1975 Evinrude 2HP Model 2502 Full Factory Service Manual, Page 39Get this manual
5-7 UPPER MAIN BEARING AND OIL SEAL upper main bearing through bottom of crankcasePress against lettered side of bearing case until bearing is recessed 116" below finish thrust face of crankcaseAvoid loss of needles in upper main bearingO NOTE
EXHAUST
Install oil seal, lip down until fiush with top of crankcasePISTON INSTALLATION
Coat piston and cylinder bore with oil and install piston and connecting rod assembly through crankcasePush piston through cylinder until piston r:ing grooves are exposedThe intake side of the piston deflector must be placed toward the intake portSee Figure 5-19
PISTON RINGS Install the piston rings on pistonSpread each ring with ring expander just enough to slip it over the head of the piston and down into placeSee Figure 5-20Be 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 th edges of the ports in the cylinder, but als to assure staggering of the ring gaps Carefully press piston and rings into cylinder bore until head of piston is flush with top of cylinder