Yamaha MM600D, Manual

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106
CHAPTER FOUR
2. Check the piston pin for excessive wear, scoring or
cracks. Replace the piston pin if necessary.
3. Measure the outside diameter of the piston pin at sev-
eral locations and compare to the specifications listed in
Table 2 or Table
3. If the piston pin is worn, replace the
piston pin and bearing as a
4.
Measure the inside diameter of the pin bore in the pis-
ton at several locations and compare to the specifications
listed in
Table 2 or Table If the pin bore is worn, re-
place the piston.
5. If accurate measuring tools are not available to per-
form Step 3 and Step 4, perform the following:
a. the needle bearing and pin and install
them in the connecting rod. Rotate the pin slowly
and check for radial and axial play
(Figure 29). The
piston pin should turn smoothly without perceptible
play. If any play exists, replace the pin and bearing,
providing the rod bore is in good condition. If the
condition of the rod bore
is questionable, check the
old pin and bearing with a new connection rod.
b. Lubricate the piston pin and install it in the piston
pin hole (Figure 30). Check for up and down play
between the pin and piston. There should be no no-
ticeable play. If play is noticeable, replace the piston
pin and/or piston.
I f there are signs seizure or over-
heating, replace the piston pins and bear-
ings. These parts have been weakened from
overheating and
fail later.
Connecting Rod Inspection
NOTE
To replace the connecting rods, the
must be pressed apart, then pressed to-
gether and aligned wing precision holding,
measuring
and
pressing equipment. These
special tools and technicians trained and
experienced at rebuilding the crankshaft as-
sembly are not available at most service
shops. The manufacturer recommends
re-
placement the connecting rods and
crankshaft i f any part other than the outer
seals
or
the main bearings at the ends of the
require replacement. Parts for
the also may not be available. I f
the condition of the
or the connecting rods, have a competent
dealership familiar with the crankshaft re-
pair inspect the assembly.
1. Wipe the piston pin bore in the connecting rod with a
clean rag and check it for galling, scratches, or any other
signs of wear or damage. If any of these conditions exist,
replace the connecting rods as described in this chapter.
2. Measure the inside diameter of the piston pin bore in
the connecting rod at several locations. If any
ment is not within the specification listed
Table 2 or
Table 3, rebuild the crankshaft and install a new connect-
ing rod.
3. Check the connecting rod big end play by rocking
the connecting rod back and forth (Figure 31). If there is
more than a very slight rocking (some side-to-side
sliding is normal), have a dealership check the
crankshaft further to see if it is satisfactory for further use.
4. Rotate the crankshaft and check the smoothness of the
connecting rod as it moves around
crankpin. If the
connecting rod catches (ratchets) as crankshaft is ro-
tated, have a dealership check the crankshaft fur-
ther to see if it is satisfactory for further use.
5. While performing the connecting rod check in Step
4,
the crankshaft main bearings should also turn smoothly.
The outer bearings can be removed and replaced without
disassembling the crankshaft.