Outboard engines fall into two major classes; 2 stroke and four stroke outboards. Both types have their advantages and disadvantages and the type you pick will rely upon the intended use. This guide will provide help to select which outboard engine is finest to your type of boat.
2 Stroke Outboards
2 stroke engines are lighter and faster so when speed and acceleration are required, this would be the engine of choice. They’re also more affordable and have a higher resale value. As 2 stroke engines have been around for nearly eighty years, parts are readily available, making repairs easy. Additionally, the design on these engines is less complicated than a four stroke, that means problems are less likely to arise.
There are some disadvantages to the two stroke engine. 2 stroke engines are more pollute than four stroke engines so they are not so kind on the environment. Their engines are lubricated by the oil that is blended into the gasoline, that means the exhaust is smoky and contains unburned oil, which in turn pollutes the water.
With new rules, outboard manufacturers are looking to seek out new ways of producing the same energy with less pollution.
four Stroke Outboards
four stroke engines are quieter, smoother and more economical. Heavier with slower acceleration, they’re normally chosen for lakes and rivers. With less air pollution and smoke they are additionally kinder to the environment. If you happen to’re after a quieter, smoother ride, then the 4 stroke outboard is the higher choice.
four stroke motors have more complicated engines which may lead to more repairs. When a repair is required it is normally more costly and parts are limited.
four stroke outboards are generally heavier than 2 stroke outboards, so should you own a smaller boat it might not be able to hold the weight of a four stroke engine.
Because four stroke engines are newer, they are regularly being improved to make buy and repair easier.
Some 4 stroke outboard engine manufacturers embrace Yamaha, Tohatsu, Suzuki, Nissan, Mercury, Honda and Johnson outboard after market parts.
Environmentally Friendly Outboards
When you’re looking for a new outboard, it’s worthwhile considering one of the newer, environmentally pleasant models. Much less air pollution, reduced noise, higher fuel economy and lower running prices are amongst the advantages.
The Mechanical Differences Between 2 and 4 Stroke Outboards
The phrases «2 stroke» and «four stroke» seek advice from the number of occasions the piston moves throughout one firing cycle of the engine. In the 4 stroke engine, the 4 movements, or strokes, are:
Intake stroke: With the intake valve open, the piston moves down permitting a mix of air and fuel to enter the combustion chamber.
Compression stroke: The piston moves up the cylinder with the valves closed, so that the air-fuel mixture is compressed.
Combustion stroke: With the valves still closed, the fuel is ignited by the spark plug. The explosion pushes the piston down again.
Exhaust stroke: The exhaust valve opens and the piston moves up to push the exhaust gasses out of the chamber so the process could be repeated.
In a 2 stroke engine, there are only movements of the piston for every combustion; one up and one down:
Combustion stroke: Combustion of fuel drives the piston downwards. Because the piston moves down, it exposes an exhaust vent and fuel inlet in the wall of the cylinder permitting exhaust gasses out, and new air and fuel to be sucked in.
Compression stroke: As the piston moves back up, it blocks off the exhaust vent and fuel inlet and thus compresses the air/fuel mixture. The spark plug ignites the air and fuel inflicting the piston to move down again.
The fuel inlet and the exhaust vent in the wall of the cylinder eliminate the need for valves and the mechanism for opening and shutting them which is why 2 stroke engines are a lot simpler in design.
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