Technical Information · issue 58 of 2005
New Model FS 90 Brushcutter
Model Application
IssueTI 58/2005
Full text
Page 1 of 9
STIH)
Technical Information 58.2005
New Model FS 90, FS 90 R Trimmer/Brushcutter – Series 4180
Contents
1. Technical Description
2. Specifications
3. Cutting Tools and Attachments
4. Accessories
5. Service Accessories
6. Repairs
7. Spare Parts
FS 90 R FS 90
(shown with optional grass blade)
TI_58_2005_30_01_01.fm englisch / English USA
)m~ge 2 Technical Information 58.2005
The new STIHL FS 90 trimmer and brushcutter 1. Technical Description
models are the latest addition to the range of
. 4-MIX® engine – method of operation and
products with STIHL 4-MIX® engines.
benefits are described in detail in TI 01.2002
The engine has a displacement of 1.8 cu in (FS 110).
(28.8 cm3) and a power output of 1.3 bhp (0.95 kW). . The engine components are similar to those
The new trimmer/brushcutters are designed for a used in the FS 110. The differences brought
broad group of users, from occasional to about by the smaller displacement of the FS 90
professional. affect the cylinder and piston.
. The fan housing is made of polymer – as on the
FS 100 RX and FC 100.
. The ergonomically shaped control handles,
drive tube and gearhead are the same as those
on the FS 110.
2. Specifications
2.1 Powerhead
STIHL 4-MIX® engine with gas-oil lubrication
Displacement: 1.8 cu in (28.8 cm3)
Bore: 1.5 in (38 mm)
Stroke: 0.98 in (25 mm)
Engine power to ISO 8893: 1.3 bhp (0.95 kW) at 7,000 rpm (1/min)
Torque: 11.5 lbf in (103 Nm) at 5,500 rpm (1/min)
Idle speed: 2,800 rpm (1/min)
Clutch
– clutch engages at: 3,700 rpm (1/min)
Cut-off speed
(electronic speed governor):: 10,500 +/- 200 rpm (1/min)
Max. output shaft speed
(cutting tool mounting): 7,500 +/- 145 rpm (1/min)
Rewind starter: Single pawl system
Starter rope
– diameter x length: 0.120 in x 33 1/2 in (3.0 mm x 850 mm)
Valve clearance
- Inlet: 0.004 in-0.015 in (0.1 mm-0.4 mm)
- Exhaust: 0.004 in-0.015 in (0.1 mm-0.4 mm)
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Technical Information 58.2005 Page 3
2.2 Ignition System
Ignition module with integral electronic speed governor
Spark plug (suppressed): Bosch USR 7AC
Electrode gap: 0.02 in (0.5 mm)
2.3 Fuel System
The STIHL 4-MIX® engine features gasoline-oil lubrication and must be run on a fuel mixture of gasoline and
2-cycle engine oil at a mix ratio of 50:1.
2.3.1 Fuel
Fuel mix: 50:1 with STIHL 2-cycle mix oil
2.3.2 Fuel Tank
Capacity: 18.0 fl oz (530 cm3)
2.3.3 Carburetor
All position diaphragm carburetor with integral fuel pump
Basic setting without limiter caps when performing repairs
Low speed screw L: Open 1 turn
High speed screw H: Open 3.5 turns
Standard setting with limiter caps
Low speed screw L: Open 3/4 turn (no further than stop)
High speed screw H: Open 3/4 turn (no further than stop)
2.4 Geahead
Gear ratio: 1:1.4
Lubrication: STIHL gear lubricant for brushcutters
Initial filling: 0.35 oz (9.5 g)
Re-lubrication: up to 0.18 oz (5 g)
2.5 Weight
Dry, without cutting tool and deflector
– FS 90: 12.1 lbs (5.5 kg)
– FS 90 R: 11.7 lbs (5.3 kg)
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3. Cutting Tools and Attachments
3.1 Cutting Tools
The following cutting tools are approved:
Part Name Part No.
