Yamaha has announced its race-winning YZ250F will receive a major overhaul for 2019, boasting a host of upgrades over the previous generation model.

The liquid-cooled, DOHC four-valve, fuel-injected engine features a forward-positioned straight downdraft intake with symmetrical intake and exhaust ports. A new, higher-compression piston and new intake and exhaust valving delivers outstanding engine character with a focus on top-end power delivery. For 2019, the cylinder is also lighter and angled more upright to improve mass-centralisation.

Breaking new ground in the industry, Yamaha has introduced the Power Tuner app, which brings the power of the GYTR Power Tuner to your iOS or Android device. Using WiFi to connect to the bike’s onboard CAN-bus network, the app allows owners to adjust air/fuel mixture and ignition timing maps to tune engine performance for track conditions, record race log information, and monitor a range of data such as maintenance and system diagnosis, engine run time, and more.

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The 2019 YZ250F now features a compact electric starter system to minimize restart delays on track and add convenience everywhere else. Powered by a high-capacity and ultra-lightweight, four-cell lithium-ion battery, the system adds minimal weight.

Two-mode adjustable engine mapping allows the rider to adjust engine character with the push of a button, making it easy to tune the YZ250F for changing track or weather conditions between motos.
Piston, Rod and Crankshaft Balance

A flat-top forged piston features a bridge-box design for additional strength with minimal weight. The piston, rings and DLC-coated piston pin, along with the offset cylinder configuration, all reduce friction loss and contribute to quick response. The engine’s intake ports, cam profiles, high-strength connecting rod and optimised crank and counter-balancer all work together to produce potent high-rpm power with user-friendly delivery and exceptional reliability.

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The adjustable fuel injection system uses a new 44mm throttle body, fed by a high-pressure electric fuel pump, injects fuel through a new 12-hole Denso®injector. This ensures optimum fuel atomisation and air/fuel calibration for excellent rideability in a wide range of riding conditions. The more compact throttle body is 12 percent lighter than the previous unit, too.

An innovative exhaust pipe design improves mass centralisation and power development characteristics. Updated for 2019, this layout moves the rear end of the exhaust pipe farther forward and enables a new muffler, positioned closer to the bike’s centre of mass.

Updated radiators are larger and angled more directly in the incoming air stream, for improved cooling under the most demanding race conditions. Inside the engine, a new impeller and water pump boost endurance and durability under the toughest racing conditions.

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The transmission gears, dogs and shift mechanisms are designed to smooth gear changes and improve durability under the heavy demands of motocross racing, even with lighter gears and selector drum for 2019. The updated YZ250F also features a larger-diameter clutch to boost reliability even further under high-heat conditions.

The 2019 YZ250F’s compact frame is completely new to further refine the instinctive handling that makes this Yamaha one of the best handling machines in the class. Larger upper frame bracing improves rigidity and durability, while wider rear frame spars and all-new engine mounts centralise mass for the best possible balance of bump absorption, stiffness and feeling of grip.

The updated YZ250F features new bodywork from tip to tail, including a new compact fuel tank specifically designed for motocross demands. In addition to shaving weight, the new body design is narrow for more comfortable knee grip and feeling of control, and the seat is updated to give the rider additional room to move aboard the machine.

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The engine, aluminium muffler and new, more compact fuel tank are positioned close to the machine’s centre of mass. This layout contributes to centralised mass for a lightweight handling feeling on the track. The wide 55mm foot-pegs help lower the rider’s centre of gravity for enhanced machine balance, control and rider comfort.

A large 270mm front brake disc is the same system fitted to the YZ450F, and uses an aggressive pad material for exceptional stopping power and braking control. Out back, a durable heat-resistant rear rotor boosts brake durability.

Industry-leading, fully adjustable KYB coil spring-type fork with speed-sensitive damping provides exceptional balance between handling and bump absorption, for race-winning handling performance. The linkage-type rear suspension features a KYB shock with revised damping characteristics to match the new chassis. 2019 also features updated internal valving for more controlled damping characteristics.

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The f-position adjustable handlebar mounts are rubber mounted to improve comfort and reduce handlebar vibration, while the handlebar itself is lighter to centralise overall mass. The YZ250F includes top-spec details, including 1-1/8” aluminium tapered handlebars, wide 55mm foot-pegs, a quick-adjust clutch perch, stylish blue rims and gold chain.

The 2019 YZ250F will hit Australian showrooms early August priced at $11,399, and it will be available in two colours: Team Yamaha Blue and White and Competition White. For more information, visit www.yamaha-motor.com.au.