Complete Outboard Engines
Your boat's speed and handling depend directly on the outboard engine used to power it. Additionally, an outboard engine affects both safety and performance. Knowing what to ask when buying an engine from Yamaha, Mercury, Honda, or another manufacturer is critical.
What does the "outboard" in outboard motor mean?An outboard motor is attached to the transom and hangs outside the back of the vessel so that the propeller is submerged. From there, it can be tilted forward on a pivot to lift the entire motor out of the water. A handle is attached to the top of the outboard motor so that you can use the direction of the propeller to steer the boat.
How much horsepower do you need?You should always get an outboard motor with the maximum horsepower your boat is rated for. Remember that horsepower equals performance. How high you can go depends on what kind of boat you have. For example, inflatable boats average between 9 and 25 HP, while pontoon vessels can go as high as 300 HP, depending on the model.
What is the difference between fuel systems?Older outboard motors are generally carburetor-driven and require a special oil to be premixed with the gas before it's added to the tank. The oil provides lubrication as the fuel is used. Contemporary outboard motors with carburetors keep the oil separate, offering a cleaner exhaust.
In electronic fuel injection, a computer introduces a precise amount of fuel into the outboard's air intake manifold. This controls the amount of fuel/air vapor entering the chamber, enhances engine power, and lessens pollution. With Direct Injection, also called Electronic Direct Fuel Injection, an exact amount of fuel is injected directly into the cylinder under high pressure. Only air is introduced through the outboard's air intake.
What is the difference between two-stroke and four-stroke outboard motors?A two-stroke, or two-cycle, outboard motor completes the power cycle with two strokes. The first draws air and fuel into the combustion chamber and creates compression. The second stroke ignites and exhausts. The two-stroke outboard engine is lighter, with more power for the same size, and offers better acceleration. It is favored for smaller, lighter boats, like dinghies.
A four-stroke, or four-cycle, engine uses four strokes to complete the cycle. The first draws fuel and air into the combustion chamber. The second compresses the fuel-air mixture. The third ignites the fuel-air mixture and generates power. The fourth and final stroke expels the exhaust. Four-stroke engines, although large and heavy, offer more torque and better fuel economy. It is a good choice for bigger, heavier boats.