Echo shindaiwa CSG-7410ES User manual

REVISED May 2021
Ref. No. 401-45
CSG-7410ES
ECHO:
shindaiwa:
EC741S
Copyright C 2020 YAMABIKO Corporation All rights reserved.
(Serial number: 30000001 and after)
(Serial number: 38000001 and after)

INTRODUCTION
This service manual contains information for ser-
vice and maintenance of ECHO ENGINE CUT-
OFF SAW, model CSG-7410ES, shindaiwa
ENGINE CUT-OFF SAW, model EC741S.
For systematic diagnosis, to avoid extra work,
time loss and to meet Emission regulation,
please refer to “Troubleshooting guide” that
describes problems, testing, remedies and
references. We recommend you make use of
Operator’s Manual and Parts Catalogue together
with this manual when servicing.
We are constantly working on technical improve-
ment of our products. For this reason, technical
data, equipment and design are subject to
change without notice. All specications, illustra-
tions and directions in this manual are based on
the latest product information available at the
time of publication.
NOTE: This service manual contains pictures
with different model name for other markets and
different colored model.

TABLE OF CONTENTS
CSG-7410ES
EC741S 1
Page Page
1 SERVICE INFORMATION.....................................2
1-1 Specications ...................................................2
1-2 Technical data ..................................................3
1-3 Torque limits .....................................................4
1-4 Special repairing materials...............................4
1-5 Service Limits ...................................................5
1-6 Special tools.....................................................6
2 STARTER SYSTEM ..............................................7
2-1 Disassembling starter assembly.......................8
2-2 Assembling starter assembly .........................10
2-3 Replacing oilseal ............................................12
2-4 Replacing starter pawl....................................12
3 IGNITION SYSTEM.............................................13
3-1 Troubleshooting guide....................................14
3-2 Testing spark ..................................................15
3-3 Inspecting spark plug .....................................15
3-4 Replacing spark plug cap and coil..................16
3-5 Inspecting and replacing ignition switch.........16
3-6 Inspecting ignition coil and switch lead ..........17
3-7 Replacing ignition coil.....................................18
3-8 Setting pole shoe air gaps..............................18
3-9 Inspecting and replacing magneto rotor and key 19
4 FUEL SYSTEM ...................................................21
4-1 Replacing air lter...........................................22
4-2 Inspecting fuel cap and fuel strainer...............23
4-3 Inspecting fuel tank and line...........................24
4-4 Testing carburetor...........................................25
4-5 Removing carburetor, fuel line and tank vent .26
4-6 Inspecting tank vent .......................................27
4-7 Replacing purge bulb .....................................28
4-8 Inspecting crankcase pulse passage .............28
4-9 Inspecting metering chamber and inlet needle valve 29
4-10 Inspecting metering lever height ....................30
4-11 Inspecting pump diaphragm and inlet screen 31
4-12 Replacing welch plug .....................................31
4-13 Installing carburetor, fuel line and tank vent...32
4-14 Adjusting carburetor .......................................35
4-14-1 General adjustment rules ...........................35
4-14-2 Initial setting Throttle adjust screw, L mixture
needle and H mixture needle .....................35
4-14-3 Adjusting carburetor ...................................36
5 CLUTCH SYSTEM AND BELT DRIVING SYSTEM...37
5-1 Adjusting belt tension .....................................37
5-2 Inspecting and replacing belt..........................38
5-3 Inspecting clutch parts....................................40
5-4 Installing clutch parts......................................41
6 HANDLE AND CONTROL SYSTEM ..................42
6-1 Replacing cushions and rear handle..............43
6-2 Replacing throttle system...............................44
7 ENGINE...............................................................45
7-1 Cleaning cooling air passages .......................46
7-2 Inspecting mufer and exhaust port ...............46
7-3 Testing cylinder compression .........................47
7-4 Testing crankcase and cylinder seal...............48
7-5 Inspecting decompressor ...............................49
7-6 Inspecting cylinder and intake parts...............50
7-7 Inspecting piston and piston ring....................51
7-8 Disassembling crankcase...............................52
7-9 Assembling crankcase ...................................53
7-10 Installing piston and cylinder ..........................57
8 CUTTING SYSTEM.............................................59
8-1 Disassembling cutter cover assembly............60
8-2 Replacing pulley, drive shaft and ball bearing 61
8-3 Assembling cutter cover assembly .....................63
9 MAINTENANCE GUIDE......................................65
9-1 Disassembly Chart .........................................65
9-2 Troubleshooting guide....................................66
9-3 Service Intervals.............................................68

