Small Engines (Lawn Mowers, etc.): briggs and stratton 5 hp, fuel air mixture, briggs and stratton

Question
hey michael,
have recently dismantled my tiller (briggs and stratton 5 hp)which had setup for two years. camshaft, camsprocket, exhaust and intake valves completely rusted. cleaned rust away and replaced piston rings. engine ran on first pull for a few hours, but smoked. heard squealing sound, engine stopped and now won't start at all. can pull cord without much effort. getting spark at new sparkplug. carb looks clean and unclogged after dismantling. getting compression at sparkplug. tried gas in the sparkplug hole, but still no go. I'm at my wits end now. any ideas?
thanks, rick

Answer
Hi Rick,

An engine needs only 3 things to run.  Compression, timed spark and proper fuel/air mixture.  You have spark and fuel.
If the pull cord effort seems like it is suddenly easier, then maybe the compression is not high enough now.  I would test it.  Low compression could be caused by bad valves, valve clearance or the rings that have not seated. The squealing sound was not a good sign.  

Let me know what you find.
Michael