Technical Information · issue 39 of 1999
FS 55: New Model Brushcutter
Model Cutting tool Sound pressure Sound Vibration Vibration
IssueTI 39/1999
Full text
Page 1 of 8
Technical Information
39.1999
New Model FS 55 Brushcutter - Series 4140
Contents
1. Technical Description
2. Specifications
3. Cutting Tools
4. Special Accessories for Users
5. Service Accessories
6. Repairs
7. Spare Parts
The new FS 55 lightweight brushcutter broadens Model FS 55 has a straight drive tube. The cutting
the line of brushcutters and clearing saws. tool mounting is the same as that of the FS 44. The
gearhead has been modified and now features only
The engine is accommodated in a compact housing
one clamp screw.
which is extended forwards to incorporate the multi-
function control handle. Recommended applications are the same as for the
FS 44.
Ergonomically designed controls and a favorable
power to weight ratio ensure easy handling and less
operator fatigue.
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Page 2 Technical Information 39.1999
1. Technical Description
Crankshaft
. Five parts presed together to form torsionally
rigid assembly.
. Both ends supported in bearings.
Cylinder
. Four port technology (better mixture control,
clean combustion, lower emissions).
. Large cooling area.
Carburetor
. Only one adjusting screw (LD).
. Balanced idle system with fixed idle jet*.
. Fixed full-load jet
Air filter
. Improved filter material with longer life
. Large effective filter surface area
Exhaust muffler
. Dual-chamber muffler
Easy start system
. Manual fuel pump
. ElastoStart (available as option)
Controls
. Multi-function control handle
Clutch
. Two clutch shoes without linings
Drive shaft
. Drive tube with flexible shaft supported in a
flexible liner
Gearhead
. Construction as FS 44
. Only one clamp screw
* Balanced idle system is described in detail in the “Carburetors” handbook dated November 1998 or later.
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Technical Information 39.1999 Page 3
2. Specifications
2.1 Powerhead
2.1.1 Engine
Single cylinder two-stroke engine
Displacement: 27.2 cm3 (1.66 cu.in)
Bore: 34 mm (1.34 in)
Stroke: 30 mm (1.10 in)
Engine power to 0.75 kW (1 HP)
ISO 8893: at 7,000 rpm
Engine speeds: see 2.1.2
Rewind starter: Single pawl system
Starter rope: 3 mm (0.12 in) dia.,
800 mm (31.5 in) long
Clutch engages at: 3,800 rpm
Model Cutting tool Sound pressure Sound Vibration Vibration
level
Lpeq
power level
Lweq
fo measurement
to ISO 7916
measurement
to ISO 7916
ISO 7917 1) ISO 108841) Idle speed Max. RPM
(m/s2) (m/s2)
Handle Handle
dB (A) dB (A) right left right left
FS 55 2) Nylon head 92 105 1.8 2.0 4.2 3.5
FS 55 2) Metal tool 93 104 1.8 2.0 6.0 6.0
FS 55 R 3) Nylon head 91 104 3.0 6.1 6.8 9.5
FS 55 R 4) Metal tool 91 103 3.0 6.0 8.2 8.4
1)
Weighted equivalent level includes idling and racing with the same duration of exposure
2)
Bike handle version, provisional data only
3)
Loop handle version
4)
Loop handle version with barrier bar
2.1.2 Fuel System
Carburetor: All position diaphragm carburetor with integral fuel pump
Idle speed screw LD (standard setting) Open 2 full turns (see 6.1)
Idle speed 2,500 to 3,100 rpm
Cutoff speed range without cutting tool (electronic speed
governor) 8,700 to 10,300 rpm
Fuel tank capacity: 0.3 L (0.63 US pt)
Fuel mix: Branded regular grade gasoline (leaded or unleaded) and brand-name two-stroke
engine oil
Mix ratio: 50:1 with STIHL 50:1 two-stroke engine oil
25:1 with other brand-name two-stroke engine oils
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Page 4 Technical Information 39.1999
2.1.3 Ignition System
Ignition module: with integral electronic speed
governor
Spark plug Bosch WSR 6F,
(suppressed): NGK BPMR 7 A or
Champion RCJ 6Y
2.2 Weight
Without cutting tool and deflector
FS 55: 4.9 kg
(10.8 lb)
FS 55 R: 4.6 kg
(10.1 lb)
3. Cutting Tools
The following cutting tools are approved
1 STIHL Supercut 20-2 4002 710 2162
2 STIHL Autocut 21-2 4002 710 2113
3 STIHL Autocut 25-2 4002 710 2108 2
4 STIHL Trimcut 30-2 4002 710 2122
1
5 STIHL Polycut 20-3 4002 710 2130
6 Cutting blade 230-2* 4001 713 3805
7 Cutting blade 230-4* 4001 713 3801
8 Cutting blade 230-8* 4001 713 3803
3 4
* Not approved for loop
handle version of FS 55
without barrier bar
6
5
233TI001 KN
7 8
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Technical Information 39.1999 Page 5
4. Special Accessories for Users
4.1 General
Part Name Part No. Application
ElastoStart 0000 190 3400 Rewind starter (grip with rope)
Starter rope 0000 195 8200 Rewind starter, also for ElastoStart
STIHL gear lubricant for hedge Drive shaft in tube
trimmers
- 80 g tube 0781 120 1109
- 225 g tube 0781 120 1110
STIHL gear lubricant for Gearhead
brushcutters
- 80 g tube 0781 120 1117
- 225 g tube 0781 120 1118
STIHL special oil Rewind spring in starter,
- 100 ml bottle 0781 417 1315
bearing bore in rope rotor
4.2 Nylon Line for Cutting Heads
Line diameter / color Application
2.0 mm / green Autocut 21-2
2.4 mm / orange Supercut 20-2, Autocut 21-2, Autocut 25-2, Trimcut 30-2, Polycut 20-3
2.7 mm / red Polycut 20-3
5. Service Accessories
5.1 Special Servicing Tools
Special servicing tools are listed in the service manuals for the series 4140 powerhead and
STIHL 4140 power tool components.
