2006 Johnson SD 3.5 HP 2 Stroke Outboard Service Manual, PN 5006562, Page 89Get this manual
POWERHEAD ASSEMBLY IMPORTANT: The piston ring must be correctly located on its dowel pin to prevent permanent powerhead damageUse suitable tool to compress piston ringInstall piston into cylinder boreCheck piston ring for spring tension by pressing it with screwdriver through exhaust portIf piston ring fails to return to its position, ring was probably broken during installation and must be replaced Install the crankshaft assembly on cylinder block and rotate bearings so that the locating pins are positioned in notches of the cylinder block