How does a Crankshaft work in a 4-cycle small engine? The crankshaft attaches to a piston by a connecting rod. During each cycle, the crankshaft rotates to push the piston up in the cylinder. Crankshafts rarely break, but if they do, it can cause serious engine damage. If you're doing an engine overhaul, don't forget to replace the crankshaft. For preventative maintenance, many engine manufacturers recommend replacing the crankshaft and the camshaft at the same time. When you're repairing your small engine, Jack’s has all the parts you need. We have replacement crankshafts from the major manufacturers, including Briggs and Stratton, Honda, Kawasaki, Kohler, and Tecumseh. Match your part or model number below. We also carry replacement camshafts.