Yamaha EF1000iS Service Manual

							2-9
MUFFLER
12
3
4
SVU2150
MUFFLER
w
The engine and muffler will be very hot
after the engine has been run.
Avoid touching the engine and muffler
while they are still hot with any part of your
body or clothing during inspection or
repair.
1. Remove:
9Muffler
Refer to “MUFFLER” in CHAPTER 3.
9Muffler band 1
9Muffler cap 2
9Muffler screen 3
9Spark arrester 4
2. Decarbonize:
9Muffler
Tap on the muffler in the area shown in
the illustration to loosen carbon
buildup, and then shake it out of the
end of the muffler.
cC
Don’t use a wire to clean, otherwise the
noise damping material may come out, and
the damping effect may be reduced.
3. Decarbonize:
9Muffler screen
9Spark arrester
cC
When cleaning, use the wire brush lightly
to avoid damaging or scratching of the
muffler screen and spark arrester.
4. Install:
9Spark arrester
9Muffler screen
9Muffler cap
9Muffler band
9Muffler
Refer to “MUFFLER” in CHAPTER 3.
INSP
ADJ
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							2-10
VALVE CLEARANCE ADJUSTMENT
4
123
VALVE CLEARANCE ADJUSTMENT
1. Remove:
9Cover 3
9Side cover 2
9Rear cover
9Front cover
Refer to “COVERS”.
9Carburetor
Refer to “CARBURETOR” in CHAP-
TER 3.
9Cylinder air shroud
Refer to “MUFFLER” in CHAPTER 3.
2. Remove:
9Spark plug cap 1
9Spark plug 2
9Breather hose 3
9Cylinder head cover 4
3. Gently operate the starter rope to bring
the piston to the top-dead-center of its
compression stroke (when the screwdriv-
er inserted into the spark plug hole reach-
es the highest position).
4. Measure:
9Valve clearance
Out of specification →Adjust.
NOTE:
Valve clearance must be measured when the
engine is cool to the touch.
INSP
ADJ
Intake Valve (cold):
0.1 mm (0.004 in)
Exhaust Valve (cold):
0.1 mm (0.004 in)
Thickness gauge:
YU-26900-9, 90890-03079
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							2-11
VALVE CLEARANCE ADJUSTMENT
1
2
3
5. Adjust:
9Valve clearance
Adjustment steps:
•Loosen the locknut 1.
•Turn the adjuster 2in or out to obtain the
proper clearance.
•Tighten the locknut 3.
use hexagonal wrench.
6. Install:
9Cylinder head cover gasket
9Cylinder head cover
9Breather hose
9Spark plug
9Spark plug cap
9Front cover
9Rear cover
9Side cover
9Side cover 2
9Side cover 3
INSP
ADJ
Adjuster Valve clearance
Turn in Decrease
Turn out Increase
Locknut:
4 Nm (0.4 m · kg, 2.9 ft · lb)
Cylinder head cover bolt:
6 Nm (6 m · kg, 4.3 ft · lb)
Spark plug:
13 Nm (1.3 m · kg, 9.4 ft · lb)
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							2-12
COMPRESSION PRESSURE
12
COMPRESSION PRESSURE
NOTE:
Measure the compression after checking and
adjusting the valve clearance.
1. Warm up the engine for several minutes.
2. Remove:
9Spark plug
3. Remove:
9Cover
4. Connect:
9Compression gauge 1
9Adapter 2
5. Measure:
9Compression
To measure the compression, pull the
recoil starter until the needle stops ris-
ing on the compression gauge.
w
To prevent sparking when cranking the
engine, ground the high-tension cord. 
Testing steps (below minimum level):
9Squirt a few drops of oil into the cylinder.
9Measure the compression again.
INSP
ADJ
Compression gauge:
YU-33223, 90890-03081
Adapter:
YU-33223-3, 90890-04082
Standard compression pressure:
400 kPa
(4 kg/cm
2, 57 psi)
Reading Diagnosis
If higher than
without oil
If the same as 
without oil9Worn cylinder, piston, and
piston ring
9Defective piston, ring(s),
valve(s), and cylinder head
gasket
9Improper valve timing and
valve clearance
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							2-13
COMPRESSION PRESSURE/
RATED ENGINE SPEED/BREATHER HOSE
1
1
a
1
Testing steps (above maximum level):
9Check the cylinder head, valve surfaces,
and piston crown for carbon deposits.
