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  • Old gas & how does a lawn mower generate spark & do timing?

    From Nick Cine@21:1/5 to All on Sat Apr 27 17:23:25 2024
    XPost: alt.home.repair

    Took apart the pull mechanism of my single-cylinder Craftsman push lawn
    mower today since it hasn't been used in a year and it wouldn't start in
    one pull and the recoil spring mechanism was not recoiling after the first
    pull (the cord just hung limp).

    https://i.postimg.cc/xjzzBZkW/lawnmower.jpg

    When I cleaned up the recoil mechanism & put it back together, I found some
    of last year's gasoline, and it worked just fine (so anyone who says you
    can't use old gas is gonna have to explain why it worked just fine for me today).

    After two or three pulls with the choke locked open (otherwise it slides
    shut too quickly), the motor started and after about ten seconds on choke,
    I removed the clamp I put on the choke lever to keep it in place.

    I cleaned out the air filter too and cleaned up old grass in the blade area (and a bunch of rope tangled around the driveshaft - I guess slowing down
    the blade is what makes the motor shut off since I defeated the shutoff mechanism due to it being a PITA as you always have to hold it on).

    Anyway, my question is I started to wonder how the spark is generated,
    and I wondered how a simple (Craftsman) lawn mower advances its timing.

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  • From Snag@21:1/5 to Nick Cine on Sun Apr 28 07:00:18 2024
    XPost: alt.home.repair

    On 4/27/2024 6:23 PM, Nick Cine wrote:
    Took apart the pull mechanism of my single-cylinder Craftsman push lawn
    mower today since it hasn't been used in a year and it wouldn't start in
    one pull and the recoil spring mechanism was not recoiling after the first pull (the cord just hung limp).

    https://i.postimg.cc/xjzzBZkW/lawnmower.jpg

    When I cleaned up the recoil mechanism & put it back together, I found some of last year's gasoline, and it worked just fine (so anyone who says you can't use old gas is gonna have to explain why it worked just fine for me today).

    After two or three pulls with the choke locked open (otherwise it slides
    shut too quickly), the motor started and after about ten seconds on choke,
    I removed the clamp I put on the choke lever to keep it in place.

    I cleaned out the air filter too and cleaned up old grass in the blade area (and a bunch of rope tangled around the driveshaft - I guess slowing down
    the blade is what makes the motor shut off since I defeated the shutoff mechanism due to it being a PITA as you always have to hold it on).

    Anyway, my question is I started to wonder how the spark is generated,
    and I wondered how a simple (Craftsman) lawn mower advances its timing.


    It uses a basic magneto , a magnet on the flywheel and a coil to
    generate the spark . Timing is static , there is no advance .
    --
    Snag
    "They may take our lives but
    they'll never take our freedom."
    William Wallace

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From AMuzi@21:1/5 to Snag on Sun Apr 28 08:33:50 2024
    XPost: alt.home.repair

    On 4/28/2024 7:00 AM, Snag wrote:
    On 4/27/2024 6:23 PM, Nick Cine wrote:
    Took apart the pull mechanism of my single-cylinder
    Craftsman push lawn
    mower today since it hasn't been used in a year and it
    wouldn't start in
    one pull and the recoil spring mechanism was not recoiling
    after the first
    pull (the cord just hung limp).

    https://i.postimg.cc/xjzzBZkW/lawnmower.jpg

    When I cleaned up the recoil mechanism & put it back
    together, I found some
    of last year's gasoline, and it worked just fine (so
    anyone who says you
    can't use old gas is gonna have to explain why it worked
    just fine for me
    today).

    After two or three pulls with the choke locked open
    (otherwise it slides
    shut too quickly), the motor started and after about ten
    seconds on choke,
    I removed the clamp I put on the choke lever to keep it in
    place.

    I cleaned out the air filter too and cleaned up old grass
    in the blade area
    (and a bunch of rope tangled around the driveshaft - I
    guess slowing down
    the blade is what makes the motor shut off since I
    defeated the shutoff
    mechanism due to it being a PITA as you always have to
    hold it on).

    Anyway, my question is I started to wonder how the spark
    is generated,
    and I wondered how a simple (Craftsman) lawn mower
    advances its timing.


      It uses a basic magneto , a magnet on the flywheel and a
    coil to generate the spark . Timing is static , there is no
    advance  .

    Difficult question about fuel. First off, there are various
    'gasolines'. Large metro areas have a very different blend
    (aka 'EPA gas') and summer fuel is different from winter
    fuel blend. And California is different again. Generally
    I've found no-ethanol fuel more stable for storage of a year
    or even two. Ethanol fuel can also grow mold in fuel bowls
    and lines after sitting a long while.

    In short, draining the system is good practice before
    storing an engine but not draining it may not be a serious
    problem.
    --
    Andrew Muzi
    am@yellowjersey.org
    Open every day since 1 April, 1971

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