Cycle News - Archive Issues - 1970's

uield-on silencer. Th e pip e wo rks good, bu t I ride th e Ex pert class wi th a bu n ch of 105 pound kids and I 'm 190 p ou nds and 32 y ears old. I need more power and hat e to ruin a cy lin der if someon e else has ,the exp erience and knows what t o do. I read in th e lat est Cycle Ne ws a lett er from a reader who said h e just fi nished reading y ou r art icle on more po wer f or th e 175. Where did he read it and h o w can I get a copy? A ny help that y o u can give me wou ld sure be ap pre ciat ed. Dan Dean Hanford, Calif. Thousands,of Used & New Parts & Accessories Go on Sa le It the BIG Sa«,~~ Dan , did y o u ever th in k of taki ng up a new sp ort li ke girl chasing ? Okay, let 's take it fro m the to p an d see what we h ave. ( 1.) The 175 Pen ton article that yo u are referrin g to was c a ll e d "M a k e your J ackpin er a Jackrabbi t. " It ran in Cycl e Ne ws Eas t , page 34, J uly 24 , 197 3. It was in Cycl e Ne ws West somewhe re aro und th e first of th at same month. Maybe we can t alk Cycle News into re -ru nnin g th is tech piece. Everyone with a 175 Penton drop a ca rd to Cy cle Ne ws West and say "reru n the J ac kp iner. " (Bac k issu es are availa ble for $ 1 each .) (2 .) Yo u we igh 190 pounds . Yo ung one s wei gh 105 . That's 85 p o un d s d ifferen ce . 10 lbs. = 1 llP. In sh ort y o u h ave spotted the m 8 .5 HP be fo re yo u ever lef t the star ting lin e. (3.) You are rid ing a hike tha t was de signe d fo r e nd uros and not scr am bl es. Wh ich m ean s as so on as yo u reach th e poin t of engine RPM that yo u nee d , yo ur engine h as been signed o ff already for 2,000 RP~ I and wishing to hell it would bre ak so it wouldn 't have to be p ut thro ugh th is punishment. (4 .) You su re yo u don' t want to go girl-ch asing? O kay , th en le t 's m ake so me ch anges a n d go a ft e r th o se y o u n g wh ip per-sn ap p ers. Y ou have to have so m e more carb ure ti o n . If it was m e I wo uld use th e new V84 Bing 32m m car b (sm al l body) th en m aybe bo re it ou t to 33 m m . You are o n the hairy sid e if yo u try and push it to a 34 m m ca rbo The ne w Pen to n 17 5 co mes with a Bing, so y ou ca n ge t a mani fo ld fro m y o ur lo cal Penton dealer. lie sho uld have the carb too . If n ot, he can ge t it fo r yo u. Now it 's tim e fo r a lit tle cy lind e r su rge ry . Raise t he exhaus t po rt .04 0 " and cu t .0 80 " o ff o f the in take skirt. If th e engine st ill won 't p ull eno ug h re vs, ta ke off another .020 . If b ike starts to get loady, yo u're get t ing close. Take yo ur pipe and p ull another half-inch out o f the cen ter section . Che ck th e deck hei gh t of the pis ton at T. D.C. an d be su re th at y o u have no m ore th an .0 50 " deck and no less th an .04 0 " fo r ro d stre tc h . Pumpin g co m p re ssio n of th e engi ne should be n o m or e th an 150 FRIDAY NIGHT SEPT. 5, 75 6 P.M. to 11 P.M. NATIONAL ORANGE SHOWGROUNOS in San Bernardino 24 hr INFO Anyone can sell ! Clean out your garage and m extra m ake oney ••• your old " junk" is another's treasure! CALL (213) 588-1616 C I.. .,.. Oul .,.0'" ~ por ~ per" a nd ... al. ~ ~ .I< a c' l'I.h. 5~ 1I te cu u a ... .. . ' _ 1,0 0..' 1001.i"9 10 ' yO,,' OCC" , ,,o.,,, ,,. O ld" . n .. _ po.I ~ .m d o c e"'''''>r'.'' mil l' b.. "o ld . o ' an .,..h ,"O) .... 