Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/141011
" 116m r- SACHS FANS: Neutralize All Those Neutrals By Ron Schneid ers Mention any b rand of motorcy cle at a bench racing se ssion and you'll ge t a stateme nt fro m so meone to th e effect, " Oh , th at 's a great bi ke b ut .,;"• And follo wing the "bu t" w ill b e a sta te ment about th e bike 's weakness that every o ne has h eard at least a do zen ti mes. T h e story always has some basis in fa ct. but years of stories, ret o ld and recirculated , exaggerated and embroidered, have made the final versi on ( un t il next week) highly unreliable. Thus yo u have some bikes with frames that "break", some th at "don 't h andle. " some wh o 's brakes do n' t work "for weeks" after havin g been wet . Sachs and Zundapps "don't shi ft ." . T he "don't shift " is exaggerat ed . Un less th ere 's actuall y something badly wo rn or broken, it 's more a case of relu ct an ce to shift q uic kly . Even more comm on is a tendency to shift to o qu ickly in some instances with the res u lt that the d esired gear is b y passed co m p letely and th e engine winds up screamin g in neutral. One tu ner asks th e questi on in h is ad vertising; "Do es your Sachs have a gea rbo x full o f neu tr als?" If it docs, it's strong b eea use even those wit h si gn i fi c an tl y m is a d ju s t e d shift er mech an ism s only have o n neutral , but it's a bit t o o eas y to find. And finall y, the problem see m s t o have b een cured for all practical purposes after engine No . 631 8 -754. Suppose ho wev er. th at you have an ea rlier S ach s (or Zundap p ) , th ey ' re about th e same). You hav e three possible choices . Each me th od has its ad vocates and the exponent of each meth od is q uite ready to tell you why his met h od works and the others don't. Each also has many satisfied customers running around, in cl ud ing many go od racers. ~ I ethod we might call the su per-cr it ical adj ust m en t me th od. The premi se h er e is th at th e sh iftin g mech anism is b asicallv o ka v, b ut it must be a dj uste d c o rrec t ly . " A leadin g exponent o f th at method is Ken Peterson, a tun er who works for Cole Bros. in North Holl yw ood wh en h e isn't making go -F rers on his own . His as method works well to a point. I found th at with a Pet erson-adjusted shifter I wouldn' t mi ss mo re than on e or two shifts in a long end uro , but t h ey would invar iable be c ru cial o nes. usually three qu art ers of th e way up a steep hill jammed with traffic. Two missed sh if ts in a long enduro is certainly no t enough to fault th e adju st me nt , b ut fo r a guy who wa nts to win it 's not reall y "", '" accep ta b le eit her . The Sachs has another charac t eristic t hat's so me t im es a problem. It 's very stiff w hen shifting up in the h igher gears without th e clu tch. Try to sh ift up quick ly without th e clu tc h, say, in a snadwash where yo u're trying to ge t on top, and y o u might find that nothing happens . The p roblem is that you didn 't apply enough toe pressure, T here 's nothing wrong wi th the adjustment. But the amount of toe pressure required is ofte n beyond norm al people's cap ab ilit ies. The critical adj ust m en t method d oesn 't do any th ing for that. For those who use the clutch and are basically trail riders or street riders, a crit ica l adjustment will b e p erfectly sati sfactory . Racers and serious enduro rid er s will find it less satisfact ory. b ut migh t live wi th its sh ortcoming b ecause it is t he ch eapest way out : as little as $ 10 if th e parts ar e in good shape a nd th e mech anism doesn 't re quire a complete overhau l. Ca ll Ke n Pet er so ns at (213) Cll 9 -73 15 if yo u 're interested. Meth od 2 is c alle d the "Kob a " method. It was develop ed by Steve Kolse th and Walt Baeh r and it is based on a spri ng-loa ded sel ect or ro d t hat can be p urchased as a k it for $3 7.50. Inst allat ion is an. ad d itional $20. How good is it ? 1 do n 't k no w. Maybe we 'll che ck it o ut in a fu tu re article. T h e telephone for KO BA is (2 13 ) 327-0310. Method 3 was developed b y E.C. Birt. We migh t cal l it the modified selector rod meth od. It's illust rat ed in th e photos . E .C.'s th eory is t hat by making a more gengle slope on the edge of each detent, th e transit io n from on e gear t o the next will be m u ch easier . In easing the edges of the detents , he also reduces the flat area between the ~ detents to almost nothing. The theory :E here is that with no flat area, th e mechanism can't han g up b etw een gears, ~ w in a false neu tr al. E.C. also stresses the Z need fo r a precisio n adjus t me n t after w -' the mach in ing is completed. U >E .C. is a very car eful workman . He U ensures th at th e sele ct or rod is gro und just so an d then polished to a m irr or finish. R emo vin g th e selector rod without splitting th e cas es is a trick t hat the factory says can 't be done, but everybody knows it can and knows how to do it. Not many. though, have go ne to th e trouble of grinding a special wrench so that it ca n be rem ov ed wi th out damage. E.C. has . Litt le t ouch es like that are what ma ke you trust a mech an ic. The lab o r o n E.C.'s mod co sts $25.95 incl uding the mach ine shop wo rk. Added t o th at are th e cost of a new cover gasket and o il, mi nim um. If some of th e parts are worn , the cost goes up . The E.C. Birt m o d ificat io n do cs a swell j ob of m aking th e shifting easi er. Missed up shifts are a thing o f th e p ast. My experienc e wit h it, do wnshi ft ing was n ' t as go od . J co uld still drop fro m t hi r d through seco nd to neutral occasionally. (For "occasionally". rea d "at t h e wo rst possib le mo ment"). 1n motocross , wh ere clean, qu ic k ups hifts are essent ial, C.C.'s modification would seem q uite w o rth whil e. For othe r fo rms of activity lik e enduros and such , whe re upshifts can he done leisurely, but downshifts are o ft en crit ical . it's of mo re do ub tfu l value. Let yo ur mo ney b e yo ur gu id e. C.C . can be reac hed at Precision Cycle. 4573 A rtesia Blvd., La wndale , CA 90 260 . (213) 3 70-8 8 2 2 . 1.) To work on a Sachs tran smission, you lay the bik e on its side and leave th e engine in t he frame . If you lay it on its side, you don't even have to d rain th e gearbo x . Leaving th e engine in the frame allows you to use the rear wh eel as a giant wrench to screw the select or rod ou t of th e T -bar . Here is E .C.'s special w rench wh ich allo ws the selector rod to be removed wi thout bending it, or rounding th e fla ts. • 4,) H ere is the old selector rod and th e machined-and -polished new one (near) . Note the easy transition s from gear to gear. .. 2.) If you were to split the case to remo ve the selector rod, this is what you'd find. Th e T -bar rides up and dow n the slot in the large shaft . By lining up the not ches in the gears to coincid e w ith th e slot , the T -ba r can be turne d on end and fished out the ho le in the near end of th e shaft afte r t he select or rod has been wi th drawn. 5.) A pri nciple cause of difficulty in shift ing a Sachs is a worn T -bar. E .C. poin ts out th e critical area. T he one he is pointing to is worn out and must be replaced . / 3 .) H ere. the selector is bein g ground in a lathe . In orde r to grind the shaft it mu st be held on both ends. Th ree of t he keyways have been part ially ground . 6 .1 Th e reassembly is exteemely critical and mu st be done w ith a dial indic at or . All adj ustment is done in third gear and the final adjustmen t of the select or roo is don e to ze ro tol erance. A ny slop at all and it w on't wo rk.