Small Engines (Lawn Mowers, etc.): B&S engine knock, ohv engine, spark plug wire

Question
I have a 6.5 B&S Intec OHV engine that knocks when you crank it.  Once up to speed it seems OK and does not shake. It was smoking a bit when you started it and recently I hit a large stick which jammed in the mulching blade and stopped the engine.  I suspected the flywheel key but that didn't resolve the problem.  I'm hoping it is something other than a bent crankshaft as I'm not sure that is worth the cost of repair.  I believe the model is 1901VE.

Answer
Well, when you take something spinning at somewhere between 2500-3000 rpm's and suddenly stop it cold a lot of things can happen. A bent crank is certainly one of them. As well as the shock placed on the other internal components, such as, wrist pins, connecting rods, and bearings. After removing the spark plug wire, and spark plug, tilt the mower back in the direction of the handle. Rotate the blade measuring the distance it travels from side to side at the crankshaft........Not too many smaller mowers are worth that type of repair....Tom