Technical Information · issue 41 of 2001
Great Britain and New Zealand only - Technical Des
Model FS 55 RT is included in the illustrated parts Arbor Bearings
IssueTI 41/2001
Full text
Page 1 of 12
Technical Information
41.2001
New Model FS 55 RT Brushcutter – Series 4140
Contents
1. Technical Description
2. Specifications
3. Tools
4. User Accessories
5. Service Accessories
6. Repairs
7. Spare Parts
The new STIHL FS 55 RT brushcutter (T = split The ability to change attachments enables a wide
boom) expands the range of STIHL units designed range of applications to be covered.
to take power tool attachments.
The quick-action coupling is designed so that the
The quick-action coupling on the split boom (drive shafts engage without having to be turned back and
tube) allows the use of a growing number of power forth.
tool attachments from the STIHL Multi-Cut system.
The following attachments are currently available:
An additional advantage of the split boom design is
BC, FC, FH, HL (0° and 0 ... 90°) and HT.
space-saving transportation.
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)m~ge 2 Technical Information 41.2001
The engine (series 4140 powerhead) and
ergonomically designed controls are exactly the
same as those of the loop-handle FS 55.
This means that the brushcutter is the basic power
unit for numerous attachments with a broad range of
applications.
1. Technical Description
Engine, controls and handle system same as
loop-handle FS 55
Split Boom / Drive Shafts
. Rigid shaft in lower part of drive tube (most
attachments), flexible shaft in upper part of drive
tube
. Quickly separated for space-saving
transportation
. Fast attachment changes
393TI005 KN
(STIHL Multi-Cut system)
Carburetor
. New carburetor with 3 adjusting screws and
caps.
H L
3 /4 1
. User can adjust carburetor within a limited range
by turning the high speed screw (H) (see 6.3.4).
. Inside of all caps is funnel-shaped to aid
insertion of the carburetor screwdriver.
LA
233TI011 KN
Gearhead
. Same as FS 55
Rewind Starter
. 10.25 in (260 mm) longer starter rope
. Polymer pawl supported on steel pin
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Technical Information 41.2001 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: 1.18 in (30 mm)
Engine power to 1 BHP (0.75 kW) at 9,500 RPM
ISO 8893:
Engine speeds: see 2.1.2
Rewind starter: Single pawl system
Starter rope: 0.120 in (3 mm) diameter, 41.75 in (1060 mm) long
Clutch:
- engages at: 3,800 RPM
2.1.2 Fuel System
Carburetor: All position diaphragm carburetor with integral fuel pump
High speed screw H (standard setting)
- without cap (during service repairs) Open 2 full turns
- with cap (user) 3/4 turn counterclockwise
Low speed screw L (standard setting) Open 1 full turn
Idle speed screw LA see 6.3.3
Idle speed 2,500 to 3,100 RPM
Maximum speed range without cutting tool (electronic speed
governor) 8,700 to 10,300 RPM
Fuel tank capacity: 0.7 US.pt (0.33 L)
Fuel mix: Mid-grade unleaded gasoline (89 octane) and
brand.name air cooled two-stroke engine oil
Mix ratio: 50:1 with STIHL 50:1 two-stroke engine oi
2.1.3 Ignition System
Ignition module: with integral electronic speed governor
Spark plug (suppressed): Bosch WSR 6F, NGK BPMR 7 A or Champion RCJ 6Y
2.2 Weight
without cutting tool and
deflector
FS 55 RT: 11.5 lbs (5.2 kg)
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)m~ge 4 Technical Information 41.2001
3. Tools
3.1 FS Cutting Tools
The following cutting tools are approved
1 STIHL Supercut 20-2 4002 710 2184
2 STIHL AutoCut 21-2 4002 710 2192
3 STIHL AutoCut 25-2 4002 710 2191 1 2
4 STIHL TrimCut 30-2 4002 710 2193
5 STIHL PolyCut 20-3 4002 710 2189
4
3
6 Grass cuting blade 230-4* 4001 713 3801
7 Grass cutting blade 230-8* 4001 713 3803
5
* Not approved for loop-handle FS 55 RT
without barrier bar fo
233TI019 KN
6
7
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Technical Information 41.2001 Page 5
3.2 Multi-Cut Attachments
Basic unit:
1 FS 55 RT with loop handle and barrier bar (shown without attachment)
2 BC cultivator 1)
3 FC power edger
4 FH power scythe 1)
5 HL 0° hedge trimme
6 HL 0 ... 90° hedge trimmer 1)
7 HT pole pruner
1)
Barrier bar must be mounted on loop handle
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)m~ge 6 Technical Information 41.2001
4. User Accessories
4.1 General
Part Name Part No. Application
ElastoStart 0000 190 3404 Rewind starter (grip with rope)
Starter rope 1120 195 8200 Rewind starter
STIHL gear lubricant for Drive shafts in boom (drive tube)
hedge trimmers
- 3 oz (80 g) tube 0781 120 1109
- 8 oz (225 g) tube 0781 120 1110
STIHL gear lubricant for Gearhead
brushcutters
- 3 oz (80 g) tube 0781 120 1117
- 8 oz (225 g) tube 0781 120 1118
STIHL lubricating grease
- 8 oz (225 g) tube 0781 120 1111
Needle bearing in upper part of drive tube (driver)
4.2 Nylon Line for Mowing Heads
Line diameter / Color Application
.095 in (2.4 mm) / orange SuperCut 20-2, AutoCut 21-2, AutoCut 25-2, TrimCut 30-2,
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
series 4140 attachments.
