Yamaha F2 5 Service Manual

							69M3E115-20
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7. If the valve seat contact area is too nar-
row and situated near the top edge of the
valve face, use a 30° cutter to cut the top
edge of the valve seat. If necessary, use
a 45° cutter to center the area and set its
width.
bPrevious contact width
8. If the valve seat contact area is too nar-
row and situated near the bottom edge of
the valve face, use a 60° cutter to cut the
bottom edge of the valve seat. If neces-
sary, use a 45° cutter to center the area
and set its width.
bPrevious contact width
9. Apply a thin, even layer of lapping com-
pound onto the valve seat, and then lap
the valve using a valve lapper (commer-
cially obtainable).
CAUTION:
Do not get the lapping compound on the
valve stem or valve guide.
10. After every lapping procedure, be sure to
clean off any remaining lapping com-
pound from the cylinder head and the
valve.
11. Check the valve seat contact area of the
valve again.
Checking the cylinder head
1. Eliminate carbon deposits from the com-
bustion chambers and check for deterio-
ration.
2. Check the cylinder head warpage using a
straightedge 1
 and thickness gauge 2
in six directions as shown. Replace if out
of specification.
S69M5390
Cylinder head warpage limit:
0.1 mm (0.004 in)
S69M5420
2
1
S69M5430
Cylinder head 
						

							POWRPower unit
5-2169M3E11
Installing the valves
1. Install the new stem seal 1
 to the valve
guide.
2. Install the valve 2
, valve spring 3
, and
valve spring retainer 4
 in the sequence
shown, and then attach the special ser-
vice tool.
NOTE:
The valve spring can be installed in any
direction.3. Compress the valve spring, and then
install the valve cotter 7
 using a thin
screwdriver with a small amount of
grease applied to it.
4. Lightly tap the valve spring retainer with
a plastic hammer to set the valve cotter
securely.
Valve spring compressor 5
:
90890-04019
Valve spring compressor 
attachment6
:
90890-06320
S69M5440
E
1
S69M5450
6
5
E
4
3
2
S69M54607
S69M5470 
						

							69M3E115-22
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Cylinder block5
No. Part name Q’ty Remarks
1 Cylinder body 1
2 Crankcase 1
3 Crankshaft 1
4Camshaft 1
5 Connecting rod assembly 1
6Piston 1
7 Oil ring 1
8 Second ring 1
9 Top ring 1
10 Piston pin 1
11 Gasket 1
Not reusable
12 Oil splasher gear 1
13 Oil seal housing 1
14 Oil seal 1
Not reusable
15 Ball bearing 1Not reusable
16 Oil seal 1Not reusable
17 Oil seal 2Not reusable
Cylinder head / Cylinder block 
						

							POWRPower unit
5-2369M3E11
5
No. Part name Q’ty Remarks
18 Clamp 1
19 Washer 1
20 Dowel 2
21 Drain bolt 1 M8 
× 20 mm
22 Bolt 8 M6 
× 45 mm
23 Bolt 1 M8 
× 14 mm
24 Bolt 1 M8 
× 20 mm
25 Bolt 2 M6 
× 29 mm
26 Bolt 1 M6 
× 12 mm
27 Piston pin clip 2
Not reusable
28 Metal gasket 1Not reusable
29 Metal gasket 1Not reusable
30 O-ring 1Not reusable
31 Valve lifter 2
32 Hose 1 
						

							69M3E115-24
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Disassembling the cylinder body
1. Remove the crankcase cover bolts in the
sequence shown.
2. Remove the crankcase.
NOTE:
Insert a flat head screwdriver between the
tab of the crankcase and the tab of the cylin-
der block to pry open the two parts.
3. Remove the camshaft 1
, and then
remove the valve lifters 2
.4. Remove the connecting rod bolts and the
connecting rod cap, and then remove the
connecting rod and piston assembly.
5. Remove the clips 3
 with pliers, and then
remove the piston.
6. Remove the washer 4
 and crankshaft
5
, and then remove the oil splasher gear
6
.
Checking the piston diameter
1. Measure the piston outside diameter at
the specified measuring point. Replace if
out of specification.
S69M5510
3
8
4
5
671 2
S69M5520
Piston diameter a:
53.950–53.965 mm
(2.1240–2.1246 in)
Measuring point b: 0 mm (0 in)
S69M555046
5
Cylinder block 
						

