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Carbon scoring

Post in 'The Gear' started by Sprinter, Sep 4, 2012.

  1. Sprinter

    Sprinter Minister of Fire

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    I was reading the thread on 5100 problems. Would you summarize what carbon scoring is and how to prevent it? I see talk of oil mixture, fuel mixture, bad gas, etc. I don't hear too much talk about carbon scoring on 4-strokes. Are 2-strokes more susceptible?

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  2. amateur cutter

    amateur cutter Minister of Fire

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    I'm going to assume that by carbon scoring they are referring to a piece of carbon breaking loose from the piston head & getting between the wall & piston. While possible I'd say highly unlikely. On a 5100 the most likely problem seems to be lean seizure. The saws come tuned way lean to meet EPA emissions specs. & promptly seize when put to work. Any two stroke will. I'm just guessing at the definition of carbon scoring here so take that with a grain of salt.

    If you own a saw, the 2 best things you can learn are tuning & chain sharpening imo. A C
    smokinj likes this.
  3. Danno77

    Danno77 Minister of Fire

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    carbon scoring would be from essentially combustion deposits. If you have more fuel than air, you are gonna get more deposits. If you have more oil than necessary, that can increase deposits. the scoring would come from those deposits breaking loose in there and scraping up the piston and cylinder walls. It definitely does happen.

    So, to recap:
    Deposits are usually from:
    1. Too much oil
    2. Running too rich.
  4. Sprinter

    Sprinter Minister of Fire

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    Well, I re-read the 5100 thread and I must have picked up the term "carbon scoring" somewhere else and assumed those 5100 problems were carbon related, so I was wondering how too lean a mixture could cause carbon build-up and scoring. Apparently those scoring problems were from burned piston heads or valves or something like that.

    I'm still wondering if I should richen my mixture or not (Husq 440e). It's as it came from the dealer who did run it before giving it to me (although I don't know how thorough he was, since the chain was on backwards when I got it:rolleyes:). I just don't want to overdo it, I guess.
  5. amateur cutter

    amateur cutter Minister of Fire

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    Have a look @ the Madsens Vid, Jay posted a link to it in a different thread. Good tutorial on tuning. A C
  6. Highbeam

    Highbeam Minister of Fire

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    Holy cripes!! !That right there tells you what we think about husky saws in the northwest. Even the dealer thinks you would be better off with the chain on backwards.
  7. Danno77

    Danno77 Minister of Fire

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    you can overdo it, but the first time you foul your plug you'll know you are running it too heavy. Then you'd come on the forum and we'd tell you to take it apart and clean it real good and lean it out a little. then you'd be set. Now, if you just keep replacing plugs, that means you are building up a nice heavy carbon coat in there and just asking for problems with plugged muffler screens and dangerous scoring potential.

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