5.2 Servicing Aids
Part Name Part No. Application
Carburetor parts kit 4227 007 1060 Zama C1Q-S44, -S53, -S58, -S66
Set of gaskets 4140 007 1050 Sealing engine
Lubricating grease 0781 120 1111 Oil seals, needle bearing in upper part of drive
- 8 oz (225 g) tube 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
chlorinated or hydrogenated
hydrocarbons
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Technical Information 41.2001 Page 7
6. Repairs
If the unit is started up in the course of repairs, it is essential to strictly observe all country-specific
safety regulations and the safety precautions outlined in the owner’s manual.
6.1 Replacing and Lubricating the Shafts
6.1.1 Lower part of drive tube
3 2
. Loosen the wing screw (1), pull the lower part of
the drive tube (2) out of the coupling sleeve (3).
. Remove the gearhead/attachment from the
drive tube.
393TI008 KN
. Press down the lock button and hold it there, pull
the drive shaft (4) with sleeve (5) out of the drive
tube (applying pressure to other end of the shaft fo
simplifies this operation).
. Coat the drive shaft with STIHL gear lubricant
for hedge trimmers, never pump grease into the
drive tube. 5 4
. Push drive shaft (4) and sleeve (5) into the drive
tube.
. Press down the lock button and push the sleeve
(5) home as far as stop (lock button must snap
into position).
5 4
. Fit and line up the gearhead/attachment.
380TI015 KN
6.1.2 Upper part of drive tube
. Remove drive tube from the engine housing.
A
. Pull the drive shaft (6) out of the engine end of
the drive tube.
. Coat the drive shaft with STIHL gear lubricant
for hedge trimmers, never pump grease into the 6 7
drive tube.
. Slide the drive shaft (6) into the drive tube as far
as stop – hold the driver (7) firmly and at the
same time rotate the shaft a little. The shaft is
233TI012 KN
properly positioned when it projects no more
than 5/16“ (8 mm) (A) from the drive tube.
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)m~ge 8 Technical Information 41.2001
. Install drive tube in engine housing.
. Finally, refit lower part of drive tube with
gearhead/attachment.
6.2 Replacing and Lubricating the Driver
. Remove upper part of drive tube and drive shaft
- see 6.1.2
. Loosen the clamp screw (8) and pull the
coupling sleeve (9) off the drive tube.
. Grip the driver (10) – clamp it in a vise if
necessary – and pull it out of the drive tube.
8 9
233TI013 KN
10
. Strip down the driver. If individual parts are badly
worn, install a new driver assembly.
. Clean the needle bearing in the bushing (11)
and lubricate with STIHL grease
(0781 120 1111).
. Assemble the driver.
. Push the driver into the drive tube as far as stop
so that the lug on the bushing engages the slot
in thedrive tube (see arrows). 11
233TI014 KN
. Push the coupling sleeve (9) on to the drive tube
as far as stop so that the lug engages the slot.
. Tighten down the clamp screw (8) firmly.
. Reassemble the drive shaft and upper part of
the drive tube - see 6.1.2
. Finally, refit lower part of drive tube with
gearhead/attachment.
8 9
233TI015 KN
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Technical Information 41.2001 Page 9
6.3 Carburetor
6.3.1 Construction 6.3.3 Repairs / Servicing
4 1
2
233TI016 KN
392TI036 KN
5
. Low speed screw (1) with cap The cap has to be removed from the high speed
. High speed screw (2) screw in the service shop to replace a damaged
high speed screw or clean the carburetor.
