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/126768
Test: 19B4 Yamaha YZ125L motocrosser TheYZ withoutthe • zing "We will race what we sell and sell what we rac.e." Yamaha Racing Manager Ken Clark Clark must not have had the 1984 YZ125L in mind; Yamaha's selling them, but there aren't any factory Yamaha pi- 16 lots in the 125cc Nationals. Broc Glover, who made his name on works 125s, is riding Open bikes; Ricky Johnson and Keith Bowan are on 250s. All three ride slightly-modified production YZs. But nobody's on a YZ125. That's a shame, because in recent years Yamahas have been major weapons for serious privateers on both a'tional and local levels, simply because they were competitive right out of the crate. The YZ's motor is a single cylinder two-stroke, water-cooled with dual radiaLOrs. It still incorporate the variable exhaust port which Yamaha caBs the Yamaha Power Valve System (YPVS). Actual displacement is I23cc and the bore and stroke is 56 x 50mm. The carburetor is a 36mm Mikuni with reed valve induction. The rear suspension uses a gasfilled, oil-damped single shock, with preload, compression and rebound damping adjustments. Linkages connecting the shock LO the frame and wingarm are slightly different for '84, with 12.2 inches of wheel travel. Up front is an air-adjustable, telescopic fqrk with 43mm LUbes and high- and low-speed damping adjustments. Travel is 11.8 inches. Rake is 27.67° and the trail is 4.57 inches. Wheelbase is 57 inches. The YZ125L has needed more power since its release: the first batch had carburetion problems that made the bikes slow. The cure was simple: drill four 1.3mm holes in the main jet baffle, and advance ignition timing from 1.24mm BTDC LO 1.88mm BTDC. These simple modifications made a big difference in available horsepower and were immediately incorporated into later YZs, before they hit the showroom floors. An update report was sen tto owners ofearly YZ ,explaining the modifications. But even after those changes, the YZ won't win any holeshot awards. Of[ the line, the YZ's good low-end power helps it keep up, but that doesn't last for long: from third gear on, the YZ has a hard time. The YZ must be shifted at exactly the right point. The Yamaha rider must click up another gear earlier than hewould on a Suzuki RMl25 or a Kawasaki KX125, but the YZ can't be shortshifted, because it lacks midrange power. Wait too long to shift and the power [Jattens out (unlike the Suzuki, which keeps on pulling and pulling.) The powerband is too narrow, and that makes the bike tiring to ride for a 30-minute maLO. Fortunately the YZ has a strong clutch, because the clutch quickly becomes the .rider's best friend: it bails him out when he shifts LOa early and the engine bogs. Fanning the clutch to keep the YZ going is easy, because the clutch has light pull one finger doe it, although most rider use two - and the cI utch takes the abuse without dragging or slipping when engaged. The Yamaha's six-speed transmission is equally strong, although we did occasionally miss the shift from second LO third. But the shift lever return spring pin 'broke on our test Yamaha YZ125L Checklist EXCELLENT GOOD FAIR POOR ENGINE PERFORMANCE: Low end .................. Mid range ................. Top end. : ................. Starting .................. SUSPENSION: Front .................... . Rear ..................... . HANDLING: Turning .................. . Front brake ................ Rear brake ................ Rider maneuverability ..... Front tire ................. Rear tira .................. MISCELLANEOUS: Seat ...................... Grips ................... .. Levers .................. .. Bar/peg/seat relationship Reliability . ................ Routine maintenance . ..... Kick starter ............... Shift lever ................ Plastic ................... . Detailing ................. . Owner's manual .......... 0 0 0 0 III 0 0 0 0 0 0 II 0 III I!I 0 0 0 III III 0 0 0 0 0 0 0 III III 0 0 0 0 III II 0 III 0 0 0 0 0 0 0 0 III 0 0 0 III III 0 0 III iii 0 0 0 0 III III III 0 0 III III 0 0 0 0 III 0 0 0 III 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0