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  1. #1
    Platinum Member PhilNH5's Avatar
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    Jan 2002
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    786
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    SE NH
    Tractor
    Kubota B3000HSDCC

    Default How long to clear a flooded chainsaw?

    Last night I went to cut some firewood. It rained all weekend so I was antsy to get back on schedule. Between suiting up in safety gear and collecting the saw, wedges. files, etc and just plain being excited to be getting some work done I flooded the chainsaw.

    It is a Stihl 025C and I am sure I pushed the primer bulb twice the recommended amount. I could smell the gas as I pulled the cord. Okay it is obviously flooded. Put the saw down and force myself to take a 10 minute break. Didn't work so in 5 minutes I am trying again - minus the priming. Still no luck. So I force myself to take another 10 minute break (from what? - I haven't done any work yet.) Still no start. Utter a few choice words and put everything away. Started raining anyway.

    Go back out 2 hours later to test - no go. Go out first thing this morning and the saw started right up.

    So how long should it take. Is the diaphragm carb in a chainsaw the reason it takes so long to "dry out" or is it because the 2 cycle mix slows it down?

    Phil

  2. #2
    Veteran Member
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    Feb 2003
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    1,121
    Location
    Thurmont, Maryland
    Tractor
    TC35D w/ SS

    Default Re: How long to clear a flooded chainsaw?

    There is nothing like tiring yourself out trying to get a tool started.. usually my Stihl will start right up.. when it doesn't.. a dirty air filter needed cleaning. This Stihl was my father's and has seen it's fair share of work.. I just hit it w/ startup spray.. and avoid tiring myself out before I even get started.

    If you want to dry-up the carb faster.. removing the air filter should help.

  3. #3
    Veteran Member
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    Jun 2004
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    1,436
    Location
    Byron New York
    Tractor
    2004 BX2230

    Default Re: How long to clear a flooded chainsaw?

    Phil,

    Typically what I've done in the past is to take the plug out, dry pull the starter a few times to dry the cylinder out and put the plug back in and give it a try with no choke. Too much fuel won't allow the spark to ignite if it has no oxygen in it.

  4. #4

    Join Date
    Jan 2005
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    247
    Location
    Maryland
    Tractor
    BX23

    Default Re: How long to clear a flooded chainsaw?

    another thing you can do if you are really really careful is to take the plug out and while pulling the starter cord slowly with one hand light a lighter and hold it behind the hole the sparkplug screws into, it will burn the excess gas out of the cylinder

  5. #5
    Super Member Highbeam's Avatar
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    Feb 2005
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    South Puget Sound, WA
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    Kioti CK30HST

    Default Re: How long to clear a flooded chainsaw?

    I treat the 2-stroke saw like my big bore 4 stroke dirt bikes. When I tip them over, don't ask, they flood out. I open the throttle fully and spin the engine ten kicks and then then I give it a try.

    On any engine that I believe is flooded, I do not sit around waiting for fuel to evaporate. I purge the cylinder with as lean a mixture as I can produce. No choke and full throttle.

  6. #6
    Veteran Member
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    May 2001
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    2,385
    Location
    Michigan
    Tractor
    New Holland TC40D Supersteer

    Default Re: How long to clear a flooded chainsaw?

    </font><font color="blue" class="small">( I purge the cylinder with as lean a mixture as I can produce. No choke and full throttle. )</font>

    How does full throttle produce a lean mixture? I would expect a lean mixture to come from no throttle and no choke.

  7. #7
    Elite Member hazmat's Avatar
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    Feb 2002
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    4,028
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    West Newbury, MA & Harrison, ME
    Tractor
    Kubota L5460HSTC

    Default Re: How long to clear a flooded chainsaw?

    <font color="blue">How does full throttle produce a lean mixture? I would expect a lean mixture to come from no throttle and no choke. </font>

    The throttle meters fuel/air mixture - full throttle is "open" - ie maximum fuel/air available - idle is "closed" - least amount of fuel/air available.

    The venturi effect draws different amounts of fuel depending on vaccum - higher engine speed = more vacuum = more fuel.

    When starting you have max available air, but the engine isn't spinning fast (starting from 0) - so you aren't drawing as much fuel = lean mixture. This is why there is a "choke" - to cut off the air intake making for a richer, eaiser to combust mixture.

    Therefore - the leanest condition for starting is full throttle, no choke.

    Wow - actually putting my Internal Combustion engines class to practical use... [img]/forums/images/graemlins/cool.gif[/img] [img]/forums/images/graemlins/tongue.gif[/img]

  8. #8
    Super Member Highbeam's Avatar
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    South Puget Sound, WA
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    Kioti CK30HST

    Default Re: How long to clear a flooded chainsaw?

    I couldn't have said it better myself. A dead or slowly spinning engine isn't sucking hard enough to pull fuel out of the carburetor while the throttle blade is wide open. This will purge the engine rapidly.

    Cars have an accelerator pump in the carburetor that squirt fuel in with each application of throttle. So don't go pumping the pedal on a car/truck with a flooded engine. Put the hammer down and leave it down while clearing the flooded engine.

    When you have the choke applied to a bike or saw engine and you give it full throttle, you are getting maximum fuel delivery since the air supply is cut off but the fuel supply is wide open. You will flood the saw quickly but on a big bike, this step precharges the cylinder with a good mess of fresh fuel to help keep it running long enough to get a good flow of mixed fuel and air out of the carburetor.

    You learn a lot about carburetor function when riding a big bore, kick started, four stroke motorcycle and crashing it every now and then.

  9. #9
    Veteran Member
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    Feb 2005
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    Olathe, Ks
    Tractor
    Yanmar 1602D

    Default Re: How long to clear a flooded chainsaw?

    Maybe so, but factory made cars haven't come with carbs in 20 years or so.................

  10. #10
    Super Member Highbeam's Avatar
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    South Puget Sound, WA
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    Kioti CK30HST

    Default Re: How long to clear a flooded chainsaw?

    That's OK, I've only been alive for 20 years or so.

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