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  1. #1

    spark plug talk:

    I recently changed out the plugs in my GTX SC. I have IXU24`s since my ski is not heavily modded. Before I removed the plugs I started up the engine a few times and let run for about half a minute so I can get a decent compression check.
    cylinder #1 = 132psi, #2 = 130, #3 = 132, not bad for an engine that ate ceramics and has over 109+ hours on it.
    since I`ve been following Nitro`s plug thread over in the Honda section, I sent Shawn a PM describing the appearance of all three plugs.
    The porcelins are white, electrodes themselves are clean, which is what I expected since they have only 30+ hours on them. But under a magnafying glass I can see what looks like Pepper on the center porcelin. it doesn`t seem to be all the way around the porcelin but looks like it was in the flame path or propagation path, like if you were indexing the plugs.
    Shawn does explain that it appears to be detonation , bits of piston top sticking to plug as it cools, slowly erroding the piston tops like sandbalasting is how I`d describe it. I didn`t think I`d have to fatten up the AF ratio since I`m only using a R&D air filter along with a race tech retro-fit thru hull pipe, but it seems so. So just to be on the safe side I`m prolly gonna go with the rotax fuel press reg to up the fuel a bit...
    Thought I`d share my PM with Nitro with you guys.

    Shawn please feel free to add comment!...PR...Thanks...


  2. #2
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    It wouldn't hurt to use IXU27 plugs either. They are a little cooler running than the 24's. Poor fuel will also help cause detonation. If you can dump a little more fuel in, that to will help cool the incoming mixture charge.

    From what you describe, I would'nt be in a panic but, i would keep a eye on things so they don't get out of hand.

    Shawn

  3. #3
    gtxscrider's Avatar
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    im not sure of the model number but i use some type given to me by ppg iridiums there supposed to be better than stock.

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    i use Denso IXU27 in my stage 3 Rude 2007 RXP and now after reading above if i SHOULDNT try the Denso IXU24 as it being the HOTTER plug according to NITROSHARK maybe it would help burn a LITTLE more of the FUEL in my boat hence a bit hotter ignition and add a FEW RPM?????????? or am i risking the HEAT FACTOR of the HOTTER plug with my set up??? i have the Rude fuel controller as well for safety! anybody?????

  5. #5

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    Quote Originally Posted by REID2168 View Post
    i use Denso IXU27 in my stage 3 Rude 2007 RXP and now after reading above if i SHOULDNT try the Denso IXU24 as it being the HOTTER plug according to NITROSHARK maybe it would help burn a LITTLE more of the FUEL in my boat hence a bit hotter ignition and add a FEW RPM?????????? or am i risking the HEAT FACTOR of the HOTTER plug with my set up??? i have the Rude fuel controller as well for safety! anybody?????
    the heat range of a plug has to do with how fast it conducts heat away from the electrode, not how hot the spark is. If you go too hot of a plug it can deteriorate and cause detonation, too cold and it will not stay hot enough to clean itself off.

  6. #6
    REID2168's Avatar
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    since my plugs seem to be a dainty light brown after about 6 hours i will leave it alone! they are NOT white or grey so i will stay where im at then as i have NO other idea how to evaluate it then and would rather NOT play with it! appreciate the information!

  7. #7
    REID2168's Avatar
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    cold u or would u if u used an A/F ratio meter see a difference in the two plugs or in plugs in GENERAL if there was a vast difference in either a detonation problem or a NO HEAT type isse? thanks

  8. #8
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    The only disadvantage If you run too cool of a plug is , it will foul. but If you run too hot of a plug you will cause all kinds of problems, including detonation and a possible meltdown.

    Rule of thumb.. go one step cooler (at least) for every new power adder you have.


    sg

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