Small Engines (Lawn Mowers, etc.): motor oil instead of 2 stroke, stroke oil, excess fuel

Question
I accidently put motor oil in with petrol instead of 2 stroke oil into my lawnmower.  What do I do? Have replaced with correct 2 stroke and petrol mix but when I start it, it wouldnt start made a bang and had lots of smoke coming out of exhaust.  Please Help!!!!My mower is an old Victa.

Answer
It's unlikely the motor oil wouldn't have caused this problem.  What you have done is the correct approach (draining and replenshing fuel).  The only thing I can think of that may have caused this is if you had the mower tipped up to drain the fuel and the carb allowed raw fuel to fill and hydraulically lock the crankcase.  First remove the spark plug and crank the engine over several times to evacuate any excess fuel (if there is any now).  Re-install the spark plug and try starting it again.  Let me know what you find.