Need plug gap for 25 merc 2 cyl .....champion QL78YC

Discussion in 'Outboard Maintenance' started by richg99, Nov 4, 2010.

  1. richg99

    richg99 1652 G3; Malibu Mini-X kayak

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    I have searched the web to no avail. Any help appreciated. thanks Rich
     
  2. Brett

    Brett > PRO STAFF <

    Your model in here?

    http://www.dixiemarinesales.com/Spark_plug_Reference_Mercury.aspx
     

  3. richg99

    richg99 1652 G3; Malibu Mini-X kayak

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    Yea, the model is in there..but...they only show NGK plugs. I have a cross-referenced Champion QL78YC. I may have to take it back and try to find a NGK. It really shouldn't be this hard to find a plug gap, though...should it? thanks for trying. Rich
     
  4. Brett

    Brett > PRO STAFF <

    Same gap for both resistor and non-resistor plugs
    what's shown should work fine for yours.
    No real difference between plugs,
    gap is to get the right spark in order to properly ignite fuel/air mix
    Unless you have a gapless plug...

    NGK BPR8HS - CHAMPION QL78YC Equivalent
     
  5. richg99

    richg99 1652 G3; Malibu Mini-X kayak

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    OK Then, you are saying that, if the NGK shows a gap of .040 (which the chart shows) then I can use the same gap for a Champion branded plug??? thanks Rich
     
  6. richg99

    richg99 1652 G3; Malibu Mini-X kayak

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    Thank you, as always.... Rich
     
  7. Jared_Traina

    Jared_Traina I Love microskiff.com!

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    CHECK YOUR GAPPING! I called merc to ask them a gapping for NGK plugs on my 2002 9.9 Merc. They told me 35 thousandths. Tried that and the engine ran like crap. After looking more closely on a tiny little sticker on the block, I found that the gap should have 60 thousandths. Just a thought on checking. I have also had a big performance difference in other motors I have owned when switching from Champion to NGK.
     
  8. Brett

    Brett > PRO STAFF <

    I like having the correct information when working on my outboards
    which is the reason why I buy the Factory Service Manual when I buy an outboard.
    Saves me time and money in the long run.

    A recent post in this section listed a link to older manuals, for free.
     
  9. richwalker71

    richwalker71 Well-Known Member

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    I found my service manual (for this same motor) on E-bay for $7 on disk. Shipping included!
     
  10. Peter2006

    Peter2006 I Love microskiff.com!

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    Use NGK plugs instead and use what they say for a gap. usually .040 on those. Some are .035
     
  11. richg99

    richg99 1652 G3; Malibu Mini-X kayak

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    Thanks, I did buy some of the NGK's and they were pre gapped to .040. Also received that gap info from another site. regards, Rich
     
  12. jgregory01

    jgregory01 I Love microskiff.com!

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    Silly question perhaps. I have been running the L78YC in my 99 johnson for over a year now. That is what they had when I bought my boat used. My mechanic said they should have the QL78YC. He explained that they are longer and fire more into the cylinder.

    My question though is will there be a difference? Anything that I can notice. I never noticed a problem to begin with. Will there be a benifit?