Yamaha YZ450F Bikes

2011 Yamaha YZ450F

Yamaha’s largest and most powerful dirt bike is the YZ450F, which has evolved from what used to be the YZ400F, and then a slightly larger YZ426F. The YZ400F was introduced in 1998, and was the first four-stroke motorcycle that was directly competing with two-strokes. It immediately caught everyone’s attention with an AMA National Motocross Championship won by Doug Henry, the first on a four-stroke machine.

Yamaha took the YZ400F and began updating it in 2000, adding 26cc to increase power and throttle response, and updating the carburetor and jets in order to make start up easier. More titanium was used starting in 2001, making the bike lighter, faster, and easier to maneuver. The suspension also had a few modifications in order to decrease weight and a smoother ride.

In 2003, the YZ450F was finally introduced, and would revolutionize the mx racing world. This was the first time that 450cc bikes were allowed in AMA Motocross races, and Yamaha was all about being the leader. In the engineering process, Yamaha was able to shed about 17 pounds from their YZ426F, and changed the YZ from a five-speed transmission to a four-speed. Many riders thought that this bike had too much power for an mx track, so in 2006, an all new YZ450F was released that was once again a five-speed transmission, wasn't "too" powerful, and was much easier to ride.

2008 brought much success to the YZ450F, allowing James Stewart to capture the AMA Motocross Championship, and Chad Reed to win the AMA Supercross Championship.

In 2010, Yamaha revolutionized the YZ450F, yet again. Yamaha figured out ways to further centralize the mass of the bike, as well as make it more powerful. The cylinder was slanted toward the rear, causing the inertial mass to be centralized. This new design also switched the intake and exhaust positions, straightening the intake tract for a more efficient combustion, equaling more power. The cylinder was then offset, which causes the connecting rod to be vertical at the point of greatest force, minimizing piston friction, increasing response time.

The 2010 YZ450F also got a 4-titanium valve cylinder head that was matched to a new fuel injection system. The new system adapted to air/fuel mixtures as soon as they change, ensuring that the engine is always running properly, no matter the conditions.

A new aluminum Bilateral Beam frame made for excellent balance, handling, and cornering on any track. The front fork protector, front and rear fenders, intake cover, fuel tank, seat, and even the number plate was re-designed, giving the 2010 Yamaha YZ450F a killer new-generation style, all of its own.

In 2011, Yamaha updated the clutch lever and pushrod. This made the clutch feel much more consistent for those long motos.

The 2012 YZ450F has both performance and visual changes. New on the 2012 YZF450 is a longer 94 dB muffler complete with ECU programming that optimizes the performance of the new muffler. New settings have been set for both the fuel injection and suspension, as well. The new settings in the fuel injection include mapping for injection and advance, which gives you more control where the low and mid range engine response is concerned.

The new suspension settings and valving give a much smoother suspension response. Dunlop Geomax MX51 tires and a much more cushiony seat round out the performance-based changes. Black rims and a gold chain add to the already sick looking new Yamaha YZ450F.