Outboard motors are everywhere and there can be few boaters who have not operated a boat with an outboard motor at some time. Even if you generally cruise in a larger boat which has an inboard engine or sails as the main means of propulsion there is a good chance that the dinghy that you use to get to the dock will have a small outboard on the back. In their simplest form an out board motor is a completely self contained unit that clamps onto the back or a small craft albeit an inflatable or rigid tender. Rumor has it that the outboard was invented by a young man called Ole Evinrude over 100 years ago. Others may dispute this claim and cite that it was actually a Frenchman who demonstrated an electric outboard some 15 years previously. Whatever the true story is there is no doubt that outboards have been a round for a very long time now and have become a very common sight. Almost any marina or boatyard is full of Evinrude, Mercury, Yamaha, Honda and many of the other common names.
Outboards come in a range of horsepower ratings, from small 2.5 hp motors weighing in the region of 20 pounds to large 300 hp behemoths capable of propelling large boats are breathtaking speeds.
While it is possible to buy electric and even propane fueled outboards by far the majority of outboard engines are fueled by gasoline. Gasoline outboards fall into two categories either two stroke or four stoke. Broadly speaking the main difference between a two stroke and four stoke is that with a two stroke oil is mixed with the gasoline and this lubricates the engine moving parts before it is burnt in the cylinder(S). With a four stroke motor, which is the type that you have in your car oil is contained in a sump or the lower half of the engine and remains in the engine and is not burnt and thus requires oil changes when the motor is serviced. Other significant differences are that with a two stroke motor every complete revolution of the engine is a power stroke as opposed to a four stoke where only every other complete revolution is a power stroke. Four stoke motors are also slightly more complex, have more moving parts and tend to be heavier than a two stroke motor of a similar horse power rating but this is changing and in truth with today’s motors this is less of an issue. Another difference is that four strokes tend to be quieter and slightly smoother in operation.
The big four in the outboard world are Honda, Yamaha, Mercury and Evinrude. Of these only Honda does not make two strokes. Yamaha offer the V Max V 6 two stroke engines in 150 and 175 hp outputs but offers no other 2 stokes, in the US at least. Evinrude on the other hand are fully committed to 2 stokes and offer the very popular rage of E-Tec motors but they do use four stroke motors for their smaller portable units.
So this begs the question, which type is right for you? It all depends. Normally the maximum or recommended output for use on your particular boat will be specified by the manufacturer of your vessel. Then you should compare engines from each of the motor manufacturers which fall into the size as recommended by the boat builder. Compare specifications, is there a dealer network in your particular area that can not only sell you the engine but who can service it for you after the sale. Talk to other owners and get their opinions. Search the web forums and see what others are saying about an engine you may be considering. Some of the smaller lakes do not allow 2 stroke motors so that may also factor into your thinking. If you can get a trial of any engine you are considering buying, most of the major manufacturers all have a strong presence at boat shows and can often arrange for you to see the motor actually operating. Finally not least is price; an outboard represents a significant outlay so shop around for the best deal. The fact is that I believe there is little to choose between modern two and four stoke motors. Long gone are the days of hard to start engines that oiled their plugs at the drop of a hat. Today's motors are long lasting reliable and will last for many years if properly maintained.
As a generally rule if you want fast acceleration and the most power from the lightest weight possible then opt for the two stroke. If on the other hand you want the quietest possible motor and are less concerned with out and out performance a four stoke may suit your needs better.
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