Hard Start

Discussion in 'Mechanic and Repair' started by Jerry Chabino, Feb 28, 2005.

  1. Jerry Chabino

    Jerry Chabino LawnSite Member
    Posts: 7

    I have an 18 hp Briggs. The magneto went bad and I replaced it. Since then it is hard to start. I'm thinking I hosed up the magneto gap. Any ideas.?
    Should I increase the gap or decrease it ?

  2. Mikes Machines

    Mikes Machines LawnSite Member
    Posts: 112

    In general most coil air gaps for most engines are about 0.012". Loosen the coil mount bolts, put the feeler guage in between the flywheel and coil, push the coil up to the flywheel and tighten it down, remove the feeler guage then roll the engine over by hand to make sure nothing is going to rub.
  3. mudpie

    mudpie LawnSite Member
    Posts: 45

    air gap should be about 0.013 in.
  4. Mower Man

    Mower Man LawnSite Member
    Posts: 100

    When setting 'air gap', make sure you do it on the magnets.
    A business card, folded pieces of paper are not a proper tools.
    Preferred gap material is plastic, or a brass feeler guage.

    Air gap affects timing thru the building, and collapse of the magnetic field (flux), so it's important to get it within specs.
    Do it right.....so it's only done once.
  5. Jerry Chabino

    Jerry Chabino LawnSite Member
    Posts: 7

    Thanks for the advice guys. Soon as the weather breaks I'll be out there.

  6. Jerry Chabino

    Jerry Chabino LawnSite Member
    Posts: 7

    Big thanks to Mower Man, Mikes machines and Mudpie. Got out to the tractor and reset the mag (it was off). Runs like a scalded dog !!
    Thanks so much for your help.


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