Yamaha's hugely successful WR250F and WR426F 4-stroke enduro bikes have received a host of updates to ensure they stay at the top of the sales charts, a place they made their own during 2001.

The amazing 5-valve 250cc power plant has received some modifications aimed at improving and broadening the spread of power available. New carb' settings, remapped ignition and timing changes are claimed to make the motor even more responsive than before.

Do not think of previous 250cc 4-strokes when you think of the WR250F. The WR has redefined the performance anyone thought possible from a 250cc 4-stroke single.

Like it's bigger WR426 stable mate the 250F also gains updated rear suspension, lighter rim hubs and improved oil flow in the aim of greater reliability. The 250F and 426F also receive a new hydro-formed swingarm.

A slim line 8-litre fuel tank keeps the 250F well fed and is designed to not hinder rider movement on the bike. Along with the serious dirt nature of the beast the WR250F now scores a MX style, on-the-fly clutch lever adjuster at the bars. Both the 250 and 426 also score a larger 245mm rear disc brake.

WR250F SPECIFICATIONS

• Engine - 249cc, 4-stroke, liquid cooled, DOHC 5-valve, forward inclined single cylinder. Dry Sump
• Bore x Stroke - 77.0 x 53.6mm
• Compression Ratio - 12.5:1
• Induction - Keihin FCR37H/1
• Ignition - C.D.I.
• Starting - Kick
• Fuel capacity - 8 litres
• Oil capacity - 1.7 litres
• Gearbox - 5 speed constant mesh
• Length - 2,165mm
• Width - 827mm
• Height - 1,303mm
• Seat Height - 998mm
• Wheelbase - 1,475mm
• Ground clearance - 382
• Dry Weight - 102.0 kg
• Front Suspension - Fully adjustable telescopic forks, 300 mm wheel travel
• Rear Suspension - Fully adjustable monocross, 315 mm wheel travel
• Front Brake - Single disc 250mm
• Rear Brake - Single disc 245mm
• RRP - $10,499