Thread: Octane-SHO

Page 1 of 3 123 LastLast
Results 1 to 20 of 47
  1. #1
    Member
    Join Date
    Nov 2011
    Location
    Atlanta GA
    Posts
    6,122

    Octane-SHO

    I have a 250 SHO. I've always ran mid grade fuel.I'm wondering if I will notice an improvement in performance with premium fuel. What say you?
    17 Ranger Z520c Black Out Edition
    Yamaha 250 SHO

  2. Member
    Join Date
    Sep 2016
    Location
    Ruma Ill
    Posts
    803
    #2
    I tried it on my 250 sho basscat puma . Less performance from what I seen . Would not break 80 . 89 octane. 81 82 any day by myself .

  3. Member RdRngR's Avatar
    Join Date
    Jun 2013
    Location
    Tillery
    Posts
    1,421
    #3
    89 non ethanol

  4. Member kk4iz's Avatar
    Join Date
    Jun 2004
    Location
    Clanton, AL
    Posts
    4,383
    #4
    Quote Originally Posted by RdRngR View Post
    89 non ethanol
    can not hardly find 89 non ethanol around here


    12 lbs 9 oz caught on 4/28/1975 Lake Eufaula

  5. Member
    Join Date
    Mar 2017
    Location
    Knoxville, TN
    Posts
    2,159
    #5
    Quote Originally Posted by kk4iz View Post
    can not hardly find 89 non ethanol around here
    Same, it's either 87 or 91 in 100% here.

  6. Member
    Join Date
    Jul 2007
    Location
    Shreveport
    Posts
    1,489
    #6
    I have seen the same results with different octanes other than 89...78-80 with 87 or 93 and 82-84 with 89 with my Eyra. i also can not find non-ethanal in 89 so I use ring free plus and everything is fine so far. I was told that it is better to run 89 with ethanol than one of the other with out ethanol.
    Elwood....Bass Cat Strong

    2020 Bass Cat Eyra
    2020 Mercury 300R 4S (1E081080)
    Hell Yeah!!!!!!!!

  7. Member
    Join Date
    Mar 2008
    Location
    Prairieville
    Posts
    4
    #7
    Quote Originally Posted by Wackyjig View Post
    Same, it's either 87 or 91 in 100% here.
    To get exactly 89 you can mix ratio of 91 & 87. 1 part 91 Octane to 1 part 87 -

    I haven't done this often but I use too when she was brand new.

  8. Member
    Join Date
    Feb 2018
    Posts
    3,151
    #8
    Quote Originally Posted by Elwood View Post
    I have seen the same results with different octanes other than 89...78-80 with 87 or 93 and 82-84 with 89 with my Eyra. i also can not find non-ethanal in 89 so I use ring free plus and everything is fine so far. I was told that it is better to run 89 with ethanol than one of the other with out ethanol.
    Are you saying that someone told you that it was better to run 89 with ethanol than say 91 without ethanol? If so, who told you that?

  9. Member
    Join Date
    Aug 2016
    Location
    Varnell, GA
    Posts
    7,410
    #9
    Quote Originally Posted by yam911 View Post
    Are you saying that someone told you that it was better to run 89 with ethanol than say 91 without ethanol? If so, who told you that?
    If you had to make a choice, which is safer for the engine?
    89 with ethanol or 91 without?

  10. Member RdRngR's Avatar
    Join Date
    Jun 2013
    Location
    Tillery
    Posts
    1,421
    #10
    Engines now are made to use ethanol. The problem with it is that it's alcohol so moisture becomes an issue if it sits too long. Yamaha says to use 89 octane so whether it's non ethanol or not, that's what should be used. If the boat is used often really no issue, if it sits for extended periods may be.

  11. Member
    Join Date
    Jul 2014
    Location
    KALKASKA MICHIGAN
    Posts
    4,065
    #11
    Quote Originally Posted by printman71 View Post
    If you had to make a choice, which is safer for the engine?
    89 with ethanol or 91 without?
    91 without. CJ
    2002 X19 200HP OX66 HO Vmax,HPDI lower, it lives, thanks Hydro Tec.

