Cycle News - Archive Issues - 1980's

I t seems that off-road competition in the U .S . has caught the attention of the Japanese again. Nineteen eighty-nine sees three ' of the four O EMs producing rather serious off-road models, all based after their motocross relatives. Kawasaki surprised everyone with a radically changed KDX200 with a mishmash of KX components, and Suzuki is near to the release of its all-new enduro 'm odel called the RMX250, closely resembling the R M250 MXer. On the other side of town, Yamaha has its own creation the YZ250WR. Like the KDX200 and the RMX250, the YZ250WR has motocross blood running deep within. The WR is closely rela ted to its hitech YZ250 MX brother. In fact , they're nearly ide ntical twins.. but ' there are two important factors tha t set these two machines apart. The YZ250W R features a wide -ratio transmission, and a lighting coil with a built-in wiring harness for easy aftermar ke t ligh ting installation . Since we've already tested the YZ250(issue #46, November 23 1988), we'll pass over most of the technical details of the YZ-WR and just touch upon some of the major features. The YZ-WR is powered by a twostroke, reed-valve, water-cooled motor with the YPVS power-valve, fed by a 38mm flat-slide Mikuni carburetor. Internally, th e five-speed gearbox has a lower first and taller fourth and fifth gear ratios than the ' MXer. Second and third gear ratios are the same. The chart below shows the ratio changes between the '89 YZ and the YZ-WR. I sl gear: 2n d: 3rd: 41h: 51h: • YZ250WR 2.285 l.i06 l.3i5 1.090 . 0.840 The YZ with the wid YZ250W 2.06i l .i06 l.3i5 1.158 1.000 The suspe nsio n is handled by an inverted Kayaba fork and Yamaha's latest Monocross rea r suspension design. The Kayaba shock has external compression and rebound damping adjustments, and the fork compression only. All these components are exactly the same as the YZ250. Chassis-wise the YZ-WR is, again, exactly the same as the YZ. The YZ: WR sports th e new inverted cartridge . fork with 11.8 in ches of travel. It also has external co m p ression damping adjustmen ts. The rear Monocross sus pe nsion boasts 12.2 inches of . trav el a nd has a beefy aluminum swingann. The frame is also identical to the YZ's , which also includes the removable left-side sub-frame section. . Like the YZ, the YZ-WR comes with a low-profile 19-inch rear wheel, and front and rear disc brakes. Unlike the YZ, though, the YZWR comes in a white and blue color combination, rather than white and red. Hittin ' the trails I0 Test: 1989 Yamaha 'YZ2S0W R Even though the YZ-WR and the YZ are so closely related, they perform quite differently . Both ma chines produce plenty of power fro m bottom-end on up, but th e wide-ratio transmission makes th e YZ-WR much more suitable on th e trail. Power delivery is more tractable and predictable on the YZ-WR making it easier to control for trail use. We found that first through four th gears on the YZ-WR are extremely useful in enduro-type riding, while fifth gear is a little too tall for an thin bu t wide and we The Yl2SO Wide Ratio (above) looks identical to its motocross brother, the Yl2SOW. The only difference is color. Internally, though , the YZ2S0WR features a wide ratio transmissionand a lighting coil with a built·in wiring harness. It shares with the YZ an inverted cartridge fork, a 19-inch rear wheel and front and rear disc: brakes. mean wide) open type riding. Fifth gear feels more like an over-drive gear than anything. There's also a huge gap between fourth and fifth , and the shift between these two gears isn't always smooth. But gear changes between first through fourth is silky smooth. Since fifth gear is so tall, the YZWR feels more like a four-speed rather than a five-speed. However, the neat thing about the YZ-WR, you really don 't miss the fifth gear. Most of the time we didn 't even feel the need to use it except on smoo th , wide open dirt roads. At speed we found th e YZ-WR to perform extremely w ell , ex ce p t having a slight case of the shakes up front. For better straightline stability, the forks need to be low ered in the triple clamps. The fork is also a little soft and 'rides too close to midstroke, causing for harsh performance, We recom- i mend swi tching to stiffer Yamaha fork springs (0.380 standard rate to 0.390) and increasing the compression dam in adiustrnent. The result is a smoother and more predictable ride. However, the rest of the motorcycle performs flawlessly. The rear suspension is extremely stable and strong enough to handle the gnarly whoops, ruts and cross -grain, and the overall layout is comfortable, which is great for those lon~ days in the saddle. Our bike came jetted too lean on top and a little rich off the bottom. We jumped from the stock #340 rnainj et to a #370 and dropped the pilot jet from a #60 to a #50, with th e a ir screw set at one-and-a-half turns ou t. We left the needle a lone. This cleaned up throttle response tremendously. At first we had our doubts about the 19-inch rear wheel with the lowprofile tire for off-road use. However, we covered over 250 mi les on desert and rocky terrain with the YZ-WR and experienced only one flat. In tight terrain, we couldn't find any major faults with the Yamaha. The YZ-WR turns well and combined with the smooth power deliv- ery, thanks. to the wide-ratio transmission, the Yamaha is tough to beat in the tight stuff. _ . Both front and rear brakes are strong but are not what, you would call touchy, but we did have some problems stalling the engine. A heavier flywheel would help. The Yamaha's clutch performs up to par but feels spongy. Clutch pull is a little too stiff for our liking and after a long ride, you're going to find your left forearm a little tired. Detailing is first rate on the YZWR. The grips are good, the seat is finn and comfortable, levers are easy to reach and the handlebars are comfortable, but we did cut ours down about an inch on each side. And? The 'motor and transmission left "the biggest overall favorable impressions in our minds. The powerful motor combined with the wide ratio transmission makes it extremely potent yet manageable on the trails. H owever, we feel fifth gear is a little too tall for norma l riding conditions,

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