Selecting The Crankshaft Main Journal Bearing; Selecting The Connecting Rod Big End Bearing - Yamaha FT50C Service Manual

POWR
Selecting the crankshaft main
journal bearing
1. When replacing the main bearing, select
the suitable bearing as follows.
2. Check the crankshaft journal mark on the
crankshaft 1 and the cylinder body mark
on the cylinder body 2.
3. Select the suitable color a for the main
bearing from the table.
Cylinder Crankshaft
body mark journal mark
A
A
B
B
C
C
5-45
Power unit
Bearing
color
A Yellow
B
Red
A
B
Pink
A
B Green
4. When installing the main bearing, insert
the projection of the main bearing into
the slot on the cylinder body.
CAUTION:
Remove any small metal particles and oil
from the contact surfaces of the cylinder
body and the main bearing.
5. Measure the main journal oil clearance
with a piece of Plastigauge (PG-1).
Crankshaft main journal oil
clearance:
0.012–0.036 mm
(0.0005–0.0014 in)
6. If the oil clearance is below specification,
check the main bearing color and clean
the contact surface of the cylinder body
and the main bearing, and then check
the main journal oil clearance again.
7. If the oil clearance is over specification,
install an oversized main bearing, and
then check the main journal oil clearance
again.
Selecting the connecting rod big end
bearing
1. When replacing the connecting rod bear-
ing, select the suitable connecting rod
bearing as follows.
2. Check the crank pin mark on the crank-
shaft 1 and the connecting rod cap mark
or painted color on the connecting rod 2.
62Y5A11