Yamaha MM700A Manual page 111

ENGINE
fusion during reassembly.
3. Before removing the piston, hold the rod tightly and
rock the piston as shown in Figure 25. Do not confuse any
rocking motion with the normal side-to-side sliding mo-
tion. Rocking indicates wear on the piston pin, needle
bearing, piston pin bore, or a combination of all three.
NOTE
Wrap a clean shop cloth under thepiston so
the clip does not fall into the crankcase.
WA RNl-VG
Wear safety glasses when performing Step 4.
4. Remove the piston pin clip from the outside of the pis-
ton (Figure 22) with needlenose pliers. Hold a thumb
over one edge of the clip when removing it to prevent it
from springing out.
5. Use a proper size wooden dowel or socket extension
and push the pin from the piston.
CAUTION
may be difficult to remove, but do not drive
the piston pin from the piston. Hammering
damages the piston, needle bearing and
Nut
Pad
Washer
Pipe
rod
Threaded
connecting rod. I f the piston pin does not
push out by hand, remove it as described in
Step 6.
6. If the piston pin is tight, use a puller as shown in Fig-
ure 26. The tool can be fabricated as shown. Assemble the
tool onto the piston and pull the piston pin from the piston.
Make sure to install a pad between the piston and the piece
of pipe to prevent scoring the side of the piston.
NOTE
I f the pin is left partly in the piston, the pin
and piston will remain together and not be
mixed with other similar parts.
8. Remove the needle bearing from the connecting rod
(Figure 27).
9. Repeat the removal procedure for the other pistons.
tion tube, or shop cloth to protect it.
NOTE
Always remove the top piston ring first.
your thumbs just enough to slide it up over the piston
(Figure 28). Repeat for the lower ring.
Piston (Wrist) Pin and
Needle Bearing Inspection
1. Clean the needle bearing in clean solvent and dry thor-
oughly. Use a magnifying glass and inspect the bearing
cage for cracks at the comers of the needle slots and in-
spect the needles for cracking. Install a new bearing if it is
questionable in any way.
105