Cycle News - Archive Issues - 1970's

.lil' ~ l1. M .... ~ ai . > ~ (J) ;: w Z w Fig . 1 . l at e mode l h ead and b arr el on left, 1971 and earlier on rig ht . cy lind er would run cooler . (Fig. I ) As fo r th is cy lin de r change I gues s th e Zundapp p eople are one ste p ah ead of me . I was co m ple te ly happ y with th e o ld sty le cy lin de r be caus e they never did o verheat. Even in a 100 mile race o u t in the d esert they would n o t overheat . Every once in a wh ile I ge t ap p ro ached wi th th is problem : " T he cyli nder is chrome pla ted and I hear th e ch ro me comes off plu s you cannot bore it. H T he only p oi n t this perso n go t righ t was it is a chrome cylinder an d fo r hal f o f the p eople that is ins tant pan ic. Bu t this is o ne of th e best p oin ts of th e engine an d I do n't thi nk Zundapp will eve r ch ange thi s p art o f th eir engi ne design . Why is it good? Well for o ne, it runs cool. T h e pi st on ru n s with les s clearan ce mak in g a b etter seal an d a mu ch quie ter ru nnin g eng ine. When th e eng ine reach es run ning te m perature, both pist on an d cylinder expan d an d contract th e same amo unt. Now, the part about chro me coming off. No way. I 've never see n a Zundapp cylin der peel. The chro me is .005 thick, o n the japanese cylin ders they run .003 th ic k and they will so metime s peel. Bu t they we re design ed as th ro w-away models . Run a race and re p lace it. The Zu nda pp cylin der , if you're not 'a d uff an d yo u use yo ur h ead, will last almos t foreve r. I have cylinde rs th at have five years of ra cin g on t hem and the m ost. wear yo u ca n fin d is .00 2. N ot mu ch is it? You will ge t th at mu ch wear in the first five min u tes of ru n ning on a slee ve cylinde r. Maybe I am a li ttle sharp-tongued whe n I say you might be a du ff . Let me explain that yes, you can damage a Zund app cy li n der. It is n o t indes tructib le. If yo u b reak a ring , it mi gh t get wedged between th e cylinde r an d p ist o n rnakin g a go uge in the cy lin der. If th is h appens th e cylin de r's rui ned. What do yo u do to keep it fr om happening? F ig. 3 If you che ck th e rings every 500 miles on an End uro m o del and every four to six races on t he MX , yo u will p ro bably neve r have any probl ems. If the air filt er is kep t serviced and yo u keep the engine clean, it will go 1000 mi les o r six days straigh t with n o p roblems. T hey d o it every year in E urope in th e Internat ion al Six Days Trial an d lo o k at th e gold m edals th a t th ey win with Zundapp engi ne s. I d on ' t th in k th at any bike th at is used for com peti tio n o r just plain h ard trailriding should be run mo re th an 5 0 0 miles without lookin g a t the to p en d. All right. Let's say y o u ge t so me th ing in th e cy lin de r o r it breaks a rin g and does ruin it. As I' ve alre ady said , it can n o t be b o red to a next over pist on . So yo ur o nly ch o ice is th ro w it awa y an d replace with ano the r cy linder. But there is a w ay o u t. I've seen thi s h appen and so I' ve m ade a replaceable slee ve with impro ved p o rting over th e st o ck cy linder th at can be inst alled in yo ur cy linder. Sin ce this is a cas t iron sleeve it can be bored just like any other kind of cylinde r on the market. Sinc e Zundapp doesn't make a oversi ze pist on , R i c k m a n co n t ac t e d a pi ston man u fac turer here in the U.S . to make oversize pistons , so that you can have three oversizes after stock. These sleeves are made t hick enough so that y o u wo n 't ge t any heat d istorti o n and can be b ored right o ut to ma ke a 15 0cc eng ine for th e o wne r that wan ts to run like a 250cc bi ke o r up in th e I 75cc class. T he other so re spot th at so me riders co m plai n about is missin g shifts. Fo r one th ing, most A me rican rid ers owned japan ese-ma de bik es be fo re they ever mo ved to .a Eu ro pe an bike and the j ap an ese bikes were designed so that you co uld jab or kick the gearshift around and n o t have to o much p roblem until yo u bend a sh ift fork or b um one up fro m abuse. A Zundap p engine wan ts t o b e shifted , n o t stom ped o r kic ke d from one gear to th e nex t. So ' yo ur shifting habits may need a little imp rovement. Maybe m o re so than the bike's. T he Zundapp pe ople don 't real ly feel we're du mk op fs b ut the y did re alize th at we may n ot be q uit e as savvy as they are so the y've d on e some thi ng ab ou t th e shifti ng. T he first ellgi ne s th at came iIi h ad a "first design " shift pall d eflect o r and t he n ot ch a cross it wa s .4 12 thousandth s as on th e left of Figure N o. 2. T his sho uld be replaced with th e one on th e righ t, th e "second design " , which m easure .3 6 0 th ousandths. T his takes th e slo p o u t o f th e sh if ting mechanism. This shift p all defle ctor is fo und ins ide the sh ift drum asse mbly (F ig. 3) . A n ot he r p oi nt th at h as been allen de d to (N ote Fig. 4 ) the sh ift rod on th e right is stock , th e rod in th e middle is facto ry m od and the one on th e le ft is m y m odified ro d . i f yo u h ave shi fting problems, check these poin ts out o r , if y o u ' re in doubt, sen