1 STIHL Supercut 20-2
mowing head 4002 710 2184
2 STIHL Autocut 25-2
mowing head 4002 710 2191
3 STIHL Autocut C 25-2
mowing head 4002 710 2196
4 STIHL Trimcut 30-2
mowing head 4002 710 2193
5 STIHL Polycut 20-3
mowing head 4002 710 2189
6 STIHL FixCut 25-2
mowing head 4001 710 2131
7 Grass cutting blade 230-4 1) 4001 713 3801
8 Grass cutting blade 230-8 1) 4001 713 3803
9 Brush knife 250-3 1) 4112 713 4100
10 Circular saw blade 200
(scratcher tooth) 2) 4112 713 4201
11 Circular saw blade 200
(chisel tooth) 2) 4112 713 4203
1)
Approved only for FS 90 equipped with bike
handle or loop handle with barrier bar and
large deflector
2)
Approved only for FS 90 with bike handle All the cutting tools listed must be used with the
and limit stop recommended deflector and/or barrier bar (see
catalog "Cutting Tools and Accessories for
Brushcutters").
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Technical Information 58.2005 Page 5
3.2 Attachments
The following attachments are approved:
Model Application
BF 1) Cultivator
FCS 2)3)
Power edger FH
1)
FH Power scythe
HL 0° 2) Hedge trimmer
1)2)
HL 135° Hedge trimmer (adjustable)
2)
HT Pole pruner
KB 2) Bristle Brush HT
2)
KW PowerSweepTM
1)
Barrier bar must be mounted on loop
handle
2) Not approved for bike-handled units FCS BF
3)
Shoulder strap is not necessary
KB KW
228TI004 KN
4. Accessories
Part Name Part No. Application
Transport guard for 4116 790 3901 Grass cutting blade 230-2, 230-4, 230-8,
metal cutting tools brush knife 250-3, circular saw blade 200
4119 790 3906 Grass cutting blade 230-2, 230-4, 230-8,
brush knife 250-3
4119 790 3901 Circular saw blade 200
Starter rope 0000 195 8203 Rewind starter
STIHL gear lubricant for brushcutters Gearhead
– 3 oz (80 g) tube 0781 120 1117
– 8 oz (225 g) tube 0781 120 1118
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5. Service Accessories
5.1 Special Servicing Tools
Part Name Part No. Application
Extension 4180 893 4400 Removing clutch drum and AV element in conjunction
with puller 5910 890 4400
Removing tool 5910 890 4602 Pressing out clutch drum
Installing tool 5910 890 2206
5910 890 2208 Installing hookless snap rings (piston boss).
Installing tool 5910 890 2208 with the latest sleeve
5910 893 1703 can be used in place of 2206.
Sleeve 5910 893 1703 Installing hookless snap rings (piston boss) in
conjunction with installing tool 5910 890 2208
Piston Stop
– previous: 4180 890 2700
– new: 4282 890 2700 Blocking the crankshaft
Existing special servicing tools are listed in the following service manuals:
Assembly Service Manual
Powerhead, control handle STIHL Series 4180 Powerhead (basic engine)
Control handle, handle, drive tube STIHL Series 4137 Components, FS 85
Gearhead and deflector STIHL CombiTools
5.2 Servicing Aids
Part Name Part No. Application
Valve clearance
adjusting kit 4180 007 1005 Checking, adjusting valve clearance
Set of gaskets 4180 007 1006 Engine
Carburetor parts kit 4180 007 1060 C1Q-S110
Lubricating grease,
8 oz (225 g) tube 0781 120 1111 Oil seals
Dirko HT sealant, red
3.2 oz (90 g) tube 0783 830 2000 Sealing engine pan/cylinder, cylinder/cam gear cover
Electrical repair kit 5910 007 1050 Electrical system
Set of screws 5910 007 1060
STIHL degreaser
(32 oz. 6-pack) 7010 881 9401 Cleaning crankshaft stubs and flywheel taper
(see TI 25.2005)
Engine decarbonizer
(8 oz. 6-pack) 0781 319 8019 Cleaning carbon from combustion chamber
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Technical Information 58.2005 Page 7
6. Repairs
If the machine is started up in the course of repairs,
it is essential to observe all country-specific safety 2
regulations and the safety precautions outlined in
the instruction manual.
6.1 Checking Valve Clearance
249TI021 KN
Check and adjust valve clearance only when the
engine is cold. Use the valve clearance adjusting kit
4180 007 1005 (consisting of feeler gauge, sealing
ring and gasket) for this purpose. . Support the ball bearing at the clutch drum side
with removing tool (2) 5910 890 4602.
