Yamaha F2 5 Service Manual

							69M3E115-10
1
2
3
4
5
6
7
8
9
NOTE:
The starter rope 1
 turns the sheave drum 3
with the force of the spiral spring.
8. Pull the manual starter handle 4
 several
times to check that the sheave drum
turns smoothly and to check the starter
rope for slack. Repeat steps 2–7 if nec-
essary.
9. Install the choke knob assembly.
Removing the power unit
1. Remove the flywheel magnet.
CAUTION:
•Apply force in the direction of the
arrows shown, to prevent the flywheel
holder from slipping off easily.
•To prevent damage to the engine or
tools, screw in the flywheel puller speci-
fied bolts evenly and completely so that
the flywheel puller plate is parallel to the
flywheel magnet.
NOTE:
Apply force to the crankshaft end until the
flywheel magnet comes off the tapered por-
tion of the crankshaft.
Use the fuel tank bolts 3
 with the specified
measurements.
S69M5B90
1
3
1
g 3
S69M5C00
4
S69M5190
1
Flywheel holder 1
: 90890-06522
Flywheel puller 2: 90890-06521
Fuel tank bolt 3: M6 × 35 mm
Power unit 
						

							POWRPower unit
5-1169M3E11
2. Loosen the throttle cable stop screw 4
and remove the throttle cable 5
.
3. Remove the carrying handle 6
, fuel cock
7
, bottom cowling 1 8
, and bottom
cowling 2 9
.
4. Remove the power unit 0
 by removing
the bolts A
. 
						

							69M3E115-12
1
2
3
4
5
6
7
8
9
Cylinder head5
No. Part name Q’ty Remarks
1 Cylinder head 1
2Gasket 1
Not reusable
3 Cylinder head cover 1
4Gasket 1
Not reusable
5 Intake valve 1
6 Exhaust valve 1
7 Push rod 2
8 Push rod guide 1
9 Stud bolt 2
10 Rocker arm 2
11 Rocker arm pivot 2
12 Valve guide 2
Not reusable
13 Stem seal 2Not reusable
14 Valve spring 2
15 Valve spring retainer 2
16 Valve cotter 2
17 Bolt 4 M8 
× 60 mm
Power unit / Cylinder head 
						

							POWRPower unit
5-1369M3E11
5
No. Part name Q’ty Remarks
18 Bolt 6 M6 
× 16 mm
19 Bolt 2 M6 
× 45 mm
20 Dowel 2
21 Nut 2
22 Blowby hose 1 
						

							69M3E115-14
1
2
3
4
5
6
7
8
9
Removing the cylinder head
1. Remove the cylinder head cover bolts in
the sequence shown.
2. Remove the crankcase bolts 1
.
3. Remove the cylinder head bolts in the
sequence shown.
CAUTION:
Do not scratch or damage the mating sur-
faces of the cylinder head and cylinder
block.
4. Remove the cylinder head, and then
remove the push rods.
NOTE:
Insert a flat head screwdriver between the
tab of the cylinder and the tab of the cylinder
head to pry open the two parts.
5. Remove the rocker arm pivot 2
, rocker
arm 3
, and push rod guide 4
.
S69M5260
6
3
451 2
S69M5270
1
S69M5280
3
12
4
S69M5290
Cylinder head 
						

							POWRPower unit
5-1569M3E11
6. Remove the intake valve and exhaust
valve.
NOTE:
Be sure to keep the valves, springs, and
other parts in the order as they were
removed.
Checking the rocker arms
1. Check the rocker arms for cracks, wear,
or damage. Replace if necessary.
Checking the push rod guide
1. Check the push rod guide for cracks or
damage. Replace if necessary.
Checking the push rods
1. Check the push rods for bends, wear, or
damage. Replace if necessary.
Checking the valve springs
1. Measure the valve spring free length a
.
Replace if out of specification.
Valve spring compressor 5
:
90890-04019
Valve spring compressor 
attachment6
:
90890-06320
S69M5310
6
5
S69M5320
Valve spring free length a
:
35.0 mm (1.378 in)
S69M5330
S69M5340 
						

