How Does a Dirt Bike Work?

Overview of Dirt Bikes

A dirt bike is a recreational motorcycle designed for off-road use. Dirt bike enthusiasts use dirt bikes for wilderness riding as well as on dirt tracks and motor courses. Dirt bikes are typically made from lightweight metals and feature small engines, significant suspension and large wheels with grooved tires. Dirt bikes typically have a simple design with very few accessories, which increases their durability and decreases the likelihood that something will break when the dirt bike is being ridden over a rough surface.

Dirt Bike Four-Stroke Engine
Most recreational dirt bikes use 250 cc or 450 cc four-stroke engines that are powered by gasoline. Dirt bike motors are internal combustion engines in which gasoline is sprayed into a combustion chamber. The resulting combustion creates power that drives the motor's piston. Gasoline enters the combustion chamber through a fuel intake line; the flow of gasoline is regulated by a valve train. The motor's spark plug causes the fuel to combust, which drives the piston in the crank case. Byproducts of the combustion process exit the motor through an exhaust outlet, which funnels the gases out through the dirt bike's tailpipe. The piston inside a typical dirt bike engine displaces between 250 to 450 cubic centimeters of air, making the motor powerful (despite its small size) given the size and weight of the average dirt bike.

As is the case with motorcycles and pedestrian bicycles, dirt bikes are powered by a large chain attached to the rear wheel's gear spool. The chain runs between the gear spool and the dirt bike's drive shaft. As is the case with an automobile, a dirt bike's drive shaft is attached to a gearbox, which rotates at different speeds depending upon the selected gear. A dirt bike's clutch is a pedal located at the bottom of the bike, and the shifting mechanism is a lever located on one of the handlebars. When the dirt bike rider presses down on the pedal, the sliding gear disengages and can re-engage with the gear that the rider selects. The various gears cause the drive shaft to rotate at different speeds, which moves the drive chain at different rates and controls the power being transferred to the dirt bike's rear wheel. Braking action occurs when the rider presses the brake levers on either handlebar, which pulls the brake cable and causes the brake pads to clamp down on the front and rear wheel rotors.