Technical Information · issue 9 of 2003
Control Handle and Throttle Cable; New Carburetor C1Q-S82 / C1Q-S83, Shrouds, Grommet; Carburetor C1Q-S51; Rotating handlebar support / handlebar for mowing applications (FS 120, 200, 250 only); Clutch; Oil Seals (crankshaft); Crankshaft (FS 120,
IssueTI 9/2003
Part changes (3)
| Was | Becomes | What the bulletin says |
|---|---|---|
| 1123 121 3300 | 4134 121 3300 | 250TI032 KN 1123 121 3300 has been replaced by version 1 2 4134 121 3300. |
| 4137 790 1701 | 4128 790 1701 | 2 Swivelling the handlebar At the same time, the existing "universal" handlebar 4137 790 1701 will be replaced by the version for mowing applications, number 4128 790 1701. |
| 9640 003 1200 | 9640 003 1195 | Oil Seals (crankshaft) To facilitate installation, the 7 mm wide oil seals 9640 003 1200 (arrow) have been replaced by the new, 5 mm wide versions 9640 003 1195. |
Full text
Page 1 of 23
STIH)
Technical Information 09.2003
STIHL BT 120 C Earth Auger – Series 4313
STIHL FS 120, 200, 250 Brushcutters – Series 4134
STIHL FS 350 Clearing Saws – Series 4134
Contents
1. Control Handle and Throttle Cable
2. New Carburetor C1Q-S82 /
C1Q-S83, Shrouds, Grommet
3. Carburetor C1Q-S51
4. Rotating handlebar support / handlebar for mowing applications (FS 250 only)
5. Clutch
6. Oil Seals (crankshaft)
7. Crankshaft
(FS 120, 200, 250, BT 120 only)
8. Rewind Starter / Spring Housing Fastening
1. Control Handle and Throttle Cable
New control handles with throttle cable will be – Control handle
installed to further improve operation. The new
– Throttle cable
assemblies will be introduced on all bike-handled
and loop-handled machines. – Throttle cable retainer
At the same time, a new carburetor has also been – Short-circuit wire between retainer and
introduced. See chapter 2.1, "Carburetor with three ignition module
adjusting screws". – Carburetor housing
The complete set of modifications comprises the – Contact plate / gasket
following parts or assemblies:
– Pin for attaching the throttle cable to the
carburetor
The features and assembly of the new parts are
described in chapters 1.1 to 1.9.
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)m~ge 2 Technical Information 09.2003
Interchangeability . The new control handles are equipped with a
semi-automatic throttle cable adjuster. The
The new versions of the assemblies and parts may
operation of this is described in 1.2.1. The new
only be installed as an assembly in previous
handles can be identified by the slot for the slide
machine versions. The pin used to attach the throttle
(1).
cable to the carburetor may also need to be
changed, depending on the existing carburetor . A sealed microswitch is used to switch the
version (see 1.11 "Retrofitting existing machines"). ignition on and off. It is activated by the slide
control (2). The microswitch is permanently
connected to the short-circuit wires and is part of
Parts availability the new "throttle cable" assembly.
As before, the "control handle" and "throttle cable"
assemblies are available from the factory only as
separate replacement parts.
The "throttle cable" assembly is new. It consists of 1.2 Throttle cable
the corrugated tube, microswitch with wires and the
throttle cable. The individual parts of the "throttle 2
cable" assembly are no longer available as separate
items (see Summary).
5
4
1.1 Control handles
6 8
1
7
3
3
250TI043 KN
2 1
Example: New control handle with throttle cable for
machines with bike handle
Features of the new throttle cables:
. Two fully insulated short-circuit wires (3) which
393TI042 KN
go directly from the microswitch (4) to the
connectors on the throttle cable retainer.
New control handles . The new throttle cables can only be installed as
Top: for bike-handled machines assemblies.
