5-32 ENGINE TOP END
Cylinder, Pistons
Piston Ring Groove Width
•
Measure the piston ring groove width.
○
Use a ve
rnier caliper at several points around the piston.
Piston Ring Groove Width
Standard Service Limit
Top [A] 0.83 ∼ 0.85 mm 0.93 mm
(0.0327 ∼ 0.0335 in.) (0.037 in.)
Second [B]
0.82 ∼ 0.84 mm 0.92 mm
(0.0323 ∼ 0.0331 in.) (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 m icrometer to measure at several points around
the ring.
Piston Ring Thickness
Standard Service Limit
Top [A] 0.77 ∼ 0.79 mm 0.70 mm
(0.0303 ∼ 0.0311 in.) (0.028 in.)
Second [B]
0.77 ∼ 0.79 mm 0.70 mm
(0.0303 ∼ 0.0311 in.) (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, using the pis-
ton 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 Service Limit
Top 0.20 ∼ 0.30 mm 0.6 mm
(0.0079 ∼ 0.0118 in.) (0.024 in.)
Second 0.35 ∼ 0.50 mm 0.8 mm
(0.0138 ∼ 0.0197 in.) (0.031 in.)
If the end gap of either ring is greater than the service
limit, replace all the rings.
