Small Engines (Lawn Mowers, etc.): scagg zero turn mower wont start, twin cylinder engines, compression stroke

Question
Dear John,
I have a 29hp kawasaki FD 791 DFI watercooled engine that wont start, bacfires through the exhaust.Would appreciate any help on this.
Regards Dan

Answer
Hello Dan:

>>You can View a Breakdown of this Unit at this Site Addy; http://scag.com/manuals.html and Select your Mower. Then Select Part Manual for Downloading.
>>You can View a Breakdown/IPL of the Engine at this Site Addy,
http://www.emerichsales.com/ and Select Parts at the Top of the Page. Now Fill Out the Quick Parts Look Up Section.
>>The Most Common Cause for this Problem is the Valve Clearances and the Fuel Pressure.
>>Check the Valve Clearances. OHV Engines have a Problem with the Valve Clearances and they May Require Setting. Both the Intake and Exhaust Valve Clearances are .005in - .007in.
>>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 Lock and  Using a Blade Style Feeler Gauge, Set the Intake Valve Clearance to .005in -.007in and the Exhaust to .005in - .007in. Loosen and Tighten the Rocker Arm and the Feeler Gauge is Placed Between the Rocker Arm and the Valve Top where the Rocker Arm Pushes on the Valve.
>>***BE SURE TO TIGHTEN THE ADJUSTER LOCK AFTER YOU HAVE THE PROPER VALVE CLEARANCE***
>>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.**
..If you Remove the Valve Cover and then Turn the Engine by Hand, you can Watch the Intake Valve Movement. When the Intake Valve Closes, the Piston will Just Starting the Compression/Power Stroke. >>On Some Engines you can Us a Straightened Coat Hanger and Feel the Piston.
>>Be Careful and Don't Jam the Wire in the Cylinder. Usually the Piston will Push the Wire Out of the Spark Plug Hole with No Problems.
>>Check the Fuel Pressure. For this a Portable Fuel Pressure Gauge is Required. What is the Fuel Pressure?
>>Please, Do Not Hesitate, If you Hit a Snag, if I Missed Something 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. Comments and Ratings are Greatly Appreciated. Thanks.

Respectfully

John