Bottom: for loop-handled machines
Grey-shaded areas: non-slip surface
Features of the new control handles:
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Technical Information 09.2003 Page 3
1.2.1 Function of automatic throttle cable As part of the changeover from the previous
adjuster "wireless" throttle cable to the version with two
When the throttle trigger (5) is squeezed once as far short-circuit wires, the throttle cable retainer has
as the stop, the tolerances (i.e. any slackness) also been modified. The electrical connection to the
between the attachment points of the throttle machine ground and the short-circuit wire extension
cable (6) on the carburetor and the throttle trigger to the ignition module are mounted on the new
are corrected. retainer.
The end of the throttle cable sheath (7) is attached A washer (arrow) is fitted under the head of the
to the slide (1). During the adjustment of the throttle retainer mounting screw.
cable, the slide is pulled in the direction of the
throttle trigger. This causes the detent arm (arrow),
held under tension by a spring (8), to move along a
notched track in the handle (arrow) until there is no 1.4 Short-circuit wire retainer / ignition
free play in the throttle cable (see illustration in module
1.12.3 or 1.12.4 under "Installing slide and throttle
cable").
1.2.2 Adjusting the throttle cable
The throttle cable has to be adjusted after first-time
installation of a control handle with throttle cable on
a new machine. For this reason a new chapter, i.e.
"Adjusting the throttle cable", has been included in
the instruction manual. For further adjustments see
250TI045 KN
service notes under 1.12.5.
Throttle cable adjustments may need to be made
Left: existing version
during new machine set-up. Especially after
Right: new version
assembling bike type handlebars onto machines.
The previous short-circuit wire made the contact via
a terminal in contact with the throttle cable sheath
1.3 Throttle cable retainer (left arrow). The new short-circuit wire makes the
contact via a plug connection (right arrow).
250TI044 KN
Left: existing retainer
Right: new retainer
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)m~ge 4 Technical Information 09.2003
1.5 Carburetor housing 1.7 Throttle cable attachment to carburetor
250TI046 KN
250TI048 KN
Left: existing version Due to the modified shape of the end (arrow) on the
Right: new version new throttle cable, a new pin is required to attach
Grey-shaded areas: throttle cable sheath seat the throttle cable to the carburetor.
As a new carburetor is also being introduced in
The existing carburetor housing has been replaced connection with the introduction of the new throttle
by a new version in order to optimize the intake air cable, the new carburetor will be fitted with the new
flow and to adapt to the modified shape of the new pin from the start of series production. See 2.1
throttle cable sheath end. "Carburetor with 3 adjusting screws".
1.6 Contact plate / gasket 1.8 Ignition lead retainer
250TI047 KN
250TI049 KN
10 9
The contact plate (9) and the gasket (10) are no Due to the introduction of the new throttle cable
longer required for the new version of the throttle retainer, the lead retainer for routing the ignition lead
cable with two short-circuit wires. on the cylinder is no longer required.
In the previous version of the throttle cable without
separate short-circuit wires, the contact plate made
the electrical connection to the short block ground
(see TI 42.2002). Electrical grounding with the new
throttle cable is described in 1.3.
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Technical Information 09.2003 Page 5
1.9 Collar screw (BT 120 C only) The plastoform thread of the collar screw fastening
the clutch housing to the crankcase has been
shortened by 4 mm to optimize throttle cable
routing. Version 0000 711 8700 (2) is used instead
1 of collar screw 4313 711 8700 (1).
24 mm Collar screw 0000 711 8700 can also be used in
(0.944 in) older machines.
