Small Engines (Lawn Mowers, etc.): JD Gator, twin cylinder engines, valve clearances

Question
I have a JD Gator with engine FD620.  The back spark plug does not fire.  The unit does run on the one cylinder.

I read that it could be the Pulser coil, ignition module or ignition coil.  

With the unit running on the one cylinder, I think, I received a shock while touching the back plug wire.  I don't know for sure, and I don't want to repeat that.

Answer
Hello Mark:

>>Try Checking for Spark this Way. It Doesn't Sting as Bad. lol.
>>Remove the Spark Plugs and Wrap the Threaded Section of the Plug with Wire, then Attach the Other End of the Wire to the Engine Block.
>>**First Make Sure the Plastic End that Snaps to the Plug is Allowing Current to the Plug. Use a Test Light or Multimeter and Check for Fire Behind this Connector (through the Large Rubber like Coil Lead to Plug) for Fire to the Plug whenever there is No Fire to the Plug.**
>>Once you are Sure the Coil Lead and Ends to the Plug are Not the Reason for No Fire to the Plug, then with the Plug Still Wired to the Engine and the Coil Lead Attached to the Plug; Remove the Coil Shut Off Wire at the Shut Off Switch.
>>Check for Fire. If No Fire, then Remove the Cut Off Wire from the Coil (removal of the blower housing required) and Check for Fire.  
>>If the Spark Plugs are Firing with the Plugs Out and Properly Grounded to the Engine, then Replace the Plugs and Start the Engine.
>>Using an Insulated Plug Wire Puller, Pull the Plug Wire from 1 Cylinder. If the Engine Continuse to Run, then Replace the Plug Wire and Disconnect the Other Plug Wire. If the Engine Quits, then Replace the Other Cylinders Coil.
>>Since you Seem to have Spark to the Dead Cylinder, I Suggest you Check the Valve Clearances First.
>>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).
>>Check the Push Tubes and make Sure they are Not Bent.
>>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 .009in -.011in and the Exhaust to .009in - .011in. 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 be 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.
>>You can Locate the Valve Clearance Specs at this Site Addy; http://outdoorpowerinfo.com/engine_specs/  and Select Valve Clearances Under you Engines OEM (FD620D). Then Set the Valve Clearances to the Specifications Listed on the Chart for your Engine.
>>If the Valve Clearances are Correct, then
>>Check the Compression. The Head Gasket may be Blown and Require Replacing.
>>You can View a Breakdown/IPL of the Engine and Mower at this Site Addy, http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.H... and Enter the Model Numbers and Click Find. Then Select your Model from the Search Results Area. Then Select the Sectional File. Then Select the Section of the Mower you Wish to View Online. *You can Drag the View Windows for Better Viewing.*
>>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 OEM Parts by Model Fit Section.
>>If you Hit a Snag or this Does Not Correct the Problem,  I Hope to be Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 5 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