SERVICE INFORMATION
CSG-7410ES
EC741S
2
1 SERVICE INFORMATION
1-1 Specications
Dimensions* Length mm(in) 620 (24.4)
Width mm(in) 240 (9.4)
Height mm(in) 407 (16.0)
Dry weight* kg(lb) 10.7 (23.6)
Engine Type YAMABIKO, air-cooled, two-stroke, single cylinder
Rotation Clockwise viewed from the output end
Displacement cm3(in3) 73.5 (4.485)
Bore mm(in) 51.0 (2.008)
Stroke mm(in) 36.0 (1.417)
Compression ratio 6.92
Carburetor Type Diaphragm horizontal-draft, Inner vent type
Model Walbro HAD-344
Venturi size-Throttle bore mm(in) 16.66 - 19.03 (0.656 - 0.749)
Ignition Type CDI (Capacitor discharge ignition) system
Digital Magneto with stop holding function
Spark plug NGK BPMR7A
Exhaust Mufer type Spark arrester mufer
Starter Type ES (Effortless-Start) / S (Soft-start)
Rope diameter x length mm(in) 3.8 x 900 (0.15 x 35.4)
Fuel Type** Mixed two-stroke fuel
Mixture ratio 50 : 1 (2%)
Gasoline Minimum 89 octane
Two-stroke air cooled engine oilISO-L-EGD (ISO/CD13738), JASO FC/FD
Tank capacity L (UK..oz.) 0.7 (23.7)
Clutch Type Centrifugal, 3 shoe slide with 3-tension spring
Cutter Size mm (in) 350 (14)
Arbor mm 20
Pulley Blade speed reducing ratio 2.57
Belt 6PJ-808
Air lter structure Main lter: Honeycomb type
Sub lter: Nonwoven fabric screen
* Without blade
** Premixed alkylate fuel for 2-stroke can be used.

SERVICE INFORMATION
CSG-7410ES
EC741S 3
1-2 Technicaldata
Engine
Compression pressure MPa (kgf/cm2) (psi) 0.99 (10.1) (143)
Clutch engagement speed r/min 3,800
Ignition system
Spark plug gap mm(in) 0.6 - 0.7 (0.024 - 0.028)
Spark test
Tester gap w/ spark plug mm(in) 4.0 (0.16)
Tester gap w/o spark plug mm(in) 6.0 (0.24)
Secondary coil resistance kΩ 1.5 - 2.5
Pole shoe air gaps mm(in) 0.3 - 0.4 (0.012 - 0.016)
Ignition timing at 2,700 r/min °BTDC 18
at 9,000 r/min °BTDC 30
Carburetor
Test Pressure, minimum MPa (kgf/cm2) (psi) 0.05 (0.5) (7.0)
Metering lever height mm(in) Flush with diaphragm seat
Tool to adjust mixture needles D-shaped tool (L) P/N X645-000031
Carburetor adjustment
Fueltype Mixedtwo-strokefuel Premixedalkylatefuel
Preparation Remove cutter.
1) Initial setting H mixture needle turn out 3 1/2 3 3/8
L mixture needle turn out 2
Throttle adjust screw turn out*12 1/2
Engine warm-up Idle - WOT : Total sec. 10 - 5 : 120
2) Find idle maximum speed Adjust L mixture needle to maximum idle speed*2
3) Set idle maximum speed w/ TAS r/min 3,700 3,750
4) Set idle speed by turning Lmixture needle CCW When
carburetoror
diaphragmis
brand-new
2,800
When
carburetoror
diaphragmis
brand-new
2,800
r/min 3,300 2,800
5) Verify nal engine speed with standard equipment Idle:
3,100 - 3,400 Idle: 2,600 - 3,000r/min
6) Verify clutch engagement speed Conrm clutch engagement speed.
If it is less than 1.25 times the idle speed,
adjust the idle speed by turning TAS CCW.
BTDC: Before top dead center. WOT: Wide open throttle CCW: Counterclockwise TAS: Throttle adjust screw
*1Turn TAS clockwise until its head touches boss. Then turn TAS counterclockwise.
*2If clutch engages during adjustment process 2), decrease engine speed by turning TAS CCW until clutch
disengages and then redo 2).

