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/128089
RIIIIRIEC:J 2001 Yamaha YZ125 NO SHADOW DWELLER By KIT PALMER & CHRIS JONNUM PHOTOS BY BLAKE CONNER It's hard to pick out the YZ125's single greatest strength since it has so many of them, but the motor just might be the bike's number-one asset. By now, we've ridden all of the major manufacturers' 2001 125cc motocrossers and, even though this isn't a comparison test (one is forthcoming), we can tell you that the Yamaha's powerplant is a great one, not so much because it's the most powerful of the 'Ols (it's not) but, because it's so user-friendly and manageable. Don't get us wrong; the YZ is plenty fast, but Yamaha has again found a way to spread out the power farther and wider than some of the other more top-end-oriented bikes that have a bit more over-rev, such as the Suzuki. Other bikes might scream harder and farther than the YZ, but the Yamaha is so easy to control that it makes up for any shortcomings it might have in the sheer horsepower department. While it might not compare to the YZ250F when it comes to torque, the YZ125 does produce a hint of that much-liked trench-digging, lowrevving pull, which, for a 125, is saying a lot. The Yamaha's ability to o listen to the hoopla, one might think Yamaha no longer made the YZ 125, as the bike has found itself dwelling in the shadows .of its brandnew sibling and competitor, the YZ250F four-stroke. But while the little thumper dominates the headlines, the little ring-ding is, in fact, still around, and the tuning-fork folks have even made several improvements to the bike since the already-strong package offered last year (see "Tech Ticker" box). Those changes appear to be working, as the YZ125 won round two of the AMAlEA Sports 125cc Westem Regional Supercross Series in San Diego at the hands of Yamaha of Troy's Justin Buckelew (rounds one and three went to teammate Ernesto Fonseca on the YZ250F). Of course Buckelew's bike is modified fairly extensively, but we've put several months on our stock 2001 YZ125, with Cycle News Pro testers Chris Sprenkel and Don Burke (as well as the CN editorial staff) spinning countless laps at Glen Helen Raceway, Elsinore Raceway, Competition Park, and secret Southern California test tracks. Here's what we've found out during that time. T 18 JANUARY 31, 2001 • c U a • • neVIl'S come alive at lower-than-usual rpm makes the YZ a joy to ride. Still, all is not perfect in YZland. Some of our faster riders said the YZ lacked a little hit off the bottom. One of our Pro riders felt the YZ is a little "sluggish" off the bottom and went on to say that you have to use a lot of clutch on slippery tracks. Forgiving, easy to ride, ·tractable • these are words not usually associated with screaming 125cc motocross bikes, but they accurately describe the 2001 Yamaha VZ125. Fast, Is another one. Our test bike seemed to be better jetted this year, though one rider complained of a slight flat spot while ENGINE • • • • • • • • • Bore of Mikuni TMX carburetor increased to 38mm for greater top-end power Shape of YPVS power valve is altered to aid low-end power Shape of cylinder head is altered and coolant route is changed for improved cooling Shapes of exhaust and scavenging ports are changed in cylinder for better low-rpm response and increased top end over-rev Reeds are changed from resin to carbon fiber and from four petals to six for better air-intake efficiency Overall diameters of connecting rod and small-end bearing are reduced for less reciprocating weight Crankshaft assembly is 20mm thinner for less friction and accompanying power loss Diameter of crankshaft oil seals is reduced 2mm, [, single lip replaces double lips for less friction and accompanying power loss Airbox joint ring material changed from steel to titanium for less weight CHASSIS • • • • • Frame reinforced in critical areas for more strength and less weight Aluminum subframe 10mm lower at rear for flatter feel Front brake master cylinder [, lever adjuster redesigned for less brake [, better braking Front brake rotor is larger (from 245mm to 250mm) Seat has new two-tone black/blue cover SUSPENSION • Swingarm material is stronger and thinner at rear for reduced weight • Shock's lower mount is changed, [, rubber bumper is larger for better anti-bottoming • Fork has new valving, new nylon spacer [, new rubber bumper for better performance OTHER • 0.1.0 chain (was Regina) is lmm thinner, top to bottom, for less weight • Less aggressive bend in clutch lever for better clearance [, feel • New inner cap seal on gas cap for better reliability