Stihl MS 390 User Manual

1MS 290, MS 310, MS 390
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© ANDREAS STIHL AG & Co. KG, 2004
Contents
1. Introduction 2
2. Safety Precautions 3
3. Specifications 4
3.1 Engine 4
3.1.1 Engine (USA only) 4
3.2 Fuel System 5
3.3 Ignition System 5
3.4 Chain Lubrication 5
3.5 Tightening Torques 6
4. Troubleshooting
Chart 7
4.1 Clutch, Chain Drive,
Chain Brake,
Chain Tensioner 7
4.2 Rewind Starter 8
4.3 Chain Lubrication 9
4.4 Ignition System 10
4.5 Carburetor 11
4.6 Engine 13
5. Clutch, Chain Drive,
Chain Brake and
Chain Tensioner 14
5.1 Clutch Drum/Chain
Sprocket 14
5.2 Chain Catcher 15
5.3 Spiked Bumper 15
5.4 Collar Stud 16
5.5 Clutch 16
5.6 Chain Brake 18
5.6.1 Checking Operation 18
5.6.2 Removing and
Installing 18
5.7 Replacing Pins 21
5.7.1 Removing 21
5.7.2 Installing 22
5.8 Chain Tensioner 23
6. Engine 23
6.1 Muffler/Spark
Arresting Screen 23
6.2 Leakage Test 25
6.2.1 Preparations 25
6.2.2 Pressure Test 26
6.2.3 Vacuum Test 26
6.3 Oil Seals 27
6.4 Shroud 29
6.5 Removing and
Installing the Engine 30
6.5.1 Cylinder 31
6.5.2 Piston 33
6.6 Piston Rings 35
6.7 Crankshaft 35
7. Ignition System 36
7.1 Ignition Module 37
7.1.1 Ignition Timing 37
7.1.2 Removing and
Installing 37
7.1.3 Testing the
Ignition Module 39
7.2 Spark Plug Boot 40
7.2.1 Ignition Lead 41
7.3 Flywheel 42
7.4 Contact Spring 43
7.5 Replacing Wiring
Harness 43
7.6 Ignition System
Troubleshooting 45
8. Rewind Starter 48
8.1 General 48
8.2 Removing and
Installing 48
8.3 Pawl 48
8.4 Rope Rotor 49
8.5 Starter Rope/Grip 49
8.5.1 Tensioning 51
8.6 Starter Rope Guide
Bushing 52
8.7 Replacing Rewind
Spring 52
9. AV Handle System/
Handle Housing 53
9.1 Front Handle 53
9.2 Handle Housing 54
9.3 Annular Buffers 56
9.3.1 Front Handle/
Handle Housing 56
9.3.2 Handle Housing/
Engine Housing 56
9.3.3 Front Handle/Engine
Housing 57
9.4 Switch Shaft 58
9.5 Throttle Trigger/
Interlock Lever 59
10. Chain Lubrication 60
10.1 Pickup Body/
Suction Hose 60
10.2 Valve 61
10.3 Tank Cap 62
10.4 Oil Pump 62
10.4.1 Removing and
Installing 62
10.4.2 Servicing 63
11. Fuel System 64
11.1 Air Filter 64
11.2 Carburetor 65
11.2.1 Removing and
Installing 65
11.2.2 Leakage Test 66
11.3 Servicing
the Carburetor 67
11.3.1 Metering Diaphragm 67
11.3.2 Inlet Needle 68
11.3.3 Fixed Jet 69
11.3.4 Pump Diaphragm 69
11.4 Adjusting Carburetor 71
11.4.1 User Adjustment
(Carburetor without
Limiter Caps) 71
11.4.2 User Adjustment
(Carburetor with
Limiter Caps) 72
11.4.3 Basic Setting
(Carburetor with
Limiter Caps) 73
11.5 Tank Vent 74
11.5.1 Machines up to 2002 74
11.5.2 Machines from 2002 75
11.6 Fuel Tank 76
11.6.1 Pickup Body 76
11.6.2 Suction Hose 76
11.6.3 Tank Cap 77
11.6.4 Replacing
Engine Housing 77
12. Special
Servicing Tools 79
13. Servicing Aids 81

Stihl MS 390 Specifications

General

Brand	Stihl
Model	MS 390
Category	Chainsaw
Language	English