Makita PM7651H Technical Information page 34

Fig. 6-14-1-1-9
[13] Remove two Ring springs 12 from the ends of Piston
pin with a pointed tool such as an awl.
Ring spring 12
Note:
Be careful that Ring spring 12 pops out.
·
Use a new Ring spring 12. Do not use the old one.
·
When assembling, assemble it as shown below.
·
Note: Remove it
from the end
gap.
6-14-1-2 Assembling
[1] Assemble Piston to Crank shaft assembly by inserting Piston pin into place. Piston is non-directional. (Fig. 6-14-1-1-10)
Note: Be sure to apply a little amount of 4-stroke engine oil to Needle roller bearing.
[2] Secure Piston pin by mounting Ring spring 12 onto each end of Piston pin. (Fig. 6-14-1-1-9)
Note: The ring gap of Ring spring 12 can be positioned at any angle to Piston pin.
[3] Install Oil ring in the grooves of Piston; Side rail first, Spacer next, then the other Side rail.
Important: Be sure to fit the three rings with the ring gaps at 120 degrees to one another as shown below.
[4] Install Second ring first then Top ring in the groove of Piston.
Important 1: Be sure to fit the two rings with the ring gaps at 180 degrees to each other as shown below.
Important 2: Second ring has a white marking on the right and chamfers on the corners. Face the white marking to the right or
the chamfers toward upward.
Note: Piston rings are easy to break. Do not enlarge them too much when fixed.
Be sure to fit the two rings with the
ring gaps at 180 degrees to each
other.
Chamfer White marking
Fig. 6-14-1-2-1
Piston
Top ring
ring
gap
Second ring
34 / 41
[14] Push out Piston pin with 1R286, and remove Piston.
Round bar (1R286)
ring gap
180°
Side rail
Spacer
Side rail
Top ring, with barrel face
Second ring, with chamfer
Side rail
Spacer Oil ring
Side rail
Fig. 6-14-1-1-10
Piston pin
Piston
Be sure to fit the three rings with
the ring gaps at 120 degrees to one
another.
ring gap
Oil ring
ring
gap
ring gap
Piston
ring