The most notable update is a new bilateral beam frame crafted from 20 forged and extruded aluminum pieces. Designed to be more compact than previous models, Yamaha says the new frame places the rider closer to the front wheel for improved rigidity balance and cornering.
The new frame forms the basis for several other changes to the chassis.
Both front and back KYB suspension have been recalibrated for the new frame. The four-way adjustable rear shock is set 33 mm lower in the frame for improved mass centralization. The KYB speed-sensitive front fork has revised damping settings, the piston rods received a new surface treatment while the oil seal was redesigned.
The handlebars are higher than the 2009 model while the foot pegs are higher for a more forward riding position. The new fuel tank, seat and rear fender are flatter to improve rider movement. The bodywork has also been designed to accentuate the horizontal lines. The tank has also been moved closer to the center of the bike to improve mass centralization
The 250cc liquid-cooled four-stroke engine has been upgraded with aluminum valve spring retainers instead of steel, a change Yamaha says will improve low-to-mid range performance. Unlike Suzuki and Honda, Yamaha opted to stay with a carbureted engine instead of fuel injection. The YZ250F has a new carburetor with a venturi-shaped bore. With recalibrated jetting and a new accelerator pump, Yamaha says the new carburetor provides improved throttle response and improved low-to-midrange performance.
The new exhaust system uses a muffler that is 50 mm longer than found on the 2009 model. The exhaust port has a new “D” shape instead of a oval, a change Yamaha says will improve throttle response.
The 2010 Yamaha YZ250F will be available in two color schemes, Team Yamaha blue with white highlights or white with red details.