Cycle News - Archive Issues - 1970's

Cycle News 1979 04 18

Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles

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~ 00 ...-4 One sure teat of your suspension to find out if it really works is its capability to absorb being bottomed out without tossing you off. The Marzocchi's did the job. We do not recommend the boots. Not even for ISDT Gold Medalists. Three inches of additional travel lrearllooks like more. Marzoc:chi's answer to the should I or shouldn't I update question By Mike Church Photos by Jack Wright You say your dirt scoot's springs have sprung, its shocks have gone south, and its forks have died? Your mind is full of '79 bikes, but the wallet won't allow one of those? Cheer up! Adriano Marzocchi has you in mind. His Italian company has a possible solution via their .. Iatest opnons, t.h e 16 38PAZTI air/oil forks and AG-4 alr/ o~l s~ocks. Cosmopolita? Motors, the distributor of Marzocchi products for the eastern half of the U.S.A. supp~ied the ~orks and shocks and our im . pressIon of them follows. Many of the latest Units from motorcycle manufacturers feature between II and 12 inches of fork travel and 9 to 12 inches of shock travel. The idea behind this evaluation is to an $WeT the age-old question of whether or not one can update suspension to stay competitive without laying out all that bread for a new bike . Or, perhaps, at least reach a good dollar value com . promise. Is it justifiable to spend $500 to $800 on suspension components to attach to a well·ma intained and reliable older bike? O r would it be better to sell your old hoss for a new one? Whatever, we hereby offer you your choice. The forks are typical of Manocchi . works of beauty that are well finished and sport up to 31~mm oftravel. They are supposedly like the new KTM forks. You know , the long booted ones with what looks like two-feet of travel. Those boots . 320mm fork gaiters . keep out the trash and UFO's that intenere with the seals and shiny sur. faces . Triple clamps are tucked closer to the steering stem to , we believe, shorten the wheelbase. Sitting on top are the latest fashion bar clamps for better leverage on that now long front end. . . After finding flex. In the . 35mm tubed: forks , Ma~occhl went to 38mm for stiffeners. ThIS .put more pressu re o~ the upper bean~g ~~rface ~f the sliders, so a n~w us Ing . · Omm ac~oss . was fabricated to relieve chatrermg and reduce stress. The good folks at Motorsports Cycle Center in Roswell , Georgia, were kind enough to provide assistance in cornparing the new Marzocchi forks with the '78 KTM 38mm air forks . We found the triple clamps were the same, but while the forks look the same on the outside, internally there's quite a bit of difference. The upper bushing is all new . The springs offer different rates due to a different low pressure system. Lightweight damping rods are of larger diameter; the old rods showed 16mm while the newer ones measured in at 21mm, with only two large oil orifices where four smaller ones were used before- again for the low air pressure and better flow. Lots of neat ideas are engineered into the new units. Things like uneven coil winding in the springs to reduce binding and evenly spread the corn pression load, plus little oil barnes within the spring collars to reduce gushing when oil squirts from corn pression. Measurement of the sliders showed a 30mm length gain over the '78's. Our original inspection led us to believe the new units were a definite improvement despite an increase in weight of three pounds over the old units. . AG gas /oil shocks from Marzocchi have been found on many fine European-rnade enduro mounts for years du e to their fin e damping and rebuildable construction. The new AG -4 magnesium bodied units offer 4 ~ inches of shock travel t h ro ug h Marzocch i's la rg est -ever pistons which measure a whopping 36mm, as compared to older 26mm pistons. Aluminum body and fins are gone; the fins are no longer needed after removing an inner cylinder which allows for better heat dissipation. The new shocks feature integral reservoirs, brim joints, dual rate springs, and a weight advantage of a half pound each. Marzocchi has long used the DeCar· bon principal for separating the oil from the gas by using an air bladder, which in principle reduces foaming and maintains more constant damping. Originally we set out to set up a '77 or '78 1-: ' M for motocross with which to go nut and banK the suspension around . \\I ell , the best laid plans of.. . Whatever, we ended up with a '78 GS model KTM. Not exactly a motecrosser at over 240 pounds, but a potent enduro/scrambles machine. for sure the GS has about ~ degree less rake at the steering head than the MX versions, and supposedly with the increased wheelbase , less rake would be needed. So, on the forks went . Cosmopolitan provided an axle in sert and bearing race collar to make the changeover work right. Instead of original size 13~ inch eye-to-eye shocks we were sent 14 inch units which raised the rear qu ite a bit . This combo brought :the bike quite a way off th e ground , and provided a measured travel of 1214 inches at the front and 7 ~ inches at the rear. Not really ideal for motocross, but. .. The rear end of caused the

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