There is usually 6 to 10 thousandths of an inch end play in the crankshaft. ALWAYS lift the flywheel that distance before hitting the "knocker". Otherwise you are just beating or the bottom bearing. Inertia will slow the flywheel and the crank should pop loose. Be sure the contact surfaces are clean and dry and torque the flywheel nut to 25 to 30 foot pounds . . . 😎
