Small Engines (Lawn Mowers, etc.): Governor Problem, work bench, hp engine

Question
Hello John,
I have a Briggs 20 hp engine I am working on.  Model 407777 ype 0126E1 code 021118YG. The starter, battery and relay were all bad and I replaced them.  I was assured the mower worked fine when they parked it for the winter.  They were continually jump starting it with vehicles and tractors. The mower is for our little league fields. When I started the mower after replacing said items, it runs almost wide open with very little left when I move the throttle to wide open. I am able to manually manipulate the governor control arm and slow the engine down, but it will backfire or begin running rough and die.  The large spring on the governor control seems like it is too big and doesn't belong.  It just sits there and flops.

Answer
Hello John:

Having No Background on the Engine, I Suggest you First Reset the Governor. **To Reset the Governor; Loosen the Governor Arm Bolt and Turn the Governor Shaft Clockwise Until it Stops. Using the Governor Arm Hold the Carburetor to Full Throttle. Now with the Shaft Full Clockwise and the Governor Arm and Carburetor Held at Full Throttle, Tighten the Governor Arm Bolt. If the Engine Still Runs Full Throttle, then Reverse the Rotation of the Governor Shaft, but Still Hold the Carburetor at Full Throttle with the Governor Arm. If it Still Runs at Full Throttle, then Check the Internal Governor.** If the Governor Still Does Not Operate Correctly, then a Question. When you Move the Governor Arm by Hand to Rev the Engine, can you Feel Pressure Pushing Against you and Trying to Return the Engine to Idle? If Yes, then the Internal Governor is Working. If No, then the Internal Governor is Broken and Requires Replacing. **This is a Simple Process. Drain the Oil and Remove the Engine to the Work Bench with the Oil Pan Facing Up. I have a Wooden Rest that was Especially Made to Hold the Engine when in this Position. Using Fine Sand Paper, Remove ALL the Rust and Debris from the Crankshaft. Remove the Oil Pan Bolts. After All the Oil Pan Bolts are Removed; Tap Lightly on the Sides of the Oil Pan to Loosen it from the Dowel Pins. When the Oil Pan is Removed, you can See the Governor Resting on Top of the Cam Gear. Lift Off and Replace with a New Governor. Check the Engine Block for Debris from the Old Governor and Wipe the Inside of the Block With a Rag, Until Clean. Set the Governor So it is Resting on the Governor Shaft and Carefully Replace the Oil Pan. Remember to Replace the Oil Pan Gasket. If the Crankshaft Seal Was Not Leaking, then Leave it Alone. It Should be OK. You can Easily Replace it While Mounted on the Machine if Required Later. Make Sure the Governor Stays in Contact with the Governor Shaft while Replacing the Oil Pan. Re - Mount the Engine to the Machine. Refill With Oil. These Instructions are Basic. Your Internal Governor May Differ.** Replace the Governor Spring. You can View a Breakdown/IPL of the Unit at this Site Addy; http://www.briggsandstratton.com/maint_repair/manual_and_more/doclist.aspx?categ... and Enter the Model Numbers (XXXXXX) and Type Numbers (XXXX) in the Appropriate Boxes and Click GO. Then Select Download PDF. The Backfire and Rough Running can be Several Things. 1- A Dirty Carburetor.  **Remove, Disassemble and Soak the Carburetor Overnight in Carburetor Cleaner (I Use Gunk). I have Found that Most People can Use a Breakdown/IPL and Disassemble the Carburetor Enough for Proper Cleaning. You Only have to Remove the Bowl (if Applicable), Float Pin (if Applicable), Float (if Applicable)  and Needle Valve and Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed. Then Soak the Carburetor Body and Parts in a 1 Gallon Can of Gunk Carburetor Cleaner Overnight. The Can has a Parts Tray Inside it for the Small Parts. Once the Carburetor and Parts are in the Cleaner, you can Replace the Lid for Safety and to Prevent Accidental Spillage. Then Blow Out the Passages with Compressed Air. Install New Parts if Required.**  2- The Valves Require Resetting. **I Do Not Use the Setting Called for by the OEMs. I have Found that the Following Works Best. Remove the Valve Cover (on the Dead Cylinder for Twin Cylinder Engines). Set the Cylinder you are Setting the Valves on to Top Dead Center (Both Rocker Arms will have Play in them when the Engine is at TDC) on the Compression Stroke When Setting the Valve Clearance. Now Loosen the Valve Adjuster Locks and Set the Intake Valve Clearance to .004in -.006in and the Exhaust to .007in - .009in. I have had Better Performance Out of the Mowers and Less Burnt Valves Using these Settings. Be Sure the Piston is at TDC on the Compression Stroke.**  3- A Blown Head Gasket between the Compression Chamber and the Push Tube Galley. Replace the Head Gasket. If the Battery is Good and is Not being Charged, then the Voltage Regulator (if this engine has one) or the Stator is Bad and Requires Replacing. Never Jump a Small Engine with a Vehicle if the Vehicles Engine is Running. The Alternator will Damage the Small Engines Stator (charger) or the Voltage Regulator. Use Just the Battery. If the Battery is Good and Fully Charged and the Engine Turns 3/4 Turn and Drags and then Turns 3/4 Turn Again, then the Valve Clearance Requires Setting. If the Starter Turns the Engine Slowly Constantly, then the Starter is Dragging and Requires Replacing. 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. 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. Thanks.

Respectfully

John