SERVICE INFORMATION
CSG-7410ES
EC741S
4
1-4 Specialrepairingmaterials
Material Location Remarks
Lubricant Starter pawl ThreeBond #1816B or equivalent
Thread locking sealant Pulley ThreeBond #1377B or equivalent
Cutter cover nut
Starter center nut Loctite #263 or equivalent
Grease Starter center shaft
EPNOC AP2 (Lithium based grease)
P/N X695-000060
Main air lter groove
Handle cushion inside
Oil seal inner lips
1-3 Torquelimits
Descriptions Size kgf•cm N•m in•lbf
Starter system Starter pawl M6 90 -120 9 -12 80 -105
Starter case M5** 30 -45 3 -4.5 26 -40
Ignition system Magneto rotor (Flywheel) M8 230 -240 23 -24 200 -210
Ignition coil M5** 50 -70 5 -7 45 -60
Spark plug M14 170 -190 17 -19 150 -165
Fuel system Carburetor, Carburetor elbow M5 30 -45 3 -4.5 26 -40
Carburetor elbow M5** 30 -45 3 -4.5 26 -40
Clutch Clutch assembly LM8 280 -300 28 -30 245 -262
Clutch drum LM8 150 -170 15 -17 130 -150
Engine Crankcase M5** 50 -70 5 -7 45 -60
Cylinder M6** 90 -120 9 -12 80 -105
Intake insulator M5** 30 -45 3 -4.5 26 -40
Decompression valve M10 120 -150 12 -15 105 -130
Muffler M6 150 -170 15 -17 130 -150
Others Cylinder cover M5** 30 -60 3 -6 26 -52
Rear handle Rear handle side M5 40 -60 4 -6 35 -52
Crankcase side M5 30 -50 3 -5 26 -45
Front handle M6 50 -70 5 -7 45 -60
M5** 50 -70 5 -7 45 -60
Cutter arm Clutch side M5** 25 -35 2.5 -3.5 18 -30
cover Pulley side M8 230 -270 23 -27 200 -235
Cutter cover plate M5** 50 -70 5 -7 45 -60
Pulley M10* 200 -230 20 -23 175 -200
Cutter guard stopper M6 70 -90 7 -9 60 -80
Regular bolt, nut and screw M3 6 -10 0.6 -1 5 -9
M4 15 -25 1.5 -2.5 13 -22
M5 25 -45 2.5 -4.5 22 -40
M6 45 -75 4.5 -7.5 40 -65
LM: Left-hand thread
* Apply thread locking sealant (See blow).
** Precoat bolt: If the coat is peeled off, replace new one or apply ThreeBond #1344 or equivalent.
If old thread locking sealant is left in threads, correct torque may not be secured.
In case old thread locking sealant is left, remove it.

SERVICE INFORMATION
CSG-7410ES
EC741S 5
5K083 5K084 5K081
5K082 5K016 5K025
5K174 5K181
5K173
5K253
5K254
5K181
1-5 Servicelimits
ABCD
F G H
K L N
E
Description mm (in)
A Cylinder bore When plating is worn and aluminum can be seen
BPiston outer diameter Min. 50.89 (2.004)
CPiston pin bore Max. 12.030 (0.4736)
DPiston ring groove Max. 1.6 (0.063)
EPiston ring side clearance Max. 0.15 (0.006)
FPiston pin outer diameter Min. 11.98 (0.4717)
GPiston ring width Min. 1.45 (0.057)
HPiston ring end gap Max. 0.6 (0.02)
KCon-rod small end bore Max. 15.025 (0.5915)
LCrankshaft runout Max. 0.03 (0.0012)
NClutch drum bore Max. 79.5 (3.13)

