CRANKSHAFT/TRANSMISSION 9-29
Pistons
Piston Ring Groove Width
•
Measure the piston ring groove width.
○
Use a vernier caliper at several points around the piston.
Piston Ring Groove Width
Standard:
Top [A]
0.82 ∼ 0.84 mm (0.0323 ∼ 0.0331 in.)
Second [B] 0.82 ∼ 0.84 mm (0.0323 ∼ 0.0331 in.)
Service Limit:
Top [A]
0.92 mm (0.036 in.)
Second [B] 0.92 mm (0.036 in.)
If the width of any of the two grooves is wider than the
service limit at any point, replace the piston.
Piston Ring Thickness
•
Measure the piston ring thickness.
○
Use the micrometer to measure at several points around
the ring.
Piston Ring Thickness
Standard:
Top [A]
0.77 ∼ 0.79 mm (0.0303 ∼ 0.0311 in.)
Second [B] 0.77 ∼ 0.79 mm (0.0303 ∼ 0.0311 in.)
Service Limit:
Top [A]
0.70 mm (0.028 in.)
Second [B] 0.70 mm (0.028 in.)
If any of the measurements is less than the service limit
on either of the rings, replace all the rings.
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 the piston.
Piston Ring End Gap
•
Place the piston ring [A] inside the cylinder (upper
crankcase), using the piston to locate the ring squarely
in place. Set it close to the bottom of the cylinder, where
cylinder wear is low.
•
Measure the gap [B] between the ends of the ring with a
thickness gauge.
Piston Ring End Gap
Standard:
Top
0.15 ∼ 0.30 mm (0.0059 ∼ 0.0118 in.)
Second 0.30 ∼ 0.45 mm (0.0118 ∼ 0.0177 in.)
Service Limit:
Top
0.6 mm (0.024 in.)
Second 0.8 mm (0.031 in.)
If the end gap of either ring is greater than the service
limit, replace all the rings.
