1980 Johnson 4HP Service Manual, Page 60Get this manual
connecting rod in position, then proceed to install the wrist pinThis accomplished easily if the piston is heated slightly, causing it to expand PISTON RINGS each pistonSpread Install the piston rings each ring with ring expander just enough to slip it over the head of the piston and down into place sure the rings fit freely in the piston ring groovesThe ring grooves pinned to secure the position of the rings, primarily to prevent ends of the rings from catching the edges of the ports in the cylinders, but also to assure staggering of the ring gaps
Ij';;ftfil NOTE
the piston bosses is bored sip (it the wrist pin and the press When installing other the side the wrist pin, drive marked "L Use appropriate fixture to guard against distortion damage during the operationdReplace retaining rings, making certain they to rest in the groove provided for this purposeCheck piston with micrometer to determine distorted during whether piston has assembIy If out of round more than 0.0025" (0 .064 replace pistonSee Figure 5-18