SERVICE INFORMATION
CSG-7410ES
EC741S
6
Madein Germany
4.0x150
4 010 5 5 7 86 9 7 4 5
Ignition Air Gap Gauge
#.014 = .35mm
P/N 91004
0
1
2
3
4
5
6
7
Key Part Number Description Reference
1 X602-000350 T-hex. wrench (3 mm) Removing and installing hex. head bolt (M4)
2 X602-000360 T-hex. wrench (4 mm) Removing and installing hex. head bolt (M5)
3 X602-000230 T-hex. wrench (5 mm) Removing and installing hex. head bolt (M6)
4 897802-33330 Tachometer PET-1000R Measuring engine speed to adjust carburetor
5897800-79931 Spark tester Checking ignition system
6 91004 Module air gap gauge Adjusting pole shoe air gaps
7 Y089-000111 Puller Removing magneto rotor (ywheel) and crankcase
8 Y089-000094 Carburetor adjustment tool Adjusting carburetor
9 X644-000020 Piston stopper Locking crankshaft rotation (Fits 14 mm threads)
10 X640-000560 Clutch tool Removing clutch assembly
11 91041 Pressure rubber plug Plugging exhaust port to test crankcase/cylinder leakages
12 897826-16131 Pressure rubber plug Plugging intake port to test crankcase/cylinder leakages
13 897827-16131 Pressure plate Plugging intake port to test crankcase/cylinder leakages
14 A131-000150 Pressure connector Testing crankcase and cylinder leakage
15 91149 Pressure/Vacuum tester Testing crankcase / cylinder leakages
16 897803-30133 Pressure tester Testing carburetor and crankcase leakage
17 91037 Compression gauge Measuring cylinder compression
18 897701-14732 Bearing tool Removing and installing ball bearings on crankcase
19 897726-21430 Oil seal tool Installing oil seal
20 X646-000590 Collar oil seal tool Set oil seal collect position
21 X646-000060 Rod oil seal Installing oil seal for crankcase
22 22182-96460 Rod oil seal Installing oil seal for crankcase
23 X646-000081 Rod bearing Installing bearing for crankcase
24 X646-000050 Rod bearing Installing bearing for crankcase
25 22160-96440 Rod bearing Installing bearing for crankcase
26 22169-96410 Holder Seat for oilseal / bearing / gearshaft
27 X643-000020 Holder Seat for oilseal / bearing
28 X646-000100 Rod bearing Installing bearing for crankcase (Engine cutter)
29 897702-30131 Piston pin tool Removing and installing piston pin
1-6 Specialtools
1, 2, 3 4 5 6 7
8 9 10 11 14
15 16 17 18 19
20 21, 22 23, 24, 25 26 27
12
13
28 29

STARTER SYSTEM
CSG-7410ES
EC741S 7
2 STARTER SYSTEM
(A) Starter case (G) Power spring
(B) Rope guide (H) Shaft
(C) Starter grip (J) Cover
(D) Rewind spring (K) Oil seal
(E) Rope reel (L) Pawl catcher
(F)
Starter rope (M) Pawl
(A)
(B)
(C)
(D)
(E)
(F)
(G)
(H)
(J)
(K) (L)
(M)

STARTER SYSTEM
CSG-7410ES
EC741S
8
2-1 Disassemblingstarterassembly
1. Remove 4 pre-coated bolts and remove starter
assembly (A) from unit.
2. Pinch pawl catcher (B) with adjustable wrench
(C) as shown not to rotate pawl catcher (B).
NOTE: Do not insert rod shaped tool between the
pawls of pawl catcher (B) to secure it, otherwise
damage of pawl catcher (B) may occur.
3. Loosen nut (D) with 10 mm socket wrench (E).
4. Remove nut (D), washer(F) and pawl catcher (B).
5. Remove 4 screws and cover (G).
NOTE: Inspect oilseal of cover (G). If damaged,
replace the oilseal with new one.(Refer to “2-3 Re-
placing oilseal”).
6. Remove shaft (H) and power spring (J).
7. Pull out starter rope (K) about 30 cm (12 in) and
hold rope reel (M) by hand. Loop excess rope in
rope reel notch (m1) as shown.
8. Rotate rope reel (M) counterclockwise to release
tension of rewind spring.
A
B
D
C
E
B
F
D
G
H
J
M
A
m1
K

STARTER SYSTEM
CSG-7410ES
EC741S 9
WARNING DANGER
Weareyeprotectionandtakecarewhen
removingropereel.Rewindspring mayun-
windsuddenlyandcausepersonalinjury.
M
N
P
N
A
M
2-1 Disassembling starter assembly (Continued)
9. Remove rope reel (M) from starter case (A)
slowly to prevent rewind spring from unwinding.
10. When removing rewind spring (N) from rope
reel (M), pinch rewind spring (N) with pliers (P) and
lift up as shown.

