Small Engines (Lawn Mowers, etc.): 18hp Sears Craftsman B&S engine will not crank, sears craftsman, crank shaft

Question
I have a fairly new (3 years old) 2005 DLT300 18hp Craftsman ridding lawn mower w/ a B&S engine.  I have had trouble starting the engine lately.  When I turn the key the crank shaft will not turn.  I first thought the battery was dead.  I replaced the battery and still same problem.  I then replaced the old starter, that worked fine, with a new one that works good and still same problem.  I then replace the silinoied with a new one and check all the electrical to make sure I was getting 12 volts to the starter, and all was good.  I then replaced the spark plug and checked to make sure it was firing off properly and it check out good.  I removed the exhaust/muffle, thinking I had a stopped up muffler and still, and still the crank shaft would not turn.  I have no idea what else could be the problem.  The carburetor looks fine and does not seem to be taking in too much gasoline.  However when I remove the spark plug for a minute or two and replace it the engine starts just fine.  But after mowing my yard with no problems and turning off the engine the crank shaft fails to rotate if I try to start the engine again.  It seems like compression is building up in the vales which is causing the crank shaft to not rotate.  I checked the valves they are running fine and nothing is wrong with the belts below that would be causing the shaft not to rotate.  Do you have any idea what my problem could be.  The engine runs fine with no problems at all when I mow the yard, but I just can't get the crank shaft to turn over when I try to restart the engine.  I have new fuel filter, full tank of gas, and oil in the engine. Help?

Answer
Hello PAul:

From your Description it Sounds like the Valves Require Resetting. When the Valve Clearance Moves on the OHV Engines, the Compression Release Does Not Operate Properly and you Get the Problem you are Having. **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 .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.**  You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.smallenginepartswarehouse.com/parts.asp and Select the Shop Online Parts Look Up. Then Select the Model Tab. Then Select the OEM and Enter the Model (5 or 6 Digits) and Type Numbers (first 4 digits Only). Example: XXXXXX-XXXX. Then Double Click on the Model in the Results Area. Now you can Select the Section of the Engine you Wish to View. 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