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Briggs 31C707-1346-B2.

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mutt07
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2022/12/12 18:05:02 (permalink)
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Briggs 31C707-1346-B2.

First off. Hello everyone. I’m mutt, pleased to meet you all. Thanks for allowing me to join. Hopefully this question hasn’t been asked before. This is my first forum. I apologize if it’s been asked. On the above Briggs engine, with a Nikki 209 carb, can anyone tell me where the low speed jet would be. I’ve watched some YouTube vids but where they are drilling out a “low speed jet”, there isn’t one on mine. This carb started surging soon after my son purchased it very used while I was trying to mow. I figured it was leaning out so I finished up riding on medium choke. Took the carb apart and the only “loose” item to fall out was the main jet which drops down the plastic tube. The low speed jet I cannot find or reference. I’ve been to Briggs site. Various other sites even messaged Nikki (mikes carbs?) and no help or answers. I am sorry for bein so long winded but to also make matters worse I noticed the idle mixture screw was sheared flush to the body. I just now got it out. Any help would be greatly appreciated. Again. Thanks for allowing me to join and hopefully I may be of some help to someone someday too. Have a blessed day all

Mutt

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    SRTsFZ6
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    Re: Briggs 31C707-1346-B2. 2022/12/13 08:14:04 (permalink)
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    To my knowledge, there isn't a place to drill out for the low speed.  
     
    If the engine ran correctly for a short period of time, it sounds like the carb is clogged up.
    Looking thru where the air cleaner is, make sure the two "venting holes" are clear.  
     
    How does the spark plug look, black (rich), lean?  
     
    They do make a richer main jet.  I'd try opening up the main jet a little and see if it helps (AFTER a thorough cleaning)
     
    The Nikki carb is notorious for running rich due to the float bowl gasket leaking. Usually, once removed, a new gasket is required... 
     
    Should you end up replacing the carb, put the Walbro on...  
     
    https://www.partstree.com/models/31c707-1346-b2-briggs-stratton-vertical-engine/carburetor-kit-carburetor-overhaul-3/ 
     
     
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    mutt07
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    Re: Briggs 31C707-1346-B2. 2022/12/14 12:50:38 (permalink)
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    Thx for the info. But what is the Walbro carb number. It doesn’t show the walbro carb part number in diagram. Also. The vents are clear, the plug is grey and looks great actually. I can definitly tell it’s not getting enough fuel tho. It’s just hunting then flattens out then hunts again. Sure is a tough one

    Mark
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    SRTsFZ6
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    Re: Briggs 31C707-1346-B2. 2022/12/14 14:34:23 (permalink)
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    Running your model # again, the parts list shows the new carberator, an updated part # of : 594593
     
     

    Briggs & Stratton 794572Carburetor
    (Superseded to 594593)
     
    An OEM carb, new style:

    https://www.amazon.com/Briggs-Stratton-594593-Carburetor/dp/B01IQXE5CG?th=1 
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