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Reading spark plugs

Discussion in 'Technical Q&A' started by Irishman, Feb 10, 2008.

  1. Irishman

    Irishman F1 Rookie

    Oct 13, 2005
    3,486
    Raleigh
    Full Name:
    Kevin
    #1 Irishman, Feb 10, 2008
    Last edited by a moderator: Sep 7, 2017
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  3. mksu19

    mksu19 Formula 3

    Jan 4, 2008
    1,816
    LAX / YVR / MNL
    Full Name:
    Capt. K. Banzon
    Did that come off of an FI or Carbed?
     
  4. No Doubt

    No Doubt Six Time F1 World Champ
    Consultant

    May 21, 2005
    67,323
    Vegas+Alabama
    Full Name:
    Mr. Sideways
    Timings off. Detonation. Too rich or an oil leak. Possible ash fouling.

    Check out the pics in my spark plug thread in my signature below:
     
  5. Irishman

    Irishman F1 Rookie

    Oct 13, 2005
    3,486
    Raleigh
    Full Name:
    Kevin
    Wow! I read your spark plug thread. Holy smokes - what a thread. If nothing else I'm glad I could bump it.

    So, yes I should have provided more details. These plugs are not from my carb 308. These plugs are from my 20-year old carb Harley. I am currently doing the 120,000 mile service on it :):). Original motor. Stock intake, carb, plugs and ignition. I have owned it since new and all services have always been done on time, mostly by myself. I haven't done the timing yet. I always do that at the end of this big service. I have never found it off. The bike has been running good, though last year I had to replace the intake manifold gaskets due to a leak that became significant. The motor is an 80 cubic inch air-cooled setup in a V configuration. The front cylinder gets all the air and the "black" plug is from the front cylinder. The rear is definitely hotter and that's the one that has the half white porcelain. The only non-stock item are the pipes that had some baffling 19 years ago but probably is burned up as evidenced by the dang equipment violation ticket I got last September courtesy of the Virginia State Police.

    I do try to take care of my vehicles. But, plug reading is an area I need help. My 308 is running good from my limited viewpoint, but hell I threw three different kinds of plugs at it last winter based on research here. I know what I should do is pull them and see how they are doing. In my defense, here is what the Harley "experts" told me about re-jetting after new pipes:

    "Blip the throttle. It should return directly to idle. If it doesn't go directly to idle, such as producing hills or valleys by dipping below and/or idling above 950 rpm before settling there, then that indicates fuel mixture problem and re-jetting is necessary."

    My main concern has been about running too lean in either the bike or the 308. Anyway, glad I posted!

    Thanks,
    Seamus
     

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