d it to me and we can mo di fy o r change as n eeded. In th e 12 D J.N. H o rsep ower engi nes we had a lighter gearbox an d wh en the 15 D J .N . HP engines cam e in they replaced th e gea r cl usters wi th bigger, ' beefier gears. T his n ew Grand Prix gearbox can b e in st alled in the 12 HP engines. T here arc tw o gearbox rati os fo r th e Zundap p engin e. A wide rati o gearbo x an d a close ratio t hat is better for m o t o cross. How d o yo u figure o u t which one y o u h ave ? Well , th e easie st way is t o sp lit th e cases an d count th e teeth on the m ain sh aft and slider gears. Close ratio h as a drive sh aft wi th in tegral gears, fo urth ge ar has 19 teeth , fifth gear h as 19 teeth with ma tching pinion gears , fourth gear has 24 te eth and fifth gear has 2 0 teeth. . Wide ra tio has a drive shaft with in te gral gears of fo ur th gea r with 20 teeth an d fifth gear o f 2 0 te eth . Pionio n gea rs: fourth gear, 24 teeth and fifth gea r, 19 teeth . The othe r improvement th a t has been m ade is in th e c ase stop pin for th e 1973 b ikes. It is alm o st im p ossib le to b reak it . (Fig. 5) T he one on th e righ t is th e impro ved p in : the o ne on th e le ft is the o ld style . The cran kshaft in th e 19 73 bike has a bigger ro d wit h a heavier threaded end for the flywheel nut. T his will ma ke it m uch har der for you to sp lit the en d of the crank when you try to re move th e flywheel without the p ro pe r tools or fly wheel p uller. ( Fig. 5 ) The crank on th e left is new style an d the crank on the right is ol d st yle . T he spar k is p roduced b y a Bosch magn et o th at ma kes a spark th at will light yo ur ears up : ..J tJ >o As I sta ted in the beginnin g, the Ri ck man Br ot hers build a true m ot o cros s m ot or cy cle that was ra ce-bred to d o one thin g: win race s. Wha t is th e diffe rence between the Six Days En d uro and the MX ? The d ifferent is that t he Six Day s is stree t legal an d th e MX is n o t. Some bi kes th at are built for motocross won 't work as well in the desert as the y sho uld. So t o see if this is the case , I loaded th e bike in th e van , h ooked up m y trailer an d fa mily and headed fo r California City for the SRA Grand Prix. Wh at will th e b ike d o fo r yo u in the desert ? After a pit cr uise , I headed ba ck o ut across th e desert fo r the trailer. All at once I heard a bi ke co mi ng up behind me . A yo ung rider on a 25 0cc bike (I won't men tio n wh at kin d] ca me by me with blo od in his eye an d the actio n of th e Old West , movi e-sty le. Full of sp it and vine gar lo o kin g for a showdown. I felt . h alfway hero-ish m yself an d answered his challenge. The de sert was smoo th as glass an d w e were fla t o u t , both bik es in fifth gea r an d n o t mo re than 10 feet ap art. A ll at o nce we hit a bunch of co b by stuff. Well , he di dn't back o ff o ne bit. Mu st h ave had mo re hair than he knew wh a t to do with. I didn't back off ei the r be cause I was petrified an d could n ' t. I just knew I was go ing to eat it. When you get o ff at 60 MPH , it h ur ts. The las t I saw of h im, h e was do ing tan k-slappers., T he Ric kman j us t d id it s th in g and stay ed straight like th ere was noth ing to d o. I guess th e o nly th in k th at I need ed t o d o to p rep ar e it fo r th e desert w ould be to leave th e kick stand o n it so I wo uld n ' t have to p rop it up with a st ick . Yo u n o tice the bi ke n o lo nge r has the lights on it an d it has a low pi p e. Well , I raced it at A rroyo Park fo r testing purposes. Now it's ra ce-re ady and Steve McF arl an d, a junior, will be raci ng it o n lo cal SoCai motocross tracks. R ic kman Si x Days Endu ro cost? $995 .00 F.D. B. T h at's a lo t of money b u t in m y way of lo o king a t th in gs, yo u get wh at you p ay for. T he rest is up to yo u ! •••the OUT-OF-THE-BOX WINNER CONTACT : K&N ENGIN EERING , P.O. BO X 1329 CN ·W RI V ERSID E. CA 92501 !GENUINE ! BU FFA LO BREATH JERSEYS $16.9 5 With you r brand of motorcycle _ sil k screened fr o nt o r back $ 17 .9 5 So lid or MUlti Colors Available . Custom Made Chest Protectors w ith you r b rand o n front. $15.95 Sen d f ar free cata l og Dea ler Inq ui res In vit e d Sam e day ma ll ord er se rvice J & J Motors Box 06396 , Portland, O rego n 9720 6 503·235·8 938 ~''---------- Out-of-the-lox, On-theSike equiprrent incl udes: 21hp Sachs six-speed 'S' engine (24hp GP version optioral) with Motoplat transistorized ignition, Sl'I.edish 4130 chromemoly tube frarre, Ceriani forks, Girling shocks, Akront rims, TI1!Ileborg tires, l'&l'Jra controlsall in a 53-irch wtlrelbase with a 100, 195-lb. v..eight. ISOT andEnduro versionsal oav lable III s ai Did v..e miss anyth ing? NO! We used the finest components and 'trickstuff' available to build the M ONARK. Join the lllinners this v..eek; your picture might beshown here in one of ouradvertisements. If your favorite local dealer isn't selling MONARK yet, tellhim to get it on ! Or, send us his name and address and we'll tell him M ark eted b y : IrJt;er.:n-ends I-Jc. 3 00 1 RED H ilL AV ENUE COSTA ME SA . CA . 92626 Telephone (714) 9 79·1550

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