							69M3E115-16
1
2
3
4
5
6
7
8
9
2. Measure the valve spring tilt b
. Replace
if out of specification.
Checking the valves
1. Check the valve face for pitting or wear.
Replace if necessary.
2. Measure the valve margin thickness a
.
Replace if out of specification.
3. Measure the valve stem diameter b
.
Replace if out of specification.4. Measure the valve stem runout. Replace
if out of specification.
Checking the valve guides
NOTE:
Before checking the valve guide make sure
that the valve stem diameter is within specifi-
cation.
1. Measure the valve guide inside diameter
a
.
Valve spring tilt limit b
:
1.2 mm (0.05 in)
Valve margin thickness a
:
Intake: 0.7 mm (0.028 in)
Exhaust: 1.0 mm (0.040 in)
Valve stem diameter b
:
Intake:
5.475–5.490 mm 
(0.2156–0.2161 in)
Exhaust:
5.460–5.475 mm 
(0.2150–0.2156 in)
Valve stem runout:
0.03 mm (0.0012 in) 
Valve guide inside diameter a
:
5.500–5.512 mm 
(0.2165–0.2170 in)
S69M5350
a
Cylinder head 
						

							POWRPower unit
5-1769M3E11
2. Calculate the valve stem-to-valve guide
clearance as follows. Replace the valve
guide if out of specification.
Replacing the valve guides
1. Remove the valve guide 1
 by striking
the special service tool from the combus-
tion chamber side.
2. Install the new valve guide 2
 by striking
the special service tool from the rocker
arm side until the valve guide reaches
the specified installation position a
.
NOTE:
Before installing the valve guide, mark its
installation position b
 as shown.
Apply engine oil to the new valve guide.
3. Insert the special service tool into the
valve guide 2
, and then ream the valve
guide.
NOTE:
Turn the valve guide reamer clockwise to
ream the valve guide.
Do not turn the reamer counterclockwise
when removing the reamer.
4. Measure the valve guide inside diameter.
Replace the valve guide if out of specifi-
cation.
Valve stem-to-valve guide clearance 
= valve guide inside diameter – valve 
stem diameter:
Intake:
0.010–0.037 mm 
(0.0004–0.0015 in)
Exhaust:
0.025–0.052 mm 
(0.0010–0.0020 in)
Valve guide remover/installer:
90890-06801
S69M5360
1
S69M5370
22 b
a
E
Valve guide installation position a
:
5.9 mm (0.23 in)
Valve guide remover/installer:
90890-06801
Valve guide reamer: 90890-06804
Valve guide inside diameter:
5.500–5.512 mm 
(0.2165–0.2170 in)
S69M5380
2 
						

							69M3E115-18
1
2
3
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6
7
8
9
Checking the valve seat
1. Eliminate carbon deposits from the valve
with a scraper.
2. Apply a thin, even layer of Mechanic’s
blueing dye (Dykem) onto the valve seat.
3. Lap the valve slowly on the valve seat
with a valve lapper (commercially obtain-
able) as shown.
4. Measure the valve seat contact width a
where the blueing dye is adhered to the
valve face. Reface the valve seat if the
valve is not seated properly or if the valve
seat contact width is out of specification.
Replace the valve guide if the valve seat
contact is uneven.
Refacing the valve seat
1. Reface the valve seat with the valve seat
cutter.S69M5390
Valve seat contact width a
:
0.6–0.8 mm (0.024–0.031 in)
Valve seat cutter holder:
90890-06316
Valve seat cutter:
30°: 90890-06328
45°: 90890-06312
60°: 90890-06315
Cylinder head 
						

							POWRPower unit
5-1969M3E11
2. Cut the surface of the valve seat with a
45° cutter by turning the cutter clockwise
until the valve seat face has become
smooth.
aSlag or rough surface
CAUTION:
Do not over cut the valve seat. Be sure to
turn the cutter evenly downward at a pres-
sure of 40–50 N (4–5 kgf, 8.8–11 lbf) to
prevent chatter marks.
3. Use a 30° cutter to adjust the contact
width of the top edge of the valve seat.
bPrevious contact width
4. Use a 60° cutter to adjust the contact
width of the bottom edge of the valve
seat.
bPrevious contact width
5. Use a 45° cutter to adjust the contact
width of the valve seat to specification.
bPrevious contact width
cSpecified contact width
6. If the valve seat contact area is too wide
and situated in the center of the valve
face, use a 30° cutter to cut the top edge
of the valve seat and a 60° cutter to cut
the bottom edge to center the area and
set its width.
bPrevious contact width É
S69M5410
S69M5B00
30˚
b
S69J5890
60˚
b
S69J5900
45˚
cb