1 0 1 ~ d 10 II, .. "'o'o. eycl .....orld. 5.. l li.... ) ~pac .. ' co,; 0 1.,. 0 ~8 .0 0 .. o e h ' 0 ' a 10' ll: 10' , p ac "h p.. ... .. I' o n l l o c~ " 0"' o .. odobl .. 10 ' ~ 13.00 p,,' 'p a c V.. h ,c1 ", "'0 d., ..... h ,cI ~ ,nlO II,. b" ,ld,"O) l et. .. 0 ..... " n loodin g. " ..,n ...... 0 10 ,... h , b ,'o ' p o. 1.i"g 101. A ll 01' 0 " " mu,1 b o.d,.. b ... "'0.1 ," ad .. an ce. S, pl .,. "'001 ,/,ou' cI,,,c;' ' 0 "'••"d,. c o l.. , h.... ...". an d ,11 <:on l" yo,,' ..poc .. by ... 0.1 and .... "d ot l odd, ';o.... l , " 10" "' 0 " 0 " " d .. d . o Post Office Box 400 ... • M aywood. CA. 90Z 10 r--_ _ CANNING.S . . . . . .! ~ : l ~J . ... OW HEAOOU... R TERtli ••• ~ . ~ I =. I . ~. Par t s- Ser vice. Frame Mods •Acc essories WHEEL SMITH OTORCVCLES M 3 64 1 W. McFadden . Sa nt a A na . CA 92704 71 4 ·83901 50 (7 i 4 ) 89 4·26 23 <, Penton. Monark & Tyran & Rupp F Machines un Sales Serv ice Part s Accessor ies D&R Cycles 718 1 West mi nster A ve . Westm inste r. CA 9 268 3 l!J , MOTORCYCLES ~® 8 PARTS ~ COMPLETE PISTONS MACHINE SHOP,REPAIR 8SERVICEONALL MAKES _";':'" ,I (7 14) 6 30 - 5720 Qa E C__ere Ena ineer inQ 8 SUQply 1I4 0 - A N Kra emer e Allo helm Co e 92 806 Knobby Tire Sale 350 x 18 ISOT 514.95 400 x 18 ISOT 6 p ly .. $16.95 T ff 0 ~AMA J.f.l 24020 Narbonne Ave., Lomita, CA 9 071 7 2 13·534·231 t John Trani's C ompetition C ycle Produ cts speciehzmq In dese rt & motoc ross 16612 Beach Blvd .• H untington Beach , CA 14 7 14-847 ·22 02 Go t a techni cal p rob lem tha t need s expe rt ad vice? Sen d queri es to " /I sk E.G." c/o Cycle News. You r reply will ap pea r in the pap er within a few wee ks. Hard questi on s may take a litt le lon ge r to ans wer. By E.C. Birt Differen t pipes for different types I have a "b ox sto ck" Yamaha LT2 .IIX. I woul d lik e to broaden th e po werband. Do y ou have a pip e kit that will do th is ? If so h ow m uch, an d where do I send my orde r? Please recom m en d a silen cer if on e is no t in cluded. Ce cil Donah o, J r. Laguna Nigue l, Calif. Pipe kit , n.9 pr o blem. They co m e in nu mber one stage fo r nervous novices an d fathers who bo rrow th e racer for a weeken d o f trail riding with the boys. No . 2 for am ate ur an d no vice racers, whe re to r que is th e impo rta n t th in g. No . 3 fo r good . amateur racers and just-made-it exper ts and No. 4 fo r p ro rac ers and he roes on ly . All m y p ipe s co m e wi th silencers in the kits . Cost o f pipe kit $3 8.4 7. There are a co up le of othe r ' th in gs yo u can do to broad en the powe rband. (1.) Run do wn to th e local Yamah a de aler an d buy a reed cage asse mbly for a C.T. 2 o r C.T. 3 175 Yamah a Enduro. You will have to open up the reed ho using in the cy lin de r en o ug h to acc ep t th e bigge r reed (be car eful or y o u m ay grin d in to dayligh t ). Replace th e carb with at leas t a 28mm car b; 30mm is better ye t. A lo t of peo ple ar e b uying th e new Yamaha Monoshocker 125 and th e car b off of it will work pe r fec t. J etting is ju st abou t spot on . You sh o uld be ab le to pi c k up one o f these carbs without too much problem . Every o ne who has the new 125 is ch anging th e carbs to 32 and 34m m Mikunis. Set the tim in g just a hair adva nced fro m stock. Abou t 2.2 to 2. 4 . Wa tch the en gin e fo r ove r-heating. If it do es, drop it bac k to stock ti m ing o f 2. 