1991 Yamaha Outboard Factory Service Manual 9.9 and 15 HP, Page 63Get this manual
ENGINE ASSEMBLY AND ADJUSTMENT Important information 1Gasket and seal All gaskets and seals should be replaced when the engine is overhauledAll gasket surfaces and oil seal lips must be cleaned2During reassembly, apply the proper type of oil to all engine moving parts and all bearings3Circlip All circlips should be inspected carefully before reassemblyAlways replace piston pin clips after one useReplace distorted circlipsPistoncrankshaft 1F it the piston rings into the grooves2Align each ring end gap with the locating pin 1Small end bearing installer
2Con rod