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  1. #1

    Default What spark plug do i need for Johnson 25 hp outboard

    What spark plug do i need for Johnson 25 hp outboard engine tipe is: 25bf78c
    as the title says i dont know how to find if the spark plug its the exact code that i need for this engine.
    So can you please help me find out, if you have the NGK or Champion code.
    Thank you !

  2. #2
    Fleet Admiral HighTrim's Avatar
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    Default Re: What spark plug do i need for Johnson 25 hp outboard

    Use Champion QL77JC4 gapped to 030

  3. #3

    Default Re: What spark plug do i need for Johnson 25 hp outboard

    Quote Originally Posted by HighTrim View Post
    Use Champion QL77JC4 gapped to 030

    can i ask why champion and not NGK?
    [URL="http://http://i701.photobucket.com/albums/ww11/NEWORLEANS-YAT/salty.jpg"]

  4. #4
    Fleet Admiral HighTrim's Avatar
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    Default Re: What spark plug do i need for Johnson 25 hp outboard

    Champions are what Johnson designed the motor to run on.

  5. #5

    Default Re: What spark plug do i need for Johnson 25 hp outboard

    Quote Originally Posted by HighTrim View Post
    Champions are what Johnson designed the motor to run on.
    should i get rid of the NGK's, will there be a difference going with the Champions?
    [URL="http://http://i701.photobucket.com/albums/ww11/NEWORLEANS-YAT/salty.jpg"]

  6. #6
    Rear Admiral rolmops's Avatar
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    Default Re: What spark plug do i need for Johnson 25 hp outboard

    If you can't find the QL you can also run it on the L series the Q just means that the plug has a resistor inside that prevents electronic feed back to your boats electronics (fish finder,gps).
    For the few dollars that 2 plugs cost,it is a good idea to get the right plugs and those are Champions.
    Make sure the plug is in

  7. #7
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    Default Re: What spark plug do i need for Johnson 25 hp outboard

    You may use NGK as long as they have no 'R' in the specification. Resistor plugs used in the Evinrude/Johnson engines may lead to powerpack failure. he recommended plugs for that engine are Champion L77JC4 or QL77JC4.

  8. #8

    Default Re: What spark plug do i need for Johnson 25 hp outboard

    Quote Originally Posted by Haffiman View Post
    You may use NGK as long as they have no 'R' in the specification. Resistor plugs used in the Evinrude/Johnson engines may lead to powerpack failure. he recommended plugs for that engine are Champion L77JC4 or QL77JC4.
    crap mine have "R'' in them
    [URL="http://http://i701.photobucket.com/albums/ww11/NEWORLEANS-YAT/salty.jpg"]

  9. #9
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    Default Re: What spark plug do i need for Johnson 25 hp outboard

    Pulled out this answer from here:
    http://www.wmi.org/bassfish/bassboar...sage_id=188390

    ' types of plugs from seahorse (216.97.214.134) 12/3/2001 7:07:00 PM
    The OMC ignition systems are made for a suppressor type plug, which is different than a resistor plug. A suppressor sparkplug has a small coil of wire that restricts high frequency AC current as the spark jumps the plug gap. It doesn't affect DC current. A resistor plug restricts both AC and DC current and weakens the spark energy. A regular plug without a resistor or suppressor, has a shorter spark duration and can feed larger amounts of AC current back to the pack thru the coil induction. This may cause ignition problems down the road. A 225 HO OMC needs a suppressor plug, Champion QL78YC. The letter Q in a Champion signifies a suppressor style, and R is a resistor type plug.

    About a year ago, Bass and Walleye mag had a story on the different types of plugs and why they were needed with different motors.


    Right off the NGK site.. from Thunder Runner 12/3/2001 8:07:00 PM
    Inductive Resistor Spark Plugs Specified as original equipment in a variety of late-model outboard engines, spark plugs with an inductive resistor are utilized when a CDI (capacitive discharge ignition) system is used. The resistor plug is necessary to reduce radio frequency interference (RFI), to prevent interference with the sophisticated electronics onboard modern boats.

    Most resistor spark plugs use a "monolithic" resistor, generally made of graphite and glass materials, to filter the electrical voltage as it passes through the center electrode. This "filter" reduces RFI to an acceptable level. Although this type of resistor develops from 1000 to 5000 ohms of resistance, there is no significant loss of voltage to affect ignitability at the electrodes in modern automotive ignition systems.

    However, outboard marine engines utilizing a CDI system have a much lower voltage output, which would be compromised by a standard resistor plug. Therefore, an inductive resistor is used. In this method, a coiled nickel wire is inserted into the center stem, and held in place by a spring.

    This coil basically acts as an electromagnet, inducing a magnetic field around the center stem, creating a natural "field" resistor, and reduces RFI to acceptable levels. This method creates only 40 ohms of physical resistance, compared to the 1000 to 5000 ohms of resistance in "monolithic" resistor plugs.

    While NGK Inductive Resistor Spark Plugs cost more than standard resistor plugs, they provide major benefits in late-model marine outboard applications.

    John M Richied

  10. #10

    Default Re: What spark plug do i need for Johnson 25 hp outboard

    wow thanks, I am changing them tomorrow before going out. Do auto parts stores carry these? (champions)
    [URL="http://http://i701.photobucket.com/albums/ww11/NEWORLEANS-YAT/salty.jpg"]

  11. #11

    Default Re: What spark plug do i need for Johnson 25 hp outboard

    should i run the QL77JC4 or the L77JC4?

    what is the difference?

    i have a 86 28 SPL Johnson

    thanks
    [URL="http://http://i701.photobucket.com/albums/ww11/NEWORLEANS-YAT/salty.jpg"]

  12. #12
    Seaman
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    Default Re: What spark plug do i need for Johnson 25 hp outboard

    Napa

  13. #13
    Seaman
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    Default Re: What spark plug do i need for Johnson 25 hp outboard

    My 2000 Johnson 25 owners manual specifies Champion QL77JC4. I would stick with what the manufacturer reccomends.

    Skidz

  14. #14

    Default Re: What spark plug do i need for Johnson 25 hp outboard

    Quote Originally Posted by Skidz View Post
    My 2000 Johnson 25 owners manual specifies Champion QL77JC4. I would stick with what the manufacturer reccomends.

    Skidz
    thanks man, and for all that helped me in this thread. much appreciated.
    [URL="http://http://i701.photobucket.com/albums/ww11/NEWORLEANS-YAT/salty.jpg"]

  15. #15

    Default Re: What spark plug do i need for Johnson 25 hp outboard

    thank you very much, dint expected for so much help, which its greatly apreciated !

    Btw for this engine i want to change oil, i am thinking to use Castrol Outboard 2t.Its this ok? and how much do i need to put ?
    thanks again to all who replied

  16. #16
    Fleet Admiral HighTrim's Avatar
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    Default Re: What spark plug do i need for Johnson 25 hp outboard

    50:1 Regular 87 ocatane gasoline to TCWIII outboard oil

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