Yamaha F25A - Big-End Oil Clearance

5-40
POWR
E
CRANKCASE, CRANKSHAFT ASSY., AND CYLINDER
BODY
Big-end oil clearance
1. Measure:
● Big-end oil clearance
Out of specification → Replace the
bearings as a set.
Big-end oil clearance:
0.020 ~ 0.052 mm
(0.0008 ~ 0.0020 in)
Measuring steps:
● Clean the bearings and bearing por-
tions of the connecting rod.
● Install the upper half of the bearing
into the connecting rod and the lower
half into the connecting rod cap.
● Put a piece of Plastigauge

onto the
crank pin.
● Assemble the connecting rod halves
onto the crank pin.
● Tighten the bolts in the proper
sequence and in two stages.
T
R
.
.
Bolt:
1st: 6.0 Nm
(0.6 m • kg, 4.4 ft • lb)
2nd: 16.5 Nm
(1.7 m • kg, 12.2 ft • lb)
● Remove the connecting rod cap.
● Measure the width of the compressed
Plastigauge

on each crank pin.
CAUTION:
Install the bearings in their original posi-
tions. Incorrect oil clearance measure-
ments can lead to engine damage.
NOTE:
Align each bearing projection with the
notch in the connecting rod cap and con-
necting rod.
NOTE:
● Make sure the “Y” mark a on the con-
necting rod faces towards the flywheel
side of the crankshaft.
● Do not move the crankshaft until the big-
end oil clearance measurement has been
completed.