. Limiter cap (3) for high speed screw
. Use suitable pliers to pull off the cap.
. Stop pin (4)
. Idle speed screw (5) with cap
Do not re-use caps because they will be damaged
during removal.
Adjustment after repairs / servicing
. Check the air filter and clean or replace as
necessary.
. Check spark arresting screen in muffler and
clean or replace as necessary.
. Check and replace fuel filter as necessary.
295TI012 KN
Standard setting of H screw
The cap is pushed over the head of the adjusting
screw and on to the knurling. The stop pin (arrow) in
the carburetor body serves to limit adjustment.
H
6.3.2 Function
392TI037 KN
270°
. Starting with the screw lightly against its seat:
Open high speed screw (H) 2 full turns
392TI035 KN
The cap limits the range of adjustment of the high
speed screw (H) to 270 degrees (3/4 turn).
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)m~ge 10 Technical Information 41.2001
Installing the cap Checking running behavior
. Open the throttle several times to check that
engine accelerates smoothly.
. Engine must run smoothly at idle speed.
H
6.3.4 Setting instructions for users
392TI038 KN
Caps that have been removed once must not be 270°
re-used because they will be damaged.
. Position new cap for high speed screw (H) so
that it is in line with “rich” stop (arrow).
295TI013 KN
. Push cap home as far as stop against
carburetor body.
The user may adjust the carburetor’s high speed
screw within a range of 270 degrees.
Adjusting idle speed
This enables the carburetor setting to be tuned to
changes in operating conditions. For example:
– Different altitude (mountains – sea level)
L – Change of cutting tool on brushcutters
(mowing head – metal cutting blade)
The procedure for setting the new carburetors is as
described in the owner’s manual (see chapter
"Adjusting the Carburetor").
392TI039 KN
6.4 Tightening Torques
Starting with the screws lightly against their seats: Tightening torques for model FS 55 RT are listed in
the service manuals for the series 4140 powerhead
. Open low speed screw (L) one full turn
and series 4140 attachments, and the manuals of
counterclockwise.
the appropriate STIHL single-purpose power tools
. Use idle speed screw (LA) to set engine speed for the Multi-Cut attachments.
to 2,800 RPM.
This adjustment must be checked with a
tachometer.
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Technical Information 41.2001 Page 11
6.5 Service Note
For servicing and repairs procedures on the Code Type of Repair FS 55 RT
FS 55 RT refer to the service manuals for the series 1 Crankcase, Crankshaft, 2.0
4140 powerhead and series 4140 attachments. Crankshaft Bearings
These service manuals do not include the chapters 2
"Servicing the Carburetor", "Troubleshooting" or any 3 Crankcase Gasket/Sealing 2.0
repairs involving standard procedures. Such
4 Crankshaft Seals (includes 1.0
procedures are described in separate handbooks,
pressure & vacuum testing)
i.e. “Carburetors” and "Standard Repairs,
5 Cylinder and/or Piston 1.0
Troubleshooting".
6 Ignition Module 0.5
The manuals of the appropriate STIHL single-
7 Fuel Hose 0.5
purpose power tools can be used for servicing and
repair procedures on the Multi-Cut attachments. 8 Replace Gear Box/Arbor Assy. 0.5
9 Repair/Rebuild Carburetor 0.8
10 Replace Carburetor, Carburetor 0.4
6.6 Repair Times Jet (if tried to repair use code 9)
11 Front Handle, Throttle Control, 0.6
The specified repair times assume that the work is
Throttle Cable
performed by trained personnel in a properly
12 Recoil Starter 0.5
equipped service workshop.
13 Clutch, Clutch Drum,
Clutch Drum Housing
0.7
The repair times are given in tenths of the hour 14 Drive Tube, Drive Shaft 0.5
(0.1 h = 6 minutes). 15 Muffler 0.4
16 Air Filter, Filter Cover, Tank Cap, 0.4
Note: This table can be added to the STIHL repair Tank Vent, Fuel Filter,
times table. Spark Plug, Cutting Attachment,
Miscellaneous Minor Repairs
17 Stop Switch 0.5
18 Fuel Tank 0.4
7. Spare Parts
19 Repair Gear Box, Gears, 0.8
Model FS 55 RT is included in the illustrated parts Arbor Bearings
list for the FS 55. 20 All Other Repairs 0.5
!
A separate parts list containing all attachments is
available for Multi-Cut and other power tool
attachments.
© 2001 Andreas STIHL AG & Co. Technical Documentation
Waiblingen D1/MTK-na 7349
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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.