Piston: Testing and Inspection

1. Check the piston for distortion or cracks.

NOTE: If the cylinder is bored, an oversized piston must be used.

Piston Diameter:

2. Measure the piston diameter at a point 21 mm (0.83 in) from the bottom of the skirt.

NOTE: There are two standard-size pistons (A or B). The letter is stamped on the top of the piston. These letters are also stamped on the block as cylinder bore sizes.

Piston Diameter, Standard (New):
A: 84.98 - 84.99 mm (3.3457 - 3.3461 in)
B: 84.97 - 84.98 mm (3.3453 - 3.3457 in)

Piston Diameter, Service Limit:
A: 84.97 mm (3.3453 in)
B: 84.96 mm (3.3449 in)

Piston To Cylinder Clearance:

3. Calculate the difference between cylinder bore diameter and piston diameter.

Piston-to-Cylinder Clearance
Standard (New): 0.020 - 0.040 mm (0.0008 - 0.0016 in)
Service Limit: 0.05 mm (0.002 in)

- If the clearance is near or exceeds the service limit, inspect the piston and cylinder block for excessive wear.

Oversize Piston Diameter:
0.25 mm: 85.23 - 85.24 mm (3.3555 - 3.3559 in)
0.50 mm: 85.48 - 85.49 mm (3.3653 - 3.3657 in)

4. Check the piston pin-to-piston clearance. Coat the piston pin with engine oil. It should then be possible to push the piston pin into the piston hole with thumb pressure.

Piston Pin-to-Piston Clearance:
Standard (New): 0.012 - 0.024 mm (0.0005 - 0.0009 in)