Stihl FS 25-4, User Manual

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1. Safety Precautions 1
2. Introduction 2
3. Specifications 3
3.1 Engine 3
3.2 Fuel System 3
3.3 Ignition System 4
3.4 Gearhead 4
3.5 Special Accessories 4
3.5.1 For User 4
3.6 Dimensions and
Wear Limits
5
3.7 Tightening Torques 6
4. Troubleshooting 7
5. Clutch 10
5.1 Removing and
Disassembling
10
5.2 Assembling and
Installing
10
6. Engine 11
6.1 Checking/Adjusting
Valve Clearance
11
6.2 Checking Oil Level/
Changing Oil
13
6.3 Exhaust Muffler 14
6.4 Rocker Arms/Pushrods 14
6.5 Cam Followers 15
6.6 Cam Gear 15
6.7 Diaphragm 15
6.8 Crankcase,
Lower Half
16
6.9 Crankshaft 17
6.10 Valves/Valve Springs 18
6.11 Crankcase/Cylinder 18
7. Ignition System 19
7.1 Ignition Module 19
7.1.1 Ignition Timing 20
7.1.2 Removing/Installing 20
7.2 Flywheel 21
8. Rewind Starter 22
8.1 General 22
8.2 Rope Rotor 22
8.3 Starter Rope 23
8.4 Starter Grip 23
8.5 Rewind Spring 24
8.5.1 Replacing 24
8.5.2 Tensioning 24
8.6 Starter Cup/Fanwheel 25
9. Throttle Control 26
9.1 Throttle Trigger/Interlock
Lever (Bike Handle)
26
9.2 Contact Springs/Detent
Spring in Control Handle
(Bike Handle)
27
9.3 Throttle Trigger/Interlock
Lever (Loop Handle)
27
9.4 Slide Control
(Loop Handle)
28
9.5 Throttle Cable 29
9.5.1 Replacing 29
9.5.2 Adjusting 30
10. AV System 30
11. Fuel System 32
11.1 Air Filter 32
11.2 Carburetor 32
11.2.1 Leakage Test 32
11.2.2 Removing/Installing 33
11.2.3 Adjusting Idle Speed 34
11.3 Tank Vent 35
11.4 Pickup Body 35
11.5 Fuel Hoses 36
11.6 Fuel Tank 37
12. Shaft 38
12.1 Bike Handle 38
12.2 Loop Handle 38
12.3 Drive Shaft/
Flexible Liner
39
12.4 Drive Tube 40
13. Cutting Tool Drive 41
13.1 Gearhead 41
13.2 Clutch Drum 41
14. Special Servicing
Tools and Aids
43
14.1 Special Servicing Tools 43
14.2 Servicing Aids 44
15. Maintenance chart 45
1. Safety
Precautions
If the brushcutter is started up
in the course of repairs or mainten-
ance work, observe all local and
country-specific safety regulations
as well as the safety precautions
and warnings in the owner’s
manual.
Gasoline is an extremely flamma-
ble fuel and can be explosive in
certain conditions.
Improper handling may result in
burns or other serious injuries.
Warning! Do not smoke or bring
any fire or flame near the fuel. All
work with fuel must be performed
outdoors only. Spilled fuel must be
wiped up immediately.
Wash hands thoroughly after
every contact with waste oil.
Do not pour waste oil down the
drain or allow it to soak into the
ground.
Collect waste oil and take it to an
official disposal site for environ-
ment-friendly disposal.
© 1998, Andreas Stihl AG & Co, Waiblingen
FS 25-4, 65-4
Contents
FS 25-4, 65-4 1