. Turn over the removing tool together with the fan
6.2 Leakage Test housing – fan housing rests on the removing
Leaks are caused by defective oil seals and gaskets tool.
or cracks in castings. Such faults may allow
supplementary air to enter the engine and change
the air-fuel-oil mixture.
This can upset the lubricating process or cause it to
fail.
3
The engine can be tested for leaks with the
carburetor/crankcase tester and vacuum pump.
Proper sealing of the intake valve, exhaust valve,
and piston rings can also be checked using a
standard automotive or small 4-cycle engine leak-
249TI022 KN
down tester.
Carry out the leakage test as for model FS 110 (see
TI 01.2002 or the service manual for Series 4180
Powerhead). . Insert extension (3) 4180 893 4400 in the
square hole and press the clutch drum out of the
bearing seat.
6.3 Clutch Drum
. Remove the fan housing
5
249TI023 KN
. Take out the screw (4).
. Remove the circlip (1). . Use a suitable arbor to press the ball bearing (5)
out of its seat.
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)m~ge 8 Technical Information 58.2005
. Press home the new ball bearing with press
arbor 4119 893 7200.
. Tighten the screw (4) to 4 Nm (35 in. lbs.).
. Reassemble in the reverse sequence.
6.4 Tightening Torques
The tightening torques are listed in the following service manuals:
Assembly Service Manual
Powerhead, control handle STIHL Series 4180 Powerhead (basic engine)
Control handle, handle, drive tube STIHL Series 4137 Components, FS 85
Gearhead and deflector STIHL CombiTools
6.5 Service Note
The following service manuals are available for servicing and repairing the FS 90:
Assembly Service Manual
Powerhead STIHL Service Training System “Diagnosis”
Powerhead, control handle STIHL Series 4180 Powerhead (basic engine)
Control handle, handle, drive tube STIHL Series 4137 Components, FS 85
Gearhead and deflector STIHL CombiTools
6.6 Serial Number
The serial number is located on the side of the
engine pan as shown in the illustration.
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Technical Information 58.2005 Page 9
6.7 Repair Times
The specified repair times assume that the work is Diagnostic time and time for test run
Repair Code
performed by trained personnel in a properly is included where applicable. FS 90
equipped service workshop. FS 90 R
This table for the FS 90 can be added to the STIHL
Repair Description
repair times table. Repair times are in minutes. in min.
1 Replace short block. 50
2 Replace crankcase, crankcase gasket
or re-seal carnkcase. Includes air leak
test. 50
7. Spare Parts 3 Replace crankshaft main bearing(s).
Includes air leak test. 50
A printed illustrated parts list for the new machine
4 Replace crankshaft seal(s). Includes air
will be available from the beginning of 2006. leak test. 70
The new machine is included in the STIHL Service 5 Perform engine air leak test. 25
Communication System (MediaCat CD-ROM) from 6 Replace cylinder and/or piston. Includes
issue 01/2006. air leak test and diagnosis and repair of
component(s) that caused failure.
100
7 Replace ignition module or flywheel.
Includes stop curcuit test. 25
8 Replace fuel tank line, tank vent, or fuel
pick-up body. 10
9 Replace intake manifold or intake
flange. 20
10 Repair or replace carburator. Includes
fuel system testing. 30
11 Repair throttle control. 25
12 Repair or replace rewind starter. 15
13 Repair or replace clutch, clutch shoes or
clutch springs. 20
14 Replace muffler 15
15 Replace air filter or filter housing. 10
16 Repair or replace stop switch. Includes
circuit testing. 20
17 Replace clutch housing. 20
18 Replace drive shaft and/or drive tube. 20
19 Repair bearing liner in drive tube. 20
20 Replace deflector. 10
21 Replace gearbox assembly. 15
22 Replace fuel tank. 15
23 Adjust valve clearance. 10
24 Replace gears/bearings in gearbox. 25
40 Miscellaneous repairs and other repairs
not listed 15
45 Handling allowance only-no labor 5
50 No labor. 0
© Andreas Stihl AG & Co. KG, 2005 Technical Documentation
D1/MTK-na
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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.