427TI000 KN
20 mm
(0.787 in)
1.10 Summary
Item Part Name Previous New Remarks
1 Retainer assembly; 4134 180 6700 --- 1)
including items 2 to 4:
2 Retainer 4134 180 6701 4134 180 6702 1)
3 Retainer, lower 4134 182 2105 4134 182 2104 1)
4 Screw IS-D5x24 9075 478 4159 9075 478 4159
5 Washer DIN125-A5.3 --- 9291 021 0120
6 Short-circuit wire 4134 440 1100 4134 440 1101 1)
(retainer / ignition module)
7 Carburetor housing 4134 120 0101 4134 120 0102 1)
8 Contact plate 4134 431 7000 --- 1)
9 Gasket 4128 129 0900 --- 1)
10 Lead retainer 4134 448 1200 --- 1)
Machines with bike handle
FS 120, 200, 250, 350
11 Control handle; 4128 790 1300 --- 1)
including items 13 to 16:
12 Control handle; --- 4128 790 1301
including items 13, 14, 17 to 19:
13 Handle, right 4128 790 0300 4128 790 0301 1)
14 Detent spring 4128 182 4200 4128 182 4201 1)
15 Contact spring 4128 442 1600 --- 1)
16 Contact spring 4128 442 1605 --- 1)
17 Torsion spring --- 4128 182 4502
18 Slide --- 4128 793 3000
19 Spring --- 4128 791 3100
All other parts as before
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)m~ge 6 Technical Information 09.2003
Item Part Name Previous New Remarks
20 Throttle cable; 4128 180 1102 --- 1)
including items 22 and 24:
21 Throttle cable; --- 4128 180 1104
including items 22 to 24:
22 Throttle cable -*- -*- 2)3)
23 Microswitch with short-circuit wires --- -*- 3)
24 Hose 690 mm -*- -*- 2)3)4)
25 Hose 960 mm 4203 711 7201 --- 5)
All other parts as before
Machines with loop handle
FS 120 R, 200 R, 250 R
26 Control handle; 4137 790 1350 --- 1)
including items 28, 29, 31, 32, 34 to 36:
27 Control handle; --- 4137 790 1307
including items 18, 19, 30, 31, 33 to 37:
28 Handle molding, inner 4137 790 1101 --- 1)
29 Handle molding, outer 4137 791 0800 --- 1)
30 Handle --- 4137 790 0300
31 Slide control 4137 182 1700 4137 182 1701 1)
32 Contact spring 4137 442 1600 --- 1)
33 Torsion spring --- 4137 182 4505
34 Throttle trigger 4137 182 1000 4137 182 1001 1)
35 Torsion spring 4137 182 4500 4137 182 4504 1)
36 Interlock lever 4137 182 0801 4137 182 0802 1)
37 Torsion spring --- 4128 182 4501
All other parts as before
38 Throttle cable; 4134 180 1107 --- 1)
including items 40 and 42:
39 Throttle cable; --- 4134 180 1103
including items 40 to 42:
40 Throttle cable -*- -*- 2)3)
41 Microswitch with short-circuit wires --- -*- 3)
42 Hose 185 mm -*- -*- 2)3)4)
All other parts as before
BT 120 C
43 Control handle; 4137 790 1350 --- 1)
including items 28, 29, 31, 32, 34 to 36:
44 Control handle; --- 4137 790 1307
including items 18, 19, 30, 31, 33 to 37:
All other parts as before
45 Throttle cable; 4313 180 1100 --- 1)
including items 47 and 49:
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Technical Information 09.2003 Page 7
Item Part Name Previous New Remarks
46 Throttle cable; --- 4313 180 1102
including items 47 to 49
47 Throttle cable -*- -*- 2)3)
48 Microswitch with short-circuit wires --- -*- 3)
49 Hose 545 mm -*- -*- 2)3)4)
50 Collar screw 4313 711 8700 0000 711 8700 6)
All other parts as before
Modifications to be introduced
USA production In progress
Remarks
1) Previous version of part remains available as spare for older machines
2) Previous version of part is not available as a separate item
3) New version of part is not available as a separate item
4) Part has to be cut from spare hose: see items 25 or 50
5) This hose should be used as a spare instead of the hoses in items 24, 42, 49 and 57
6) Previous version of part will be supplied from factory only as long as existing stocks last
1.11 Retrofitting existing machines The following parts may be removed when installing
The following existing parts have to be replaced by a new control handle with throttle cable on older
new versions in order to make use of the new machines:
control handle in older machines: – contact plate including gasket 4128 129 0900
– control handle assembly (see 1.1) (see 1.6)
– throttle cable assembly (see 1.2) – ignition lead retainer (see 1.8)
– throttle cable retainer assembly (see 1.3) Before doing any conversion work on older
machines, it is essential to read the instructions in
– short-circuit wire between retainer and ignition Technical Information 21.2000, 22.2001 and
module (see 1.4) 42.2002.
