• Ring end gap
Out of specification → Replace.
You cannot measure the end gap on
the expander spacer of the oil control
ring. If the oil control ring rails show
excessive gap, replace all three rings.
CHECKING THE PISTON PIN
• Piston pin
Blue discoloration/grooves → Re-
place, then inspect the lubrication
• Piston pin-to-piston clearance
a. Measure the outside diameter
(piston pin) "a".
If out of specification, replace the
Outside diameter (piston
b. Measure the inside diameter (pis-
Inside diameter (piston):
c. Calculate the piston pin-to-piston
clearance with the following for-
Piston pin-to-piston clearance =
Inside diameter (piston) "b" -
Outside diameter (piston pin)
d. If out of specification, replace the
INSTALLING THE PISTON RING
• Piston ring
Onto the piston.
• Be sure to install the piston rings so
that the manufacturer's marks or
numbers are located on the upper
side of the rings.
• Lubricate the piston and piston
rings liberally with engine oil.
• Top ring
• 2nd ring
• Oil ring
Offset the piston ring end gaps as
CYLINDER AND PISTON
<Limit>:0.07 mm (0.003
Top ring end
2nd ring end
Oil ring end (upper)
Oil ring end (lower)
• Piston "1"
• Piston pin "2"
• Piston pin clip "3"
• Apply engine oil onto the piston pin
• Be sure that the arrow mark "a" on
the piston points to the exhaust side
of the engine.
• Before installing the piston pin clip,
cover the crankcase with a clean
rag to prevent the piston pin clip
from falling into the crankcase.
• Install the piston pin clips with their
ends facing downward.
INSTALLING THE CYLINDER
• Piston ring
Apply a liberal coating of engine oil.
• Dowel pin "1"
• O-ring "2"
Apply the lithium soap base grease
on the O-ring.