Mazda 121 - Crankshaft; Main Bearing and Connecting Rod Bearing

INSPECTION
/ REPAIR
CRANKSHAFT
1. Check the
iournals
and
pins
for damage, scoring, and
oil
hole clogging.
2.
Set
the crankshaft
on V'blocks.
3. Measure
the crankshaft
runout at the
center
lournal.
Replace the crankshaft
if
necessary.
Runout: 0.04mm
(0.0016
in) max'
4. Measure each
iournal
diameter
in X and
Y directions at two
points.
Main
iournal
Diameter:
49.938-49.956mm
(1.9661-1.9668
in)
Out-of-round:
0.05mm
(0.0020
in) max.
Crankpin
iournal
Diameter:
39.940-39.956mm
(1.5724-1.5731
in)
Out-ol-round:
0,05mm
(0,0020 in) 6ax.
5. lfthe diameter
is less than
the minimum,
grind
the
lournals
to match an
undersize bearing.
Undersize
bea ng:
0.25mm
(0.010
in), 0.50mm
(0.020
in),
0.75mm
(0.030
In)
Main
iournal
diameter undelsize
Crankpin
iournal
diameler
undersize
mm
(in)
BEARING
Maln Beadng
and Connecting
Fod Bea
ng
Check the main
bearings and
the connecting
rod bearings
for
peeling,
scoring,
and other
damage.
tt\
f----T----i
\i_,i
Bearino size
0.25
(0.010)
undersze
49.688-49.706
0.9562
1.9569)
0.50
(0.020)
undersze
49.438-49.456
(1.9463-1.9470)
0.75
(0.030)
undelsEe
49
188-49.206
(1.9365-1.9372)
0.25 {0.010)
unde6ize
39.690-39.706 {1.5626-1.5632)
0.50 10.020)
irndersize 39.440-39.456
(1.5528-1.5534)
0.75 10.030) Lrndersize
39
190-39.206
(1
5429-1
5435)
$dr
E BE
E
BB
B-58