Combustion engines are easier to understand than you think. If you are currently going to school to learn about motorcycles or searching for information on how your motorcycle works it can be a bit frustrating. To be honest much of this reminds me of AP Chemistry. Let’s start with the science behind combustion in your motorcycle engine.
Thermodynamics is the science of energy and heat. Like how we burn energy in our bodies the engine of your motorcycle burns fuel to make heat that the engine converts to energy.
In your motorcycle engine, there are several laws of physics at work. These universal laws of physics are what make your motorcycle run.
Energy can not be created or destroyed. This means that you can not make your own energy or destroy energy that exists only convert one type of energy into something new. Inside your motorcycle is the energy of combustion into the energy that propels your motorcycle where you want it to go.
No conversion of energy is 100 percent efficient. When your motorcycle converts fuel to energy some of that energy is lost in the process.
Gas laws are the theory formulated to predict the behavior of expanding gases. This is a basic explanation of how your engine works:
- As air, is compressed the temperature rises.
- When this air then tries to expand.
- The more air is compressed and heated the higher the pressure gets.
- This heated air creates the pressure that moves the pistons in your engine.
This is done in a pattern of Intake, compression, power that pushes it forward, and exhaust the removal of the spent compressed air.
How combustion runs your motorcycle engine
Combustion uses the chemical energy of the fule you put into your motorcycle to create heat energy that then controls the pistons and moves your motorcycle. Your engine works by compressing air and fuel in a small contained space. As it is heated it expands.
Before your fuel and air mixture is compressed it is gaseous and fast-moving. This gas is then compressed by the piston and ignited by the spark plug causing the mixture to burn.
This burning is not the explosion most people think, but rather rapid oxidation, a very quick chemical reaction. During rapid oxidation, the fuel and air in your engine combine creating carbon dioxide and water.
This process of conversion causes the air and fuel to lose some of its internal energy that is released as heat. This heat increases the pressure in the cylinder and pushes the piston down. When the pistien is pushed down it pushes the other piston up creating the exhost cycle. Some of this heat is absorbed by the cylinder.
There are several things that can get in the way of this process ranging from the fuel to air mixture, the condition of your spark plugs, and the condition of each part of your engine. If any part of this process has an issue your motorcycle will not run properly. These issues can range from the entire bike being disabled to simply having poor fuel economy.