STARTER SYSTEM
CSG-7410ES
EC741S
10
2-2 Assemblingstarterassembly
WARNING DANGER
Useofeyeprotectionandsafetyglovesare
stronglyrecommendedwhileworkingonre-
windspring.
1. If rewind spring (N) is removed from rope reel (M),
wind the spring (N) inside rope reel (M) as shown.
NOTE: Apply small amount of lithium based
grease to surface (m2) of rope reel before winding
the spring.
2. Apply lithium based grease on around shaft (a1)
of starter case (A) if dry.
3. Carefully install rope reel (M) on starter case (A)
as shown.
4. Pull out starter rope (K) inside starter case (A).
Rotate rope reel (M) clockwise several turns with
starter rope hooked at notch (m1) as shown. Hold
rope reel (M) to prevent spring from unwinding and
pull out starter grip to take the rope slack.
5. Pull starter grip several times to check rewind
spring tension. If starter is not rewinding fully, in-
crease spring tension by rotating rope reel (N) one
more turn clockwise following above step 4.
NOTE: Lightly hold rope reel (M) by hand to pre-
vent rewind spring from unwinding when pulling
starter grip.
6. Pull out starter rope (K) all the way, and check
that rope reel can be rotated an additional half or
more turn clockwise as shown, to prevent rewind
spring from breaking.
7. If rope reel can not be turned clockwise, reduce
tension by rotating rope reel counterclockwise one
turn with starter rope hooked at notch (m1).
M
N
m2
A
M
a1
m1
A
M
K
lithium

STARTER SYSTEM
CSG-7410ES
EC741S 11
2-2 Assembling starter assembly (Continued)
8. Install power spring (J) to rope reel (M) placing
hook (j1) of power spring into groove(m3) of rope
reel.
9. Apply small amount of lithium based grease to
inside (h1) of shaft (H).
10. Install shaft (H) on rope reel placing hook (j2)
into groove (h2).
11. Place cover (G) on starter case and tighten
with 4 screws (R).
12. Put washer(F) and pawl catcher (B) on cover (G).
13. Apply thread locking sealant (Loctite #263 or
equivalent) to nut (D) and tighten the nut (D) by
hand until it can not be turned further.
14. Pinch pawl catcher (B) with adjustable wrench
(C) as shown not to rotate pawl catcher (B).
NOTE: Do not insert rod shaped tool between the
pawls of pawl catcher (B) to secure it, otherwise
damage of pawl catcher (B) may occur.
15. Tighten nut (D) with 10 mm socket wrench (E).
16. Reinstall starter case (A) to unit and secure
starter case (A) with 4 pre-coated bolts.
NOTE: If the coat is peeled off, replace new one or
apply ThreeBond #1344 or equivalent. If old thread
locking sealant is left in threads, correct torque
may not be secured. In case old thread locking
sealant is left, remove it.
m3
j1
J
M
H
J
h2
h1
j2
lithium
F
G
R
Loctite#263 D
B
A
B
D
C
E

STARTER SYSTEM
CSG-7410ES
EC741S
12
Q
G
d
E
B
A
F
d
A
B
C
D
B
2-3 Replacingoilseal
1. Remove cover (G) from starter assembly. (Refer
to “2-1 Disassembling starter assembly”)
2. Pry oilseal (Q) from cover (G).
3. Install new oilseal (Q).
2-4 Replacingstarterpawl
1. Remove starter assembly from unit.
2. Loosen bolt (A) with 10mm socket wrench and
remove pawl (B), spacer (C) spacer (C) and tor-
sion spring (D). Replace damaged or worn parts.
NOTE: When it is hard to loosen bolt, install piston
stopper X644-000020 (E) in spark plug hole to stop
crankshaft rotation and remove bolt easily.
3. Install torsion spring, spacer, pawl (B) and bolt (A).
To avoid torsion spring from pinching, install these
parts without setting the end (d) of torsion spring
on pawl (B).
4. Using ne wire (F) or appropriate tool, place the
end (d) of torsion spring on pawl (B), by hooking
and passing under pawl as shown. Remove fine
wire (F) or tool.
5. Make sure pawl (B) can move smoothly. If it
does not move smoothly, check parts for correct
installation.

