Cycle News - Archive Issues - 1990's

Cycle News 1995 09 06

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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1996 Yamaha YZ125 By Donn Maeda Photos by KInney Jones and Kit Palmer ~ ealisticallY, Yamaha has not been known for producing firebreathing 125s in recent years. Honda has traditionally dominated in the engine deparqnent, followed closely by Suzuki, then Kawasaki. So just where has the YZ125's forte been lately? Mostly in the handling department. Low and long, the YZ125 is traditionally one of the most stable bikes in the class. Last year, the '95 YZ125 won the Cycle News 125cc Shootout. Highlighted by a great-handling chassis, the Yamaha tiddler was actually pretty fast. Though by no means a powerhouse, the YZ's engine had a respectable hit that started down low and pulled through the middle of the powerband before signing off on top. We liked the '95 YZ125, but still, we ,ended up turning it into a'16Occ firebreathing cheater bike when we tired of it in stock condition. No such fate lies in the future of our '96 YZ125 test bike. We'll cut to the chase right from the start: the newest YZ125 is one of the best - stock or modified - 125cc motocrossers that we have ridden to date. WHY? Yamaha basically started from scratch when it came time to design the new YZ125. Enginewise, several refinements were made to the existing motor, all of which produce a stronger, longerpulling powerband. For low- and mid-range gains, Yamaha engineers reworki!Q the YPVS power valve mechanism. The revised 'power valves are wider and have a flat edge that seals the exhaust port more efficiently. The crank balance was rework- ed and reduced, the primary compression ratio was increased, and a thinner set of carbon-fiber reed valves were installed. To improve top-end performance, the cylinder's exhaust-port shape was changed and the ignition timing was altered. Secondary compression (with the power valves open) was reduced, and the seal between the exhaust pipe and cylinder was improv- ' ed. In addition, the airbox boot has a new, straighter shape that is claimed to improve throttle response. In' order to better put the power to the ground, the transmission boasts a new shift fork that is designed to improve shifting under power. The YZ125's chassis has undergone several important changes - all with greater rigidity in mind. The backbone was actually reduced in size, but the cross brace is considerably larger. Several key portions of the frame were beefed up, including the areas near the steerer tube and the ,swingarm pivot. Gone is the gaping hole behind the steerer tube that could be found on previous YZS. An all-new swingarm is considerably stiffer than its predecessor, and -like the frame, is lighter than the previous version. The shock linkage is now mounted through the swingarm, rather than underneath it. The newest VZ125 sports a color scheme almller to that of the '95 team blkas. Like the plastic;, the rest of the bike Ie an new as well. Perhaps the biggest news of all are the new Kayaba 46mm inverted forks. Compared to last year's 43mm units, the larger legs are considerably beefier and offer greater rigidity. Inside the massive legs is a larger internal cartidge, up 3mm to 28mm. The larger cartridge and fork legs allow for a wider range of compression aI!d rebounddamping control. The front axle is now held to the forks with a double-pinch design. The single-side pinch and thread-in design of the past has been cast aside because of it's inherent flex, and the new system is claimed to be much more rigid. The Kayaba rear shock has been revalved to compensate for the new linkage system. Thanks to the throughswingarm mounting, the '96 linkage doesn't hang below the swingarm as far as the old-style links did. The new Yamaha brakes have also undergone several changes. The rear brake enjoys a new pedal, one that's not as curvy and flexy as the previous piece. The new lever incorporates new leverage ratios. Up front; an all-new master cylinder graces the handlebar. The master cylinder has a fully adjustable linkage system that allows the lever position to be adjusted in or out. The front brake hydraulic line has been rerout¢ to provide better feel and increased strength. And let's not forget about the new bodywork. The blue and white plastics are almost completely new - the OIrly parts that remain the same are the front number plate and front fender. The new, blue fuel tank and radiator

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