1
INTRODUCTION
We are constantly working on technical
improvement of our products. For this reason,
technical data, equipment and design are subject to
change without notice. All specifications,
illustrations and directions in this SERVICE DATA
are based on the latest products information
available at the time of publication.
For further information to service these models,
please refer to ECHO SERVICE MANUAL Ord. No.
402-21.
TRIMMER/BRUSHCUTTER
SRM-3805
SRM-4605
Reference No. 10-37A-00
ISSUED: 199807
SERVICE DATA
1
10-37A-00 SRM-3805, SRM-4605
CONTENTS
page
1 SERVICE INFORMATION ............................. 2
1-1 Specifications ............................................ 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 SERVICE HINT ............................................. 7
2-1 Gear case construction ............................. 7
INDEX
2
SERVICE INFORMATION
SRM-3805
SRM-4605
1 SERVICE INFORMATION
1-1 Specifications
OD: Outer diameter.
ID: Inner diameter.
*Without shoulder harness and cutter head.
**With standard cutter head.
***Install and use U-shaped handle when operating with steel blade.
Model
SRM-3805 (L) SRM-3805 (U) SRM-4605(L) SRM-4605(U)
Dimensions Length* mm(in) 1820 (71.7) 1820 (71.7) 1820 (71.7) 1820 (71.7)
Width mm(in) 360 (14.2) 720 (28.3) 360 (14.2) 720 (28.3)
Height mm(in) 350 (13.8) 455 (17.9) 350 (13.8) 455 (17.9)
Dry weight
**
kg(lb) 8.1 (17.9) 8.7 (19.2) 8.1 (17.9) 8.7 (19.2)
Engine Type KIORITZ, air-cooled, two-stroke, single cylinder
Rotation Counterclockwise as viewed from the output end
Displacement cm
3
(in3) 37.4 (2.284) 45.7 (2.790)
Bore mm(in) 38.0 (1.496) 42.0 (1.654)
Stroke mm(in) 33.0 (1.299) 33.0 (1.299)
Compression ratio 6.3 6.6
Carburetor Type Diaphragm, horizontal-draught
with primer without primer
Model WALBRO WT-297 WALBRO WT-120B
Venturi size-Throttle bore mm(in) 11.11 - 15.85 (0.437 - 0.624) 12.7 - 15.85 (1/2 - 0.624)
Ignition Type Capacitor discharge ignition system
in a single integrated piece
Spark plug Champion RCJ-7Y
Starter Type Automatic rewind
Rope diameter x length mm(in) 3.8 x 950 (0.15 x 37.4)
Fuel Type Premixed two-stroke fuel (Refer to Operator's manual.)
Tank capacity cm
3
(U.S.fl.oz.) 950 (32.1)
Clutch Type Centrifugal, 2-shoe pivot
Handle Type Front Crescent loop U-shaped Crescent loop U-shaped
Rear Integrated --- Integrated ---
control grip control grip
Drive shaft Type Solid
Diameter - Length mm(in) 8 - 1590 (0.31 - 62.6)
Housing OD - ID mm(in) 28 - 24.0 (1.10 - 0.94)
(Main pipe)
Length mm(in) 1530 (60.2)
Gear case Reduction ratio 1.33
Gear tooth Spiral bevel gear
Lubrication Lithium based grease
Cutter Type Nylon line cutter, 8-tooth blade***, 80-tooth blade***, Others
Pilot diameter mm(in) 25.4 (1.0)
Fastener type, size mm Left-hand thread nut, M10 x 1.25 pitch
Cutting rotation Counterclockwise as viewed from top
1-2 Technical data
Model SRM-3805 SRM-4605
Engine
Idling speed rpm 2400 - 3000
Operating speed rpm 6000 - 8000
Clutch-in speed rpm 3300 - 3700
Compression pressure, standard kgf/cm
2
(psi) 7.5 (107) 8.0 (114)
Ignition system
Spark plug gap mm(in) 0.6 - 0.7 (0.024 - 0.028)
Minimum secondary voltage
at 1000 rpm
kV 15
Secondary coil resistance kΩ 1.0 - 1.5
Pole shoe air gaps mm(in) 0.3 - 0.4 (0.012 - 0.016)
Ignition timing °BTDC 25
Carburetor
Type Diaphragm horizontal-draught
Supplier Walbro WT-297 Walbro WT-120B
Venturi Size mm(in) 11.11 (0.437) 12.7 (1/2)
Throttle Bore mm(in) 15.85 (0.624) 15.85 (0.624)
Idle speed screw initial setting
turn in
22
H needle initial setting turn back 1 1/2 1 1/4
L needle initial setting turn back 1 1
Test Pressure, minimum kgf/cm
2
(psi) 0.5 (7.0)
Metering lever height mm(in) 1.65 (0.065) lower than diaphragm seat
BTDC: Before top dead center.
H needle: High speed needle.
L needle: Idle needle.
