Small Engines (Lawn Mowers, etc.): Toro S200 adjustment, stomach flu, moderate load

Question
Hi John, I read your article about s200 governor adjustment.  It sounds like it could be part of my problem, I'll explain.  I recently fueled up my machine for winter use, started it and it ran great. I let it run for about 20 minutes. It had a tune-up and carb overhaul last season and it ran well all winter.  I ran it dry in the spring. We got snow today and shortly after I started it the engine began loping.  You know,...RPM's were going up and down.  sometimes stalled under moderate load. Both the carb screws are about 1&1/8th to 1@1/4th turn out from seated.  I dumped the fuel tank and made a fresh batch at 32:1 with new pump gas and put it in.  It ran much better but still not at full song.  After a while I adjusted the screws a bit but not much improved.  Could you also elaborate on the screws' functions and adjustment procedure.  If I remember correctly, the one(inboard) is idle speed and the outer one is high speed mixture,...right?  Thanks for your time and happy Holidays.  Sincerely, Don from Chicago.

Answer
Hello Don:

Sorry for the Delay. I Awoke Saturday Morning with the Stomach Flu and am Just Now able to Sit Up without a Problem. From your Description it Sounds like the Loping is Due to; 1- A Restricted Exhaust. Did you Check the Exhaust Port and Muffler? If Either of these are Restricted with Carbon Deposits, then the Engine May Run at Idle but will Flood when you Try to Rev the Engine above Idle. The Following is a Basic Instruction File for Doing a Diagnostic on the Engine for this Problem. Any Input is Appreciated. **Remove the Muffler and Make Sure the Exhaust Port is Clear. If it is, then Try to Start the engine with the Muffler Off. If it Starts and Runs Properly, then Clean the Spark Arrestor Screen in the Muffler or Replace the Muffler if Required. 2- A Bad Fuel Filter (if there is One). 3- Trash in the Carburetor Jet. Since this Carburetor was Serviced Last Year, you can Simple Disassemble and Blow out the Passages with Compressied Air. The Carbuertor should Not Require New Gaskets or a New Diaphragm. You can View a Breakdown/IPL of the Mower at this Site Addy, https://lookup3.toro.com/partdex/default.cfm and Select Start Parts Viewer. Now Enter the Model Numbers (XXXXX) and Click Search. Now Select View Assembly Drawings for your Year Model. The Air Mixture Screws Regulate the Air/Gas Mixture going to the Engine During Operation. The Following is the Instruction File for Setting the Air Mixture Screws. Any Input is Appreciated. The Procedure is the Same for 1 or 2 Mixture Screws, Just Use the Instruction File and Skip Over the Section with the Missing Mixture Screw ( Usually the H Mixture Screw). Now Setting the Air Mixture Screws:  ****Turn the Idle Air (L) and Main Air (H) Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 Turns. Set the Throttle Full Open, Start the Engine. Turn the Main Air (H) Mixture Screw Clockwise Until Proper Revs are Obtained. Carefully Use your Finger and Move the Governor Arm to Rev the Engine (on Chainsaws and Trimmers Use the Trigger to Rev the Engine) Until you Reach Max RPMs (on Chainsaws and Trimmers, the RPMs are Not Set to MAX. Set to MAx and then Reverse the Setting Screw 1/4 or 1/2 Turn. If the H Mixture Screw is Set too High; the Engine will be Starvewd for the Oil in the Gas and Damage the Piston and Jug/Cylinder) and the Engine is Running Proper at Full Throttle Up a Grade. 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 (L) Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.**** If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. Have a Happy Holiday Season and May the All Mighty Bless You and Yours. Be Safe and Happy. 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