Small Engines (Lawn Mowers, etc.): 2004 6.5 HP Quantum Runs Rough, valve spring compressor, piston valves

Question
Hi John, My B&S 6.5hp Quantum died on me while going thru some long grass.  I tried to start it again and it does turn over for about 5 seconds very roughly, a little bit of a backfire, coughs and dies again.  I have disassembled and cleaned the carb, air filters, plug and checked the blade was not caught.  That didn't seem to resolve anything so I have gone a few steps further and removed the oil pan and cylinder head.  Nothing appears to be obviously damaged, except for a buildup of carbon on the piston, valves and head.  Any ideas on what else could be the problem? I was wanting to give it a complete overhaul while its apart, the parts are relatively inexpensive but theres all those special tools req'd, ie. valve spring compressor, piston ring installer... am I better off just taking the block to a shop to get them to clean it up and replace the rings?

Answer
Hello Stu:

From the Description of the Procedures you have Performed Already, I Suggest you Check the Flywheel Key. Is this an OHV Engine? If Yes, then the Valve Clearance Could be the Cause of your Problem. As for the Overhaul, the Only Special Tools Required is the Valve Spring Compressor and a Cylinder Deglazer/Hone. You can Use a Screw Type Hose Clamp to Compress the Rings for Installation into the Cylinder. To Clean the Piston Ring Groves, Use a Section of the Old Ring for the Groove you Wish to Clean and Clean the Ring Grooves Until the Grooves are Free of Carbon. You Use the Edge of the Old Ring as a Scraper and Pull the Half Section of the Old Ring Around the Grove Until Clean. Send me the Model Numbers Off the Engine, Please. With these I can Locate the Proper Manual and Better Assist you. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. 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 you Question at or Just After 9pm EST (US). My New Day Starts then. Thanks.

Respectfully

John