Small Engines (Lawn Mowers, etc.): craftsman riding mower, blown head gasket, twin cylinder engines

Question
my 12hp tractor backfires and won't run.ran well prior to this problem, mod.143.366202 12hp

Answer
Hello Jim:

Try Resetting the Valves. 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. If the Valves Do Not Correct the Problem, then the Carburetor or a Blown Head Gasket Between the Cylinder and the Valve Galley are Also Possible Causes. I List the Diagnostics in the Order of the Most Frequent Cause. Go to this Site Addy, http://www3.sears.com/ and Enter the Model Numbers (143.366202) in the Upper Left Search Box and Click Go. Then Visually Verify the Equipment and Click Continue. From this Page you can View Diagrams or Parts Lists for you Equipment. 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