Technical Information · issue 40 of 1999
FS 46, 55: New Brushcutters
IssueTI 40/1999
Full text
Page 1 of 8
Technical Information
40.1999
New Model FS 46, 55 Brushcutters - 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 46 and FS 55 lightweight trimmers/ The FS 46 features a curved drive tube. Its cutting
brushcutters round off the lower end of the STIHL tool mounting is the same as the FS 36, but with an
line of grass trimmers, brushcutters and clearing M8 thread on the shaft.
saws. Model FS 55 has a straight drive tube. The cutting
tool mounting is the same as that of the FS 44. The
The engine is enclosed in a compact housing.
gearhead has been modified and now features a
Ergonomically designed controls and a favorable one clamp screw.
power to weight ratio for easy handling and less
Recommended applications are the same as for the
operator fatigue.
FS 36 and FS 44.
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1. Technical Description
Crankshaft
. Composite crankshaft to form a 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
. Large filter surface area
Exhaust muffler
. Dual-chamber muffler
Easy start system
. Purge Primer
. 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 (FS 55)
. Construction similar to the FS 44
. Only one clamp screw
* Balanced idle system is described in detail in the “Carburetors” handbook.
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Technical Information 40.1999 Page 3
2. Specifications
2.1 Powerhead
2.1.1 Engine
Single cylinder two-stroke engine
Displacement: (1.66 cu.in (27.2 cm3)
Bore: 1.34 in (34 mm)
Stroke: 1.10 in (30 mm)
Engine power to 1 HP (0.75 kW)
ISO 8893: at 7,000 rpm
Engine speeds: see 2.1.2
Rewind starter: Single pawl system
Starter rope: 0.12 in (3 mm) dia.,
31.5 in (800 mm) long
Clutch engages at: 3,800 rpm
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: 10 fl.oz (0.3 L)
Fuel mix: Branded mid grade gasoline (89 octane minimum) and brand-name two-stroke
engine oil
Mix ratio: 50:1 with STIHL 50:1 two-stroke engine oil
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 attachment or deflector
FS 46: 9.0 lbs
FS 55: 10.8 lbs
FS 55 R: 10.1 lbs
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3. Cutting Tools
The following cutting tools are approved
FS 46:
1 STIHL Autocut 5-2 4006 710 2103
2 STIHL Polycut 6-3 4006 710 2104
FS 55:
3 STIHL Supercut 20-2 4002 710 2184
4 STIHL Autocut 21-2 4002 710 2192
5 STIHL Autocut 25-2 4002 710 2191
6 STIHL Trimcut 30-2 4002 710 2193
7 STIHL Polycut 20-3 4002 710 2189 1 2
8 Grass cutting blade 230-4* 4001 713 3801
9 Grass cutting blade 230-8* 4001 713 3803
* Not approved for loop
handle version of FS 55 3 4
without barrier bar
5 6
7
233TI002 KN
8 9
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Technical Information 40.1999 Page 5
4. Special Accessories for Users
4.1 General
Part Name Part Name 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
- 2.8 oz tube 0781 120 1109
- 8 oz tube 0781 120 1110
STIHL gear lubricant for Gearhead
brushcutters
- 2.8 oz tube 0781 120 1117
- 8 oz tube 0781 120 1118
4.2 Nylon Line for Mowing Heads
Line diameter / color Application
0.080” / green Autocut 5-2, Autocut 21-2
0.095” / orange Supercut 20-2, Autocut 21-2, Autocut 25-2, Trimcut 30-2, Polycut 20-3
0.105” / 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
Set of gaskets 4140 007 1050 Engine
Dirko sealant 0783 830 2120 Engine pan/cylinder sealing faces
Standard commercial solvent- Cleaning crankshaft stub
based degreaser containing no
chlorinated or hydrogenated
hydrocarbons
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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 behavior, 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 models FS 46 and 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 40.1999 Page 7
6.4 Repair Times .
The specified repair times assume that the work FS 46
is performed by trained personnel in a properly Code Type of Repair FS 55
equipped service workshop.
1 Crankcase, Crankshaft, Crank 0.9
Bearings
The repair times are given in tenth of an hour 2
(0.1 = 6 minutes). 3 Crankcase Gasket/Sealing 0.8
4 Crankshaft Seals 0.9
(including pressure & vacuum test)
Note: This table for models FS 46, 55 can be added
5 Cylinder and/or Piston 0.9
to the STIHL repair times table manual.
6 Ignition Module 0.5
7 Fule Hose 0.5
8 Replace Gear Box/Arbor Assy 0.5
9 Repair/Rebuild Carburetor 0.8
7. Spare Parts 10 Replace Carburetor, Carburetor 0.4
An illustrated parts list is available for the new Jet (if tried to repair use code 9)
models. 11 Front Handle, Throttle Control, 0.6
Cable
12 Recoil Starter 0.5
13 Cluch, Cluch Drum, Drum Housing 0.7
14 Drive Tube, Drive Shaft 0.5
15 Muffler 0.4
16 Air Filter, Filter Cover, Tank Cap, 0.3
Tank Vent, Fuel Filter, Spark Plug,
Cutting Attachment,
Misc. Minor Repairs
17 Stop Switch 0.6
18 Fuel Tank 0.4
19 Replace Gears, Arbor Bearings 0.8
20 All Other Repairs 0.5
✂
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© 1999 Andreas STIHL AG & Co. Technical Documentation
Waiblingen D1/MTK-na 6717
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