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  1. #1
    Cadet
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    Default What octane gas is best to use for a two stroke outboard motor.

    I am new to the boating family and I want to make sure I get all my stuff ready for the spring. I have a 96 Bayliner Capri 1700 LS.
    1996 Bayliner Capri 1700 LS

  2. #2
    Lieutenant Dave Abrahamson's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    What motor do you have? Force?
    87 is what most outboards need. Anything more is a waste of $
    There may be a label on the side of the motor, if so it probably says 87.

    Good Luck!
    DAve
    I get by with a little help from my friends

  3. #3
    Cadet
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    Quote Originally Posted by Dave Abrahamson View Post
    What motor do you have? Force?
    87 is what most outboards need. Anything more is a waste of $
    There may be a label on the side of the motor, if so it probably says 87.

    Good Luck!
    DAve
    Yes, it's a 120 force mercury
    1996 Bayliner Capri 1700 LS

  4. #4
    Captain Sea Rider's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    Although using higher octane gasolines are a waste of $, on the other hand, more pricey gasolines have better cleaning solvents than cheaper ones, will clean better, burn better, produce less carbon buil up on pistons & cylinder head specially if you are a non carbon guard products user at all.

    Happy Boating

  5. #5
    Master Chief Petty Officer r.j.dawg's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    The higher octane fuel (91), at least up here, is ethanol free. Shell and Husky stations for sure.
    Crews Inn II
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    I would like to pass away like my Grandfather, quietly in his sleep. Not screaming like the passengers in his car.

  6. #6
    Fleet Admiral Texasmark's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    I put premium in my tank this time, for the first time that I can remember. Since I don't get out much any more I felt that the premium would have more of the violatile compounds to evaporate so that when I get around to using my boat I will still have the equivalent of 87 octane....but that is just a theory, unfounded and non supported.

    But I do use Sea Foam and it keeps my engine squeaky clean.

    Mark
    If you are new to boating or have a new boat, a knowledgeable friend could show you how to operate your boat and save you a lot of grief, maybe some money, and maybe your life.

  7. #7
    Captain Philster's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    Fuel does lose octane over time. So, for storing it or nursing it all season, little extra octane is good.
    Checkmate 2400BRX/Optimax 300xs
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    Date an I/O, but marry an outboard!


  8. #8
    Lieutenant Dave Abrahamson's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    If you're looking for solvents in the higher octane fuels to clean out the fuel system, the ethanol itself is a great solvent to loosen up crud in the fuel system. Unfortunately it's a great solvent and loosens up crud in the fuel system....tiny little jets in the carb don't like that. I second the Seafoam...great product.
    I get by with a little help from my friends

  9. #9
    Admiral
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    In the US (I have no idea about Peru) the additive package is the same for all octane ratings, all you get is a higher octane, which is of no value in an outboard unless the manual states otherwise (which it does on a few motors).

    Premium is E-free in only some regions and stations, and they are few and far between.

    There are many self proclaimed miracle products on the market that claim to solve every perceived issue you may have with E-10 fuel, most do nothing, a few may help a little in just a few problem areas. These aren't really needed, but if you plan to leave the motor sit for a long period of time (a month is not a long period of time) use a fuel stabilizer.

  10. #10
    Commander RogersJetboat454's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    Quote Originally Posted by ondarvr View Post
    In the US (I have no idea about Peru) the additive package is the same for all octane ratings, all you get is a higher octane, which is of no value in an outboard unless the manual states otherwise (which it does on a few motors).

    Premium is E-free in only some regions and stations, and they are few and far between.

    There are many self proclaimed miracle products on the market that claim to solve every perceived issue you may have with E-10 fuel, most do nothing, a few may help a little in just a few problem areas. These aren't really needed, but if you plan to leave the motor sit for a long period of time (a month is not a long period of time) use a fuel stabilizer.
    ^^^ +1
    1976 Rogers Custom Boats 18' "Bonneville" W/ Chevy 454/ Berkeley 12JC

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  11. #11
    Supreme Mariner Frank Acampora's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    You Know: We could go on and on ad infinitum (can you spell redundant?) about the merits or lack thereof of various octane and brands of gasoline and additives. In fact, in previous threads we have!

    The fact is this: Force engines are about as simple and old school engineering as you can get. They are not fussy at all and almost anything that burns will not harm them.

    If you are going to store it for a long while: The engine simply doesn't care! I have used gas that was five years old and smelled like turpentine.

    I regularly leave my gas in the tank over the winter with no additives-- The engine always fires right up the next season.

