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  1. #1
    Petty Officer 3rd Class
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    Default Oil/Petrol Mixture Evinrude 25hp 1985 ??

    Hi all


    I have a 25hp 1985 Evinrude and am wondering the recommended mixture ratio.
    I ran the engine for 3 hours the other day with brand new plugs using a 50:1 ratio.
    I whipped the plugs out today and there was quite a bit of oil down in the core of the plug. The electrode wasnt too fouled but some oil residue around there.

    Could i go to 100:1 ?
    Should there be the amount of oil left on the plugs that there was if that 50:1 is the right mixture!

    any advice grateful

    thanks
    nathan

  2. #2
    Moderator JB's Avatar
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    50:1 is the nominally correct ratio, Nathan, though we really mix it at 48:1 in the "standard" 6 gallon tanks.

    What make and number spark plugs are you using?

  3. #3
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    Don't be worrying about that oil on the plugs. That's just the way it normally is. On a two-stroke, the oil that you put in the gas goes through the combustion chamber. The electronic CD ignition is able to deal with it. If there was no oilyness in there, you would be in big trouble. And Don't go running less oil than 50:1!!!!

  4. #4
    Supreme Mariner kenmyfam's Avatar
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    Agree, stick with 50 to 1 ratio.
    Marada 2100 Executive Series, 5 Litre V8 with Mercruiser Alpha 1 outdrive. 2007 K-Z Spree 260 RBH, all = a whole lot of family fun !!!!

  5. #5
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    thanks for the advice gentlemen.
    I am using a champion QL77 JC4 but i think i replaced them with the compaitble NGK's of BZ7HS-10 as i could get them cheaper than the champions.

    thanks

  6. #6
    Moderator JB's Avatar
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    Go back to the Champions and don't be in a frazzle to change plugs so often. Clean and gap annually and those Champs will last 10-15 years.

  7. #7
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    i had to change the original plugs when i got the engine as they were very black and rusty, had lots of corrosion in the core. They looked like they had never been changed.

    the plugs were the QL type which apparently has noise suppression in them, will it make any difference using the plugs without the Q noise supp i.e. the L77JC4 plugs?

    Part of my question about oil ratio was also due to the engine not being very smooth when at trawling speed, it didnt cut out but didnt sound as smooth as my 15hp evinrude of the same era. The 25hp was a bit chuggy low down so if the its not the oily plug then i think the carb may need a clean, slow run jets?!


    might start a new thread for that one!!

    .

  8. #8
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    Champion QL77JC4 are the recommended plugs. The Q denotes that it has inductive (low resistance suppression) It is important to use those rather than ones with ordinary resistive suppression with the electronic ignition system but if suppressed plugs are not required L77JC4 should be acceptable,
    (Note though that the Q type should be used with VRO systems)
    L78V (surfaced gapped) and QL82C are also listed for this engine.

    The recommeded gap is now 0.030"

    BZ7HS-10 are the NGK equivalent of QL77JC4 (The Z denoting inductive suppression) and B7HS-10 are the equivalent of L77JC4.

    Personally I have a set of Champion plugs and a set of NGK plugs. It makes not a jot of difference which are in use.

    The only plugs I have ever had trouble with were Champions. The motor club at work were supplied with a whole box full of defective ones which had to be returned to the supplier so little biased against them.

  9. #9
    Commander wbeaton's Avatar
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    I use the QL82C in my 1988 30 hp. I like them better for trolling as they are a slightly hotter plug.

    The OMC 20-25-30-35 hp of that era don't idle and troll as nice as their 9.9-15 hp little brother. I find I'm forever tweaking the idle mixture on my 30 hp to get the best and lowest idle possible. I had to do the same with my 1987 20 hp too. The 9.9-15 hp motors never seem to need any adjustment.
    Wayne

  10. #10
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    I have a Evinrude 25hp 1985 and recently phoned Evinrude with the same question.

    On my engine there is a sticker that states 100/1. I queried this with Evinrude as colleagues had told me that Evinrude generally are 50/1.

    Evinrude said 50/1.

    I took the boat out on 50/1 and regretted it. Sparks gunked up with oil, very uneven idling and prone to cutting out if ignored, Evinrude did say that if the label said 100/1 and i used 50/1, this may happen,

    Returned to 100/1 and everything runs smooth.

