better choice 2 stroke or 4 stroke?

Discussion in 'Outboards' started by Phildave, Jan 7, 2009.

  1. Phildave
    Joined: Jan 2009
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    Phildave Junior Member

    Have chance to buy 35 foot Simpson Woodsong with 2 30hp Mariner 2 stroke. Good choice. Any advice?
     
  2. Frosty

    Frosty Previous Member

    Where does the 4 stroke bit come in?
     
  3. CDK
    Joined: Aug 2007
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    CDK retired engineer

    Maybe 2 times 2 stroke = 4 stroke(s)?
     
  4. StianM
    Joined: May 2006
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    StianM Senior Member

    If the boat is a good buy take it.
    Dos it really mater what engines is on it?
    If I was to buy new engines I would go for Evinrude two strokes.
    They comply with all new regulations and two strokes has few moving parts compared to a four stroke and weigh a few kg less.
     
  5. messabout
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    messabout Senior Member

    A 35 foot boat with total 70 HP. Not enough power if it is a planing boat. Unecessary excess of power if it is a strictly displacement type. If displacement type then big slow turning props are generally the best option. That means that lower unit gear ratio needs some thought. For economy, the 4 stroke is a better option. Two stroke engines are signifigantly lighter in weight than the 4 stroke counterparts. Either type is reliable enough if maintained satisfactorily.
     
  6. sandhammaren05
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    sandhammaren05 Senior Member

    2 stroke motors are much lighter and smaller, and accelerate about twice as fast as a 4 stroke. I personally wouldn't own a 4 stroke, they came into existence only to meet environmental rules, but the new Evinrude direct injected 2 strokes are cleaner and better. The Mariner 30 is probably a Yamaha, a very good motor. But as stated below, with only 60 hp you're way underpowered. I'd take a 250 (or, if you want insurance in case a motor goes south far from shore, a pair of 150s).



     
  7. mwatts
    Joined: Jul 2009
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    mwatts Martin

    There's a few strong statements for ya.

    In the first place, the time that 2 strokes where twice as fast to accelerate, is really quite a few years behind us. In fact a 50hp 2-stroke has never been twice as fast as a 50hp 4-stroke.

    As far as size is concerned: the powerhead is usually just as fat, maybe at the most 10% lower in most cases (depends a bit on the brand).

    2 strokes usually ARE lighter, you are right about that. Sometimes 30%.

    Another big reason for people to by 4-strokes, is fuel economy. Here in the Netherlands, we can't believe the complaints US citizens are making about fuel prices! If you are feeling sorry for yourselves because you have to pay US $2,51 for a gallon of fuel, come over here where you can pay US $ 7,59 a gallon ;)
     
  8. sandhammaren05
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    sandhammaren05 Senior Member

    2 vs 4 stroke

    Check out the APBA speed records for the 1970-1980 era Classes SD and DP, now defunct, and show me a 4 stroke 50 that will run like that. I live mainly in Austria and rebuild 1980s era 2 stroke OMCs for personal use and resale on the Baltic Coast, in case you want a good motor instead of an overweight piece of lumbering 4 stroke pot metal. We offer 15s, 25s and 35s for sale.
     
  9. Yellowjacket
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    Yellowjacket Senior Member

    Don't get me wrong, I am a big fan of 2 strokes and probably wouldn't consider a 4 stroke engine for anything I want to do with an outboard...

    But.. 2 Strokes have on Achilles heel and that is scorching and lack of lubrication near the exhaust port. This can eventually result in ring failure and/or bore scuffing in this area and it is, generally speaking the life limiting part of a two stroke if you run it real hard.

    If you don't run them really hard they will last forever, but if you take advantage of that higher power to weight ratio there is a good chance that they won't last as long as a four stroke. I can't tell you the number of 2 strokes that I've seen with bore scuffing near the exhaust port and stuck rings.... Yes there are fewer parts and less to go wrong, but you don't buy a 2 stroke for long life, you buy it for performance.

    My experiece is old, but my father in law had to rebuild the power head of his 200 hp Johnson a few years ago for just this reason, so it would appear that some things never change. Maybe newer generation lubricants and newer materials can address this issue, so if I am wrong here somebody enlighten me.
     
  10. powerabout
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    powerabout Senior Member

    Was that a cross flow or looper 200?
     
  11. Yellowjacket
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    Yellowjacket Senior Member

    Not sure, it was older, 1995 vintage...
     
  12. ondarvr
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    ondarvr Senior Member

    Stuck rings and scored cylinders are not a design flaw, its a sign of poor maintenance, setup, or possibly another type of failure. Rarely do outboards wear out, they die from dirty carbs and/or a lack of cooling (neglect), plus the wrong prop.
     
  13. Yellowjacket
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    Yellowjacket Senior Member

    Frankly most outboard motors don't get used enough to wear out in any way shape or form. They see a couple of hours a week in most applications and in these cases are lucky to see a hundred hours a year. Unless you are running the heck out of your boat you aren't likey to ever wear one out.

    But eventually everything wears out. What I am saying is that you will most likely see wear and carbon buildup in the rings of an outboard that has been consistently run hard. There is essentially no cooling in this area of the cylinder (as opposed to the rest of the cylinder that has a water jacket around it) so this is where you start to see coke buildup in the rings and after a while the hard carbon buildup wears the cylinder. Take apart any two stroke that has been run a lot and you will see carbon buildup in the rings and scuffing in the bore area around the exhaust port. That is where the wear out first, that's all.

    The engines I'm talking about weren't modified in any way, they were run the way the factory delivered them, and near as I can tell were properly maintained. Like I said I'm a two stroke fan, and two strokes have a better power to weight ratio than a 4 stroke, but if you use all of it, it won't last as long, at least that has been my experience.
     
  14. ondarvr
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    ondarvr Senior Member

    Running hard at a higher RPM can actually clean out some of the gunk, over propping and never using a decarb type product like is recommended leads to coking and stuck rings. I've raced 2 strokes for the last 40 years and these problems exist in poorly setup engines. If there's a problem this is where it shows up first, its not something that happens on its own and creates other issues.

    I'm not a fan or hater of either type and only own 2 strokes, but my next purchase may be a 4-S.
     

  15. mwatts
    Joined: Jul 2009
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    mwatts Martin

    Actually, I owned a 1991 Johnson 50HP 2S for quite some time. It is still running (a close friend owns it now) and it's a fast and powerful engine; pulls 2 wakeboarders or a mono skier with 3 people in the boat without any problem. And it ran on virtualy anything, as long as it was more than 60 octane. :) It not being so "delicate" can be a welcome thing in some area's.

    But 4 strokes have come a long way since then, as far as power / weight ratio is concerned.

    If I would have to choose now, I would choose a 4S, simply because I don't sail at WOT ever anymore. If you never open the throttle further than 2/3 anyway, 4S is a smarter choice.
     
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