The Yamaha YZ125 might have the best balanced chassis of the 125cc class, allowing riders to throw the nimble bike into corners.
It’s no secret that the YZ125 is and has been a class-leading, solid performer for the past several years. After quite a few changes last year, Yamaha took an approach aimed at refining the potent little YZ. The motor receives changes that include slightly increased compression as well as changes to the exhaust ports, intake manifold (straighter), power valve (better sealing), carburetor and reeds (thicker). The first- and second-gear ratios have also been raised just a little in the 5-speed transmission.
To save weight, the frame tube thickness is altered in places and three holes have been drilled behind the steering head. The axle-end of the aluminum swingarm has gotten smaller and it is now anodized instead of painted. The brakes also received some changes, the most notable being the integration of the rear reservoir with the master cylinder.
When it comes to performance, the Yamaha is still no slouch. Test riders noted the motor has good bottom-end power that transitions into a hard-hitting midrange pull. The top-end was a little flatter compared to the midrange, so some riders commented that they shifted the bike a little more often. Don’t get us wrong, though, as the motor is still very good and is in the top-three for overall performance. The stock jetting was never altered and seemed to be spot-on for our divergent locations and weather conditions.
Unfortunately, the YZ’s transmission didn’t fare as well, as all riders reported missing shifts. Additionally, the clutch engagement was rather awkward due the fact that the clutch did not start disengaging until the very end of the lever travel. This also made the clutch feel grabby and strange. It very well could have been an isolated incident as we have not ridden many YZs with a clutch like, well, a Suzuki.
All of the riders liked the way the YZ125 worked on the track. “I could turn this bike really well, and it hooked up great,” said tester Justin Mace. The YZ proved to be very good in flat corners and it never exhibited headshake.
Both ends of the YZ’s brakes work nicely, with good feel and modulation, although a few testers wanted a little more power from the front binders. This might be a reality if the rest of the Japanese manufacturers could route their front brake cable in a shorter manner like Honda CRs, but a Japanese patent prevents them from doing so. Therefore, Suzuki, Yamaha, and Kawasaki front brakes must suffer due to front brake cables about six inches longer than Honda’s. The aftermarket can help out with shorter, steel-braided cables.
Some riders did complain about the YZ’s rather wide seat and tank junction compared to the rest of the bikes, and some thought the bike felt bigger than the rest. Also, the rock-hard seat will have you squirming on your drive home. Regardless, the YZ125 stacks up nicely and still holds it own against the competition.
2003 125 MX Shootout
2003 Suzuki RM125 Comparison
2003 Yamaha YZ125 Comparison
2003 Kawasaki KX125 Comparison
2003 Honda CR125 Comparison
2003 KTM 125SX Comparison
2003 125 MX Shootout Conclusion