First World Racing

. It was launched in 1974 and has been regularly updated since. It is one of the only two-The Yamaha YZ250 is a two-stroke motocross race bike made by Yamahastroke bikes of this displacement to still be in production and release every year. For the Yz250 the top speed is 75mph.

The Yamaha YZ250F is a motocross motorcycle first released in 2001 by Yamaha. It has a five-valve, DOHC, four-stroke engine and initially had a steel frame and an aluminum subframe, which was replaced in the 2005 model with an all-aluminum frame.

This combination leads to the YZ250F being praised for combining the broad-power characteristics of a four-stroke engine with the light handling more common in smaller, 125 cc two-stroke motorcycles

CR125

Honda started to build the CR125M in 1973. Honda called it the "20 Horsepower Feather". It sold for a stunning $749. It had a top speed of 60 mph and was equipped with a two-stroke 123cc air cooled motor. It was really a sub-par attempt at building a dirt bike. Just like the CR250R in 1981 the CR125 also took a step back. It was really heavy and slow, and had a horrible single shock. In 1985 was when the CR125 got the Showa suspension and had more problems because it was the new technology. They had not perfected the technology they put into the bike and had many problems with parts and operation. Honda was somewhat ahead of themselves when it came to technology and that really hurt Honda for a couple years. Honda was struggling with the new technology which hurt them at the time because the other companies had perfected the old school technology. 1988 and 1989 were the two years that the technology came together and everything really clicked for the CR125.

1973 was the year the CR250M Elsinore had been launched. This 2-stroke was one of the first of its class, and set the bar high for two-stroke motorcycle development. In 1974 and 75 the CR250M didn’t change much. Which gave the upper hand to Suzuki and Yamahawhich let them design and develop better dirt bikes than Honda. In 1978 Honda released its newer version of the CR250M. They renamed the bike the CR205R. The "R" in the name stood for Race  The fire engine red bike was a real eye opener. This was what everybody remembered about the CR250R this year. When 1981 came around Honda was trying to put better technology into their bike, They wanted to put new suspension on the bike but didn’t know much about the new technology. They went with the new suspension and had numerous problems. The suspension didn’t work correctly at all and the bike had reliability issues. They tried to put too much technology into the bike and it turned out to haunt them. This year was a huge let down for Honda. 1984 was really the next big year for Honda and the CR250R. This was when the bike caught up to the technology that had been put in in 1981. They did add new features such as a hydraulic front disc brake, and a new exhaust valve. All the way up to 1990 the CR250R had virtually stayed the same except for a couple little changes such as hydraulic rear brake, Showa front suspension, and a bigger carburetor. 1992 was when the CR250R took on a newer more aggressive look but had some downfalls. One of the biggest downfalls was the amount of power the new engines were producing and the weak steel frame. This was bad news for Honda. Many riders told Honda to change the frame to something stronger. But successful riders who were sponsored by Honda such as Jeremy McGrath had preferred the old stiff weak frame. 1997 was when the aluminum frame was introduced. Many racers liked this frame but casual desert riders weren’t buying the bike. So Honda had to go back to the development department and rethink the CR250R. The year 2000 was the year that Honda perfected the aluminum frame. It was it. It only got better from here. In 2003 the only real change that was made was the electronic power valve. The Honda CR250 had a 249cc liquid-cooled single-cylinder engine that made about 45 HP. It has a five speed transmission with Showa suspension and a two-gallon fuel tank. In 2007 Honda said they will produce no more two-strokes after that year.

1984 was the first year the CR500 was produced. It was nicknamed the "Ping King". The CR500 had a 491cc liquid cooled two stroke engine that could make 52.8HP, the most powerful motocross bike that Honda had ever produced. It was a two-stroke design but since the CR500 had a big single bore it was hard to kick start it. The manufacturers started to jet the bike really rich in order to make it easier for people to start. The CR500 was an absolute monster. The only problem with it was it was terribly hard to ride because of the uncontrollable power it produced. The CR500 was also used for long desert races like the Baja 500 and the Baja 1000. The CR500 was discontinued in 2001. Many people believe that the CR500 was discontinued because of the CRF450 four-stroke. Honda sold the CRF450 four-stroke very well. It could have very well been the bike that put the CR500 out of production. Though the CRF450 was slightly heavier than the CR500 and the difference in peak horsepower was marginal, the power band on the four-stroke motorcycles proved to be much more linear and easier for the rider to use.

