Small Engines (Lawn Mowers, etc.): carburetor adjusting on B&S mower, air mixture, air screw

Question
QUESTION: Hello John, I have a B&S mower engine 124702-3106-0192102959 and I need to adjust the carburetor. I can find three screws to adjust it with but I need to know which is which. I got it running but it does not idle correctly. Can you please help?

ANSWER: Hello Jerry:

>>The Following is an Instruction File I made for Correcting this Problem. Any Input is Appreciated.
>>****All the Carburetor Adjustments are the Same for Lawn Mower and Trimmers.
>>There are Several Location for the Air Mixture Screws.
>>The Idle Air Mixture Screws are Usually Located at the Top of the Carburetor Bowl and the Top of the Carburetor Body.
>>If the Main Air and Idle Air Mixture Screws are Side by Side on the Side of the Carburetor, then the Idle Air is the Nearest to the Engine.
>>The Main Jet Air Mixture Screw is Located in the Bottom of the Carburetor Bowl or Beside the Idle Air Screw on the Side of the Carburetor Body.
>>The Engine Idle Screw is Usually Easy to Identify because you can See where it Makes Contact with the Carburetor Throttle Shaft Plate Stop Ear. The H and L Air Mixture Screws Go Into the Body of the Carburetor and the Tips Cannot be Seen.
>>Some of the Older Model Carburetors have the Main Jet Mixture Screw Straight in from the Top of the Carburetor Body (this is Rare anymore).
>>If you have Cleaned the Carburetor (Disassembled and Soaked Overnight in Carburetor Cleaner (I Use Gunk). Then Blow Out the Passages with Compressed Air and Install a New Kit if Required.
>>Now Setting the Air Mixture Screws:  
>>****Turn the Idle Air and Main Air Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 Turns.****
>>Holding the Throttle Full Open, Start the Engine.
>>Turn the Main Air Mixture Screw Clockwise Until Proper Revs are Obtained. Occasionally you May have to Turn this Counter Clockwise to Achieve the Proper Revs. Now Allow the Engine to Idle.
>>Set the Engine Idle Screw (Not Idle Air) so the Engine will Stay Running if Required.
>>Now Set the Idle Air Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle.
>>Reset the Engine Idle if Required. If This Carburetor has a Single Air Adjustment.
>>Use the Section Above that Pertains to Full Throttle RPM Air Mixture Screw and then Adjust the Screw if Required to Eliminate Any Hesitation when Rapidly Throttling from Idle to Full Throttle.**
>>1- http://www.repairfaq.org/samnew/lmfaq/lmclctc.htm   
>>2- http://www.cpdonline.com/692509.pdf   .
>>You can View a Breakdown/IPL of the Engine at this Site Addy; http://www.briggsandstratton.com/maint_repair/manual_and_more/doclist.aspx?categ and Enter the Model Numbers (124702) and the First 4 Type Numbers (3106) in the Appropriate Boxes and Click GO. Then Select Download PDF.
>>Please, Do Not Hesitate, If you Hit a Snag, if I Missed Something or this Does Not Correct the Problem, I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

>>PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Comments and Ratings are Greatly Appreciated. Thanks.

Respectfully

John

---------- FOLLOW-UP ----------

QUESTION: Thanks for the reply John,
After further investigation I see that this carburetor has two screws that enter the body. One is at the very top of the bowl and the other is only governing the amount the second butterfly opens in the inner throat of the air inlet. I had adjusted both to the 1 1/2 turn setting and the mower cranks well from the choked throttle setting. Just getting it to idle and rev correctly are the only questions now. There is some kind of allen wrench setting on the throttle mechanism too but it is not part of the actual carburetor. That is why I reported "three screws" earlier.
This service is wonderful and may God Bless You and Yours too.
Respectfully
Jerry (MS)

Answer
Hello Again Jerry:

>>Go to this Site Addy; http://www.smallenginepartswarehouse.com/parts.asp and Select the Shop Online Parts Look Up. Then Select the Model Tab. Then Select the OEM and Enter the Model (5 or 6 Digits) and Type Numbers (first 4 digits Only). Example: 124702-3106. Then Double Click on the Model in the Results Area. Select Sectional Index. Now Select the Carburetor File.
>>The Idle Air Mixture Screw is Show as #118 and the Engine Idle Screw is #98 in the Carburetor Breakdown.
>>Using the Breakdowns at this Site can you Direct me to the Other Screw you were Describing?
>>Thanks.

Respectfully

John

>>PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Comments and Ratings are Greatly Appreciated. Thanks.

Respectfully

John