Yamaha 4-Stroke History
With the introduction of the four-stroke YZM400F factory prototype in 1997 Yamaha changed off-road motorcycle sport as few other manufacturers have ever achieved before. The YZM400F brought four-stroke power and traction with an agile two-stroke type of chassis to the race track, a concept that in the end proved to be more competitive then the commonly used two-stroke machines of that era.
The initial stones in the YZ ‘wall’ of superiority were laid in 1998 when Doug Henry took the YZ400F to a thrilling debut in the AMA-MX championship, winning five nationals on the way to the crown. He also gained four podiums within the Supercross campaign of that year.
In 1999, Andrea Bartolini won the machine’s first Rider’s World Championship in the 500cc class with the production based YZ400FM, and ever since that time Yamaha have led the four-stroke revolution. The bike has formed the basis of winning technology in MXGP, MX1, MX3 and AMA Supercross and AMA Nationals since the turn of the century.
In 2008 innovations of the production YZ450F involved a new aluminium frame with altered geometry, making the base for racing machinery extremely competitive straight from the crate.
For 2009 an altered swingarm and linkage system helped lighten and add precision to the handling while the rear hub also carries less weight.
2010 saw Yamaha surprise the market and race paddocks again with the brand new YZ450F. The rear slanting and re-positioned fuel-injected engine unit benefitted from a new configuration with innovative displacements of the airbox and exhausts. Housed within a chassis that helped lower and further centralise the riding sensation the motorcycle was feted by the world’s press and its undoubted potential now has to be proved on tracks around the world.
|Engine type:||Liquid-cooled, 4-stroke, DOHC, 4-valve, rear ward slanting single cylinder|
|Bore x stroke:||97.0 x 60.8 mm|
|Lubrication system:||Dry sump|
|Oil tank capacity:||1.2 litres|
|Ignition system:||Full Transistor|
|Type:||Constant mesh, 5-speed|
Chassis and running gear
|Frame type:||Bilateral Beam frame|
|Front suspension:||Telescopic forks|
|Front travel:||310 mm|
|Rear suspension:||Swingarm (link suspension)|
|Rear travel:||312 mm|
|Caster angle:||26° 47′|
|Front/rear wheels:||80/100-21 51M Front, 110/90-19 62M Rear|
|Front brake:||Ø250 mm single disc|
|Rear Brake:||Ø245 mm single disc|
|Wet Weight:||111.9 kg|
|Seat height:||999 mm|
|Wheel base:||1487 mm|
|Minimum ground clearance:||383 mm|
|Fuel capacity:||6.0 litres|