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Thread: Plug issues?

  1. #1

    Question Plug issues?

    Guys; I just pulled my plugs at 5 Hrs. I placed a brand new identical plug right next to the used plug. See pics below. The new plug is an identical NGK PM9RB. My 250 runs great; I just wanted to see what a 5 Hr. plug looked like.

    Observation: The new plug's washer is about .5mm thicker than the stock plug (new plug is on top). Can this cause a problem? The electrode will be that much deeper into the cylinder..

    Also, there is a good amount of carbon on the end of the threads. Is this normal? My Honda ran it's first 10 hours on too much oil and it looked similar, but I may be overreacting given all of the oil level confusion. Should I put the new plugs in for kicks?

    Anyone else want to post pics of their new or used plugs to compare?

    Thanks, LB






  2. #2
    The washer is thicker because it hasn't been compressed yet, that's the purpose of it. Your old plugs look fine to me, running a little rich by I suspect that's by design. At the price of those plugs, I certainly wouldn't change anything out yet or if you do, send me your old ones

  3. #3
    He's totally right, It needs to be compressed is all

  4. #4
    blownhotrodder's Avatar
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    Plug looks fine to me.

  5. #5
    Silence! I Keel You! earthshaker's Avatar
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    To properly "read" plugs, you must be WOT for ~5 minutes (which IMO is actually a little long) then hit kill @ WOT, then pull plugs and read the ring near the bottom of insulator.

  6. #6

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    Wink

    Quote Originally Posted by earthshaker View Post
    To properly "read" plugs, you must be WOT for ~5 minutes (which IMO is actually a little long) then hit kill @ WOT, then pull plugs and read the ring near the bottom of insulator.

    Haaa........
    That`s an old method to read main jetting of your carburetor....
    That does not apply to today's modern fuel injected engines.
    You can use this method for all RPM ranges on today's F/I motors.
    It wont tell you much, but you`ll get a good idea of overall mixture/burn condition of the plugs.

  7. #7
    Silence! I Keel You! earthshaker's Avatar
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    the real deal is that you can't adjust, however the read still rings true.

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