Disassembly and Reassembly

Piston, Piston Ring and Connecting Rod Disassembly and Reassembly

Piston, Piston Ring and Connecting Rod Removal and Installation

NOTE:

Using the parts removed from a piston for another piston may lead to engine problems.

If the following parts are to be reused, be sure to use them only in the original combination.

- Piston
- Piston pin
- Piston rings
- Connecting rod
- Connecting rod bearings
- Connecting rod bearing cap

NOTE:

For identification of each cylinder, refer to Precautions for Identification of Cylinder Precautions for Identification of Cylinder.

Disassembly

1) Using piston ring expander, remove 1st and 2nd rings and oil ring from piston.
2) Remove piston pin from connecting rod as follows.
a) Remove piston pin circlips (1), as shown.





b) Take out piston pin.






Reassembly

Cylinder, Piston and Piston Ring Inspection

Piston Pin and Connecting Rod Inspection

Crankshaft Pin and Connecting Rod Bearing Inspection

NOTE:

The engine will seize up if it is operated when the parts listed below are not properly lubricated.

Be sure to lubricate all the friction surfaces of these parts with engine oil before installing them.

- Piston pin hole
- Piston pin
- Connecting rod small-end bore

NOTE:

Two sizes of piston are available as standard size spare part so as to ensure proper piston-to-cylinder clearance. When installing a standard size piston, make sure to match piston with cylinder.

1) To replace piston, select proper piston according the following procedure
a) Check stamped number (2) on piston (1) as shown in figure.
b) Check stamped number (4) on lower crank case (3) as shown in figure.











c) Stamped number on piston and stamped number on lower crank case correspond with each other.
Select proper piston referring the following table.

Piston selection table






2) Remove carbon deposit from piston head and ring grooves using a suitable tool.
3) Assemble piston pin, piston (1) and connecting rod (2) as follows.
a) Apply engine oil to piston pin, piston pin hole in piston and connecting rod.
b) Fit connecting rod to piston.

NOTE:
Be sure to position front mark (4) on piston and oil hole (5) of connecting rod (2) at specified position as shown in figure.

c) Insert piston pin to piston and connecting rod.
d) Install new piston pin circlips (3).

NOTE:
Install so that circlip end gap comes within the range indicated by arrow (6).









4) Install piston rings to piston noting the following.
- As indicated in figure, 1st and 2nd rings have direct discrimination mark (1) respectively. When installing these piston rings to piston, direct discrimination mark side of each ring toward top of piston.
- 1st ring (2) differs from 2nd ring (3) in thickness, shape and color of surface contacting cylinder wall.
Distinguish 1st ring from 2nd ring referring to the figure.
- When installing oil ring (4), install spacer first and then install two rails.





5) After installing three rings (1st, 2nd and oil rings), distribute their end gaps as shown in figure.