– carburetor housing (see 1.5)
– pin for attaching the throttle cable to the
carburetor (see 1.7 and 1.12.2) 1.12 Installation, Repairs
Only the most important procedures are described
below.
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)m~ge 8 Technical Information 09.2003
1.12.1 Fit throttle cable and wires to retainer
(all models) 4
256TI011 KN
1
256TI009 KN
. Fit the retainer (cover)
. Use IS-D5x24 screw and washer to secure
. Push the short-circuit wire with connector (1) terminal (4) of black ground wire to the top of the
(coming from the ignition module) into the retainer
recess in the "lower retainer"
. Push the throttle cable into its seat on the
carburetor housing as far as stop (arrow)
1.12.2 Attaching throttle cable to carburetor
2
5 6
250TI050 KN
256TI010 KN
3
Sections through cable end and pin
. Position the throttle cable in the retainer Left: existing version
. Slide connector (2) of blue short-circuit wire on Right: new version
to terminal (3)
. Attach version 4128 121 8901 (6) instead of pin
4128 121 8900 (5) to the carburetor C1Q-S35,
-S36 and -S51
. Attach throttle cable end to carburetor pin
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Technical Information 09.2003 Page 9
1.12.3 Machines with bike handle
14
Installing microswitch and wires
8 9
15
393TI048 KN
17 18
. Attach the bent throttle cable end sleeve (14) to
393TI046 KN
the throttle trigger (15)
10 7
. Position the straight end of the spring (16) in the
throttle trigger, in front of the bent end
. Place the microswitch (7) in the handle molding sleeve (14), and then fit the ring-shaped part of
as shown in the illustration the spring over the pivot (17) at the lower end of
. Push the ground wire (8) into the guide channel the throttle trigger
(10) first and then the short-circuit wire (9) . Fit the throttle trigger and position the spring
loop around the boss (18) for the screw
Installing slide and throttle cable
Installing control handle with throttle cable
8, 9 . Check the correct position of the corrugated
tube and slide
Important!
Do not squeeze the throttle trigger until instructed
to do so in chapter 1.12.5!
. Screw the handle moldings together, taking care
11 12 13 not to pinch any wires!
393TI047 KN
. Mount the control handle on the handlebar
. Attach the throttle cable to the carburetor. If this
has already been done, check that the cable
. Press the throttle cable (11) into the slide (12) end is correctly positioned in the pin (see 1.12.2)
until the throttle cable ferrule (13) snaps into
position . Reassemble the powerhead
. Place the slide (12) in the handle molding so . Secure the throttle cable to the throttle cable
that the groove (arrow) is at the end of the slot retainers on the drive tube
– this is the basic setting for adjusting the . Set and secure the handlebar in the required
throttle cable working position
. Pay attention to the position of the two . Go to 1.12.5 "Adjusting the throttle cable"
wires (8, 9) between the channel and
corrugated tube (see second illustration under
1.12.4 – "Installing microswitch and wires")
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)m~ge 10 Technical Information 09.2003
1.12.4 Machines with loop handle Installing slide and throttle cable
Installing microswitch and wires
7 11 12 13
10 9
393TI051 KN
393TI049 KN
. Press the throttle cable (11) into the slide (12)
until the throttle cable ferrule (13) snaps into
position
. Place the microswitch (7) in the handle molding
as shown in the illustration . Place the slide (12) in the handle molding so
that the groove (arrow) is at the end of the slot –
. Push the ground wire (8) into the channel (10) this is the basic setting for adjusting the throttle
first and then the short-circuit wire (9) cable
Installing the throttle trigger
14
16
15
19 20
393TI050 KN
393TI052 KN
. Make sure that both wires are in the channel
right up to the end of the handle (neither wire 17 18
may project from the channel)
. Attach the bent throttle cable end sleeve (14) to
. Place the wires in the recess (20) at the the throttle trigger (15)
attachment point for the corrugated tube (19).
