1978 Evinrude Outboards 9.9/15HP Service Manual, Page 66Get this manual
bUsing piston cradle (Special Tool #319919), wrist pin stop (Special Tool #319917), and wrist pin pressing pin (Special Tool #319920), press wrist pin through "L" side of piston until seatedSee Figure 5-32Wrist pin stop will locate wrist pin between retaining ring grooves cUSing piston cradle, wrist pin driver (Special Tool #319944) and wrist pin cone (Special Tool #319945) start retaining ring in tapered end of conePress retaining rings into pistonMake sure retaining rings seat in grooves in pistonSee Figure 5-33dCheck piston with micrometer to determine if piston has been distorted during assemblyIf piston is more than 0.003" (0.08 mm) out of round, replace pistonPISTON RINGS (UPPER RING IS PRESSURE BACKED RING) Install the piston rings on each pistonSpread each ring with ring expander just enough to slip it over the head of the piston and down into placeBe sure the rings fit freely in the piston ring groovesThe ring grooves are pinned to secure the position of the rings, primarily to prevent ends of the rings from catching on the edges of the ports in the cylinders but also to assure staggering of the ring gapsBOTTOM OF CRANKCASE