Small Engines (Lawn Mowers, etc.): briggs and stratton no go, engine model type, briggs and stratton

Question
i have a 2 hp briggs and stratton lawn mower which was given to me, at first it would only run breifly before dying and then just would not start at all . i have pulled it apart and have done a valve grind, checked the points and adjusted to 020". when turned over with the plug out it gives a good spark. have put petrol in the spark plug hole but will not fire.it has reasonable compression, the crankshaft and camshaft are timed, can the plug spark on the outside but not in ? how many wires should be coming of the condensor, this has only one, but have seen 2 on other motors? any other ideas would be gratefully recieved
rob koster
chch
new zealand

Answer
It is possible to have spark outside but no spark under compression.  Try setting the points at .018.  What are the valve clearances?  One wire is fine coming from the condenser.  The second wire you have seen is for shutting off the engine...usually connected to the throttle movement switch.
Send me the engine model, type and code so I can look up the valve clearance.
Eric