    My engine model is be25balcos.

  11. #11
    Supreme Mariner kenmyfam's Avatar
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    Quote Originally Posted by zhaan View Post
    I have a Evinrude 25hp 1985 and recently phoned Evinrude with the same question.

    On my engine there is a sticker that states 100/1. I queried this with Evinrude as colleagues had told me that Evinrude generally are 50/1.

    Evinrude said 50/1.

    I took the boat out on 50/1 and regretted it. Sparks gunked up with oil, very uneven idling and prone to cutting out if ignored, Evinrude did say that if the label said 100/1 and i used 50/1, this may happen,

    Returned to 100/1 and everything runs smooth.

    My engine model is be25balcos.
    I think if it runs rough on a 50 to 1 ratio then there are other issues to solve.
    Did you increase the plug gaps with the 50 to 1 ratio ???
    Marada 2100 Executive Series, 5 Litre V8 with Mercruiser Alpha 1 outdrive. 2007 K-Z Spree 260 RBH, all = a whole lot of family fun !!!!

  12. #12
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    My engine model is be25balcos
    IIRC 1985 was the year Evinrude switched over to 100:1.( In fact I know it was) Within 2 or 3 years they realised it was a mistake and swtiched back to 50:1 including for all those previously sold as 100:1 motors. The 100:1 decals should have been removed and the manual amended to read 50:1 back around 1988.

    You'll get away with 100:1 provided it does not get a lot of heavy use and provided you fog it out properly for winter storage.

    100:1 is just not enough oil for heavy use ... even those brands which continued to use 100:1 recommend 50:1 for commercial use, nor does it leave enough oil to protect the motor during storage.

    As said if it does not run properly on 50:1 you have other issues to resolve.

  13. #13
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    Now why didnt someone just say that??

    I will revert to 50/1 which is a result really because my auxiliary is 50/1 so therefore no seperate tank needed now!

    Thank you all for your posts.

    I assume the plug gap is still 1 mm as thats what I have set with my NGK BZ7HS plugs.

  14. #14
    Supreme Mariner kenmyfam's Avatar
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    The only thing I don't like about that is the NGK plugs.
    There has been much debate here about spark plug manufacturers and which is the best. I personally stick with Champions and have never had an issue. Other members report otherwise.
    You pays your money and you takes your choice !!
    Marada 2100 Executive Series, 5 Litre V8 with Mercruiser Alpha 1 outdrive. 2007 K-Z Spree 260 RBH, all = a whole lot of family fun !!!!

  15. #15
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    The recommended plugs are, Champion QL77JC4, QL82C or L78V (surface gapped). coneventionall plugs should be gapped at 0.030" (0.7 to 0.8mm)

    The nearest NGK equivalent of QL77JC4 is BZ7HS-10,
    I dont see a direct equivalent of QL82C,
    but BUHW-2 is the equivalent of L78V.

    BZ7HS should do you fine (the -10 only indicates that they are supplied ready gapped to 1mm)

    "Q" and "Z" in the plug numbers indicate that they have low resistance inductive suppression. With OMC electronic ignition systems do not be tempted to use ordinary resistor plugs, such as BR7HS

  16. #16
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    OK, moving on from that, my needle valve is 12 full turns out from the carb.

    A boating colleague said that like other small engines, it should be about 1 and a half turns from the carb.

    This might explain the problems I had running a 50/1 mix previously? Maybe?

    Just wondering what setting their needle valve was for other folks on here.

  17. #17
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    The needle valve controls the fuel:air mixture ratio at low speeds ( Some engines also have one for high speed adjustment as well, others have all fixed jets with no adjustment)

    1 turns out from gently seated is the basic setting from where final slight adjustment is made with the engine running.

    The procedure is described in an Engine FAQ by Joe Reeves see http://forums.iboats.com/engine-frequently-asked-questions-faq/carb-needle-adjustments-asorted-carb-variations-joe-reeves-167352.html

    12 turns out is way further than it should be. If It will not run reasonably when closed down to about 1 turns then very probably your carb is in need of cleaning.

  18. #18
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    Default Re: Oil/Petrol Mixture Evinrude 25hp 1985 ??

    Thank you Vic.

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