5.2 Servicing Aids
Part Name Part No. Application
Carburetor parts kit 4227 007 1060 Zama C1Q S44
Set of gaskets 4140 007 1050 Engine
Lubricating grease 0781 120 1111 Oil seals
- 225 g tube
Dirko sealant 0783 830 2120 Engine pan/cylinder sealing faces
Electrician’s repair kit 5910 007 1050 Electrical system
Standard commercial solvent- Cleaning crankshaft stub
based degreasant containing no
chorinated or hydrogenated
hydrocarbons
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Page 6 Technical Information 39.1999
6. Repairs
If the unit is started up in the course of repairs or maintenance work, it is essential to strictly observe
all local and national safety regulations and the safety precautions outlined in the owner’s manual.
6.1 Carburetor Adjustment
Standard setting
. Mount the cutting tool
. Check air filter and fit a new one if necessary
.
Carefully screw down the idle speed screw (LD) counterclockwise (left-hand thread)
until it is against its seat, then open it two full turns clockwise.
Adjusting idle speed
. Carry out standard setting
. Start and warm up the engine
Engine stops while idling:
. Turn the idle speed screw (LD) slowly clockwise until engine runs smoothly - the cutting tool must not rotate.
Cutting tool rotates while engine is idling:
. Turn the idle speed screw (LD) counterclockwise until the cutting tool stops rotating and then turn the screw
about another full turn in the same direction (counterclockwise).
Erratic idling bahavior, poor acceleration:
. Turn the idle speed screw (LD) slowly counterclockwise no more than 1/2 turn until engine runs smoothly.
6.2 Tightening Torques
Special servicing tools are listed in the service manuals for the series 4140 powerhead and
STIHL 4140 power tool components.
6.3 Service Note
The service manuals for the STIHL series 4140 powerhead and
STIHL 4140 power tool components can be used for servicing and repair procedures on model FS 55.
These service manuals do not include the chapters "Servicing the Carburetor", "Troubleshooting" or any repairs
involving standard procedures. Such procedures are described in separate handbooks, i.e. “Carburetors” and
"Standard Repairs, Troubleshooting".
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Technical Information 39.1999 Page 7
6.4 Repair Times .
The specified repair times assume that the work is Repair procedure FS 45, 55
performed by trained personnel in a properly 1 Remove and refit engine 10
equipped service workshop.
2 Crankcase, pressure test* 55
3 Crankshaft, bearings, pressure 55
The repair times are given in minutes. test*
4 Sealing rings, pressure test* 55
5 Crankcase leakage test, test run 55
Note: This table for models FS 45, 55 can be added
6 Cylinder, piston, pressure test* 55
to the STIHL repair times table.
7 Ignition system, contact* 10
8 Fuel supply, tank vent, test run 10
9 Manifold or flange, pressure test -
10 Carburetor, check* 25
7. Spare Parts
11 Handle and throttle control 10
An illustrated parts list is available for the new 12 Rewind starter, test run 15
model. 13 Clutch, test run 20
14 Muffler 10
15 Air filter 5
16
17
fo Stop switch, test run
Clutch housing
20
18 Drive tube 15
19 Replace gearhead or bearing 5
housing
20 Limit stop or deflector 5
21 Drive shaft 10
22 Fuel tank 10
23 Check compression pressure -
24 Adjust valve clearance -
25 Replace crankcase, bottom half -
26 Replace crankshaft -
27 Replace cylinder, piston -
28 Oil supply -
29 Oil pump, test run -
✂
* Test run under load
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Page 8 Technical Information 39.1999
© 1999 Andreas STIHL AG & Co. Technical Documentation
Waiblingen D1/MTK-na 6717
TI_39_1999_01_01.fm Extracted from the manufacturer's 2012 service catalogue. Most of these PDFs embed fonts with a shifted character map, so the text above was recovered rather than copied — read it as a faithful but imperfect transcription, and treat the page image above each block as the authority where the two disagree — the figures exist only there, because they are vector drawings that text extraction cannot keep.