The 2 Stroke Dirt Bike Engine: How It Works
The 2-stroke engine that you see in the dirt bikes these days is nothing short of a modern marvel. It has just three moving parts – piston, connecting rod and a crankshaft; and still generates enough amount of power to impress several dirt bike enthusiasts. The size of the 2-stroke engine is relatively small and this is what makes everyone curious. How does an engine so small generate so much power?
How Does a 2-Stroke Engine Work?
An engine works by burning the fuel to produce a spark, expand the air inside the engine and eventually move the crankshaft while forcing the air out of the exhaust. To break it down further, here is what actually happens:
- The fuel and air are mixed and introduced into the cylinder of the engine.
- The piston presses down on this the mixture inside the cylinder and creates a pressure.
- The pressure forces the mixture to flow towards the combustion chamber which is located above the piston.
- The piston now moves towards the combustion chamber, again exerting the pressure on the mixture. At the same
time, the cylinder below the piston is filled with more fuel and air mixture.
- The spark plugs of the (petrol) engine, which is present on the top of the combustion chamber, light up to burn the mixture of fuel and air (oxygen present in the air supports burning of the fuel).
- This produces a small explosion, or as the mechanics love to call it, fires the engine.
- The piston is forced to move in the downwards direction and rotate the crankshaft. At this time, the mixture of air and fuel inside the cylinder is sent in the combustion chamber to fire up in the next movement of the piston. Moreover, the burnt gases are thrown out
of the combustion chamber before the fresh mixture enters the chamber.
- This continues and the crankshaft keeps on gaining rotation.
Video Overview: How 2 Stroke Engine Works
The Difference Between a 2-stroke and 4-stroke Engine
A lot of people think that a 4-stroke engine is better than a 2-stroke engine. While that may be true in certain cases, it is definitely wrong if you see it from a perspective of a dirt bike enthusiast. To begin with, since a two-stroke engine does not have any valves, it is lighter than a four-stroke engine.
This is important since the dirt bike needs to be lighter. Plus, a two-stroke engine produces power per revolution whereas a 4-stroke engine needs to make 2 revolutions to fire. This means that in the same amount of time and for the same amount of fuel, a 2-stroke engine produces twice the power of what is produced by a 4-stroke engine.
When it comes to dirt bikes, power and weight of the bike are all that matter. While putting a 4-stroke engine would have made the bike more fuel efficient, it would have definitely made it heavier and harder to maneuver over the pits and puddles.
If you have ridden a dirt bike or if you have ever been around one, you would be able to understand my feelings better. Other than the fuel efficiency, the only downside of a 2-stroke engine is the fact that you need to use a special lubricant along with petrol to ensure smooth operation of the engine.
That being said, a dirt bike is an engineering masterpiece and the two-stroke engine is the soul that conquer the hearts. Until we are able to engineer a better and a lighter engine, we will stick to the 2-strokes for our dirt bikes.
Related Post: How to Ride a Dirt Bike like a pro? The Ultimate Guide.