  12. Member
    Join Date
    Feb 2018
    Posts
    3,151
    #12
    Quote Originally Posted by printman71 View Post
    If you had to make a choice, which is safer for the engine?
    89 with ethanol or 91 without?
    91 without.

  13. Member
    Join Date
    Feb 2015
    Location
    Columbia SC
    Posts
    2,270
    #13
    Quote Originally Posted by printman71 View Post
    If you had to make a choice, which is safer for the engine?
    89 with ethanol or 91 without?
    91 without.

  14. Member
    Join Date
    Jan 2010
    Location
    Abilene,Texas
    Posts
    651
    #14
    I would consider a four stroke outboard a high compression engine. Higher-compression engines need the higher octane so that the fuel doesn’t pre-ignite in the combustion process and damage the motor. Octane slows and controls the detonation of the fuel during the compression and detonation of the fuel. So I would think 91 octane with or without ethanol would be allowable in a SHO.
    X

  15. Member
    Join Date
    Jul 2007
    Location
    Shreveport
    Posts
    1,489
    #15
    I am running the 89 (with or with out ethanol) and Yamaha Ring Free Plus, just like the Yamaha tech told me to. I can also see a big difference in performance with a higher or lower octane regardless of with or with out ethanol. I also run my boat 2-3 times a week and neither tank will last over a couple weeks in the boat. I also only fill them half way (boat holds 54 gallons) and run them out alternately. Call your Yamaha Tech and ask him if you want a straight up answer. That is what I did. 122 hours on a 18 motor and not even a hiccup and I run mine hard. At 102 hours I had 8.6 hours at 1000-2000 rpm and 11.3 hours at 5000 - 6000 rpm and 1.3 hours at 6000 - 7000 rpm. So more time at full throttle than idle.
    Elwood....Bass Cat Strong

    2020 Bass Cat Eyra
    2020 Mercury 300R 4S (1E081080)
    Hell Yeah!!!!!!!!

  16. Member Rick H's Avatar
    Join Date
    Sep 2011
    Location
    Northern Cincinnati Ohio
    Posts
    3,357
    #16
    What ever the owners manual says is what it is designed to operate on.

    Steve McQueen "Le Mans"
    Own the Champ! Life Long Petty Fan!

    2003 ChampioN 2006 250 Merc. XB, Prop By Mark C.
    2002 Ranger Okeechobee Special EvinRude Ficht 90 / 9.9 4-Stroke GLAD to have a Get me to the Dock motor maybe!

  17. Member
    Join Date
    Nov 2011
    Location
    Atlanta GA
    Posts
    6,122
    #17
    Quote Originally Posted by Elwood View Post
    I have seen the same results with different octanes other than 89...78-80 with 87 or 93 and 82-84 with 89 with my Eyra. i also can not find non-ethanal in 89 so I use ring free plus and everything is fine so far. I was told that it is better to run 89 with ethanol than one of the other with out ethanol.
    I was just complaining on another post about my boat being slower than before. I just remembered that I tried premium fuel in it! I'll be going back to 89 octane.
    17 Ranger Z520c Black Out Edition
    Yamaha 250 SHO

  18. Member
    Join Date
    Mar 2006
    Location
    Maine
    Posts
    3,368
    #18
    89 octane is whats called for on the 225/250 Yamaha SHO. The 200 recommends 87.

  19. Member
    Join Date
    Feb 2018
    Posts
    3,151
    #19
    Quote Originally Posted by bgibson View Post
    89 octane minimum is whats called for on the 225/250 Yamaha SHO. The 200 recommends 87 minimum.
    Fixed it for you.

  20. Member
    Join Date
    Aug 2016
    Location
    Varnell, GA
    Posts
    7,410
    #20
    Why do some folks on the Mercury forum get into fights (and get banned), about arguing over octane? That higher octane actually damages the engine.

Page 1 of 3 123 LastLast