Inspection

Piston and piston pin

PROCEDURE

1. Check the outer surface of the piston for damage, scoring or uneven wear. Replace the piston if necessary.
2. Check each piston ring for damage and uneven wear. Replace the piston rings if necessary.
3. Check the piston pin by inserting it into the piston bore. The piston pin should slide smoothly into the piston when pressed by hand (at room temperature).

Piston Rings

PROCEDURE

1. Insert a new piston ring into the piston ring groove and measure the clearance between the piston ring and the groove wall with a feeler gauge. If the clearance exceeds the maximum allowable value, replace the piston.
Piston ring side clearance in piston groove:
No. 1 compression ring: 0.04–0.085 mm
No. 2 compression ring: 0.04–0.085 mm
Maximum allowable clearance: 0.1 mm
2. Measure the piston ring end gap by manually inserting the piston ring into the cylinder bore. Using the piston crown, push the piston ring to the bottom of the cylinder. Measure the piston ring end gap with a feeler gauge.
Piston ring end gap:
No. 1 compression ring: 0.15–0.30 mm
No. 2 compression ring: 0.20–0.40 mm
Oil control ring: 0.20–0.70 mm
Maximum allowable gap: 1.0 mm