New liquid-cooled, DOHC 4-valve, fuel-injected engine with the same forward-positioned, straight intake, rear-inclined cylinder, and rear-positioned exhaust layout as the YZ450F. This new engine has more power than the ’13 YZ250F, especially in the mid-to-high rpm range.
The 4-titanium-valve cylinder head is matched to a new fuel injection system that provides more power at mid-to-high rpm. The fuel injection system instantly adjusts the air/fuel mixtures depending on altitude and temperature, for a hesitation-free engine that delivers no matter the conditions.
The new aluminum Bilateral Beam frame offers a superb rigidity balance and, with new front and rear suspension components and settings, provides unmatched lightweight handling. Even fans of the previous YZ250F will be sure to notice the solid handling characteristics, including the light feel in tight corners and during direction changes.
The exhaust pipe has an innovative layout, circling the cylinder, giving the exhaust pipe proper length for an excellent exhaust pulse effect. At the same time, the exhaust pipe has three different diameters throughout the exhaust tract, bringing out excellent power characteristics. This new layout allows the silencer to be positioned 190mm further forward, behind the side panel, making it closer to the middle of the bike for centralized mass for superior handling.
The all-new layout of the seat, fuel tank, air box, and wrap-around exhaust system moves the bike’s mass towards the center for exceptional handling. And, in addition to an all-new appearance, the front intake layout with larger air filter element adds the benefit of reduced air filter maintenance due to its positioning away from dirt roost from the rear wheel.
Accessory GYTR® Power Tuner lets owners adjust air/fuel mixture and ignition timing maps to match engine performance characteristics to the rider and track conditions in a matter of seconds with the push of a few buttons.
A new liquid-cooled, DOHC 4-valve, fuel-injected engine with the same forward-positioned straight intake, rear-inclined cylinder and rear-positioned exhaust layout as the YZ450F. The new engine, with its straight and symmetrical intake and exhaust ports and compact, high-compression combustion chamber, delivers outstanding engine character with more power output and deeper power in the high-speed range.
The new, adjustable fuel injection system uses a 44mm throttle body fed by a high-pressure battery-less electric pump to ensure optimum fuel atomization and air/fuel calibration for excellent readability in a wide range of riding conditions The system provides 3-dimensionally mapped control of the volume of fuel injected and the ignition timing based on engine rpm and throttle opening. This ensures hesitation-free response and controllability and contributes to the high level of high-rpm power.
Various detailed design measures are adopted to reduce horsepower loss. The forged 2-ring piston is light weight and is cooled by an oil spray jet. In addition, the compression ring is a single-ring design instead of the conventional two ring. This new piston and rings, along with the offset cylinder configuration reduce friction loss and contribute to quicker response. What’s more, the new specs for the intake/exhaust ports, new cam profiles, new ECU, new carburized crank, optimized balance ratios for the crank web, the newly designed transmission, strengthened clutch design, and other features, all work together to create the YZ250F’s outstanding engine character with more power output and deeper power in the high-rpm range.
As with the YZ450F, an innovative exhaust pipe design is adopted to increase mass centralization and improve power development characteristics. This layout moves the rear end of the exhaust pipe farther forward and enables a muffler position that is closer to the machine’s center of gravity. Adjustments are made in the pipe diameter in its various sections resulting in excellent exhaust pulse effect that contributes to stronger high rpm power output.
The compact wet sump lubrication system with piston cooler spray jet maintains excellent engine durability and eliminates the need for an oil tank, which lowers engine weight. This creates a more compact engine that contributes to mass centralization and unmatched handling.
Newly designed transmission and shift mechanisms reduce drive-force loss during gear changes and produce smoother shift operations and surer shift action.
A newly designed aluminum Bilateral Beam frame is adopted. The overall dimensions are roughly the same as the frame of the 2013 model YZ250F. This gives the new YZ250F a compact chassis that provides a lightweight feeling while leaned over and in the air while also providing solid handling and bump stability.
The aluminum muffler is positioned closer to the machine’s center of gravity as it is almost completely hidden by the side number plate. The layout allows a shorter, lighter rear sub frame and also contributes to centralized mass for a lightweight handling feeling.
The front suspension has proven KYB® air-oil separated forks. It adopts new spec inner and outer tubes coupled with optimized suspension settings. The new rear suspension also features a new reservoir location and spring spec with settings optimized for ideal damping characteristics to match the new chassis dimensions.
The new larger diameter 22mm front axle and new top triple clamp increases rigidity for improved handling and front end feel. The handlebar mounts are now rubber mounted to improve comfort and reduce handlebar vibration.
The air filter is now positioned away from the rear wheel which means less maintenance for the rider.
“In-mold graphics” technology is a method in which the graphics are molded into the radiator shrouds for improved decal durability and reduced scratches.
Riders have a choice of two color options: Team Yamaha Blue/ White or White/Red.