Yamaha EF1000iS Service Manual

							3-32
CYLINDER (CRANKCASE 1) AND VALVE
a4. Measure:
9Valve spring tilt a
Out of specification →Replace.
5. Inspect:
9Valve contact surface
More than 2/3 of the contact surface
does not contact →Replace.
ENG
Tilt limit:
2.0 mm (0.079 in)
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							3-33
CYLINDER (CRANKCASE 1) AND VALVE
a
b
c a
VALVE SEAT INSPECTION
1. Remove carbon deposits from the valve
face and valve seat.
2. Apply a small amount of coarse mechan-
ics blueing dye (Dykem) to the valve
face.
3. Insert the vale into the valve guide and
use a valve lapper to contact the valve
face with the valve seat.
NOTE:
Do not rotate the valve while the valve face is
contacting the valve seat.
4. Measure:
9Valve face contact width a
Make sure that the contact width along
the entire valve face is within specifica-
tions.
Out of specification/rough/
eccentric/wear →Replace.
5. Measure:
9Valve seat contact width b
Make sure that the contact width along
the entire valve seat is within specifica-
tions.
Out of specification/rough/
eccentric/wear →Replace.
ENG
Valve face contact width: 
(Intake/Exhaust)
0.8 mm (0.03 in)
Limit:
1.8 mm (0.07 in)
Valve seat contact width: 
(Intake/Exhaust)
0.5 mm (0.02 in)
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							3-34
CYLINDER (CRANKCASE 1) AND VALVE
b
c a
6. Remove the carbon deposits on the valve
face a and valve seat.
9Valve face contact seat width b
9Valve margin thickness c
Apply a small amount of coarse
mechanic’s blueing dye (Dykem) to the
valve seat.
Press the valve through the valve guide
and onto the valve seat to make a clear
impression.
9Valve margin thickness
Out of specification →Replace.
9Valve face contact width
Out of specification →Replace.
ENG
Valve seat width: 
(Intake/Exhaust)
0.8 mm (0.03 in)
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							3-35
CYLINDER (CRANKCASE 1) AND VALVE
a
b
a b
32 1
CYLINDER (CRANKCASE 1) INSPECTION
1. Measure:
9Cylinder inside diameter
NOTE:
Take side to side aand front to back bmea-
surements at each of the three locations A, B,
C (total of six measurements), and then find
the average of the measurements.
Out of specification →Replace.
VALVE AND VALVE SPRING ASSEMBLY
1. Install:
9Valve 1
9Valve spring 2
9Valve spring retainer 3
NOTE:
9Apply a small amount of molybdenum disul-
fide oil to the valve stem and use the valve
spring compressor 5 to install the parts.
9Press the spring retainer by your finger
while installing the spring retainer.
ENG
Maximum wear = Maximum A, B, C.
Cylinder taper =
Maximum A– Minimum C.
Cylinder inside diameter:
41.00 ~ 41.02 mm
(1.614 ~ 1.615 in)
Cylinder inside diameter wear
limit:
41.10 mm (16.18 in)
Cylinder taper limit:
0.05 mm (0.002 in)
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							ENG
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I iii  
						

							4-1
CARBURETOR
CARBURETOR
CARBURETOR
12
3
4 5
6 78910
2 Nm (0.2 m · kg, 1.4 ft · lb)
7 Nm (0.7 m · kg, 5.1 ft · lb)
6
CARB
Order Job name Q’ty Remarks
Carburetor removalRemove the parts in the order listed 
below.
Front cover and rear coverRefer to “COVERS” section in CHAPTER 2.
Air cleaner case
1 Breather hose 1
2 Hose 3 1
3 Hose 4 1
4 Joint 1
5 Gasket 1
6 Throttle control motor coupler 1 Disconnect.
7 Carburetor assembly 1
8 Gasket 1
9 Carburetor joint 1
10 Gasket 1
For installation, reverse the removal
procedure.
1
2
3
4
5
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							4-2
CARBURETOR
CARBURETOR DISASSEMBLY
7 Nm (0.7 m · kg, 5.1 ft · lb)2
3
4
5
6 7 8 9 0q we
r tu
y
1
CARB
Order Job name Q’ty Remarks
Carburetor disassemblyDisassemble the parts in the order listed 
below.
1Throttle control motor cover 1
2Throttle control motor 1
3Motor bracket 1
4Plate 1
5Drain screw 1
6Bolt 1
7Gasket 1
8Float chamber 1
9Float chamber gasket 1
0Float pin 1
qFloat 1
wNeedle assembly 1
eMain jet 1
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							4-3
CARBURETOR
7 Nm (0.7 m · kg, 5.1 ft · lb)2
3
4
5
6 7 8 9 0q we
r tu
y
1
CARB
Order Job name Q’ty Remarks
rMain nozzle 1
tCap 1
yPilot screw 1
uPilot jet 1
For assemble, reverse the disassembly
procedure.
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							4-4
CARBURETOR
a
1
2
FLOAT HEIGHT INSPECTION
1. Measure:
9Float height
Out of specification →Replace.
NOTE:
9Lift up the float height so that the tip of the
float valve lightly contacts the float arm, and
then measure the float height a. (This mea-
surement should be made with the gasket
removed.)
9Do not adjustable the float height.
2. Clean:
9Carburetor body
Blow out all passages, jets, and carbu-
retor body with compressed air.
3. Inspect:
9Valve seat
Wear/damage →Replace.
Dirt →Clean.
1Wear at groove
2Dirt
CARB
Float height:
1.5 mm (0.06 in)
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							4-5
CARBURETOR
1
1
a
a1
1
a
b
CHOKE CABLE INSTALLATION
1. Install:
9Choke cable
NOTE:
Push the choke knob 1entirely in before
installing it to the panel.
2. Install
9Choke cable 1
NOTE:
Be sure install the choke cable end cap push
out a3mm (0.118 in) form the holder.
3. Install:
9Inner cable 1
NOTE:
Place the carburetor choke valve in its fully
open position a, insert the tip of the inner
cable into drum hole, and then secure it in
place with the screw.
THROTTLE CONTROL MOTOR
1. Install:
9Throttle control motor 1
NOTE:
9Install the shaft aof the throttle control
motor by aligning it with the groove bof the
throttle shaft.
9Install the throttle valve, and then make sure
that is moves smoothly.
CARB
1 Nm (0.1 m · kg, 0.7 ft · lb)
3 Nm (0.3 m · kg, 2.2 ft · lb)
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