Cycle News - Archive Issues - 1990's

1993 Kawasaki KX MIers NEW BIKES ~ Kawasaki debuts new KX line .~ at Mammoth Mountain MX YZ80 Photos by Donn Maeda awasaki debuted its lineup of 1993 KX motocrossers at the June 25-28 Mammoth Mountain MX . in Mammoth Lakes, California. While the KX60, KX80, KX80 Bigwheel and ~X500 have undergone only minor changes, the KX125 and KX250 boast many. The KX125's motor is claimed to have more power, thanks to a redesigned power-valve system, piston, expansion chamber and reed-valve area. In addition, a new ignition timing curve, reduced flywheel effect and revised carburetion reportedly produce a wider powerband. The frame is lighter, due to thinner wall construction, as is the swingarm. The front fork features aluminum push rods, rather than the steel, and the outer fork tubes are thinner. While lighter weight is achieved, the real benefit of the thinner tubes is balanced· rigidity between the inner and outer tubes, according to Kawasaki. The front brake has a new master cylinder ratio that is claimed to provide a better, more-progressive feel. Like the KX125, the KX250 features an all-new frame, reduced flywheel K an attempt to keep heat away from the larger airbox and to lessen the decibel output. The front and rear suspension have also undergone extensive modification. In front, the fork has received changed valving and a different spring rate, while outwardly the fork features a darker works-like color and a reduction of 10 millimeters in the amount of axle underhang. Front travel is 12.2 inches. In back, the rear shock now has a larger body and linkage ratios that are softer on the initial pari of the travel. The linkage has also been tucked up higher. To gain additional rear wheel travel (now 12.8 inches) and ground clearance (15.5 inches), the swingarm has a slight downward angle and, like the frame, has received substantial gusseting. The front and rear brakes both feature new sintered compound pads, and the front brake unit has a different lever ratio as well. In addition to the body and suspension changes, the engine has also undergone refinement. Clutch capacity has been increased through the addition of an extra plate for a total of eight, while the springs feature a slightly softer ratio. The YPVS power valve has been repositioned closer to the cylinder, which has undergone porting changes in an attempt at providing more midrange and upper hit. Cooling capacity has been improved by increasing the size of the radiators by a claimed 20%. At a claimed 214 pounds dry, the weight of the YZ250 is slightly higher than last year's model. The Yamaha YZ125, which suffered last year from what many felt was an underpowered engine, received several changes to the motor. To up thehorsepower output of the quarter-liter powerplant, the head was redesigned and the crankcase pressure increased. The intake tract was reduced slightly to increase velocity, and the angle of the reed cage, which features thicker reeds, has also been altered. The cylinder has received new port timing and the redesigned power valve has been added, while the transmission and primary ratios have both been changed. The YZ125 has undergone many of the same changes as its bigger brother, including the new plastic, all of which is interchangable between the two bikes. In addition, it has received the same changes to the front and rear suspension, although softer springs are used on the smaller bike. Like the YZ250, it has a removable subframe, new swingarm, larger airbox, bigger radiators, lower pipe position, stronger brakes and an extra clutch plate. Finally, the CDI box has been repositioned from the airbox to the head stay. Like the YZ250, the weight of the 125 is up over last year at a claimed· 193 pounds dry. Even more changed than the YZ125 and 250 is the YZ80, which was rebuilt from the ground up. In an attempt to appeal to the more aggressive mini riders, Yamaha built a much larger bike. All-new bodywork is used, giving the YZ80 a look similar to that of the larger YZs. The new frame, which has larger tubes and more gusseting, is said to be much more rigid than last year's, as is the swingarm. The left rear subframe member is now removable to aid in access to the shock and larger airbox. Foot pegs are wider and longer than those of the '92, and tapered roller bearings in the upper and lower headsets replace the ball types that were used last year. A 7.5-inch rear disc brake replaces the drum used on the '92 and a larger· diameter 8.6-inch rotor is featured on the front as well. New pad material is used front and rear. The YZ becomes the first normal-sized 80cc machine to come stock with inverted forks. While the 36mm aluminum fork does not offer the possibility of external compression or rebound adjustments, the new larger rear shock does. Revised linkage is mated to the shock and travel is up one inch front and rear. The new engine, which now features case reed induction and a Nikasil cylinder, is claimed to offer a startling 35% increase in horsepow:er, and is angled forward in the chassis to improve the weight bias of the machine. Transmission ratios have been altered to match the increased power of the motor. The radiator was moved to the left side of the bike, while the pipe runs along the right, and is mated to a large aluminum silencer. The YZ80's claimed dry weight is 146 pounds. The YZ80 receives the largest suggested retail price increase, jumping $600 to $1899, while the YZ125's $3699 price tag is the same as last year's. The YZ250 is up $150 to $4449. CN effect, reprogrammed ignition and carburetion, and front fork updates. The big news, -though, is the new guillotine-type power-valve. Similar to the system used on the KX125, the valve is designed to produce more power throughout the powerband. Both bikes are said to be much lighter than their predecessors, as the fuel tank, front fender and front disc have also been redesigned with weight trimming in mind. . "We don't have an exact weight figure on them yet," said. Team Green's Jose Gonzales, "but I can tell you that both the 125 and 250 are about five pounds lighter than last year's. " The KX60 sports a new ignition, while the KX80 and KX80 Bigwheel received· fork updates. Carburetion modifications are the only change on the KX500. N~w seat and tank graphics round out the new KX lineup, and each model will increase approximately $100 to $200 over the suggested retail prices of the 1992 models. Release is scheduled for the first week in September. CN 41

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