Small Engines (Lawn Mowers, etc.): Mower leaking oil/blowing black smoke, briggs and stratton, breather tube

Question
Hi
I replaced the blade on my Briggs and Stratton Classic 35 mower Model - 9D902 Type -2022(had it on its side)and when trying to start it it was 'stiff at a certain point. It did start eventually but oil is now sqiuirting out of the muffler area and it is blowing black smoke but it is running. Have you any idea what this could be ? There was sufficient oil in the machine and i thought it was well maintained. Also pics below.
http://smg.photobucket.com/albums/v662/romanski/?action=view¤t=DSCF0244.jp...
http://smg.photobucket.com/albums/v662/romanski/?action=view¤t=DSCF0243.jp...
Thanks


Answer
This is easy.

You tipped the mower the wrong way when you replaced the blade.  The air filter must be turned up, not down.  You dumped oil into the airfilter through the breather tube.

Remove the air filter and start the engine, in the street not the drive, it will belch out oil and smoke for a couple of seconds and then run fine.  Then replace the air filter.

I take in 3 mowers every Saturday with this exact problem.