starting Lawn-boy problems

Discussion in 'Mechanic and Repair' started by calhoontuna, Sep 27, 2005.

  1. calhoontuna

    calhoontuna LawnSite Member
    Messages: 7

    Have an M-Series Lawn-boy that I am having trouble starting. Two stroke.

    When I pull the cord either nothing happens or the thing backfires (w/ choke closed).

    Before this, I replaced the magnito/spark plug wire because the spark plug wire had gone bad. The mower had been getting progressively harder to start all Summer so perhaps my problems were more then just a bad magnito.

    Used a business card to gap the magnito from the flywheel and it seems to be working right because I am getting a spark.

    I also checked the flywheel key and it looks fine.

    I took apart the carburator and everything seems to be moving fine (though I may not have gotten the two screws on top to their original positions).

    Took off the muffler to make sure it wasn't clogged. It isn't.

    Is there anything else I could try/test to try to get this thing started again?

    One thing: when I pour gas directly into the spark plug hole, replace the spark, and pull the cord, the thing doesn't so much as briefly sputter.

    Any suggestions?

    Thank you for your time,
  2. MBDiagMan

    MBDiagMan LawnSite Senior Member
    Messages: 852

    You say you are getting spark. Is it a fat blue spark or an orange spark? If orange, then the spark is weak.

    The only other things would be lack of compression or timing problem. Have you done a leak down test?

    Good luck,
  3. calhoontuna

    calhoontuna LawnSite Member
    Messages: 7

    No, it's blue with some flecks of orange. I would not call it fat by any means.

    What is a leak down test?

  4. lawnmaniac883

    lawnmaniac883 LawnSite Silver Member
    Messages: 2,613

    Dont worry about a leak down test on a two stroke, if you want to check the pressure being built up, then by all means do so with the proper equipment (forgot name of test instrument) but I think your problem is a timing issue. Did you perhaps replace the magneto upside down?
  5. Lawn Masters

    Lawn Masters LawnSite Senior Member
    Messages: 850

    Its possible that the problem is relating directly to timing, and I suspect that myself from what you describe. try replacing the flywheel key, and adjusting the air gap on the coil of this engine to the thickness of a matchbook cover, not a business card. the matchbook is more likely to get the gap right, and you'll probably get a better spark from it then.
  6. calhoontuna

    calhoontuna LawnSite Member
    Messages: 7

    No luck.

    I replaced the flywheel key and gapped the magnito with a matchbook. Still does the same thing.

    Could the timing be screwed up at some other, deeper, level?

    What do you make of the fact that the sparkplug seems dry after a few pulls. I checked and the gas is getting as far as the carburator fine.

  7. jeffex

    jeffex LawnSite Bronze Member
    Messages: 1,933

    ignition module

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