Cylinders, Pistons and Rings

Submitted by xjcdadmin on Mon, 06/14/2010 - 15:41


1. Inspect the cylinder walls for vertical scratches and  Rebore or Replace cylinder as required.

2. Measure the cylinder inside diameter.

Obtain measurements at three depths by placing measuring instrument parallel to and at right angles to crankshaft.

Out of specification -> Rebore cylinder, and replace piston and piston rings.




Wear Limit

Cylinder bore: C

68.000-68.005 mm 
(2.6772 ~ 2 .6774 in)

68.1 mm
(2.6811 in)

Cylinder taper: T


0.05 mm 
(0.002 in)


C= Maximum D
T= Maximum of D1or D2 minus Minimum of D5 or D6


Piston 1 . Measure the piston skirt diameter "P" 2

Measure the piston skirt diameter where the distance 1 is 5.0 mm (0.197 in) from the piston bottom edge.


Piston Size P


68.00 mm 
(2.6772 in)

Oversize 2

68.50 mm 
(2.6969 in)

Oversize 4

69.00 mm 
(2.7165 in)

2. Measure the piston clearance

Piston Clearance = Cylinder inside diameter "C" minus Piston skirt diameter "P"

Out of specification -> Rebore cylinder, and replace piston and piston rings.

Piston Clearance: 0.06 - 0.08 mm (0.0024 - 0.0031 in)

Piston Ring 1 .

Measure ring side clearance. Use a feeler gauge. 

Out of specification ->  Replace piston.

Clean carbon from piston ring grooves and rings before measuring side clearance.


Piston Ring Side Clearance (Limit):

Top Ring

0.15 mm (0.006 in)

2nd Ring

0.15 mm (0.006 in)

2. Position the piston ring in cylinder.

Insert a ring into cylinder, and push it approximately 2 0 mm (0.8 in) into cylinder. Push ring with piston crown so that ring will be at a right angle to cylinder bore.

3. Measure the ring end gap. Replace if out of specification.

You cannot measure end gap on expander spacer of oil control ring. If oil control ring rails show excessive gap, replace all three rings.


End Gap Limit (Installed):

Top Ring

1.0 mm (0.040 in)

2nd Ring

1.0 mm (0.040 in)

Oil Ring

1.5 mm (0.060 in)


Piston Ring Oversize

•Top and 2 nd piston ring Oversize top and middle ring sizes are stamped on top of ring.

Oversize 2

0.50 mm (0.0197 in)

Oversize 4

1.00 mm (0.0394 in)


• Oil control ring Expander spacer of bottom ring (oil control ring) is color-coded to identify sizes.



Oversize 2


Oversize 4


Piston Pin

1. Lubricate piston pin (Lightly)

2.  Install:

• Piston pin 1 into small end of connecting rod 2.

3.  Check for free play

Free play ->  Inspect connecting rod for wear.

Wear ->  Replace connecting rod and piston pin.

4.  Position the piston pin 1 into piston.

5.  Check for free play in piston.

Free play -> Replace piston pin and/or piston.