The throttle is placed over the recess in a later . Push the straight end of the spring (16) under
step. the end sleeve (14) and then fit the ring-shaped
part of the spring over the pivot (17) on the
throttle trigger
. Fit the throttle trigger and position the spring
loop around the boss (18) for the screw
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Technical Information 09.2003 Page 11
Installing control handle with throttle cable – on bike-handled machines, after a big change in
the position of the handlebar (e.g. change
. Check the correct position of the corrugated
between transport and operating position).
tube and slide
Important! – after the throttle cable has stretched, or after a
Do not squeeze the throttle trigger until instructed change in the position of the slide as a result of
to do so in chapter 1.12.5! force due to the throttle cable snagging on an
object during operation.
. Screw the handle moldings together, taking care
not to pinch any wires!
. Attach the throttle cable to the carburetor. If this
Adjusting the throttle cable
has already been done, check that the cable
end is correctly positioned in the pin (see 1.11.2)
12
. Reassemble the powerhead
. Slide the control handle on to the drive tube and
secure the drive tube to the powerhead
. Line up and secure the control handle,
tightening the hose clamp screws with a torque
of 5 Nm (44 in/lbs.).
. Go to 1.12.5 "Adjusting the throttle cable"
393TI054 KN
. Use a screwdriver to press down the slide (12)
1.12.5 Adjusting the throttle cable (all models)
and push it to the end of the slot – this is the
Important! basic setting!
Adjust the throttle cable only when the machine is
completely and securely assembled – the handlebar
and control handle must be in the normal operating
position! 21 12
This adjustment procedure removes free play from
the throttle cable.
Correct adjustment of the throttle cable is necessary
for correct operation of the machine at full throttle,
starting throttle position and idling!
393TI053 KN
Checking throttle cable adjustment 15
The throttle cable should be readjusted:
. Press down the throttle trigger interlock (21) and
– if the throttle trigger was squeezed accidentally squeeze the throttle trigger (15) all the way (full
while handling or mounting the control handle, throttle position) – the slide (12) now moves
i.e. too early. away from the end position – the throttle cable is
– after servicing or repair work. adjusted automatically.
– before readjusting the carburetor. . Adjust the carburetor if necessary
– during new machine set-up.
TI_09_2003_02_01_02.fm
)m~ge 12 Technical Information 09.2003
2. New Carburetor C1Q-S82 / 2.1.1 Mechanical design
C1Q-S83, Shrouds, Grommet
2.1 Carburetor with 3 adjusting screws
5
1 2
3
LD H
256TI023 KN
4
. Low speed adjusting screw (1)
250TI055 KN
LA . High speed adjusting screw (2)
Left: existing carburetor with one adjusting screw . Cap (3) of high speed adjusting screw
Right: new carburetor with three adjusting screws . Idle speed adjusting screw (4)
and caps
. Stop (5) indicating end of travel for high speed
adjusting screw cap
The existing BIS (BIS = Balanced Idle System)
carburetor will be replaced by a new version with
3 adjusting screws to further improve functionality.
These adjusting screws are fitted with caps. 2.1.2 Functions of the cap on the high speed
adjusting screw
The advantages of the new carburetor compared to
the previous version are:
– the cap on the high speed adjusting screw (H)
enables the user to adjust the carburetor to
different working conditions, within a specified
adjustment range. 270°
– all the caps have a funnel on the inside as a
guide to inserting a screwdriver.
