The WR in the name indicates a wide-ratio gear box common to most enduro or trail bikes and stands in contrast to the close-ratio gearbox essential to a motocross racer.

Like the YZ400, it was considered to be a groundbreaking model in motorcycle history, ushering in the four-stroke era which ended the dominance of two-stroke engines in motocross and offroad racing.

While many modern performance four-stroke dirt bikes have been criticized for excessive rebuild costs and short motor lifespans, the Yamaha WR400F has an impressive record of reliability, often attributed to its steel valves and generous oil capacity.

This was the last WR to make use of a manual compression release for starting.For 2003, the engine displacement was increased to 449 cc (27.4 cu in), the fuel tank was reduced to 2.6 gallons [1] and an electric starter was added as standard equipment.

[8] In addition to the aluminum frame, the 2007 WR450F saw a revised dry-sump engine, with a new balancer, cylinder head, and camshafts with less lift and duration than previous generations and restyled plastics.

[clarification needed] After 3 years of design, the all-new 2012 WR450F was released and featured a 2012 YZ250F frame, KYB SSS forks, fuel injection, and an altered motor position.

[10] The engine was rotated back to move the center of gravity and improve handling[10]For 2016, the WR was given the reverse slant, 4-valve, fuel injected motor previously available in the YZ450F since 2010.

[13] Other changes include a revised, more compact frame, new speed sensor, bigger fuel tank and one fastener airbox access.