A 4-stroke outboard motor is similar to the engine in a typical family sedan. Using a 4-stroke combustion system, the 4-stroke outboard motor is a cleaner alternative for the environment than its 2-stroke cousin. Instead of mixing oil with gasoline in an effort to lubricate the 2-stroke motor's top end, the 4-stroke outboard motor uses an oil pump in conjunction with an oil reserve within the engine itself to pump oil to the critical areas of the motor. This system produces much less smoke, runs more quietly and also is less destructive on critical engine components, such as spark plugs. Many 4-stroke outboard motor designs also operate at slower speeds and remain cooler than 2-stroke models, making them a good choice for fishermen who like to troll.
The advantage a 2-stroke outboard motor typically had over a 4-stroke outboard motor is that they made power very easily with a small engine package. This engine trait made the 2-stroke a popular engine for chainsaws, dirt bike-style motorcycles and outboard boat motors. In applications in which weight was a primary concern, an air-cooled 2-stroke engine was often the logical choice. Advancements in 4-stroke outboard motor design has created a package that offers plenty of power in a relatively lightweight engine package. This has been accomplished through the use of improved alloys as well as increased performance in cylinder head design.
These advancements don't only benefit 4-stroke outboard motor design; commonly 2-stroke only markets, dirt motorcycles, snowmobiles and even some chainsaws now are powered by 4-stroke engines. This use of 4-stroke engines is much more environmentally friendly due to the reduction in exhaust emissions. The typical 4-stroke outboard motor is also much quieter than a comparable 2-stroke version. This cuts noise pollution and creates a friendlier and more enjoyable outdoor experience for most enthusiasts. Many owners also report fuel savings from their 4-stroke outboard motor as compared to a 2-stroke motor, and this helps in the reduction of fossil fuel usage.
Another benefit of using 4-stroke motors over 2-stroke motors lies in the cost savings of routine maintenance. A typical 2-stroke motor will require new spark plugs multiple times during a single season, depending on frequency of use. The 2-stroke engine is also notorious for becoming oil and dirt covered, requiring frequent cleaning between uses. The 4-stroke motor is not only much friendlier to spark plugs, requiring changes only at normal intervals, it is much cleaner. The cleaner exhaust reduces the oil and dirt film that so frequently accompanies the 2-stroke motor.