233TI023 KN
If the cap is permanently attached to the high
speed adjusting screw, the high speed adjusting
screw can only be turned through a range of
270 degrees (3/4 turn).
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Technical Information 09.2003 Page 13
2.1.3 Maintenance / repair 2.1.4 Basic setting without cap on high-speed
adjusting screw
H L
256TI024 KN
256TI025 KN
1 2
The Service Technician must remove the high
speed adjusting screw cap in order to replace the . Carefully turn the adjusting screws (H) and (L)
adjusting screw or to clean the carburetor. all the way in
. Insert the extractor 5910 890 4501 (1) between . Back off the high speed adjusting screw (H)
the cap (2) and the carburetor housing. 1 3/4 turn
. Pry off the cap . Back off the low speed adjusting screw (L)
1 turn
If the cap binds on the adjusting screw:
. Turn the extractor until the closed side of the
U-shaped blade is opposite the carburetor
housing Fixing cap on H screw
. Slide the extractor under the cap
. Pry off the cap fully
Caps must not be reused!
Adjustment after maintenance / repair
. Check the air filter – clean or replace it if
necessary
256TI026 KN
. Check the muffler / spark arresting screen and
clean or replace if necessary
. Inspect fuel filter and replace if necessary. Never reuse a cap!
. Check throttle cable setting and adjust if . Fit a new cap facing towards the rich stop
necessary – see 1.12.5 (arrow) and press on until it is felt to engage in
position 2.
. Adjust the carburetor, see 1.1.4 "Basic setting
without cap on high-speed adjusting screw"
(adjustment carried out by Service engineer).
Next carry out adjustment for the user if
necessary, see 1.1.5 "Standard setting with cap
on high-speed adjusting screw".
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)m~ge 14 Technical Information 09.2003
Speed varies when idling; engine stops when
a swivelling machine to different position–
the idle setting is too rich!
. Turn the low speed adjusting screw (L)
clockwise about 1/4 turn until the engine runs
uniformly and accelerates correctly
Whenever the low speed adjusting screw (L) has
been adjusted, an adjustment is usually required on
256TI027 KN
the idle speed adjusting screw (LA).
Do not press on the cap all the way to the carburetor
housing, as this will damage it: distance a = 1 mm
2.1.5 Standard setting with cap on high speed
adjusting screw
The adjustment instructions for the new carburetor
Idle speed adjustment
on page 15 are an extract from the chapter headed
"Carburetor adjustment" or "Carburetor adjustment
with the idle speed adjusting screw LA" in the
L operator’s manual for the new machines.
If necessary, customers can be given a copy of the
user instructions that follow.
250TI052 KN
. Turn the idle speed adjusting screw (LA) to set
the speed to 2800 rpm with a tolerance of
+/- 200 rpm
A tachometer should be used as an aid to
adjustment.
Speed varies when idling, poor acceleration,
engine stops –
the idle setting is too lean!
. Turn the low speed adjusting screw (L)
counterclockwise about 1/4 turn until the engine
runs uniformly and accelerates correctly
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Technical Information 09.2003 Page 15
Carburetor adjustment The standard setting should be used for metal
cutting tools or other attachments!
. Carry out standard setting procedure
. Let the engine warm up:
approx. 3 minutes if a mowing head is attached
approx. 5 minutes if a metal cutting tool or other
attachment is fitted
. Open the throttle fully and in mountain country
H
1 turn the high speed adjusting screw (H)
clockwise (= leaner) until the speed ceases to
increase. Maximum speed is normally reached
LA at the standard setting
Instructions for mountain country: a marginal
adjustment to the high speed adjusting screw of
250BA039 KN
approx. 1/8 turn per 1,000 m (3,300 ft) may be
necessary.
Standard setting
. Switch off the engine Idle speed adjustment
. Fit the cutting tool (brushcutters and clearing Whenever the low speed adjusting screw (L) has
saws only) been adjusted, an adjustment is usually required on
. Check the air filter and replace if necessary the idle speed adjusting screw (LA).
