Shibaura ST318, Workshop Manual

Page: 46 / 247

45
9) Crankshaft
Inspection
(1) To measure run-out of the crankshaft, support the
crankshaft using a V block as shown in the right figure,
apply a dial gauge to the crankshaft center journal, read
the indication on the dial gauge rotating the shaft one
turn gently. If the service limit is exceeded, correct or
replace.
(2) Check the crankshaft oil seal for damage or wear on
the contact surface and oil hole clogging.
(3) Check the crankshaft journal and pin for damage,
irregular wear (ellipticity, conicalness), and shaft
diameter and grind the journal and pin if the service
limit or repair value is exceeded and replace the
bearing (bush) and connecting rod metal respectively
with one of undersize. Measure the dimensions of the
journal and pin in the AA and BB directions at the
position 1 and 2 avoiding the oil holes.
NOTE: Finishing accuracy when grinding the
crankshaft to undersize shall be as follows.
Ⓐ R at pin and journal: 3R ± 0.2
Ⓑ
Finishing accuracy: 1.6 Z (
▽▽▼
)
Ⓒ R around oil hole
At max. part: 2R
At min. part: 0.5R
Finish using #400 sand paper.
T136
Crankshaft run-out (mm)
Standard assembling value Service limit
Less than 0.03 More than 0.06
T134
T135
Irregular wear limit of crankshaft journal and pin (mm)
More than 0.05
Shaft dia. At crankshaft journal
Outside dia. Finishing
dimension
Repair value
STD. 45.964 – 45.975 Less than 45.9
U.S. 0.25 45.714 – 45.725 Less than 45.65
U.S. 0.50 45.464 – 45.475 Less than 45.40
Shaft dia. At crankshaft pin (
∅
)
Outside dia. Finishing
dimension
Repair value
STD. 38.964 – 38.975 Less than 38.90
U.S. 0.25 38.714 – 38.725 Less than 38.65
U.S. 0.50 38.464 – 38.475 Less than 38.40
* Replace the crankshaft if U.S. 0.50 is exceeded.