? Sh ort overall pipes see m to be more peaky th an on es with longer cone s or cent er sections. I'm very interested in pipe. building and any info you can give me will help, Thanks very mu ch fo r yo ur tim e. Byron Wright R iversid e, Calif. Byron , the art of bu ild in g expansion cham bers is, at its best, black magic. T he re are many th eories and formu las. Books h ave been written by leadin g pr ofes so rs, b ut th ese are only guid elin es , as they will tell you if you read the fine prin r, With what y o u already know you 're on the right tr ack . Dr. Gordon Blair, I feel, has it pu t to gether abo ut as well as anybody. As far as giving you my formulas, sorry abo u t that. But if you're eighteen, I might give you a job as a pipe-b uilde r. .

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