							POWRPower unit
5-2569M3E11
Checking the cylinder bore
1. Measure the cylinder bore (D1, D2, D3,
D
4, D5, D6) at measuring points a
, b
,
and c
, and in direction d
 (D
1, D3, D5),
which is parallel to the crankshaft, and
direction e
 (D
2, D4, D6), which is at a
right angle to the crankshaft.
2. Calculate the taper limit. Replace or
rebore the cylinder block if out of specifi-
cation.
3. Calculate the out-of-round limit. Replace
or rebore the cylinder block if out of spec-
ification.
Checking the piston clearance
1. Calculate the piston clearance using the
piston outside diameter and the cylinder
bore specifications. Replace the piston
and piston rings as a set or the cylinder
block or all parts, or rebore the cylinder if
out of specification.
Checking the piston rings
1. Check the piston ring dimensions of B
and T. Replace if out of specification.
2. Level the piston ring 1
 in the cylinder
with a piston crown.
3. Check the piston ring end gap d
 at the
specified measuring point. Replace if out
of specification.
Cylinder bore (D1, D2, D3, D4, D5, D6):
54.000–54.015 mm 
(2.1260–2.1266 in)
Taper limit:
D
1–D5 (direction d
)
D
2–D6 (direction e
)
0.08 mm (0.0031 in)
Out-of-round limit:
D
2–D1 (measuring point a
)
D
6–D5 (measuring point c
)
0.05 mm (0.0020 in)
S69J5B70
D1D2
D3D4
D5D6
cba
d
e
Piston clearance:
0.035–0.065 mm 
(0.0014–0.0026 in)
Piston ring dimensions:
Top ring a
:
B: 0.97–0.99 mm 
(0.0382–0.0390 in)
T: 1.95–2.15 mm 
(0.0768–0.0846 in)
Second ring b
:
B: 1.17–1.19 mm 
(0.0461–0.0468 in)
T: 2.30–2.50 mm 
(0.0906–0.0984 in)
Oil ring c
:
B: 1.87–1.95 mm 
(0.0736–0.0768 in)
T: 2.10–2.40 mm 
(0.0827–0.0945 in) 
						

							69M3E115-26
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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.
Piston ring end gap d
:
Top ring:
0.15–0.30 mm 
(0.0059–0.0118 in)
Second ring:
0.30–0.45 mm 
(0.0118–0.0177 in)
Oil ring:
0.20–0.70 mm 
(0.0079–0.0276 in)
Measuring point e
: 10 mm (0.39 in)
Piston ring groove:
Top ring a
:
1.03–1.05 mm (0.040–0.041 in)
Second ring b
:
1.21–1.23 mm (0.047–0.048 in)
Oil ring c
:
2.01–2.03 mm (0.079–0.080 in)
S69M5580
1
e
d
S69M5590
a
b
c
Piston ring side clearance:
Top ring a
:
0.04–0.08 mm 
(0.0016–0.0031 in)
Second ring b
:
0.02–0.06 mm 
(0.0008–0.0024 in)
Oil ring c
:
0.06–0.16 mm 
(0.0024–0.0063 in)
Piston pin boss bore:
12.009–12.017 mm 
(0.4728–0.4731 in)
Cylinder block 
						

							POWRPower unit
5-2769M3E11
Checking the piston pin
1. Measure the piston pin diameter.
Replace if out of specification.
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 crankshaft
1. Check the teeth of the crankshaft gear
for damage or wear. Replace if neces-
sary.
2. Measure the crankpin diameter a
 and
crankpin width b
. Replace the crank-
shaft if out of specification.
Piston pin diameter:
11.996–12.000 mm 
(0.4723–0.4724 in)
Connecting rod small end inside 
diameter a
:
12.006–12.020 mm 
(0.4727–0.4732 in)
S69M5650
a
Connecting rod big end side 
clearance a
:
0.2–0.6 mm (0.008–0.024 in)
S69M5660
a
S69M5670
S69M5680
a 
						

							69M3E115-28
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3. Measure the crankshaft runout. Replace
the crankshaft if out of specification.
Checking the crankpin oil clearance
1. Clean the connecting rod.
2. Put a piece of Plastigauge
® (PG-1) onto
the crankpin, parallel to the crankshaft.
NOTE:
Be sure not to put the Plastigauge (PG-1)
over the oil hole in the crankpin of the crank-
shaft.
3. Install the connecting rod to the crankpin
1
.
NOTE:
Align the marks a
 on the connecting rod cap
and connecting rod.
Crankpin diameter a
:
23.969–23.984 mm 
(0.9437–0.9443 in)
Crankpin width b
:
21.0–21.1 mm (0.827–0.831 in)
Crank stand alignment:
90890-03107
Crankshaft runout limit:
0.01 mm (0.0004 in)
S69M5690b
S69M5610
Cylinder block 
						

							POWRPower unit
5-2969M3E11
4. Tighten the connecting rod bolts 2
 to the
specified torques in two stages.
NOTE:
Reuse the removed connecting rod bolts
when checking the oil clearance.
Do not turn the connecting rod until the
crankpin oil clearance measurement has
been completed.
5. Remove the connecting rod cap and
measure the width of the compressed
Plastigauge (PG-1) on the crankpin.
Replace the connecting rod assembly or
crankshaft if out of specification.
Checking the camshaft
1. Check the teeth of the camshaft gear for
damage or wear. Replace the camshaft if
necessary.2. Check the decompressor for damage or
wear. Replace the camshaft if necessary.
3. Measure the camshaft lobe. Replace if
out of specification.
T R..
Connecting rod bolt:
1st: 5 N·m (0.5 kgf·m, 3.7 ft·lb)
2nd: 9 N·m (0.9 kgf·m, 6.6 ft·lb)
Crankpin oil clearance:
0.016–0.046 mm 
(0.0006–0.0018 in)
S69M5640
2
Camshaft lobe a:
26.139–26.239 mm 
(1.0290–1.0330 in)
Camshaft lobe b:
21.950–22.050 mm 
(0.8642–0.8681 in)
S69M5710
S69M5720