Outboard motors are the most popular means of propulsion for runabout boats. On small craft such as fishing boats, they are often the only option as there simply isn't enough room to mount an inboard engine. Even on larger pleasure craft, the outboard is popular because it leaves more space to move around inside the boat. Plus, the investment made in the motor can be transferred to a new boat when the time comes to replace the old hull.
In the past, most outboards were two stroke models. Anyone who has used a two stroke outboard motor knows it burns oil, this is an inherent part of the design of two stroke engines. That means the operator has to either mix oil into the fuel at every fillup, or check and top off the oil tank (on more advanced oil injected models). A four stroke engine recirculates the oil through a filter instead of burning it. Not only is this better for the environment, it's also less hassle for the user.
Four stroke outboard motors have mostly replaced the older two strokes, in large part because of the increasingly stringent government-mandated environmental regulations on boat motors and engines in general. Four strokes are cleaner, quieter, and more fuel efficient than their two stroke counterparts, enabling them to meet those strict environmental laws.
The only downsides to four strokes are increased size, weight, and complexity. A two stroke engine, being simpler in design, has fewer moving parts to break and so might be more reliable if well cared for. However, four stroke engines have matured over the years to the point where they are incredibly reliable and so the reliability advantage of two strokes isn't very significant these days.
The one major advantage the two stroke still holds is that it's lighter and smaller than a four stroke of the same rated horsepower. This better power-to-weight ratio makes up for the oil burning and noise for those boaters who want the lightest, most powerful engine available, but again the maturing four stroke designs are closing the performance gap.
Four Stroke Outboard Motors for Sale
