Cycle News - Archive Issues - 1970's

Spiny cylinder head. 38mm Mikuni carb and a custom pipe made up the m inimum engine package. It can be made a lot faster but may be fast enough. with th e kit inst all a tion . T he Terry Kit p rovides eig ht inches of fo rk travel as part of the cos t lier m od a nd ca rr ies a mo n e y -back -if -not sa t is f ied g uara ntee . Go ki a ir fork ca ps a nd va lves were screwed into th e to ps of th e fo rk legs. Air fo rks a re an excelle n t way to go. allowi ng fine tuning of the fro nt sus pe nsion to ma tch you r wildest fantas ies. T o ensu re 90 m inutes of relia bility. you sho ul d ret ain th e CZ fork sp rings o r a softe r eq ua l lengt h sp ring - just in ca se yo u blow a seal. It d oes h a ppen . T he ri de isn ' t com p rom ised but the sp ri ngs m ak e t he fro nt en d over a pound heavier. The complete it em . Not too far off from the Strakonice model. Speci a lties at 15 13 J 8t h 51. in Sa nta Mo nica . CA an d execu ted bv t hem . All parts an d acces so r ies th a t ' we re-n 't a lrea dv in t hv ga ragl' wen ' o bta ined through Cycle Prod ucts W est . 11900 Pico Blvd .. W"st Los Ange les. CA . So the Ba ck ya rd CZ e m e r g e-d as some th ing less tha n a shop bike and something m o re than a wel lintentioned but limited racer -owner effort . All mods were kep t on the mi ld side with t he idea of decreasing both cos t of constru ction a n d co st of opera ting t he be ast. No matter whi ch engin;: a nd chassis yo u base your GP bi ke on . th is is somet hi ng to keep foremos t in m ind . There was no room for th e vicissi tudes of a S20 .000 racing bud ge r. . Final rear frame mod on GP CZ w ith Marzocchis laid in place for fit. Note triangulation of all possible frames t resses and heavy-enough gussening. A lot of th o ug ht went into th e fra me m ods befo re a n ybody p icked up a tor ch . w.· studied deta il ph o tos of th e wo rks bike s fro m a ll a ng lt's be fo re deciding we co uld do better both in term s of struct u ralstre ngt h a nd rear whee l tr avel. T Ilt' wo rks bi kes have only six inches of re ar a xle tr avel using sta nd a rd- loo king C Z a ir shocks. Ga ry H ym es . p ropr iet or o f Off- Road Racin g . ca rne u p with an im pro ved re ar fr am e desi gn t ha t yie lde d a co nse r vat ive 7.:l:) in ches of rea r ax il' t rave-l. Ma rz o cc h i gas -fl uid shoc ks were - la id do w n in SOffit" s p e c ia lly fab rit·,ltt·d hox mo un ts . Shock le n/(t11 is 13 inch es in ,It'h ieving t he desired rear shoc k m ount to .steering he ad a t full co m pressio n . Bilsreins and S&W d t·sigm· d . Monroe -bu ih fr eon bag shocks will a lso be- tested . T he ph ot o shows t he st reng t h and intt'grity of thi s desi).(n . It is better br aced than th e wor ks bike fr a mes. W orks CZs has 8.5 -inch ai r fo rks to ho ld up the fro nt end . We fo llow ed that a p pro ac h wit h two options . T he N umber O ne Products for k kit was th e least expe nsive and has th e in he re nt advan tage th at Br ian Fabre will wo rk with yo u in a n a ttempt to ge t it right for yo..,r prefere nce . Dam pin g of both fo rk legs was adjus ted and m at ch ed Th e LTR su sp ens io n defi ni tely requ ires a cha in ten sioner , W orks CZs have a 38m m Mikuni carburetor hooked up to a reed, valve a nd ce nte r port ba rr els . They are ported so rad ica lly for top end pow er t r a n sm itt ed th ro u gh a fou r- sp eed gear box th a t t he reed is a req u irement for crisp low end res po nse . A center po rt barrel a nd a reed va lve a re not n ecessary wit h t he porting skills avai la ble fro m m any Am erican m etal grinder s. Rex Sta ten's CZ. o n whic h he led 20 m inu tes of th e firs t m o to at the U.S. G P . had a standard barrel. a J H pipe . and porting by C hend a Le lek. Cycle Prod uc ts W est offers a power boo st thro ugh different hol es th at does ' not co m pro m ise