Small Engines (Lawn Mowers, etc.): B&S engine, high hope, oil level

Question
I sent you a question on a old reliable lawnmower that I have B&S 4HP that was kicking back real hard when i tried to start it, you said to replace the flywheel key which I did (didn't see anything wrong the old one) the first couple of pulls were free like normal almost started  but then back to the same problem where it kicks back real hard. I hate to take this to a repair shop because they want $40.00 just to look at it? with the spark plug out it pulls freely like when your trying to start it, normally this lawnmower always started on 1-2 pulls, what should i try next? Thank You.

Answer
Did you also check the blade and hub?  If you replace the flywheel key and there is still an issue with the blade or blade hub, it will shear the new key.  The reason the engine kicks back is because the spark timing becomes severely advanced when the flywheel key shears and this causes it to fire too far before TDC and tries to send the piston in the opposite direction you are trying to pull it.  The only other thing I can think of is it hydraulically locking because the oil level is way too high.  Hope this helps.