Small Engines (Lawn Mowers, etc.): riding lawnmower will not spin over, twin cylinder engines, compression stroke

Question
i have a craftman riding mower model 917.254750 12.5 hp  the mower will spin over as long as the plug is out but will not spin over with the plug in how do i fix this compression problem

Answer
Hello Tony:

This Problem is Usually caused by the Valve Clearances Not Being Correct. The Following is a Basic File I made for Setting the Valve Clearances. Any Input is Appreciated. **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 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 .006in - .008in. 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.** On Some Engines you can Us a Straightened Coat Hanger and Feel the Piston. Be Careful and Dont Jam the Wire in the Cylinder. Usually the Piston will Push the Wire Out of the Spark Plug Hole with No Problems. To View a Breakdown of this Unit Go to this Site Addy, http://www.searspartsdirect.com/partsdirect/index.action and Enter the Model Numbers and Click Search. From this Page you can View Diagrams and Parts Lists for you Equipment Using the "View Sub Components" Section Near the Bottom Left. 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

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Respectfully

John