Piston Installation

GENERAL INFORMATION

Cylinder Bore Diameter Measurement Point

Piston Measurement. PISTON TAPER. Measure the piston diameter at the level of the piston pin bore axis and the skirt diameter.

PISTON DIAMETER. Measure the piston diameter at a section located 19 mm below the piston pin bore axis.

Warning.

When installing pistons, check the piston fit in the cylinder. Factory-fitted

pistons and pistons supplied as spare parts have the same mass and can be installed in the engine without preliminary sorting and matching by mass. Engine balance is not disturbed. If necessary, it is permissible to

install used pistons in individual cylinders, provided that they

are in good condition.

To avoid disturbing engine balance, it is prohibited to machine pistons to a smaller diameter.

The cylinder bore diameter identification number is stamped near the

engine identification number.

Measure

PROCEDURE.

1. Piston. If worn or otherwise damaged, replace with a piston of standard or oversize diameter.

standard or oversize diameter.

2. Cylinder bore, see figure. Cylinder Bore Diameter Measurement Point. If necessary, restore serviceability by boring and honing to repair size. Warning.

Finish the cylinder bore diameter by honing after selecting the piston.

3. Install the piston into the cylinder.

Warning.

The piston and cylinder bore must be dry.

4. Thoroughly clean the cylinder bore and piston with a brush and soapy water.

Remove all foreign particles. Dry and lubricate with clean engine oil.

5. Check the piston fit in the cylinder bore.

5a. Measure the cylinder bore diameter with a telescoping gauge and micrometer.

5b. Measure the piston diameter and taper, see figure. Piston Measurement.

5c. Subtract the piston diameter from the cylinder bore diameter to determine the clearance.

5d. Compare the obtained clearance value with the specified value.

5e. Determine whether the piston is suitable for the given cylinder.

6. If the used piston is not suitable, select a new piston. (Pistons of both standard and oversize repair sizes are supplied as spare parts.)

7. If the cylinder bore is to be machined, measure the new piston and

hone the cylinder bore diameter to the required size.

8. Mark the new piston with the number of the cylinder for which it is intended.

(Some engines may use pistons with a diameter increased by 0.25 mm.)

9. Thoroughly clean the cylinder bore and piston with a brush and soapy water.

Remove all foreign particles. Dry and lubricate with clean engine oil.