In my case it was a flooded engine. I wasn't in a rush (as it happened after mowing the lawns), so resolved it the long way - Left it in the shed for a week to dry out.Three things can cause kick back. Damaged flywheel key, loose blade or fluid in the combustion chamber. To clear the flooded engine, remove spark plug and pull start cord rapidly several times.
FYI a few years ago a had a rider that had flooded the engine after transporting it about thirty miles. pulled the plug, gas ran out, while sitting on the seat and holding the disconnected spark plug in my hand, the the spark plug wire was about four inches from the engine cranked the engine. The first crank blew out raw gas, the second crank lit it and lucky I had a fire extenquisher in the truck otherwise I may have lost the lawn mower and my trailer. since then I have always blew the cylinder out with compressed air.
Thanks! It has been raining almost all day, so I'm expecting to wake up tomorrow to a much longer lawn!jmurray - that's a tidy little patio and well-trimmed lawn. Good job!
Note that I said to remove the spark plug before clearing the engine, the fire that was mentioned is the reason.