Service Manual

ENGINE TOP EN D 5-17
Cylinder, Piston
Pist on Ring and Ring Groove Wear
•
Clean the piston (see Piston Cleaning).
•
Visually inspect the piston rings and ring grooves.
If the piston rings are worn unevenly or damaged, replace
them.
If the ring grooves are worn unevenly or damaged, re-
place both the piston and piston rings.
•
Measure the clearance between the top and second rings
and their grooves using a thickness gauge [A].
If the piston ring/groove clearance is greater than the
specified value, replace the piston.
Piston Ring/Groove Clearance
Service Limit
Top, Second 0.17 mm (0.007 in.)
NOTE
The oil ring is a three piece assembled ring. It is difficult
to measure the ring groove clearance and thickness,
visually inspect only.
•
Measure the piston ring thickness [A].
Use a micrometer to measure at several points around
the rings.
If any of the measurement are less than the service limit,
replace the entire set of rings.
Piston Ring Thickness
Service Limit
Top, Second 1.40 mm (0.055 in.)
NOTE
When using new rings in a used piston, check for un-
even groove wear. The rings should fit perfectly parallel
to the groove sides. If not, replace t he piston.
Piston Ring End G ap
•
Removethepistonrings.
•
Push each ring (one at a time) in the cylinder bore to a
point close to the bottom of the cylinder bore.
Use the piston to push it in to be sure it is square.
•
Measure the gap [A] between the ends of the ring [B] with
a thickness gauge.
If the end gap of any ring is greater than the service limit,
replace the entire set of rings.
Piston Ring End Gap
Service Limit
Top, Second 0.75 mm (0.029 in.)
Oil 1.05mm(0.041in.)