Mike Stevens | Jul 22, 2009

LOOKING TO RIDING ENTHUSIASTS for feedback during development, Yamaha has created its 2010 YZ250F with the rigorous demands of motocross in mind.

The feedback Yamaha’s engineers received helped them develop a better handling bike: the new YZ250F allows earlier acceleration out of corners and a less tiring ride.

From the ground up, Yamaha concentrated on building a purpose-built machine. Instead of adapting an existing 450cc frame, a stand-alone frame, built around the unique power and weight characteristics of a 250cc engine, has been developed.

Yamaha YZ250F

The compact and lightweight frame makes for a better balanced bike which requires less rider feedback.

Items like the fuel tank, which sits lower in the frame, and the radiator, mounted lower and further back, all contribute to a more centralised weight distribution.

Front and rear damper settings have also been fine-tuned, allowing riders a better feel for the terrain. The resulting added traction and improved turn-in are also designed to provide a competitive edge.

Yamaha’s engineers also discovered the existing 250cc engine already provided the best balance of power, compact dimensions and light weight.

Yamaha YZ250F

Yamaha’s five titanium-valve engine remains, although it has been thoroughly revised. A higher lift intake camshaft and revised exhaust port and carburetor intake funnel allow for a punchier riding feel.

Also coming in for attention are new valve springs and retainers, revised ignition mapping, and a re-shaped air cleaner box to improve intake efficiency. Yamaha's engineers have concentrated on power characteristics from quarter to half throttle to improve feel when accelerating out of corners.

Styling too has been revised: the purposeful ‘dart-like’ profile of the YZ250F remains, but all plastic parts have been made as small as possible while still retaining their protective functions.

A flatter tank, seat and rear mud guard also allow easy rider movement. The relationship between four-position adjustable handlebars, pegs and seat has also been tweaked to allow for a roomy and natural riding position.

Yamaha's Sean Hawker confirmed to TMR that while no specific date has been confirmed, the YZ250F should launch in Australia around late September to early October. Pricing details will be announced closer to the launch.

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