6. Install:
•Spark plug
RATED ENGINE SPEED
1. Remove:
9Cover
2. Connect:
9Inductive tachometer 1
3. Inspect:
9
Rated engine speed
Specified engine speed →OK
Out of specification →Refer to “TROU-
BLESHOOTING” in CHAPTER 3.
Inspection steps:
9Operate the engine (with no load).
9Turn economy switch 1to “OFF” a.
9Measure the rated engine speed.
BREATHER HOSE
1. Remove:
9Cover
2. Inspect:
9Breather hose 1
Cracks/damage →Replace.
Poor connection →Correct.
INSP
ADJ
Spark plug:
13 Nm (1.3 m · kg, 9.4 ft · lb)
Inductive tachometer:
YU-8036-A
Engine tachometer:
90890-03113
Rated engine speed:
5,000 r/min
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							2-14
SPARK PLUG
1
2
a
ELECTRICAL
SPARK PLUG
w
Inspect and adjust the areas around the
cylinder head after the engine has cooled
down completely.
cC
Before removing the spark plug, use com-
pressed air to clean the cylinder head
cover to prevent dirt from falling into the
engine.
1. Remove:
9Cover
2. Remove:
9Spark plug cap
9Spark plug
3. Inspect:
9Electrode 1
Wear/damage →Replace.
9Insulator color 2
4. Measure:
9Spark plug gap a
Use a wire gauge or thickness gauge.
Out of specification →Regap.
If necessary, clean the spark plug with
a spark plug cleaner.
Before installing the spark plug, clean
the gasket surface and plug surface.
INSP
ADJ
Spark plug gap:
0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
Standard spark plug
(with resistor):
CR6HSA (NGK)
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							2-15
SPARK PLUG/ENGINE SWITCH/
ECONOMY SWITCH/PILOT LIGHT
a
b
b 1
a
1
a
1
5. Tighten:
•Spark plug
NOTE:
To prevent thread damage, finger tighten a
the spark plug before tightening it to the spec-
ified torque b.
ENGINE SWITCH
1. Check:
9Engine switch 1
Checking steps:
9Set the engine switch 1to “ON” a.
9Start the engine.
9Check that the engine stops when the
switch is set to “STOP” b.
ECONOMY SWITCH
1. Check:
9Economy switch 1
Checking steps:
9Set the economy switch 1to “ON” a.
9Start the engine.
9Turn the switch of the electric device con-
nected to the AC outlet “ON” and “OFF” to
check whether the engine speed increas-
es and decreases.
PILOT LIGHT
1. Check:
9Pilot light 1
Checking steps:
9Start the engine.
9Make sure that the pilot light 1turns on.
INSP
ADJ
Spark plug:
13 Nm (1.3 m · kg, 9.4 ft · lb)
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							2-16
RECEPTACLE/DC CIRCUIT BREAKER
2
1
1
a
b
RECEPTACLE
1. Check:
9AC receptacles (7.5 A) 1
9DC receptacle (12V, 8 A) 2
Cracks/damage →Replace.
Poor connection →Correct.
DC CIRCUIT BREAKER
1. Check:
9DC circuit breaker
Checking steps:
9Press the reset button 1to the position of
“RESET” a.
9Connect the pocket tester (DC 20 V).
9Start the engine.
9Set the economy switch to “OFF”.
9Measure the DC voltage.
9Set the reset button to “OFF” b.
Voltage is zero →OK
NOTE:
If the restet bottn pup out (“OFF”) again, refer
to “GENERATOR SYSTEM” in CHAPTER 5.
INSP
ADJ
Pocket tester:
YU-03112, 90890-03112
Digital circuit tester:
90890-03174
DC voltage:
More than 12 V at 5,000 r/min
(with no load at AC output cur-
rent)
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							INSPADJ
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							ENG
3-1
CONTROL BOX
ENGINE
CONTROL BOX
1
2
Order Job name Q’ty Remarks
Control box removalRemove the parts in the order listed 
below.
Front cover and rear coverRefer to “COVERS” section in CHAPTER 2.
1 Tapping screw 4
2 Control box assembly 1
For installation, reverse the removal
procedure.
1
2
3
4
5
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