Small Engines (Lawn Mowers, etc.): erratic idle, carburetor body, adjustment screws

Question
I have a 2000 Scotts by John Deere 16/42 riding mower. Model CV16S Scotts 1642H.  The tractor has always run well but over the last cutting season I have noticed that the idle would surge up and down and not be smooth.  It has gotten worse over the last week and up until 2 days ago, the idle would fluctuate up and down- being very irregual and would speed way up and then slow right down until it stalls.  Now, I can't even get it to start.  One thing I noticed is that once it was warmed up, I could start it with full choke and it would run rough for a couple minutes and smooth out and it would run fine with full choke.  Any suggestions?  What could be the problem?  Many thanks.  Brian

Answer
Hello Brian:

Usually the Cause of the Problem you Described is the Carburetor.  Remove, Disassemble and Soak the Carburetor Overnight in Carburetor Cleaner (I Use Gunk). I have Found that Most People can Use a Breakdown/IPL and Disassemble the Carburetor Enough for Proper Cleaning. You Only have to Remove the Bowl, Float Pin, Float (if Applicable)  and Needle Valve and Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed. Then Soak the Carburetor Body and Parts in a 1 Gallon Can of Gunk Carburetor Cleaner Overnight. The Can has a Parts Tray Inside it for the Small Parts. Once the Carburetor and Parts are in the Cleaner, you can Replace the Lid for Safety and to Prevent Accidental Spillage. Then Blow Out the Passages with Compressed Air. Install New Parts if Required. You can View a Breakdown/IPL of the 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 the Sectional File. Then Select the Section of the Mower you Wish to View Online. 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. Have a Happy Holiday Season and May the All Mighty Bless You and Yours. Be Safe and Happy. 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