reliabilit y. a lso with a custo m-fa b ric a te d pipe to m at ch . T he 38 m m M ikuni a nd a pipe may be eno ug h for you to handle . It m ak es for a ver y q uic k bike . Porting is goi ng to cost $50 -60 wit h nearly tha t m uc h m ore for a reed valve . Of co urse. the porti ng is different a n d more e xpe ns ive if yo u do use t he reed . Re pl acin g the reed pe ta ls periodically is anothe r expense and m a intena nce it em . T he cvli nder head wa s porcupine d m a in ly so it would look like the works bike in pictu res. Only abou t half a pound of weig h t is a ct ua lly save d . Wher e d o we sta nd finan ciall y afte r treating the fr ame . suspe ns io n . and to the mildest d egree co nsistent wit h im p ro ved performance . t he engine? Betw een $ 380 a nd $425 . depending on t he front fo rk mod fina lly selected . Add a nother $1 00 if you opt fo r the reed va lve and reed po rt ing so 'you rs will be even closer to th e works bikes. Th irty doll a rs more for th e porcu pi nes o n t he cy lin der he ad . If yo u a re co nserva tive and ca n ge t a 10% ra ce r's dis count o n the parts. it' II com e o ut rig ht a ro u nd $500. If yo u sta rted with t he used m od el . you r rot a I cost is stiII und er $ 1200. If you bo ug ht o ne in th e crate to sta rt fro m . it 's m ore like $1 600 but yo u ge t to br eak it in yo urself. As far as go in g for t he co m p lete works bi ke rep lica . we still wer en 't fin ish ed . A GP sea t is $20 a nd a good idea wh eth er 'yo u're racing Grands Pr ix or not. Saves your buns. Works CZ s use sto ck ca bl es . g r ips. and handlebars. W e used Inter-Am solid a lu m in u m ba rs in a CZ bend . Terryca b les for cl u tc h a nd brake (wh ic h sho u ld last lo nger) . a n d American Pro grips (which a re kinder to yo ur p aw s) . So me th in gs . America ns build better. Ad d a Preston Pet ty " M u der " up fro nt a nd you have parted with another $40 or so . W e d id not b ui ld new wh eels a nd don't really th ink it's th a t necessary at this stage. If you do . approx im ately $170 will la ce . u p two Sun rim s from CPW . TriVid Distrib ut ing makes a vailable a works replica tripl e clamp that eliminates the dreaded CZ fork flex . W e used it and it works. bu t it is a rea l. hassle to insta ll. When finished . yo u will have a m achine tha t is stro nger . more reliable and probably m ore tract able tha n th e works CZs. H ere's t he fina l ta lly for parts and m od ifi cat io ns . o n an item by item basis: Fr a me m od ification $ 100 T erry fork kit $49.95 . or N um ber O ne fork kit. $17 .95 Goki air fork caps & valves $1 1.99 Marzocchi gas-fluid d ampers $99 Rea r shoc k springs $ 12 .95 (in a ny weight you need ) Cha in tensioner $2 1.99 38 mm Mi kuni carb o a ppro x . $90 $59.95 Cus to m p ip e . . _ -Porcu pine head $30 G P po rting - S50 : S60 with ree d va lve Reed is a bo ut $50 ext ra Pro seat kit. S20 PPP pla stic front fen d er $7 .95 T erry ca bles. clu tch & brak e . . S10 .50 W o rks replica tripl e t ree fo r forks $39.9 9 T he bottom : lin e for th e full treatment comes out rig ht a bo ut $6 15. Elim in at in g a few items lik e reed po rt ing a nd the spiny cylinder head brings that down to $453. T he result is a works replica CZ tha t , ex cep t for its weight . is actua lly a more refin ed . u p to date ra cer than t he works bike itself. It will be competitive if yo u a re and is basica lly simple and easy to ma int a in . $ 150 0 Fo r a to t al u n d er ( Remember . yo u bo ug ht the basic machine used or in th e cra re .) you are the proud ow ner of a G P-rea dy 500 class m otocross racing m a ch in e . Your pl ane tic ket to Europe and ai r freig ht for th e scooter will be more than tha t. Be su re a nd ge t your ent ries in to the F IM rig ht awa y. T he fi rst World C ha mpionship ro und is in April. • , 7

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