IGNITION SYSTEM
CSG-7410ES
EC741S 13
3 IGNITION SYSTEM
(A) Magneto rotor (Flywheel) (E) Spark plug cap
(B) Ignition coil (F) Switch lead
(C) Spark plug (G) Ignition switch
(D) Spark plug cap coil
(A)
(B)
(C)
(E)
(G)
(F)
(D)

IGNITION SYSTEM
CSG-7410ES
EC741S
14
3-1 Troubleshootingguide
Not
OK
Not
OK
Not
OK
OK
OK
OK
Spark plug
Spark
plug cap/
coil
Ignition
switch
Clean /
Regap /
Replace.
Replace.
Start
OK
OK
S.T.
Not
OK
S.T.
Not
OK
Not
OK
S.T.
OK
S.T.
Not
OK Pole
shoe air
gaps
Replace.
Not
OK OK
Not
OK
S.T.
OK
OK
Replace
ignition
coil.
Leads
connections
Not
OK
OK
OK
Not
OK
S.T.
Repair /
Replace.
Not
OK
Remedy
Inspect
Not
OK
Flywheel
key
OK
R.T.*
End
Not
OK
Flywheel
magnet
Replace.
Not
OK
R.T.
Not
OK
OK
OK
Replace ignition coil and / or inspect other
systems.
Replace flywheel.
OK
OK
Adjust pole shoe air gaps.
(Inspect flywheel magnet
at the same time. Go to
Aif OK.)
S.T.
Not
OK
A
S.T.: Spark test.
R.T.: Running test including actual cutting.
OK
OK
Secondary
coil
resist-
ances

IGNITION SYSTEM
CSG-7410ES
EC741S 15
3-2 Testingspark
WARNING DANGER
*Donottestnearsparkplugholewithout
sparkpluginstalled,otherwisethereisa
chancetoignitefuelmixtureinsidecylinder.
*Donottouchmetalpartsofsparktester
whileperformingthetesttoavoidreceiving
electricalshock.
*Donotchecksparkinareawheregasoline
isspilledorammablegasesmayexist.
1. Remove cylinder cover. (Refer to “4-1 Replacing
air lter”)
2. Connect Spark tester 897800-79931 (C) to high
tension lead (A) and connect tester lead (D) to
spark plug (B).
3. Screw in adjuster (c1) until the needle tips
contact. Turn out adjuster (c2) 4 turns to set spark
tester gap (c2) to 4 mm (0.16 in).
4. Pull starter grip several times.
5. If spark is steady blue or white at the tester gap,
ignition system is considered good. Go to inspect-
ing spark plug.
6. If no spark exists or spark is intermittent in
yellow, orange, or red, continue with further inspec-
tion.
3-3 Inspectingsparkplug
1. Remove spark plug to inspect for spark plug gap
fouling, cracked or broken insulator, cracked outer
electrode, or rounded center electrode. Replace
spark plug as required.
Spark plug gap (A) standard
: 0.6 to 0.7 mm (0.024 to 0.028 in)
2. If engine does not start with correct spark plug,
inspect if spark plug is wet or dry. If it is exces-
sively wet or dry, inspect fuel system.
GASO
LINE
3K069
A
A
C
D
B
c1
c2

