Yamaha F50 Service Manual

62Y3A115-54
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È
 Tightening sequence No. Part name Q’ty RemarksTightening torques
Stage N·mkgf·mft·lb
31 Anode 1
32 Cover 1
33 Cover 1
34 Bolt 1 M6 ×
 20 mm
35 Bolt 1 M5 ×
 12 mm
36 Bolt 10 M6 ×
 35 mm 1st
2nd6
120.6
1.24.3
8.7
Cylinder body 

POWRPower unit
5-5562Y3A11
Removing and installing the oil filter
1. Place a rag under the oil filter, and then
remove the filter.
NOTE:
Be sure to clean up any oil spills.
2. Apply a thin coat of the new engine oil to
the O-ring of the new oil filter.
3. Install the oil filter, and then tighten it to
the specified torque.
Disassembling the cylinder body
1. Remove the exhaust cover bolts in the
sequence shown. Oil filter wrench: YU-38411 / 90890-01426
S62Y5690
S62Y5700
E
Oil filter wrench: YU-38411 /...

62Y3A115-56
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2. Remove the crankcase bolts in the
sequence shown.
3. Remove the connecting rod bolts and the
piston assemblies.
4. Remove the crankshaft, oil seals, and
dowel pins.
5. Remove the piston pin clip 1
 with pliers,
and then remove the piston.
Checking the piston diameter
1. Measure the piston outside diameter at
the specified measuring point. Replace if
out of specification.
Checking the cylinder bore
1. Measure the cylinder bore (D1–D6) a
 at
measuring points b
, c
 and d
,...

POWRPower unit
5-5762Y3A11
2. Calculate the taper limit. Replace or
rebore the cylinder body if out of specifi-
cation.
3. Calculate the out-of-round limit. Replace
or rebore the cylinder body if out of spec-
ification.
Checking the piston clearance
1. Rebore the cylinder or replace the piston
and piston rings as a set or the cylinder
body, or both if out of specification.
Checking the piston rings
1. Check the piston ring 1
 dimensions of B
and T. Replace if out of specification.2. Level the piston ring...

62Y3A115-58
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Checking the piston ring grooves
1. Measure the piston ring grooves.
Replace the piston if out of specification.
Checking the piston ring side 
clearance
1. Measure the piston ring side clearance.
Replace the piston and piston rings as a
set if out of specification.
Checking the piston pin boss bore
1. Measure the piston pin boss bore.
Replace the piston if out of specification.
Checking the piston pin
1. Measure the piston pin diameter.
Replace if out of specification....

POWRPower unit
5-5962Y3A11
Checking the connecting rod small 
end inside diameter
1. Measure the connecting rod small end
inside diameter a
. Replace the connect-
ing rod if out of specification.
Checking the connecting rod big end 
side clearance
1. Measure the connecting rod big end side
clearance a
. Replace the connecting
rod or crankshaft, or both if out of specifi-
cation.
Checking the connecting rod bolt
1. Measure the connecting rod bolt thread
diameter at the two points a
 and b
. 
2. Calculate...

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2. Measure the crankshaft runout. Replace
the crankshaft if out of specification.
Checking the crankshaft main 
journal oil clearance
1. Clean the bearings, main journals, and
bearing portions of the crankcase and
cylinder body.
2. Place the cylinder body upside down on
a bench.
3. Install half of the bearings 1
 and the
crankshaft 2
 into the cylinder body 3
.
CAUTION:
Install the bearings in their original posi-
tions.
NOTE:
Insert the projection a
 of the bearing into...

POWRPower unit
5-6162Y3A11
NOTE:
Do not move the crankshaft until the main
journal oil clearance measurement has been
completed.
8. Remove the crankcase and measure the
width of the compressed Plastigauge
(PG-1) on each main journal. Replace
the main bearing if out of specification.
Checking the crankshaft pin oil 
clearance
1. Clean the bearings and the connecting
rod.
2. Install the upper half of the bearing into
the connecting rod 1
 and the lower half
into the connecting rod cap 2
.
CAUTION:
Install...

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NOTE:
Align the alignment marks b
 on the con-
necting rod cap and connecting rod.
Face the embossed “Y” mark on the con-
necting rod toward the flywheel side of the
crankshaft.
5. Tighten the connecting rod bolts to the
specified torques in two stages.
NOTE:
Do not turn the connecting rod until the crank
pin oil clearance measurement has been
completed.
6. Remove the connecting rod cap and
measure the width of the compressed
Plastigauge (PG-1) on each crank pin.
Replace...

POWRPower unit
5-6362Y3A11
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).
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...