Stihl MS 191, Service Manual

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1 MS 311, MS 391
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© ANDREAS STIHL AG & Co. KG, 2009 RA_542
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1. Introduction and
Safety Precautions
3
1.1 Introduction 3
1.2 Safety Precautions 4
2. Specifications 5
2.1 Engine 5
2.2 Fuel System 5
2.3 Ignition System 5
2.4 Chain Lubrication 5
2.5 Tightening Torques 6
3. Troubleshooting 8
3.1 Clutch 8
3.2 Chain Drive,
Chain Brake,
Chain Tensioner
9
3.3 Chain Lubrication 10
3.4 Rewind Starter 11
3.5 Ignition System 12
3.6 Carburetor 13
3.7 Engine 16
4. Clutch 17
4.1 Clutch Drum 19
5. Chain Brake 20
5.1 Checking Operation 20
5.2 Brake Band 20
5.3 Brake Lever 22
5.4 Cam Lever 24
5.5 Pins 25
5.6 Chain Tensioner 25
5.7 Bar Mounting Studs 26
6. Engine 27
6.1 Muffler 27
6.2 Leakage Test 28
6.2.1 Preparations 28
6.2.2 Vacuum Test 29
6.2.3 Pressure Test 29
6.3 Oil Seals 30
6.4 Shroud 31
6.5 Cylinder / Crankshaft 32
6.6 Bearings / Crankshaft 35
6.7 Piston 36
6.8 Piston Rings 38
6.9 Decompression Valve 38
7. Ignition System 39
7.1 Ignition Timing 39
7.2 Preseparator 39
7.3 Ignition Module 39
7.4 Testing the
Ignition Module
41
7.5 Spark Plug Boot /
Ignition Lead
42
7.6 Flywheel 43
7.7 Short Circuit Wire 44
7.7.1 Testing 44
7.7.2 Removing and
Installing
44
7.7.3 Ground Wire 46
7.7.4 Contact Spring 46
7.8 Ignition System
Troubleshooting
48
8. Rewind Starter 51
8.1 General 51
8.2 Fan housing 51
8.2.1 Segment 51
8.3 Pawls 51
8.4 Rope Rotor 52
8.5 Starter Rope / Grip 53
8.6 Tensioning the
Rewind Spring
54
8.7 Replacing the
Rewind Spring
55
9. Servicing the
AV System
57
9.1 Buffer on Oil Tank 57
9.2 AV Spring on Oil Tank 57
9.3 AV Spring on
Fuel Tank
57
9.4 AV Spring on
Front Handle
58
9.5 Stop Buffer at
Clutch Side
59
9.6 Annular Buffer at
Ignition Side
59
9.7 Handlebar 59
10. Control Levers 61
10.1 Master Control Lever 61
10.2 Throttle Trigger/Interlock
Lever
61
10.2.1 Choke Rod 63
10.2.2 Throttle Rod 64
11. Chain Lubrication 65
11.1 Pickup Body 65
11.2 Oil Suction Hose 65
11.3 Oil Pump 66
11.4 Valve 67
Contents