Yamaha F100B F100C Outboards Factory Service Manual, Page 12Get this manual
GEN INFO
General information
Piston and connecting rod The piston pin has been installed by shrink fitting it to the small end of the connecting rod, as result, circlip is not used to install the piston pinThe top ring has been nitrided and the second ring has been chrome plated for use with leaded gasolineThe connecting rod and end cap are processed as single unitAfter being heat treated, the single unit is struck and the connecting rod and end cap are split apart as shown in the illustrationTo increase accuracy during installation, the connecting rod and end cap that were processed together are always installed as setThe hollow volume at the top of the pistons has been made larger and the compression ration has been lowered to increase reliability and durability