Even though Yamaha started the four-stroke wildfire that is sweeping motocross, they also were first to production with many innovations in the two-stroke world. And the drive and talent pool that led them to sell the first reed valve and power valve two-stroke engines still motivates. As a result, Yamaha has not stopped development of the two-stroke YZ's, and the '05 YZ125 is ample proof. An all-new aluminum chassis and a motor minimized in weight and proportion but maximized in performance shaved a whopping nine pounds off the 2004 bike, and there are other weight savings. So much that Yamaha hasn't even claimed a dry weight, but have weighed the bike that same way that the AMA does at national level pro races: tank empty but otherwise wet and ready to ride. If their claim is close, the Yamaha will be an easy 10 pounds lighter than other bikes in the class. Add a drastic design change in the KYB fork, and you have a machine that is ready to give the four-strokes fits.Riding ImpressionsYamaha claims a light overall weight, and from the first instant you move the bike around, it feels feathery, as if maybe something important—like the crankshaft was left out! Lifting it off the stand, rolling it around and riding it on the track emphasizes the light feel. Another early impression is that there is none of the harsh and unforgiving feel to the Yamaha aluminum chassis that plagued early Honda CR alloy-framed machines. The '05 YZ125 feels like a very light, fast and trick version of the '04. Like all recent Yamaha it steers with surgical precision, yet offers ample stability at speed. Our initial ride was at Perris Raceway and the track was fast, but too well prepped to be super rough. Still, the chop the track developed didn't hinder the bike at all. It stayed plush and composed through anything we threw at it.
Yamaha has had a great 125 engine since at least 1997, and this newest version is another winner. The power hits hard and pulls strongly, but with the six-speed the response is even more solid and predictable. Even when you aren't in the perfect gear, the engine still pulls. The six-speed didn't mean noticeably more shifting either. We shifted about the same number of times per lap, but the bike pulled harder more of the time during each lap. Add in a new clutch pull that is one of the lightest in the business, and sweet shifting with no hit of past Yamaha notchiness, and you have a reason to buy two-stroke oil again.Showa-equipped machines have had a decided advantage in comparison tests during the last few years, but this year my be a new story. The twin-chamber fork is smooth and controlled with excellent bottoming feel. The rear shock is likewise very nice with no notable bad habits. Both ends responded well to external adjustments to allow the bike to fit a variety of riders of different abilities and physical profile.Look for a full test of the 2005 Yamaha YZ125 in the October issue of Dirt Rider Magazine.