IGNITION SYSTEM
CSG-7410ES
EC741S
16
AB
3-5 Inspectingandreplacingignitionswitch
1. Remove cylinder cover assembly, lter case and
cover stay. (Refer to “4-1 Replacing air lter” and
“4-5 Removing carburetor, fuel line and tank vent”)
2. Disconnect terminal (A) of ignition switch from
switch lead.
3. Connect one probe of Ohm-meter or multi-meter
to terminal (A). Connect the other probe to screw
part (B) of ignition switch.
4. When not pushing ignition switch, tester should
indicate innite resistance.
5. When pushing ignition switch, tester should
show that the circuit is in conducting state (closed
circuit).
6. If ignition switch is defective, replace with a new
one as follows.
7. Remove cap (C) and replace ignition switch.
8. Connect terminal of ignition switch and terminal
of switch lead.
9. Twist leads counterclockwise and place the
leads as shown.
C
3-4 Replacingsparkplugcapandcoil
1. Disconnect spark plug cap (A) from spark plug.
2. Apply some oil in spark plug cap (A) for easy re-
moval from high tension lead (B).
3. Pull spark plug cap (A) away from high tension
lead (B).
4. Inspect spark plug cap coil (C) for corrosion
and correct connection. Inspect spark plug cap for
cracks. Replace as required.
NOTE: Make sure spark plug cap coil (C) contacts
center core of high tension lead when reinstalling
it.
5. Coat end of high tension lead (B) with small
amount of oil, and insert it into spark plug cap (A)
as shown, until the spark plug cap coil is properly
seated in the cap.
A
B
C
A
B

IGNITION SYSTEM
CSG-7410ES
EC741S 17
3-6 Inspectingignitioncoilandswitchlead
Remove cylinder cover assembly, starter assembly
and fan cover.
Inspecting ignition coil resistance
1. Connect one probe of Ohm-meter or multimeter
to spark plug cap coil.
2. Connect the other probe to ignition coil core to
measure secondary coil resistance. Secondary
coil resistance should be in the range of 1.5 to 2.5
kΩ.
3. If the meter reading indicates innite
resistance, remove spark plug cap and spark
plug cap coil, and measure resistance between the
conduction wire of high tension lead and ignition
coil core.
5. If the reading at step 2 or 3 is not in the range of
1.5 to 2.5 kΩ, replace with a new ignition coil (Go
to “3-8 Replacing ignition coil”).
Inspecting switch lead
1. Disconnect terminals of switch lead from ignition
switch and ignition coil.
2. Connect each probe of Ohm-meter or multime-
ter to each terminal of switch lead as shown.
3. Ohm-meter or multimeter should show that the
circuit has continuity. (Electrical current can flow
between each.)
4. If the meter reading indicates innite resistance,
replace switch lead with new one.

IGNITION SYSTEM
CSG-7410ES
EC741S
18
3-7Replacingignitioncoil
1. Remove cylinder cover assembly, filter case,
cover stay (Refer to “4-1 Replacing air lter” and
“4-5 Removing carburetor, fuel line and tank vent”).
2. Remove starter assembly and fan cover (Refer
to “2-1 Disassembling starter assembly“).
3. Disconnect switch lead terminal (B) from ignition
coil. Loosen 2 pre-coated bolts (A).
4. Remove ignition coil (C) from crankcase.
5. Remove spark plug cap and spark plug cap coil
from high tension lead (D) (Refer to “3-4 Replacing
spark plug cap and coil”).
6. Install spark plug cap and spark plug cap coil to
new ignition coil (C)(Refer to “3-4 Replacing spark
plug cap and coil”).
7. Loosely install new ignition coil (C) with 2 pre-
coated bolts (A). Set air gap (Refer to “3-8 Setting
pole shoe air gaps“). And then tighten 2 pre-coated
bolts (A).
NOTE: If the coat is peeled off, replace new one or
apply ThreeBond #1344 or equivalent. If old thread
locking sealant is left in threads, correct torque
may not be secured. In case old thread locking
sealant is left, remove it.
8. Connect switch lead terminal (B) to ignition coil.
9. Pass high tension lead (D) over switch lead as
shown.
NOTE: When reinstalling fan cover, refer to the
note on page 20.
BA
D
C
3-8 Settingpoleshoeairgaps
1. Insert Module air gap gauge: 91004 or 0.3 - 0.4
mm (0.012 - 0.016 in) thick feeler gauge (B) be-
tween ywheel and ignition coil shoes.
2. Rotate magneto rotor (C) until magnetic poles of
magneto rotor face ignition coil shoes (D).
3. Hold ignition coil against magneto rotor (C) and
tighten 2 bolts (A) to specied torque (Refer to “1-3
Torque limits”). After tightening 2 bolts (A), remove
feeler gauge (B) or Module air gap gauge: 91004.
NOTE: When air gap is too narrow, contact with
magneto rotor may result. When the air gap is too
wide, spark is weak.
A
C
B
D