. If described in the operator’s manual: check the . Let the engine warm up
throttle cable adjustment and adjust if
necessary. See "Adjusting the throttle cable"
Engine stops when idling
. Turn the high speed adjusting screw (H)
. Carry out standard setting procedure on low
counterclockwise as far as possible – max. 3/4
speed adjusting screw (L)
turn
. Turn the idle speed adjusting screw (LA)
. Carefully turn the low speed adjusting screw (L)
clockwise until the engine runs evenly. The
clockwise lightly against the seat, then back off
cutting tool should not turn
1 turn
. Start the machine and let the engine warm up if
necessary The attachment turns when idling
. Adjust the idle speed by means of the idle speed . Turn the idle speed adjusting screw (LA)
adjusting screw (LA) so that the cutting tool counterclockwise until the cutting tool stops,
does not turn! then turn approx. 1/2 to 1 more turn in the same
direction
Instructions for different working conditions
If the engine does not run satisfactorily, a marginal
adjustment to the high speed adjusting screw (H)
setting may be necessary.
A mowing head with nylon line should always be
attached before adjusting the high speed adjusting
screw (H) on brushcutters and clearing saws. The
lines should reach the deflector.
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)m~ge 16 Technical Information 09.2003
2.1.6 Set of carburetor parts 2.4 Retrofitting existing machines
A new set of carburetor parts is required when The following existing parts have to be replaced by
carrying out repairs to the new carburetor. See 2.5 new versions in order to adapt the new carburetor in
"Summary". older machines:
– carburetor assembly (see 2.1).
– pin for attaching the throttle cable to the
carburetor, see 2.4.1.
2.2 Shroud
– shroud (see 3.2). On older machines the
nameplate 4134 967 1514 has to be affixed to
the new shroud (see TI 22.2201).
– the grommet described in 2.3 can be removed.
The instructions in previous issues of Technical
Information must be followed when doing any
conversion work on older machines.
250TI053 KN
2.4.1 Replacing throttle cable pin on
carburetor
Left: existing shroud
Right: new shroud
In connection with the introduction of the new
carburetor with 3 adjusting screws, the shroud has
5 6
also been modified in the area of the adjusting
screws.
On the new shroud, the carburetor adjusting screws
are directly accessible without a guide grommet.
250TI050 KN
The carburetor adjustment symbols are located on
the shroud.
Sections through cable end and pin
Left: existing version
Right: new version
2.3 Grommet
. Attach version 4128 121 8900 (5) instead of pin
4128 121 8901 (6) to the carburetor C1Q-S35,
-S36 and -S51
. Attach throttle cable end to carburetor pin
. Adjust the carburetor
250TI054 KN
At the same time as the introduction of the new
shroud, the screwdriver guide grommet has been
discontinued.
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Technical Information 09.2003 Page 17
2.4.2 Service notes apply. Give the user a copy of the adjustment
After fitting a new carburetor to an older machine, instructions in 2.1.5 (page 15) as the new
make the user aware that the carburetor adjustment adjustment instructions.
instructions in the operator’s manual no longer
2.5 Summary
Item Part Name Previous New Remarks
BT 120 C
1 Carburetor C1Q-S51C 4134 120 0651 --- 1)
2 Carburetor C1Q-S82 --- 4134 120 0603 2)
3 Shroud 4134 080 1601 4134 084 0912 1)
FS 120
4 Carburetor C1Q-S51C 4134 120 0651 --- 1)
5 Carburetor C1Q-S82 --- 4134 120 0603 2)
6 Shroud 4134 080 1600 4134 084 0911 1)
FS 200, 250
7 Carburetor C1Q-S51C 4134 120 0651 --- 1)
8 Carburetor C1Q-S83 --- 4134 120 0604 2)
9 Shroud 4134 080 1600 4134 084 0911 1)
FS 350
10 Carburetor C1Q-S51C 4134 120 0651 --- 1)
11 Carburetor C1Q-S83 --- 4134 120 0604 2)
12 Shroud 4134 080 1601 4134 084 0910 1)
All machines
13 Grommet 4134 123 7502 --- 1)
14 Set of carburetor parts 4134 007 1060 1129 007 1062 1)2)
Modification to be introduced: see 1.10 "Summary" – "Modification to be introduced"
Remarks
1) Previous version of part remains available for older machines
2) New carburetor parts: see Parts List for the machine concerned
TI_09_2003_02_01_02.fm
)m~ge 18 Technical Information 09.2003
3. Carburetor C1Q-S51 3.2 Idle speed adjustment screw LD
The following modifications have been made to
carburetor C1Q-S51 to optimize engine running.
