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Technical Information · issue 51 of 2005

New Model FC 90 Power Edger

IssueTI 51/2005

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TI 51/2005 page 1
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Technical Information                                                  51.2005

  New Model FC 90 Power Edger – Series 4180

  Contents
  1.   Technical Description
  2.   Specifications
  3.   Cutting Tools
  4.   Accessories
  5.   Service Accessories
  6.   Repairs
  7.   Spare Parts

                                              The new STIHL FC 90 with 4-MIX® engine and
                                              curved drive tube extends the range of power
                                              edgers.
                                              The 4-MIX® engine incorporates STIHL’s patented
                                              system of lubrication and operates according to the
                                              four-stroke principle. It uses the same fuel mix as
                                              STIHL two-stroke engines.
                                              The engine has a displacement of 1.73 cu in
                                              (28.4 cm3) and a power output of 1.3 bhp (0.95 kW).
                                              The range of applications is the same as for model
                                              FC 100.

  TI_51_2005_30_01_01.fm                                                  englisch / English USA
)m~ge 2                                                                           Technical Information 51.2005

1.       Technical Description

1.1      STIHL 4-MIX® Engine                                  1.2     Tank Cap
The 4-MIX® engine features gas-oil lubrication.
Compared to a conventional four-stroke engine, the
4-MIX® engine has no separate oil supply in the
crankcase. Engine lubrication is provided by the fuel
mixture of gasoline and 2-cycle engine oil.
The benefits of this new concept are:
.     Same familiar fuel mix as for STIHL two-stroke
      engines
.     Favorable fuel consumption
.     Operates in all positions
.     Good acceleration                                       The tank cap is designed for quick and simple
.     Compact construction – attractive design                opening and closing.

.     Favorable power-to-weight ratio
.     Simple maintenance – service-friendly
.     Automatic decompression system

2.       Specifications

2.1      Powerhead

STIHL 4-MIX® engine with gas-oil lubrication
Displacement:                                    1.73 cu in (28.4 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
Torque:                                          11.5 lbf in (1.3 Nm) at 5,500 rpm
Idle speed:                                      2,800 rpm
Clutch
 – clutch engages at:                            3,700 rpm
Cut-off speed
(electronic speed governor)::                    10,500 +/- 200 rpm
Max. output shaft speed
(cutting tool mounting):                         8,500 +/- 160 rpm
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 51.2005                                                                       Page 3

2.2     Ignition System

Ignition module with integral electronic speed governor
Spark plug (resistor type):                   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
air cooled 2-cycle engine mix oil.

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     Weight
with blade and deflector: 13.7 lbs (6.2 kg)

2.5     Gearhead
Gear ratio:                                   1:1.235
Lubrication:                                  STIHL gear lubricant for brushcutters
Initial filling:                              0.5 oz (15 g)
Re-lubrication:                               0.2 oz (5 g)

TI_51_2005_30_01_01.fm
)m~ge 4                                                                   Technical Information 51.2005

3.       Cutting Tools

3.1      Blades

Description Length x thickness          Part No.
Blader         8 in x 3/32 in           4133 713 4101
               (200 x 2.4 mm)
Blade          8 in x 5/32 in           4133 713 4102   special accessory
               (200 x 3.8 mm)

3.2      Aid

Description                             Part No.        Application
STIHL balancer                          5910 850 2600   Balancing the blade

4.       Accessories
Description                             Part No.        Application
Starter rope                            0000 195 8203   Rewind starter
Skirt                                   4137 716 3200   Deflector
Deflector                               4137 713 4503   Gearhead
Depth wheel                             4133 712 1000   Gearhead
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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Technical Information 51.2005                                                                            Page 5

5.       Service Accessories

5.1      Special Servicing Tools

Description                    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) ; for
                                                      retrofitting older 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 KombiTools

5.2      Servicing Aids

Description                    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
Press Fluid OH 723,
3.4 fl oz (100 ml) bottle      0781 957 9000          AV rubber elements, fuel hose connector
Standard commercial,
solvent-based degreasant
without chlorinated or
halogenated hydrocarbons                              Cleaning crankshaft stubs and flywheel taper
                                                      (see TI 25.2005)

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 6.      Repairs
 If the machine is started up in the course of repairs,       The engine can be tested for leaks with the
 it is essential to observe all country-specific safety       carburetor/crankcase tester and vacuum pump.
 regulations and the safety precautions outlined in           Carry out the leakage test as for model FS 110 (see
 the instruction manual.                                      TI 01.2002 or the service manual for Series 4180
                                                              Powerhead).

 6.1     Checking Valve Clearance
 Check and adjust valve clearance only when the               6.3    Clutch Drum
 engine is cold. Use the valve clearance adjusting kit        see TI 49.2005.
 4180 007 1005 (consisting of feeler gauge, sealing
 ring and gasket) for this purpose.                           6.4    Fuel Tank, Hose
                                                              see TI 49.2005.

 6.2     Leakage Test                                         6.5    Adjusting Throttle Cable
 Leaks are caused by defective oil seals and gaskets          see TI 49.2005.
 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.

 6.6     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 KombiTools

 6.7     Service Note
 The following service manuals are available for servicing and repairing:

 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 KombiTools

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Technical Information 51.2005                                                                    Page 7

6.8    Serial Number                                 6.9    Repair Times
                                                     The repair times for the FC 90 are the same as for
                                                     the FC 100 power edger – see repair times table for
                                                     FC 100, 110.

The serial number is located on the side of the
engine pan as shown in the illustration.

7.    Spare Parts
Spare parts documentation is already available for
the new machine.
The new machine is included in the STIHL Service
Communication System (SCS / MediaCat CD-
ROM) from issue 01/2006.

© ANRDREAS STIHL AG & Co. KG, 2005                   Technical Documentation
                                                     D1/MTK-na

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