Small Engines (Lawn Mowers, etc.): engine runs only on choke, blown head gasket, twin cylinder engines

Question
I have a John Deere JE75 mower with Kawasaki FC150 engine.  Was working fine but suddenly will only run on choke.  It starts easily (choked) but as soon as throttle lever is backed off choke it sputters (backfires?) and dies.  You can repeat this indefinitely but it never changes. I've dismantled and cleaned the carburator, replaced fuel with fresh and changed the spark plug all to absolutely on effect. Any ideas? Thanks very much.

Answer
Hello Chris:

Is the Gas Free Flowing to the Carburetor Inlet Port? If Yes, Did you Soak the Carburetor Overnight in Carburetor Cleaner? If Not, then the Carburetor Jet May Still be Restricted.  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, Float Pin, Float 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. If Yes, then Check for a Blown Head Gasket or the Valves Requiring Adjustment. For Valve Adjustment: 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) When Setting the Valve Clearance. Now Loosen the Valve Adjuster Locks and Set the Intake Valve Clearance to .004in -.006in and the Exhaust to .008in - .010in. I have had Better Performance Out of the Mowers and Less Burnt Valves Using these Settings. You can View a Breakdown/IPL of the Mower at this Site Addy, http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.H... and Enter the Model Numbers (JE75) and Click Find. Then Select the Sectional File. Then Select the Section of the Mower you Wish to View Online. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. 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 9pm EST (US). My New Day Starts then. Thanks.

Respectfully

John