Not Enough Improvements - Yamaha YZ450F
By Staff Writer

The 2005 Yamaha YZ450F has seen a number of improvements since the original ’98 YZ400F, but there has not been a huge progression—quite honestly, a little more is expected from this machine. The ’05 YZ benefits from some appreciable engine and chassis changes, just not enough. Comparing this year’s and last year’s models allows for the simple observation that Yamaha succeeded in making a better bike.

The bike is now faster and smoother than ever. Yamaha redesigned the combustion chamber, piston, intake ports, carburetor jetting and airbox for improved combustion efficiency, resulting in smoother, more controlled power delivery. They also redesigned the CDI unit for smoother, more controlled power delivery. The primary drive gear ratio has been changed from 2.82 to 2.65:1; clutch spring rate is reduced to 6 percent for lighter lever pull, and a new shift mechanism provides more positive shifting. They included an all-new fork with TCV (transfer control valve) for stable damping, improved mid- to full-stroke performance and better rider feedback.

The new, aluminum Renthal handlebar is 90 grams lighter and more durable. The triple clamps were revised for even better handling. The bike now has a shorter, re-routed front brake hose for increased brake feel and easier bleeding. Also, it has a stronger swingarm with stronger new linkage for better performance. The rear shock has a new, full-rebound oil lock circuit for a smoother ride. The new-design rear sprocket and chain guide reduces wear, chain wobble, and noise for more efficient power transfer. The rear brake bracket is 35 grams lighter, and designed for easier rear wheel installation. The new front fork protectors are larger for better coverage.

As a result, the new YZ has great throttle response, matching twistgrip position to power output perfectly and smooth power delivery, improving ridability, but making the bike feel a little sluggish.