Small Engines (Lawn Mowers, etc.): Honda GX670, twin cylinder engines, compression stroke

Question
I have this in a small mini-skid and need to find out what the compression should be when testing with a gauge.  Can you help?  The unit stalls and dies under moderate to light load and we think the engine has lost compression.

Answer
Hello Dane:

Have you Checked the Valve Clearance? This is an OHV Engine and when the Valve Clearance become Out of Adjustment you will have the Problem you Described. The OEM Suggest .005in - .007in Intake and .007in - .009in Exhaust. 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 .008in - .010in. 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. This Engine has a Compression Release and the Compression can Only be Checked with the Rocker Arms Completely Releasing the Valves. This Way the Cam and Compression Release Do Not Operate the Valves and True Compression can be Seen. The OEM Says to Quickly Turn the Engine in Reverse Rotation and if the Engine Kicks Back Hard then the Compression is Good. If you Check the True Compression; it can be No Lower than 80psi. Some People will Say 70 to 90psi but I have Found that Most Times Compression Lower than 80psi will Cause Idling Problems. You can View a Breakdown/IPL of the Mower/Engine at this Site Addy, http://hayward.arinet.com/scripts/EmpartISAPI.dll?MF&app=ASP&lang=EN&TF=Mainfram... and Select the Catalog American Honda. 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

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Respectfully

John