TOHATSU BFT75A Service Manual page 412

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Install the top ring [1] and the second ring [2] in the ring
grooves in the piston with the maker marks facing up.
Install the oil ring [3] in the ring groove, aligning the
retaining tab [4] of the side rail (top side) [5] with the
positioning groove [6] in the ring groove.
• Clean the ring grooves thoroughly before installing
the piston rings.
• Install the piston rings with care not to break them.
Take care not to score or scratch the piston.
• Do not confuse the top ring and the second ring. The
top ring is glossy while the second ring has a dark
color.
• Check that the retaining tab of the side rail (top side)
is in the positioning groove of the ring groove
securely.
To install the oil rings, install the spacer first, and then
install the side rails.
After installing the piston rings, turn each ring by hand
to check for smooth movement (except the side rail (top
side)).
Stagger the piston ring end gaps as shown.
• Do not align with the piston pin, and avoid the
direction that makes a right angle with the piston pin.
CYLINDER BLOCK
SPACER
[6]
APPROX. 10°
APPROX. 15°
SPACER RING
END GAP
SIDE RAIL
END GAP
(TOP SIDE)
[FIXED
POSITION]
APPROX. 120°
SECOND RING END GAP SECOND RING END GAP
TOP RING END GAP
[1]
[2]
[5]
[3]
SIDE RAIL
(SKIRT SIDE)
[4]
[5]
TOP RING
SECOND RING
SIDE RAIL
(TOP SIDE)
SPACER
SIDE RAIL
(SKIRT SIDE)
APPROX. 15°
SIDE RAIL
END GAP
(SKIRT SIDE)
APPROX. 120°
PISTON PIN
15-11