Yamaha F2 5 Service Manual

69M3E115-10
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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...

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
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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
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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...

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...

69M3E115-16
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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...

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...

69M3E115-18
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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....

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...