Yamaha YZ450F is a four-step motor racing motor made by Yamaha Motor Corporation. It was the successor to the previous YZ426F that was discontinued in 2003. It is credited by the Cycle World and Dirt Rider magazine as a bicycle that embarked on a four-stroke motorcycle revolution. This is a replacement for the YZ250, which is slowly removed. YZ250F and YZ450F 2006 are the first production bikes equipped with titanium suspension springs.
WR450F is the enduro version of YZ450F.
Video Yamaha YZ450F
Introduction
Over the years, the motocross world has almost exclusively used a two-stroke engine. The AMA racing class has two classes: 125Ã, cc and 250Ã, two-stroke cc, without provision for four strokes. Most motorists consider the four-stroke engine technology to be largely utilitarian and uncompetitive, only derived for trail riding.
In 1996, the AMA changed the rules of racing to allow 450 cc four strokes to compete in the same racing class with 250 cc two strokes. Yamaha Yoshiharu Nakayama engineers first came up with the idea to create a competitive first four-step motor racing motor. Yamaha YZ400F was developed to fit into this category. This solves the power dilemma by borrowing superbike technology and giving YZ five head valves, liquid cooling and 12.5-1 compression ratio.
In 1997, Yamaha rocked the motocross world by introducing the YZ400M prototype, a concept motorcycle that borrows a lot of technology from street racing. YZM is way ahead of all the competition between four-stroke motocross motors. Doug Henry piloted the YZ400M for his first victory in 1997 in Las Vegas Supercross. This is the first time a four-stroke has won an AMA event. YZ400M is the precursor of YZ400F production, which was released the following year.
Maps Yamaha YZ450F
First generation: YZ400F 1998-2000
Yamaha introduced the YZ400F in production in 1998 after a successful AMA season in 1997. It was "the first four-step modern motocrosser that is directly competitive against two-stroke." Initially, Yamaha targeted a dry weight of 233 pounds (106 kg) (equivalent to 250 two-strokes by then), but with production, the motor weighed 250 pounds. This motor has a power of 11,600 rpm redline and torque approaching 250 cc rivals two-stroke. This benefits from the engine compression braking, which allows the engine to slow the bike down during deceleration, giving the brakes a break. The 1998 YZ400F was the first bike to come with Keihin FCR carburetor.
In 1998, Doug Henry won the AMA National Motocross Championship on board the YZF, becoming the first rider to win the championship on a four-stroke motorcycle. This victory is considered by some to be the main turning point in the motocross world - for the first time, four strokes are considered competitive racing engines. Second generation: YZ426F 2001-2002 Also in 2001 the subframe was changed from steel to blue painted aluminum style. In 2002 the blue painting was stopped and left to look like aluminum. Motorcycle.com says that "The petrol tank is quite thin and allows good forward and backward movement while providing something that looks good to hold on with your knees.Even the whole ergonomic package on YZF is well thought out, handlebars have nice bends for them and are placed well for good rider control and legroom. "Footpegs are well-made units with wide platforms and sit in positions that prevent them from dragging on ruts without moving the rider's legs." In 2002 Yamaha re-mapped the digital CD burning system that provides a more precise spark and optimal time for faster and stronger response during harsh acceleration, and fewer kickbacks during start. Also a new swingarm that is lighter and stronger to reduce weight, greater rigidity, and more suitable rear suspension action. While anodized finish gives the bike look out cheated. 426 also includes a larger pivot shift for increased endurance. Larger rear brakes are also added which means greater stopping power.
Third generation YZ450F 2003-2005
For 2003, YZF received the greatest update in its history. First, engine displacement is upgraded with 449 cc according to the new max. AMA Motocross replacement rules, the engine now generates more than 52 hp (39 kW). Furthermore, frames and plastics are updated for a sleeker new look. In addition, the weight of YZF decreased from its original 250 pounds (110 kg) to 233 pounds (106 kg). The motor produces tremendous power; However, many think that the motor has too much power for motocross tracks. YZ450F 2005 is the first YZ450F featuring KYB twin chamber cartridge forks.
Fourth generation YZ450F 2006-2009
YZ450F received a major update in 2006, with over 300 parts altered and improved. The power is smoothed out, and the bike is made easier to drive, putting to rest the complaint that YZ has too much power. Transmission is restored to five more traditional speeds. A single new aluminum backbone frame shaves 10 pounds more.
Year 2006 saw the fork KYS SSS.
2007 saw the camshaft and exhaust changes, moving power from low RPM to mid RPM. 2008-2009 further pushed the powerband to mid RPM.
The fifth generation of YZ450F 2010-2013
September 8, 2009, Yamaha introduces its new YZ450F with fuel injectors. The engine cylinder is tilted backwards, the angle of the crank rod has been altered to provide more complete combustion, the 5 head valve is now the head of 4 valves, the gas tank is located under the seat, the exhaust pipe out from the rear of the cylinder, and the air intake is now in front of the bike. They have a new bi-lateral frame that allows for the enhancement of new rudders and new engine components. The whole package united to create a mass-centered bike. This motor was introduced by Yamaha Factory Motocross rider, James Stewart. The highest speed has been recorded at 80 mph stock.
References
External links
- Long History of Reverse-Cylinder Machine Design - motocrossactionmag.com
Source of the article : Wikipedia
0 Comments