Cycle News - Archive Issues - 1970's

CZ 250 Five-Speed: StUI the Racer's Choice? .......--....- ..... --III!!!!I!I!I~~~~-CZ 250 FIVE-SPEED CZPECS M~~~h :::::::::::::::::::::::::::::::::::::::::::::::::33~~ :: Se at He igh t .. . . . . . • . . . ..• . . . . . . . . . . .• . . . ..• . . . .. . .•.• . . . ..3 2 " Wh eelbase .• • ... . .. . . ... . •. . . . . . . . . . .. . • . • . • ; • . . .. . . . . . . S4 .5 " G ro u nd C le a ran ce . . .. . .• . .• .. . . . . .. . . . . . . . ••.• . .. . . .. ... . . . •7 " Dry Weigh t • •. . . . .. . ... • .. .. .. . . .. . .... . . . , . . .• . .. : . . . . 230 Ibs . Frame Type • . . . . . . . . . . . . .. .. ..... . . • .. . .. .. .. .Sem l-d ouble cradle Front S usp en sio n : T elescopic Fork 5 .7 " t ravel Rear Susp ension . .. . . . . . .. . • . . . . . ... . . .. . Hyd raul ic S h ock 4 " tra ve L Bra ke s, Fro nt & Rear .. . . . . . . . . .. . . . . .. . . • .. In te rn a l expand ing sh o e Fu el Ca pacity . . . . .. ... ... . . . . . • : . . • • . . .. . . . . . . . . ... . . .. 2 .5 ga L T ire , Front & Rea r . .. . . . .. • . .. . . . 2 .75 x 2 1 ; 4 .2 5 x 18 Barum Kn obby Type of E ngine . . .. . . ... . . . .. . . .. . . . . . • . • . . . . . ... . 2 c ycle; 4 port Bore x St ro ke . . . .. . . . . . . . . • . . . • . . . . .... .. .. . .. . . .70mm x 64mm Disp lacement 246.2cc Compression Ra t io . .. . .. . . • .. . . . . . ..... . .. .. . . . . . .... •. • • 10.5 : I Carburetion .. . ... • ... • . . .. . . ... . . .. . . .. 32mm JIKOV (new model) Fi ltration .. .. . • .... .. • . . . . .. . .. . ... ...• .. . . . . . . • . . . . O iled f oam Transm ission . . ... . • • • . .. . • • . . • • •. . . . . . . .. . . 5 speed con stant mesh S h ift Patte rn . .. . . . . . . . . . . .. . . .• • . .. . . . . . . . . . Down l ·n -2-3-4-5 up F inal Drive • ... . . . . .. . ... . 13 , 14 or 1 5T counter ; 52 T driven sprocket G ear Rat io I . . . . . . . . ... .. . . .. • • .... • . .. . . . . . . . . . . . . . . . . 2.47 :1 Gear Rat io II 1.85 :1 Gear Rat io III 1.47:1 Gear Rat io IV .. . . . . . . . . . • . . .. . . . .. . ..... . . ... . . .. ... . . . 1.23: I Gear Ratio V . . . .. . . • . . . . . . . . . . . . . .. . . . . . . . . . . . . •. . . • . • . 1.1 1:1 ~ w Z w ..J U >- U • i ~ !" ~, ~ Th is is th e stock CZ 25 0 engine. It now has f ive perf ectly spaced gears to get pow er to the rear wheel and puts out another one or two horsepower. b y D av e Schoo n ma ke r an d J ohn Huer ter Blah -b lah -blah , tri ck th is, tri ck that. G otta have a 4 7cm Bifun i an d a 5 . 75x 15 V a tr oom. Th at' s the wa y it goes eve ry ye ar . Hundreds o f sm a ll m anu f ac ture rs des cen d up o n us and d eve lop 1,71 6 n ew w a ys to im p ro ve yo u r 2 0 1 Ilandersnatch er MX . So un d s d is gust in g, e xp en sive, and mostly su p erlluous, h u h ? T o a la rge ex te n t , oil is. ' But one sign ifican t b en efit is th a t i t give s th e ma nu fact urers so me ide as to w o rk fro m . Manufa ctu re rs, b eing an isolated as th ey ar e , will p ic k up on so me tr ick . inn o vat io ns and se em to blin dly m iss o the rs. Ne ver th eless a comp nay w ith grea t n o torie ty fo r m a kin g m otorcycle s which become " tric k" af ter purch ase is Jawa-CZ . T h is year th ey've made m ore th an m in or ch anges in th eir lon g st an ding m o to cro ss lay o u t, some of wh ich will e m ba rrass eve n th e mos t tric k o f trick s tu ff m anufac turers. In o rde r to avo id being to o auante gard e , CZ h as c reated a new. m odel rather th an dras tic a lly re d esign in g th e o ld . (The re ar e lo ts o f o th e r good re aso ns f or thi s o th er than avo id ance of being avante garde). J aw a·CZ h as developed the "Tric k CZ In carnate. " T he all n ew 25 0c c, five speed , w o rk s replica CZ . N o d o ub t abo u t it , it is trick . Don 't get to o exci te d th ough , it still d o esn 't h ave a rea r. brak e re turn spring. Kind a restores yo u r fai th . But w hat is n ew ? S ome good stu ff is wh a t. First o f a ll, an d much t o yo u o ld CZ fan 's j o y , the red tank h as c o me b ack . It 's n ot quite th e same o ld jewel , th ough . It 's styl ed a fte r t h e w o rk s co ffi n tan ks and ca r ries the gas d o wn, lo w. T he re d t ank is u n fo rtu n a te ly m arred b y so m e b lack , fin n e d ru b ber kn ee p ads. It a lso h as bi g we ld s covered by an a lu m in u m stra p, whic h b rou ght lo ts o f visu al com p lai n ts b ut w as h ar d to fa u lt fun ction ally . It h old s 2 .5 ga llon s wh ich is a .3 ga llo n in crease for yo u d esert fre aks . T h e ne xt ite m .o f ch an ge is th e five 'J Fef) 6-1 ) Engine Temperature, __Exhaust ~~~~-- .' G'St ock C UMPAP- i )c& TORQUE (25 I 24 23 22 21 20 w :J 0 cr 19 0 f- 18 til 17 0 '-j/M/JJ '1 1 'il 1) 16 CI. f- a a u, 15 14 13 cr 12 w :3 0 a. : 1 w til 10 cr a :x:: 9 ..J il ~I 8 7 6 5 4 I-- ._ . 