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Sharper Yamaha YZ250F announced for 2021

The Yamaha YZ250F gets significant updates for 2021 including a completely redesigned engine and revised frame

YAMAHA has announced a raft of updates for its class-leading MX bike, with the YZ250F getting a significant overhaul prior to the 2021 season beginning.

Yamaha WR450F (2019) review

Yamaha YZ250F (2021) engine changes

The big news comes in the form of a heavily redesigned engine, boasting smoother throttle response and more top-end power. To achieve this, Yamaha’s engineers have adopted new profiles for the exhaust camshaft, reducing valve overlap, optimising the engine’s power from the mid-range right through to the redline.

The Yamaha’s front-facing inlet has also been heavily revised, with the airbox now without the intake funnel of the old model and overall is 20mm than before. Both of these revisions provide the intake air with a smoother route into the engine.

With the exhaust camshaft and intake getting updates, it’s no surprise to find out the exhaust has also been adapted for 2021. The new unit is 70mm longer than before, with the new system claimed to give smoother acceleration, especially at higher engine rpm.

Rounding out the engine updates is a revised clutch assembly, featuring thicker, stronger walls to help increase durability. Furthermore, 3 , 4 and 5 gears on both the input and output shafts have been redesigned to give improved transmission performance, and selected gears are shot peened to give greater strength to match the increased engine performance.

Chassis improvements

For 2021, the Yamaha YZ250F gains a new bilateral beam frame that, on the face of it, looks very much like the outgoing model. Beneath the welds though the new item is heavily revised, with a focus on improving performance and feel for the rider.

To do this, the frame has been optimised by fine-tuning its rigidity in key areas, with components such as the top triple clamp, handlebar mounts, and front axle also having been redesigned to complement the new frame.

New suspension settings will also be applied to 2021 YZ250F, with its KYB forks and rear shock featuring more progressive damping throughout the entire stroke. It’s hoped the new settings will give the rider a stronger feeling of contact with the track surface while also delivering better bump absorption that helps conserve rider energy. At the rear, the KYB shock runs with revised settings that give a more stable ride with a reduced tendency to pitch.

Yamaha Power Tuning

The YZ250F also benefits from the Yamaha Power Tuning interface, allowing riders to fine-tune the bike's engine power character at the trackside using their smartphone. Riders and mechanics can simply download the free Power Tuner App for IOS or Android devices, and then instantly connect with the YZ250F to adjust fuel injection and ignition timing via the bike's CCU. In the Power Tuner app riders can create their own settings and using the handlebar-mounted button they can switch between two of the maps. Besides being able to make changes to the engine's performance, the Power Tuner can also be used to record race log information and monitor a range of data, including system diagnostics, run time, and maintenance - as well as comparing and sharing race logs and settings with fellow riders.

Yamaha YZ250F (2021) key features

· Redesigned high-performance engine with stronger top-end power

· Smoother throttle response with longer over-rev feeling

·Optimized exhaust camshaft design with a new profile and reduced overlap

· Idealized fuel injection settings deliver enhanced power character

· Completely redesigned intake system boosts high rpm performance

· Larger capacity muffler for seamless high rpm acceleration

· Stronger clutch housing to handle increased engine performance

· Redesigned transmission gears with optimized performance and strength

· New-specification bilateral beam frame with idealized strength/rigidity balance

· Revised front and rear suspension settings offer improved controllability

· Lighter and more powerful front (Ø270 mm) and rear brakes (Ø240 mm)

- Lighter handlebar crown and revised handlebar position

- Lighter chromoly steel footpegs

- Lighter front axle shaft

· Icon Blue bodywork and matching blue front and side plates

2021 Yamaha YZ Model Availability

YZ250F from October 2020

YZ250F Monster Energy Yamaha Racing Edition from October 2020

YZ450F from June 2020

YZ450F Monster Energy Yamaha Racing Edition from September 2020

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