3
SERVICE INFORMATION
SRM-3805
SRM-4605
1-3 Torque limits
Descriptions Size kgf•cm in•lbf
Starter Pawl carrier M 8 80 - 100 70 - 85
system Pawl carrier nut M 8 160 - 200 140 - 175
Starter center post M 5 * 25 - 35 22 - 30
Starter case M 4 35 - 50 30 - 45
Ignition Magneto rotor (Flywheel) M10 350 - 400 300 - 350
system Ignition coil (CDI module) M 5 30 - 50 26 - 45
Fan cover M 5 70 - 110 60 - 95
Spark plug M14 130 - 170 110 - 150
Fuel Carburetor insulator M 5 40 - 55 35 - 50
system Carburetor (SRM-3805) M 5 30 - 45 25 - 40
Carburetor (SRM-4605) M 5 35 - 45 30 - 40
Throttle cable nut M 6 25 - 35 22 - 30
Fuel tank bracket , Stand M 5 30 - 45 26 - 40
Clutch Clutch shoe M 8 * 160 - 200 140 - 175
Clutch drum case M 5 70 - 100 60 - 95
Engine Crankcase M 5 70 - 110 60 - 95
Cylinder M 5 70 - 110 60 - 95
Cylinder cover M 5 30 - 45 26 - 40
Top guard M 5 30 - 45 26 - 40
Muffler M 5 60 - 100 52 - 85
Muffler bracket M 5 30 - 45 25 - 40
Muffler cover M 4 14 - 28 12 - 24
Muffler cover (with starter case) M 4 35 - 50 30 - 45
Others Blade fastening nut LM10 280 - 320 245 - 280
Regular bolt, nut, and screw M 3 6 - 10 5 - 9
M 4 15 - 25 13 - 22
M 5 25 - 45 22 - 40
M 6 45 - 75 40 - 65
M 8 110 - 150 95 - 130
M10 210 - 300 180 - 270
LM: Left-hand thread.
* Apply thread locking sealant. (See below.)
Material Location Remarks
Grease Gear case
Rewind spring Lithium based grease
Starter center post
Thread locking sealant Starter center post screw Loctite #222, ThreeBond #1342, or equivalent
Clutch shoe
1-4 Special repairing materials
4
SRM-3805
SRM-4605
SERVICE INFORMATION
mm(in)
Description SRM-3805 SRM-4605
A Cylinder bore When plating is worn and aluminum can be seen
B Piston outer diameter Min. 37.90 (1.492) 41.90 (1.65)
C Piston pin bore Max. 10.025 (0.3947) 10.025 (0.3947)
D Piston ring groove Max. 1.3 (0.051) 1.3 (0.051)
E Piston ring side clearance 1st Max. 0.15 (0.006) 0.15 (0.006)
2nd Max. 0.1 (0.004) 0.1 (0.004)
F Piston pin outer diameter Min. 9.98 (0.3929) 9.98 (0.3929)
G Piston ring width Min. 1.15 (0.045) 1.15 (0.045)
H Piston ring end gap Max. 0.5 (0.02) 0.5 (0.02)
K Connecting rod small end bore Max. 14.025 (0.5522) 14.025 (0.5522)
L Crankshaft runout Max. 0.05 (0.002) 0.05 (0.002)
M Clutch drum bore Max. 79.0 (3.11) 79.0 (3.11)
5K223 5K224
5K225 5K016 5K042
5K182 5K222
5K188
0
5
1
23
4
5
6
7
8
5K1895K219 5K220
ABCD
EFGH
KLM
5
SERVICE INFORMATION
SRM-3805
SRM-4605
1-5 Service limits
6
SRM-3805
SRM-4605
SERVICE INFORMATION
1-6 Special tools
a
1.5
1
.6
5
1
.3
0.4
c
a
b
1
5
16
2
6
17
3
7
12: c=34 mm
13: c=31 mm
18 20
9
4
8
14
Key Part Number Description Used for:
1 Tachometer Measuring engine speed to adjust carburetor
2 895610-79920 L-hex. wrench(4 mm) Removing and installing hex. socket bolt (M5)
3 897563-19830 Metering lever gauge Measuring metering lever height on carburetor
4 897501-03938 Puller Removing flywheel
5 897603-23030 PTO shaft puller Removing PTO shaft
6 897701-06030 Bearing wedge Removing ball bearings remaining on crankshaft
7 897701-14732 Bearing tool Removing and installing crankcase / clutch drum bearing
8 897702-30131 Piston pin tool Removing and installing piston pin (Use 8 mm dia. adapter)
9 897712-04630 2-pin wrench Removing and installing pawl carrier
10 897714-22830 Oil seal tool Installing drive gear assembly into gear case
11 897714-24330 Oil seal tool Installing drive gear ball bearings
Installing PTO shaft ball bearing
Installing crankcase oil seal (starter side)
12 897718-02830 Bearing tool Installing crankcase ball bearings (clutch side)
13 897718-03930 Bearing tool Installing crankcase ball bearings (starter side)
14 897719-02830 Piston holder Making piston steady to remove and install piston and rings
15 897726-16130 Oil seal tool Installing crankcase oil seal (clutch side)
16 897800-79931 Spark tester Checking ignition system
17 897803-30130 Pressure tester Testing carburetor and crankcase leakages
18 897826-16131 Pressure plug Plugging intake port to test crankcase and cylinder leakages
19 897827-16131 Pressure plate Plugging intake port to test crankcase and cylinder leakages
20 897831-16131 Pressure plug
Plugging exhaust port to test crankcase and cylinder leakages
21 897835-16131 Pressure connector Testing crankcase and cylinder leakages
15
19 21
10:
a = 10 mm
b = 25.5 mm
11:
a = 12 mm
b = 32 mm
2 SERVICE HINT
2-1 Gear case construction
7
SERVICE INFORMATION
SRM-3805
SRM-4605
Drive gear
Driven gear
PTO shaft
Nut
Adapter plate (L)
Gear case
Adapter plate (U)
Cover plate
Dust seal plate
O-ring
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