00 3 . 1-- 1-_ ' 1-. - 2 1 ~ . -_. .. .. .. -. - -_ ._ -...... _- ---'" "' - - - . _. I ._ . _ r -- '- --I -- - I ---t--~ 0 0 a a . . CJ 0 If) ,.., ,.., \ a a 0 0 0 If) a a a If) 0 0 If) q q If) If) 10 10 0 0 0 . . . 0 0 a a 0 0 0 If) 0 0 0 e- a:> 0 0 0 0 0 0 . . . eo . . . . e- ENGINE SPEED (RPM) a If) a a 0\ If) 0\ a 0 .~ I speed gear b o x. It wo rks j ust as we ll as the o ld fo ur spee d b ut ca rries its rat io s a li ttle closer togeth er than w as p ossible on a fo u r sp eed. Pa rt o f th e slac k is taken up in the closeness o f ra tios, b u t an o ther m e asure is tak en up w it h a lo w er firs t gear m a kin g c o w trailin g a b it ea sie r. The sh ifte r h as th e sam e long th row o f all CZs, a lon g wi t h th e same p osi t ive fee l an d the sa me fee ling o f in d estru ctibility . Wh ile runnin g th e CZ o ff agains t th e Ho n d a it was easy to p op sh ifts wi th n ar y a h esitation in th e ro ta tion of th e throttle hand. Ho w a transm issi on ca n sh ift, es pecially as e as ily as t h is one, when the th ro ttle is wide o pen , is hard to com p re he n d. About twice , b e fo re becomin g fu lly acc us tome d t o th e box, there w as a false n eu tral so mewhe re , but it d isap peared , n ever to b e fo u n d again. O th er riders n ever d id find it. What th e five speed d oes , m ore th a n a n y th in g els e , is allow a h igh e r horsepower o ut p u t with a resu ltan t slight n ar rowin g o f the m a ximum powerband. T his is n o t to say th at th e CZ is p e ak y ; it is to say th a t it defin itely ma kes m o re p on ie s up h igh th an d own low. The five speed keeps th e en gine w orkin g in the R PMs all th e tim e. A ll five gear ra tios a re sp aced supe rb ly . Not onl y d o es th e n ew b o x ge t th e engin e in to th e p owerband, it m akes the rider's j ob sligh tl y easier b y redu cin g th e p os sibility of getting o ff th e powe rban d . Briefl y , there is a grea te r incre ase in th e u sabili ty o f .th e ge arbox than th ere . is narrowin g of powerband. . T he p owe r s tarts to come o n very stron g o n th e C Z a t about 6 0 0 0 R PM and in crease s f rom th ere t o a p e ak nash readin g o f a lm os t 20 H P to th e gr o und at 85 0 0 RPM . By tha t ti me, h owever , torque is trailing o ff fa ir ly drastically . 2 0 HP is an e xc ee di n gly respectable figu re fo r a 25 0 . It is, in fa c t , ab ou t ave rage fo r a 400. T ha t ma y e xp la in w h y the CZ proves to b e n e arl y as fast as som e 400 m o to cro ssers enco u n tere do T he 2 50 C Z gives away three H P t o th e Honda E lsin ore, and th at ho rsep owe r di ff erenc e shows up as ab out tw o bike len gths a t th e en d o f a 1 10 yard drag race ( th e Arro yo Cycle Par k star ti n g ar ea ). T he re was more diffe ren ce in th e drag ra ce th an j us t horse p ower th ou gh. T he CZ' s Baru m ti re . an d its re la ti ve tractabili ty, b rou ght it o u t of the h o le q u ic ker but soon th er e a ft er the H on d a 's hors epower w o ul d carr y past. As delive re d , th e CZ ca rr ies sligh t ly ta lle r gea rin g and w ould just b e gin to u se it s top end a t the end o f th e race. A t th e end the H onda was up by two b ik e len gths . A fav or ite m odific ation o n pr ev ious CZs was' to install some o bs c u re Japanese c ar b ure t o r. That w as on acc o u nt of t h e fa ct that th e J ik ov sta r te d hard, lo ad ed up an d th en sta rve d o u t a t sus ta in ed fu ll throttle. T his ye a rs TC ZI ( tric k C Z In carnat e ) c ome s with an all-n ew re d esign ed Jikov. S urp rise ! Yo u d o n't eve n re all y h ave to th row it away . Star tin g is re aso n abl e , .th o u gh w arm up is slow (cough , cho ke); lo ad in g up at low RPMs is go ne; an d th e Il o at b owl h as gotten a ho u t 50% bi gge r, all evia t ing th e starva tio n problem. Obscure J apan ese ca rb u re tors still m igh t b e a stan d a rd, b u t th e J ik ov is com p le te ly ac cep table in it s presen t ver si o n . Wi th o u t it s past h ist ory, a t est rider w o uld n ot t h in k to questi on h ow w ell it work ed. en What y o u get in th e " d is the sa m e o ld CZ en gin e with on e intake port

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