The 104M02-0020-F1 163cc 675 Briggs and Stratton Ready-Start Push Mower Engine has a 25 mm x 3-5/32-Inch Length Crankshaft. The crankshaft is also tapped 3/8-24, contains 2 woodruff keyways. The Ready-Start system requires no priming or choking of the engine to start the engine; just pull the rope. Features a 1.6 qt. tank, and recoil start.
Briggs Stratton 104M02-0020-F1 725 Series Engine