Yamaha BR250F Service Manual page 22

3. Separate the crankcase halves by rapping
the indicated points with a rubber
mallet.
4. Remove the crankshaft.
Inspection
1. Crankcase
a. Thoroughly wash the case halves in a
mild solvent. Blow them dry with com-
pressed air.
b. Thoroughly clean the crankcase mating
surfaces.
c. Visually inspect the case halves for
cracks or damage.
d. Inspect the oil delivery passages in the
transfer ports for signs of blockage.
2. Bearings and oil seals
a. After cleaning and lubricating the bear-
ings, rotate the outer race with your
finger. If rough spots are noticed, replace
the bearings.
b. Check the oil seal lips for damage or
wear. Replace the seals as required.
b. Install bearings with their manufacturer's
marks or numbers facing outward. They
should be visible when intalled.
c. Install oil seals with their manufacturer's
marks also facing outward.
d. Always thoroughly lubricate bearings
and oil seals with the specified lubricant
before installing them on the crankshaft.
4. Crankshaft
a. Check the connecting rod axial play at
the small end. This will indicate the
condition of the big-end bearing and
crankpin. If the rod axial play exceeds
specification, disassemble the crankshaft
and check the connecting rod, crankpin,
and big-end bearing. Replace any defec-
tive or worn parts. Reassemble the
crankshaft, and recheck the rod axial
play.
Rod axial play:
Maximum: 2.0 mm (0.079 in)
b. Check the connecting rod side clearance
at the big end. If it exceeds specification,
disassemble the crankshaft and replace
any worn parts.
Rod side clearance
3. Bearing and oil seal installation
a. When install ing or removing the left
crankshaft bearing or oil seal, remove the
oil-pump drive sprocket. Replace it with
a new one during installation.
2·11
Minimum
0.25 mm (0.010
in)
Maximum
0.75 mm (0.030
in)