The Honda CRF series is a line of four-stroke motocross and trail motorcycles manufactured and marketed by Honda.

The CRF line was launched in 2000 as a successor to the Honda XR series. The full sized motocross bikes are equipped with liquid-cooled, single-cylinder four-stroke engines that are available from 149 cc to 449 cc. They now have dual-sport motorcycles. The more trail friendly CRF's have simple air-cooled engines, and are available from 50 cc to 230 cc. The Honda CRF450R was the first in the series, followed with the CRF250R in 2004. Further down the line, the CRF450X and CRF250X bikes emerged, both designed for mostly off-road use. They are considered among the best motorcross bikes of their class, and have been a leading seller since their introduction. The CRF450R was CycleWorlds Best Motocrosser for a record eight consecutive years from 2002-2009.

The Kawasaki KX is a 2-stroke motocross motorcycle that was introduced in 1974. The 2-stroke KX-250 was discontinued in October 2007 due to the rise of the four-stroke KX250F. The Kawasaki KX250F introduced in 2004 and KX450F was introduced in 2006 and both utilize a 4-stroke DOHC engine. Many factors came into play with the demise of the 2 stroke market, however 2 strokes are once again becoming popular due to the costs associated with maintenance of the very complex workings of the 4 stroke design.

This bike has been ridden to several AMA Motocross Championship wins, including a number of titles, in the hands of Jeff Ward, Jeff Emig, and Ricky Carmichael.

The Kawasaki KX 450F is a liquid-cooled DOHC 449 cc (27.4 cu in) four-valve four-stroke single motocross motorcycle made by Kawasaki.

Unlike the Kawasaki KX250F, the KX450F was not co-developed under joint-venture with the Suzuki Motor Co. and differed greatly from Suzuki's 450cc offering. The first year of the KX450F was 2005, but the machine suffered catastrophic frame failure during the Japanese MX season. As a result, plans for a 2005 retail version were postponed and the KX450F debuted as a 2006 model in most markets.

Initial reviews of the KX450F were tepid, citing a positive response to the engine and power delivery, but finding the suspension and geometry of the bike unsatisfactory. Reviewers also took exception to the choice of a 4-speed transmission, as Kawasaki chose to break from the industry standard by not to including a fifth gear.

Despite these perceived shortcomings, the 2006 Kawasaki KX450F would win both the AMA World Supercross GP title and the BooKoo Arenacross title, as well as the Hare and Hound title.

For 2007 the KX450F received a series of minor engine and frame refinements, but its most notable upgrade was a 5-speed transmission. The transmission received a slightly taller 1st gear, while second through forth remained the same and the fifth added.

The next major innovation would be in 2009, as Kawasaki introduced fuel injected. Reviewers raved of the performance effect of the new injectors, and in proceeding years the technology would spread across the KX lineup.

A series of major revisions came in 2012. The KX450F received an all new frame, significant engine modifications and a new electronics set that included Launch Control. Launch Control is designed to prevent wheel-spin at take off, and automatically disengages once third gear is reached. It is activated by holding a switch until an indicator light glows green, at which point the bikes computer modifies acceleration factors. Kawasaki has continued to insist since inception (for safety reasons) that this system is not traction control but a unique system onto itself.

These later models allow for extensive customization of the ECU using Kawasaki's optional software system, as well as including a Digital Fuel Injection (DFI) coupler system. DFI couplers allow for immediate trackside changes to the ECU through the simple change of a plug-and-play module. Kawasaki provides three modules with new bikes, a Green (standard mapping), White (soft track conditions mapping) and Black (hard track conditions mapping).