Stihl MS 291 User Manual

1MS 271 C, MS 291 C
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© ANDREAS STIHL AG & Co. KG, 2010
RA_574_00_01_01
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 11
3.4 Rewind Starter 12
3.5 Ignition System 14
3.6 Carburetor 15
3.7 Engine 18
4. Clutch 19
4.1 Clutch Drum 19
4.2 Clutch 19
5. Chain Brake 20
5.1 Checking Operation 20
5.2 Brake Band 20
5.3 Brake Lever 22
5.4 Brake lever on
machines with
QuickStop Super 24
5.4.1 Adjusting the
brake cable 26
5.4.2 Brake cable
Removing and
Installing 27
5.5 Cam Lever 29
5.6 Pins 30
5.7 Chain Tensioner 31
5.7.1 Quick chain tensioner 31
5.8 Bar Mounting Studs 32
6. Engine 33
6.1 Muffler 33
6.2 Leakage Test 34
6.2.1 Preparations 34
6.2.2 Vacuum Test 35
6.2.3 Pressure Test 35
6.3 Oil Seals 36
6.4 Shroud 37
6.5 Cylinder / Crankshaft 38
6.6 Crankshaft / Bearings 41
6.7 Piston 42
6.8 Piston Rings 44
7. Ignition System 45
7.1 Ignition Timing 45
7.2 Preseparator 45
7.3 Install new
ignition module 45
7.4 Testing the
Ignition Module 47
7.5 Spark Plug Boot /
Ignition Lead 48
7.6 Flywheel 48
7.7 Short Circuit Wire 49
7.7.1 Testing 49
7.7.2 Removing and
Installing 50
7.7.3 Ground Wire 52
7.7.4 Contact Spring 52
7.8 Ignition System
Troubleshooting 54
8. Rewind Starter 57
8.1 General 57
8.2 Fan housing 57
8.3 Pawls 58
8.4 ErgoStart 59
8.5 Rope Rotor 60
8.6 Starter Rope / Grip 60
8.7 Tensioning the
Rewind Spring 62
8.8 Replacing the
Rewind Spring 62
9. Servicing the
AV System 65
9.1 Annular Buffer and AV
Spring on Oil Tank 65
9.2 AV Spring on
Fuel Tank 65
9.3 AV Spring on
Handlebar 66
9.4 Stop Buffer at
Clutch Side 67
9.4.1 Stop Buffer at
Ignition Side 67
9.4.2 Buffers on Filter Base 68
9.5 Install new handlebar 68
10. Control Levers 70
10.1 Master Control Lever 70
10.1.1 Removing and
Installing 70
10.2 Throttle Trigger/
Lockout Lever 70
10.3 Throttle Trigger/
Lockout Lever –
QuickStop Super 72
10.3.1 Switch Lever –
QuickStop Super 73
10.3.2 Lockout Lever –
QuickStop Super 74
10.3.3 Choke Rod 75
10.3.4 Throttle Rod 75
11. Chain Lubrication 77
11.1 Pickup Body 77
11.2 Oil Suction Hose 77
11.3 Oil Pump 77
11.4 Valve 79
Contents

Stihl MS 291 Specifications

General

Engine Power	2.8 kW
Displacement	55.5 cm³
Weight	5.6 kg
Vibration Level (left/right)	4.5/4.5 m/s²
Guide Bar Length	16 in to 20 in
Fuel Tank Volume	460 ml
Chain Pitch	3/8"
Fuel Capacity	500 cc