Briggs/Stratton 4 hp Quatro

Discussion in 'Home Repair' started by Puddin' Man, Mar 30, 2007.

  1. Puddin'  Man

    Puddin' Man Guest

    Briggs/Stratton 4 hp Quatro

    On an MTD 21 " mower, maybe 8 years old.

    For several years, even right after disassembling/cleaning
    air filter, carb, changing oil, etc etc, it'll start up
    and run steady for about 10 seconds, then it revs up and
    down (almost killing) in an endless cycle. About 30% of
    similar B&S mowers I see running in the 'hood do the
    same thing. Oh, and, of course, it fouls spark plugs.

    I cleaned it up last fall. Start it up this spring, does
    the same thing, but, after reaching minimum rpm, it
    clanks while trying to rev up again. Sounds like serious
    pre-ignition or even a flogging rod knocking. Motor has
    had no hard use: I mow my little lawn at an idle.

    Anybody got a handle on such behavior? Smokes a little
    only when first started. Compression feels OK.

    Cheers,
    Puddin'

    "Life is nothing but a competition to be the criminal rather
    than the victim."
    - Bertrand Russell
     
    Puddin' Man, Mar 30, 2007
    #1
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  2. Puddin'  Man

    Puddin' Man Guest

    I kinda figgered ...
    Approximate weight of blade assy? Approximate weight of FAM?
    Maybe it's "half a flywheel"? :)
    OK ...
    Thanks. I guess I'll start by pricing the Honda's.

    Tecumseh's are no less a PITA?

    P

    "Life is nothing but a competition to be the criminal rather
    than the victim."
    - Bertrand Russell
     
    Puddin' Man, Apr 1, 2007
    #2
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  3. Puddin'  Man

    DanG Guest

    The Honda is prone to the exact same problems.

    You either need to buy, own, and learn to use the tools to deal
    with a lawn mower engine, or you hire someone else to do it for
    you, or you buy a new lawnmower as necessary. Simple choices.

    Honda engines are very well made and would be my engine of choice,
    but they also need attention.
     
    DanG, Apr 1, 2007
    #3
  4. Puddin'  Man

    Puddin' Man Guest

    Absolutely! :)
    Is true, is true. Mea Culpa!

    Only thing is, it hasn't run properly for years, and:

    And there's no mixture adjust on the "carb", etc etc.

    And when I post a query -here- as to why it fouls plugs, revs
    up and down, etc, I get 100 zillion blank stares. :)

    So, question becomes, how much do I wanna invest in tools, etc
    to repair/maintain my B&S? Prevalent evidence indicates they
    (say, 3.5-6 hp, enyway) were designed as throw-aways.

    Thx,
    Puddin'

    "Life is nothing but a competition to be the criminal rather
    than the victim."
    - Bertrand Russell
     
    Puddin' Man, Apr 1, 2007
    #4
  5. Puddin'  Man

    Puddin' Man Guest

    Having had a Honda (not a mower) in the garage these
    last 19 years:

    "I Believe Every Word You Say!" :)

    Puddin'

    "Life is nothing but a competition to be the criminal rather
    than the victim."
    - Bertrand Russell
     
    Puddin' Man, Apr 1, 2007
    #5
  6. Puddin'  Man

    clivver

    Joined:
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    Found out that there is a plastic duct that connects from the carb to the engine, it was broken allowing air in and destroying the negative pressure needed to draw fuel. Engine was revving and dying every second and a half, never stopped and worked better under load for some reason.
     
    clivver, Aug 27, 2018
    #6
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