There are two main types of outboard engines: 2 stroke and 4 stroke outboards. There advantages and disadvantages to each type and you should select which you will use based on your needs. This guide will help you determine which the best engine is for you.
2 Stroke Outboards
When you want speed and acceleration, a 2 stroke engine is the right choice because they are lighter and faster. The resale value of 2 stroke engines is greater than 4 stroke, and they sell for cheaper new. Also, since they are so common, finding spare parts for repairs is relatively easy. Need for said repairs is infrequent due to their simple design.
The main disadvantage of a 2 stroke engine is its environmental unfriendliness. 2 stroke engines are more pollutive than 4 stroke engines because they release unburned oil that pollutes the water. Manufactures are trying to innovate new types of 2 stroke engines that maintain their power without the same amount of pollution. These manufacturers include: Mercury, Nissan, Yamaha and Evinrude.
4 Stroke Outboards
If you’re after a quieter, smoother ride that is also fuel efficient, a 4 stroke engine is for you. They are heavy, so not all boats can handle them, and they are also slower, but they yield much less pollution. 4 stroke outboards are more complex, so repairs need to happen more frequently and are more expensive to execute. Spare parts can be harder to find, but as they become more common and further developed, repair is getting easier. Johnson, Honda, Mercury, Nissan, Suzuki, Tohatsu and Yamaha all manufacturer 4 stroke outboards motors.
Environmentally Friendly Outboards
When purchasing an outboard engine, look at the newer models since they are more environmentally friendly. They offer less pollution, reduced noise, better fuel economy and lower running costs.
The Mechanical Differences Between 2 and 4 Stroke Outboards
The number of times the piston moves during one firing cycle of the engine is how many “strokes” it has, hence “2 stroke” and “4 stroke.” In the 4 stroke engine, the four strokes are:
Intake stroke: Having an open intake vale, the piston falls in the chamber creating a vacuum for a mixture of air and fuel to enter the combustion chamber.
Compression stroke: The piston rises in the cylinder with the valves closed, compressing the air-fuel mixture.
Combustion stroke: With the valves remaining closed, the spark plug ignites the fuel, resulting in an explosion that pushes the piston down again.
Exhaust stroke: The exhaust valve opens and the piston rises again pushing the exhaust gasses out of the chamber so the process can begin again.
There are only two movements in a 2 stroke engine; one up and one down:
Combustion stroke: The explosion of fuel launches the piston downward. In the process, it uncovers an exhaust vent and fuel inlet in the wall of the cylinder. These permit exhaust gasses out, and new air and fuel to be sucked in, respectively.
Compression stroke: When the piston ascends, it covers the exhaust vent and fuel inlet in order to compress the air/fuel mixture. The piston is forced back down again when the spark plug ignites the air and fuel.
The design is much simpler because there are no need for valves or a device to open and close them.
David has been writing online for a while now and loves outboard engines, however he also writes about computer desks. Check out his sites: Uk marriage visa Used Outboard Engines and Uk marriage visa Computer Table Desk.