Crankshaft size is 1″ diameter x 3-5/32″. Working hour meter reads 752 hours. The engine starts right up when cold with choke engaged. It usually starts when warm without engaging the choke. If you throttle down too low it will stall. Sometimes the starter does not initially engage requiring multiple turns of the key. Engine runs smoothly and does not smoke. It provides ample power to the mower which runs and cuts. See the short video of the engine starting, running, throttling down and up and shutting down. If you search for the “Yard Man 50″ mower deck we have for sale there is a video in that listing of the mower running and cutting. Pics are of the engine for sale still mounted. For a brief period the engine can be started and the mower can be test driven. Starter is included but you may want to replace it. Muffler is not included but it is available for sale. Message me for additional info and deals on multiple parts. I’ll make sure you get everything you need. I part out Troy-Bilt, Cub Cadet and many other brands of lawn and garden tractors and zero turn mowers. If you don’t see a related part you need feel free to message and I’ll let you know if I still have it and at what bargain price.