Carbon on spark plug?

Discussion in 'Lawn Mowing' started by Gruneich Lawn Care Inc., May 15, 2002.

  1. Gruneich Lawn Care Inc.

    Gruneich Lawn Care Inc. LawnSite Senior Member
    from SD
    Messages: 295

    I have a Exmark Turf Tracer with a 22hp Kohler Command, I had it tuned up at the begining of the year. When I would start it, it sometimes blows some blue smoke at startup, and sometimes when you pull it down to slow the RPM's down. Today it started to run really bad, it sounded like it was not firing on one cylinder, so I pulled the plugs, and one plug was fine, but the other plug was so full of carbon deposits and other junk that there was hardly any room for the spark to fire. So I replaced both plugs and it runs alot better. What my questions is what caused the plug to get that bad and full of carbon?

  2. 2 man crew

    2 man crew LawnSite Senior Member
    Messages: 403

    It could be a number of things. But the first thing that comes to mind is a bad ring or valve.
  3. I'm thinking the same place as 2 man crew.
    Do a compression test to check for these problems
  4. awm

    awm LawnSite Gold Member
    Messages: 3,354

    sounds like two different things . one the motor may be showing u some wear.
    thats the start up smoke etc. the command is a good engine tho and may have a lot left in it. two sounds like carb or gas problems.the black carbon could just have happened because of weak spark on bad gas or what ever.the one plug was strong enough to ignite the poor gas .the other mabe the others said,it could be a number of things .these are just things, ive seen that turned out not to be to serious
    hope its something simple like that.
  5. danzig

    danzig LawnSite Member
    Messages: 103

    I had the same problem with my 20 horse kohler. At 750 hours the rings were bad. I change oil and filter every 40 hours but things like this happen. Get the new air filtration system that kohler now uses on its engines. The old style single air filter is not large or dense enough to keep out dirt. Good luck!!

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