Motocross Bike

Motocross bikes come in a range of engines from 50cc to 550cc. In the beginning years of motocross, the 500cc class was considered to be the leading category of Motocross bike. However, as technology moved forward, the majority of riders could not take advantage of the constantly increasing potential of these powerful open class Motocross bikes. The top spot was eventually taken by the 250cc Motocross bike because while advancements in technology made them faster, they were still more manageable and handled much better than the 500cc bikes.

The most common way of distinguishing between Motocross bikes is by noting whether they have two-stroke or four-stroke engines. All of the original Motocross bike from before 1965 had four–stroke engines. As the two-stroke engine was technologically improved in the 1970s, 80s and 90s, they began to take a leading spot in the sport. When considered at the same capacity (cc), the two-stroke engine produced was much more powerful than the four-stroke engine, despite the fact that a mixture of fuel and oil had to be used. During this time, however, Motocross bikes with four-stroke engines still competed in their own specialist classes partially in the 500cc group. During the technological advancements of the 1980s, Motocross bikes that were water cooled and fitted with monoshock rear suspension replaced those that were the typical two-stroke air cooled and fitted with twin shock rear suspension. This produced even more powerful Motocross bikes within the existing 125, 250 and 500cc categories of displacement.

As awareness about environmental impact grew, especially in the U.S., two-stroke engines became less popular while newer and more environmentally friendly four-stroke engines were developed. While there is a cleaner fuel burn in four-stroke engines, there is also less power for the same displacement. These engines also have another major drawback; they are much louder than two-strokes because of the deeper sound they produce. This led to a huge increase worldwide in complaints about sound. The world sanctioning body made changes in the displacement categories to make the four-stroke Motocross bike competitive. Now a 125cc two-stroke would compete against a 250cc four-stroke, and a 250cc two-stroke would compete against a 450cc four-stroke. Because there were only a small number of riders with enough talent to ride them at their limits, the 500cc class had begun dying out by this time as it just seemed to be too much Motocross bike to easily handle.