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  1. #1

    Ultra 250X/260X/300X Spark Plug Torque

    Use a torque wrench and tighten to the factory torque spec when installing spark plugs on your Ultras.


    Not only the properly torqued plugs would come out easier later, but also they ensure the peak performance of your Ultra’s engine. Over-torqued plugs are more likely to develop an internal crack causing intermittent "no-spark" condition. Have you ever heard or experienced Ultra 250/260/300 suddenly running poorly, and then runs better right after replacing the plugs? And then, you wonder, “Why does Ultra go through plugs like 2-strokes?” That’s because one or more of your spark plugs have the internal crack and they are not firing.

    Through the crack in the spark plugs center core ceramic insulator, the current will find an easier route (with less resistance) to find the ground, instead of trying to jump the ground electrode gap. When that happens, you are running on either 3 cylinders only or less.
    Supercharged engine's peak combustion pressure is approximately 56% higher than that of the same N/A engine. More fuel/air in the same volume combustion chamber (1498 cc, same as 15F) means higher combustion pressure even though compression ratio is substantially less, Ultras 7.8 (250/260), 8.4 (300) vs. 15F’s N/A 10.6. The NGK PMR9B spark plug for Ultras is specifically designed for such high combustion pressure engines against the possible internal cracking. That's when the proper plug installation torque becomes critical - you don't want to induce any unnecessary stress on the plugs by over-tightening them. According to NGK, only 2 vehicle manufacturers use the PRB9B plugs. Kawi (on their Ultras) and Maserati's first gen supercharged 405 HP 4.2L V8 Gran Turismo in 2007 (now 4.7L making 440 HP) , Quattroporte, etc. Do yourself a favor and use a torque wrench on plugs next time. After all, it's your ski.


  2. #2
    CJ River Rider's Avatar
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    Great advice about over-tightening. I learned this the hard way yesterday winterizing my 15F and getting lazy/stupid by not checking the manual and snapping the last one after fogging. 5 years winterizing this ski I should have known better. I'm going to re-torque 3 others as I don't want any "intermittent no-spark conditions" as you mention in your write-up. Thanks again for the great advice.

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  3. #3
    nicjak's Avatar
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    wow even ngk suggest antiseize you would think if they were against copper based they would say so!!! http://www.ngksparkplugs.com/pdf/tb-...1antisieze.pdf

  4. #4
    steve45's Avatar
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    Is that torque spec for wet or dry installation? It's important to remember that there are two ways to measure plug tightness: torque, and rotation after initial seating. The second method must NEVER be used if you are re-using the gasket. New gaskets are always recommended.

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  6. #5
    nicjak's Avatar
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    common sense prevails for most that actually know what they are doing. most spark plug mishaps happen to guys that think they can do everything just by reading it on the inet or in a book. plain and simple some should never be given tools of any kind.

    Quote Originally Posted by steve45 View Post
    Is that torque spec for wet or dry installation? It's important to remember that there are two ways to measure plug tightness: torque, and rotation after initial seating. The second method must NEVER be used if you are re-using the gasket. New gaskets are always recommended.

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  8. #6
    LITTLEZ187's Avatar
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    Do you guys add anti seize on your plugs?

  9. #7
    "just sayin".. jetdave56's Avatar
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    Yep ,I believe most do,there's mixed feelings whether to torque to specs do to anti seize application making reading possibly inaccurate or just hand tighten and then some (1/4 more)

    I anti seize then hand tighten then tighten down to specs 9.6 ft-lbs..
    Last edited by jetdave56; 01-17-2015 at 08:56 PM.

  10. #8

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    Quote Originally Posted by nicjak View Post
    wow even ngk suggest antiseize you would think if they were against copper based they would say so!!! http://www.ngksparkplugs.com/pdf/tb-...1antisieze.pdf

    Yeah, I once thought copper should not be used and now agree it wouldn't matter.

  11. #9
    Quote Originally Posted by nicjak View Post
    wow even ngk suggest antiseize you would think if they were against copper based they would say so!!! http://www.ngksparkplugs.com/pdf/tb-...1antisieze.pdf
    Hi Nic

    I put in new plugs in my 300x maybe 8 hrs ago, all is good I torqued them to spec 13Nm, but my question is can I remove them to add some anti seize, and then put them back in? or will the ring gasket at the bottom the spark plug become ineffective if torqued twice? Also I ride in fresh water only. Do I need anti seize? Anyways just a copper coat type anti seize will do?

    Thanks

  12. #10
    I Come from Automotive background and I use never seize on spark plugs if I have Brassica us it. you have no idea what a pain in the ass it is to remove a broken spark plug from inside the cylinder but my question is any thoughts about spark plugs itself I went to Advance Auto Parts to get new spark plugs they price them out for $90 I went to for the generic brand for auto lights for $2.75 For 1The manual says to run NGK which I would agree with but not for $15 for one well I'm going to run it up until it is knocking or misfiring my question to everybody agree or disagree

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