    Bottom line: Use the cheapest gasoline you can find at 87 octane and the cheapest TCW-3 oil.

  12. #12
    Admiral
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    Quote Originally Posted by Frank Acampora View Post
    You Know: We could go on and on ad infinitum (can you spell redundant?) about the merits or lack thereof of various octane and brands of gasoline and additives. In fact, in previous threads we have!

    The fact is this: Force engines are about as simple and old school engineering as you can get. They are not fussy at all and almost anything that burns will not harm them.

    If you are going to store it for a long while: The engine simply doesn't care! I have used gas that was five years old and smelled like turpentine.

    I regularly leave my gas in the tank over the winter with no additives-- The engine always fires right up the next season.

    Bottom line: Use the cheapest gasoline you can find at 87 octane and the cheapest TCW-3 oil.
    That's about what I do, I have a couple bottles of Stabil that are several years old, I keep thinking I'm going to add them, but I never do.

  13. #13
    Vice Admiral 5150abf's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    Most people don't know how the octane rating works they just see a guy putting premium in his Corvette ro built up stret rod and think high octane equals high performance but the higher the octane the slower the gas burns and the harder it is to ignite, the extra octane is to prevent preignition or knock so it may actually make a normal engine run worse.

    Premium is for high compression engines which outboards aren't, regular unleaded is fine and run the Sea Foam or similar and it will be fine.
    GO IRISH!!!!

  14. #14
    Petty Officer 3rd Class
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    I burn premium in my pre 1958 Johnson's because I was told that it burns hotter also I seem to use less in these motors as a result (they don't have thermostats)

  15. #15
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    Two stroke engines are very forgiving. On the other hand higher octane gas can cover the dieseling symptom that many I/O engines have so not totally useless. I think my old Force could run on vegetable oil if I tried.
    2003 Chaparral 183SS

  16. #16
    Admiral
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    Quote Originally Posted by Shane7 View Post
    I burn premium in my pre 1958 Johnson's because I was told that it burns hotter also I seem to use less in these motors as a result (they don't have thermostats)
    It doesn't. Like has been said, there are many myths and misunderstandings about premium gas.

  17. #17
    Petty Officer 1st Class mxcobra's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    its a trick from the gas company.
    85/87/91 really... big difrance here- not!
    my guess is usually the gas all comes from the same bat anyway.
    Now like the purple race fuel at like 118 octain at 6 bucks a gallen,
    only achives one thing -to stop pre ignition ping in high compresion motors- it ads 0 hp. and in some cases decreases hp.
    its purpase
    so imho those who by the more expensive gas must enjoy watching their gas bill explode...

  18. #18
    Vice Admiral 5150abf's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    It makes me giggle evertime I see Junior putting racing gas in his moms buick for a big night out racing around town.
    GO IRISH!!!!

  19. #19
    Supreme Mariner Silvertip's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    The only time higher octane fuel is an advantage is if the engine is ECU controlled and even then it must have a knock sensor or other means of identifying detonation. Higher octane means less tendency to detonate and the ECU can then automatically provide increased ignition advance. Without such an ignitiion system the engine needs only the octane the manufacturer specifies. Anything more is indeed a waste. If an engine runs-on (diesels), adjust it or add an anti-diesel solenoid that was standard on the early emissions engines.

  20. #20
    Petty Officer 2nd Class
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    Basically dont worry about the octane just try to find gas without ethanol" that stuff is hard on the rubber parts and your mileage drops"If you cant find ethanol free fuel in your location use a fuel treatment.
    There is no such thing as a "free" boat. Unless forget to tie it off properly.

  21. #21
    Ensign 86 century's Avatar
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    Default Re: What octane gas is best to use for a two stroke outboard motor.

    Quote Originally Posted by Frank Acampora View Post
    You Know: We could go on and on ad infinitum (can you spell redundant?) about the merits or lack thereof of various octane and brands of gasoline and additives. In fact, in previous threads we have!

    The fact is this: Force engines are about as simple and old school engineering as you can get. They are not fussy at all and almost anything that burns will not harm them.

    If you are going to store it for a long while: The engine simply doesn't care! I have used gas that was five years old and smelled like turpentine.

    I regularly leave my gas in the tank over the winter with no additives-- The engine always fires right up the next season.

    Bottom line: Use the cheapest gasoline you can find at 87 octane and the cheapest TCW-3 oil.
    One of the few people that have anything good to say about force.(im with you frank I like um)
    +1 to all above
    Myself I run marine stabil all the time(have no clue if it does any thing but I feal better)


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