1969 Evinrude 40 HP Big Twin, Big Twin Electric Lark Service Manual 4596, Page 49Get this manual
One side of piston is marked "Loose" on insideSee Figure 5-17When wrist pin is to be removed, "Loose" side of piston must be up and driving tool must be applied to loose sideAlways drive from loose side to tight side, being careful not to distort pistonSee Figure 5-18 Figure 5-15Removing Center Bearing hLift retaining ring out of groove and slide aside to remove crankshaft center main needle bearings for cleaning and inspectionSee Figure 5-15iRemove the rings from the pistons by prying the ends loose enough to grip them with pliers and then breaking them away from the pistonDO NOT try to save the rings even when they are not stuckInstall complete set of new rings on every power head service job