What does the term “stroke” mean when referring to a boat engine?

Question by Coras Grandson: What does the term “stroke” mean when referring to a boat engine?
In referring to the term “stroke”, I mean as in a 2 stroke or 4 stroke boat engine.

Best answer:

Answer by waxingtheturtle2
The only “stroke” I know isn’t remotely related to boating. Infact, some consider it a hobby.

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11 Comments
  1. Reply
    Joe U May 29, 2013 at 11:21 am

    Stroke in referring to internal combustion engines, refers to the number of cycles to intake/fire/exhaust…
    In the Otto cycle (4 stroke cycle) there are 4 complete strokes to each cycle; intake, compression, power, exhaust.
    In the 2 stroke cycle engine, there are only 2 complete strokes to each cycle with intake/exhaust being combined at bdc of the power stroke.
    http://science.howstuffworks.com/two-stroke.htm

  2. Reply
    wnruger May 29, 2013 at 11:56 am

    THE STROKE OF Any engine refers to the number of times the piston moves up and down during a cycle that is the intake of fuel (1) compression(2) power or explosion (3) and exhaust (4) for a 4 stroke motor a 2 stroke the intake and exhaust is on the same stroke hope this helps

  3. Reply
    cranknbank9 May 29, 2013 at 12:39 pm

    It’s a misnomer. They’re referring to the cycles of the process. 4-cycle = intake, compressions, combustions, and exhaust. In the 2-stroke process intake and exhaust are combined as are compression and combustion.

  4. Reply
    Robert P May 29, 2013 at 12:47 pm

    two stroke …engines use oil mixed with the gas

    “stroke” is the term used for the distance your piston travels between the down position and the Top Dead Center (pistion at the highest possible point)

    4 “stroke” is intake>compression>ingnition>exhaust

  5. Reply
    Big C May 29, 2013 at 1:03 pm

    2 stroke add oil to gas and 4 stroke the gas and oil seperate like in a car.

    The two-stroke cycle of an internal combustion engine differs from the more common four-stroke cycle by completing the same four processes (intake, compression, power, exhaust) in only two strokes of the piston rather than four. This is accomplished by using the space below the piston for air intake and compression, thus allowing the chamber above the piston to be used for just the power and exhaust strokes. This causes there to be a power stroke for every revolution of the crank, instead of every second revolution as in a four-stroke engine. For this reason, two-stroke engines provide high specific power, so they are valued for use in portable, lightweight applications. They are among the smallest internal combustion engines in use.

  6. Reply
    Fatty May 29, 2013 at 1:27 pm

    Stroke can mean a couple thing in terms of engines.
    One definition is the distance the piston moves up or down in the cyllinder.
    If you are reffering to 2-stroke vs. 4-stroke, it refers to the way the engine operates over one cycle of the piston.

    In a 2 stroke engine, the piston moves up and down 1 time between firings, intaking the fuel/air mixture, igniting it and expelling exhaust.

    In a 4 stroke engine, the piston moves up and down twice to accomplish the same thing.

    Examples of 2 stroke engines are chainsaws and many other small engines along with some smaller motorcycles, especially dirt bikes.

    4 stroke engines are used in cars, large motorcycles and almost every kind of conveyance.

    They have very different maintenance needs so make sure you understand what you are getting and how to maintiain it properly.

  7. Reply
    John B May 29, 2013 at 1:40 pm

    Stroke is the distance the piston travels up and down. A two stroke engine travels down and up and then the sparkplug fires. A four stroke travels down and up twice before the sparkplug fires. It’s been a long time since I was into this stuff, but you have to mix oil with your gas with a two stroke and it sounds like a chainsaw.

  8. Reply
    stewpid May 29, 2013 at 2:17 pm

    some doozies for answers there, huh?! the term “stroke” describes the piston either traveling from the top of the cylinder to the bottom, or the bottom to the top…regardless what stroke the engine is classified. a 2 stroke goes up once and down once, thus it’s name. guess what! a 4 stroke goes up and down and then up and down again to achieve a complete cycle. does that help?

  9. Reply
    p1ayerz_4_life May 29, 2013 at 2:50 pm

    4 stroke goes vrrrum and a 2 stroke goes V RRROOOOOMMMMM

  10. Reply
    proud american May 29, 2013 at 3:15 pm

    Two stroke uses oil mixed in with the gas. This is how the engine is lubricated.
    Four stroke has an oil reservie to lubricate the engine. Both engines have advantages and disadvantages. Depends on what your intended use is.

  11. Reply
    boat guy May 29, 2013 at 3:20 pm

    Two stroke engines are also generally less heaver than a four stroke. The four strokes get better fuel efficiency except in the case of the direct injection models such as the Evinrude E-Tec motors. In a two stroke where the intake and exhaust is combined in a stroke, some of the fuel is passed directly to the exhaust.

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