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Spark Plug Questions

Discussion in 'XJ Technical Chat' started by Pizzaman, Sep 6, 2019.

  1. Pizzaman

    Pizzaman Member

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    When I first got my bike (550 Maxim) it was tough to start especially in cold weather. Spark Plugs looked decent and had a little under 5000 miles so I thought they were not the issue. However when I changed them the bike then started up with just a quick hit of the starter button. Recently the hard start issue has returned so today I changed them out again. Only about 2k on these plugs. Again this solved the problem and it fires up with a quick touch of the button.
    The gap was still in spec on the old plugs and they look pretty good. My thinking is I'm running lean and its burning them up? I took some pictures. Do I need to sign up with a hosting site to post them?
    Also anyone use those sandblaster spark plug cleaning tools with success? I remember my dad using one for chainsaws and lawn mowers back in the day.
     

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  2. Pizzaman

    Pizzaman Member

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    figured out how to upload picture. cylinder 1-4 left to right. I did notice number one header was cooler than others at start up before changing plugs
     
  3. XJ550H

    XJ550H Well-Known Member Premium Member

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    have you checked the spark plug caps they are resistor type and the wires may be a little corroded at the ends all would lessen the spark to plugs.

    I have a harbor freight spark plug cleaner works well.
    I pay under 2$ per plug for my 550 always have a new set on hand. then clean the old set
     
  4. Jetfixer

    Jetfixer Well-Known Member

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    You are lean and the gap looks off , I set mine at 0.32 . I'm not positive on the 550 looks like you are running 8 es at least on my 750 I run 7 es , the 8 is a hotter plug , I can't say for sure if this correct plug or not....my mistake I just looked it up the 8 is correct for the 550 ...are your mixture screws set at 2.5 turns out? That is best starting point.
     
    Last edited: Sep 7, 2019
  5. Polock

    Polock Well-Known Member

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    kind of hard to see but 2,3,4 look lean and 1 looks wet
    look at the wires and caps
     
  6. XJ550H

    XJ550H Well-Known Member Premium Member

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    550 spark plugs and gap

    .024 to .028 inch .6 to .7mm gap D8EA NGK plugs
     
  7. Pizzaman

    Pizzaman Member

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    Yes D8EA gapped at .024. They are pretty cheap and easy to replace so its not a big deal to replace them. All you people with starting issues I would recommend it. Can't believe the difference it makes for me. 2k miles though seems really low for lifespan.
    Thanks everyone. I will try trimming a little bit of the end of the wires. Sure does run great with the new plugs. Ran great with the old plugs just wouldn't start all that well.
    I'll also try cleaning /sandblasting the old plugs.
     
  8. a100man

    a100man Well-Known Member

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    could be a red herring or symptom - check your valve clearances
     
  9. Ryengoth

    Ryengoth Active Member Premium Member

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    An NGK 8 heat range is actually cooler running than a 7. The 'heat range' number is an inversion of the heat retention factor of the plug itself. It's a factor of the amount of insulator and metal exposed into the combustion space to help ignite the mix charge. The higher the number, the less stuff is exposed to the combustion area to retain heat.
     
  10. Pizzaman

    Pizzaman Member

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    Done this spring. Every one was tight but all in spec now.
     

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