0 BTDC. If your je tting is right yo u won't have any heating problem wi th the ti m in g bu mpe d up just a touch . Do a little th umb j o b with some san d paper in the ports to re m ove th e bi g lu m ps. By us in g no m or e than your th umb and sand p aper you won't have to worry abo u t ta king ou t to o m uch because y o u will wear a blis te r firs t and sel f preservation will take over. po u nds. May be pu ll the nmmg bac k abou t .0 0 2m m (less timing adv an ce fo r RPM, advance j us t a to uch for m ore to rq ue) . Mo t opla t : If yo u r en gine is th e o ne that has the external flywheel , you can go to the in ter-rotor model, but do all the o ther things first . I don ' t.know if this is goi n g to m ake up all the diffe rence you're go ing to need, but it will help. Also keeping yo u r eyes closed when y o u go into the turns helps too scar es the competition when you bounce o ff of th e wall. Why Maico forks? What do th e leading (d la Maico) axle fo rks have to offe r over regular forks ? Larry By ward , Costa Mesa, Calif. T wo th ings : ( 1.) Lo ng fork tr avel with out having the fro n t of the bike five mil es in th e ai r. (2.) Bette r cornering an gle. Mai co fo rks ar e the one s tha t every one wish es he h ad . Honda gave in and m ade th eirs like Maico. Su zuki is ge tting ready to do th e same. Next question? I have a 19 74 250cc Mag lIusk y CR and my p rob lem is that the re is very little po wer at lo w revs. Then a burst a po wer comes on, making it hard to keep my line while racing and keep ing the back wh eel under th e bik e. I w ould like' f or y ou to tell me h ow to sm ooth ou t the transition of po wer while still reta ining so me p o wer do wn low. I've tried to correct my p rob le m by tu ning and ha ve used every conceiuable je t. Than ks. Help ! Eric Heideman So. Pasadena, Calif. Did yo u ever ge t th e feeling tha t you have bought a m otorcy cle th at yo u m aybe sh ouldn 't have? The Mag Huskys are nothing bu t race rs and th ey tak e a very good ex p ert rider to ride one of th em proper. The bike was desi gned with a rider in mi nd th at wo uld keep the engine j ust abo ve this ex p losi ve poin t at all times. Maybe a wee k o f school with Ru ss Darn ell would so lve you r pro bl em better than an ything else th at yo u can do. I do n ' t kn o w what to tell yo u to do with t he engine. Anythin g th at yo u do to it is p robably go ing to h urt your top-end. Fr om th is point on I wo uld have to have a po rtin g lay ou t o f yo u r engi ne to st udy, th en wi th that I m ay be ab le to recommen d a portin g change th at wo ul d cu re the p roble m or m ake th e bike a little m ore ridea bl e for you . • FLA SH! TZ 750 wins Indy mile Yamaha Racing seeks new worlds to conquer. 17See versus 190 Ibs. I recently pu rchased an early 175 Pento n (wi th Amal conce n tric} and after going through th e engine and trans. I decided to use it f or a scrambles bike. The original p ip e was "lunched " so I modified it a lit tle. I removed one inc h f rom the head p ip e. ma de the cen te r cone 4.5 in ches long an d a rear co ne seve n inches long, do w n to a seuen-eigh tb inc h sm all end and a ~ :.: o UJ o ::; Z I " Now rem ember, Mick , use top gear only be tw een sec t ions ." , ,. Q "'~----~-------------~~ .

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