Small Engines (Lawn Mowers, etc.): Kohler engine lacks power, twin cylinder engines, ohv engines

Question
I have a Troy Built riding mower with a Kohler Command 14HP, Model CV14S, Spec 1444, Serial # 2212803254, engine.  Over the past mowing season the mower has been loosing power on grades and thicker grass.  There appears to be no obstruction to the mower blades, and the blade shafts turn freely.  This year, the lack of power problem is getting worse.  The carberator has a fixed high speed jet and adjusting the low speed needle seems to do no good.  I thought that the engine might be just worn out, but it seems to have good compression (I did not measure it) and has about 500 hours running time on it.  Thanks for your help

Answer
Hello Jim:

When Properly Maintained, the 500 Hours Means Very Little. I have Several Engines with well in Excess of 500 hrs and they Operate Like New. Have you Checked the Valve Clearance? 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 When Setting the Valve Clearance. Now Loosen the Valve Adjuster Locks and Set the Intake Valve Clearance to .003in -.005in and the Exhaust to .008in - .010in. I have had Better Performance Out of the Mowers and Less Burnt Valves Using these Settings. The OHV  Engines are have Problems with the Valve Settings. I Started Using High Temp (Red) Thread Lock on the Valve Locks to Help Prevent the Adjuster from Loosening. On Most of the Engines We have Repaired in the Shop; this has Worked. About 1 Out of Every 100, we will have to Set the Valves a Couple of Times Before they Stay. If the Valve Clearance is Correct, then Check the Engine Compression. If you have Good Compression When the Engine is Cold, then Check the Compression When the Engine is Hot. There May be a Ring Sticking. If the Compression is Good, then  Remove, Disassemble and Soak 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 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 Accidential Spillage. Then Blow Out the Passages with Compressed Air. Install New Parts if Required. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.

Good Luck

Respectfully

John