Tohatsu 4 Stroke MFS 2/2.5/3.5A Outboards Service Manual, Page 97Get this manual
Power Unit 29) Installation of Piston and Connecting Rod
1Install connecting rod 2, piston pin 3, and piston pin clip to piston Point "3AB-UP" mark of connecting rod and "UP" mark of piston to the same direction Be sure to use new piston pin clip, and place clip gap away from piston pin groove as shown Be sure to install the connecting rod cap in original position (direction)
6 2Put expander (#4) in the oil ring groove, and check that ring end makes gap as shown3While holding expander (#4) gap with thumb, put upper side rail (#3) into the groove so that the gap is away from gap of expander (#4) to the left by 90 degrees4In similar way, put lower side rail (#5) into the groove so that the gap is away from gap of expander (#4) to the right by 90 degrees5Install second ring (#2 taper) and top ring (#1) to pistonInstall top Ring (#1) and Second Ring (#2) so that their side with manufacturer's identification (T) faces upward (valve side)