Small Engines (Lawn Mowers, etc.): Honda GX670 smoking, blown head gasket, crankcase oil

Question
My generator run by the above motor jaust started smoking out of the exhaust (White smoke) It is relitavly new and in good condition. this is not the first time and would appreciate some help.  It was not under any serious load at the time

Answer
Hello Angus:

Usually the White Smoke is Caused by a Bad Diapgragm in the Fuel Pump, Gas in the Crankcase Oil, a Blown Head Gasket between the Cylinder and Push Tube Galley, the Crankcase Vent Stuck/Frozen/Broken or the Carburetor Flooding the Engine. If the Engine is Running Good but Smoking White Smoke, 1- Block the Outlet Port and Pull a Vaccum on the Fuel Pump. If it Holds Vaccum, then it is Good. If Not, then the Diaphragm is Busted and the Pump Requires Replacing.  If the Fuel Pump is Good, then Check the Crankcase Oil for Gas Contamination. If the Crankcase Oil is Contaminated, then Drain and Refill the Crankcase Oil with Fresh Oil. 2- **If the Mower has a Manual Gas Shut Off Valve:  Check the Manual Cut Off Valve and Make Sure it is Cutting Off the Gas Flow to the Carburetor. If Not Dtopping the Gas Flow, then Replace the Valve. If the Mower Does Not have a Manual Cut Off Valve: Install a Manual Cut Off Valve and Turn Off the Gas Flow when the Engine is Not in Use.** 3- If the Valve is Good or has Been Installed, then Remove the Cylinder Head. On the OHV Engines the Head gasket will Blow Between the Cylinder and the Push Tube Galley. This Allow Oil to be Sucked Into the Cylinder from the Crankcase and the Extra Oil is Just Enough to Cause the White Smoke. 4- Check the Crankcase Breather and Make Sure it is Clean and Operating Properly. If the Crankcase Breather Sticks, then Oil is Pulled from the Crankcase into the Carburetor Throat and this Causes the White Smoke. 4- I Listed the Possible Causes in the Order they Usually Occur. I have had Some People Ask me Why I do the Diagonstics in the Order I Use and it is Simply that Over the Years I have Made a List of the Equipment, the Models and the Problems they have When I Receive them for Repair. Then I Listed the Cause and Repairs Made. I Suggest you Purchase the Service Manual for this Engine. It will have All the Information you Require to Maintain and Keep this Engine Running Good for Many Years. I have Seen So Many Different Makes and Models of Equipment Over the Years, that I Use the Manuals Always for Any and All Repairs. The Basics are Not My Worry; it's the Specifications that Change. Thanks for Using All Experts. 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