TOHATSU MFS 25D Service Manual page 214

Power Unit
45) Installation of Piston and
Connecting Rod
Install the connecting rod 2, piston pin 3 and piston pin
1.
clips 4 in the piston 1.
• Align the connecting rod "UP" mark a and
piston "O" mark b to the positions shown in the
diagram.
• Be sure to use new piston pin clips, and place
the clip gap away from the piston pin groove c
as shown.
• Be sure to install each connecting rod cap to its
original connecting rod.
• Apply 4-stroke engine oil to the piston pin hole,
piston pin outer periphery, and connecting rod
small end inner diameter.
Place the expander 5 (#4) into the oil ring groove and
2.
check that the ring ends meet each other correctly as
shown in the diagram.
3. Install by sliding the end of the upper side rail (#3) to
pressing down on the expander (#4) gap with your thumb.
4. Similarly, place the lower side rail (#5) into the groove by
shifting it 90° to the right from the gap.
5. Install the second ring (#2 taper) and top ring (#1) in the
piston. Install the top ring (#1) and second ring (#2) so that
the respective manufacturer marks d (T) are on top.
Piston Ring Tool:
P/N. 353-72249-0
6. Install the piston rings so that their gaps are away from
each other as shown in the diagram on the right.
Be careful not to scratch the piston surface
and damage the rings.
• Install the piston rings so that their gaps are
away from the thrust direction of the piston and
the direction of the piston pin.
• After installing the piston rings, check that they
move smoothly.
5-74
CAUTION
5
5
4st 25/30 2022