The modified parts can be replaced in older
carburetor C1Q-S51 models. a b
3.1 Throttle shutter
As the first stage, throttle shutter
250TI032 KN
1123 121 3300 has been replaced by version 1 2
4134 121 3300.
As the next stage, the existing throttle shutter 4134 a = 16.6 mm (0.654 in)
121 3300 has been replaced by the new version b = 16.9 mm (0.665 in)
4134 121 3301. This has a hole through which
additional air can flow when idling.
The previous idle speed adjustment screw 4134 122
6300 (1) will be discontinued and replaced by the
new, slightly longer version 1130 122 6300 (2). The
idle speed screw adjustment range will thus be
optimized for the different series.
3.3 Summary
Item Part Name Previous New Remarks
1 Carburetor C1Q-S51B; 4134 120 0651 ---
including item 3:
2 Carburetor C1Q-S51C; --- 4134 120 0651 1)
including item 3:
3 Throttle shutter 1123 121 3300 4134 121 3300 2)
4 Carburetor C1Q-S51C; 4134 120 0651 --- 1)
including items 6 to 7:
5 Carburetor C1Q-S51D; --- 4134 120 0651
including items 6 to 7:
6 Idle speed adjustment screw 4134 122 6300 1130 122 6300 2)
7 Throttle shutter 4134 121 3300 4134 121 3301 2)
All other parts as before
Modifications to be introduced: in progress
Remarks
1) Previous version of part will be supplied from factory only as long as existing stocks last; after that the
part as in item 5 will be supplied
2) Previous version of part remains available
TI_09_2003_02_01_02.fm Page 10 of 23
Technical Information 09.2003 Page 19
4. Rotating handlebar support / . The handlebar support is mounted at a distance
handlebar for mowing of a = 36 cm (14 1/8 in.) from the powerhead.
applications (FS 250 only) . The handlebar does not protrude beyond the
handlebar support by more than dimension
To facilitate transport in future the bike-handled
b = 15 cm (5 7/8 in.).
machines will be supplied with a rotating handlebar
support. The new handlebar support enables the
handlebar to be installed and swivelled without
requiring tools.
4.2 Swivelling the handlebar
At the same time, the existing "universal" handlebar
4137 790 1701 will be replaced by the version for
mowing applications, number 4128 790 1701.
The new handlebar is specially shaped to
accommodate mowing movements (for extended 2
periods of mowing use). 1
4.1 Installing the handlebar 90°
249TI038 KN
From the operating position to the transport
position
. Slacken the wing bolt (1) and unscrew it until the
handlebar (2) can be turned clockwise
1 2 . Turn the handlebar through 90°, then swivel it
downwards
250TI056 KN
. Tighten the wing bolt again
The handlebar is mounted on the new handlebar From the transport position to the operating
support in the same way as on brushcutters FS 350 position
to FS 450. . Reverse the procedure described above,
During installation, ensure that: turning and swivelling the handlebar
counterclockwise
. The ridge (arrow) in the support (1) points
towards the gearhead.
. The wing bolt (2) points towards the powerhead.
TI_09_2003_02_01_02.fm
)m~ge 20 Technical Information 09.2003
1
15
2
3
14
10
11 4
5
12 6
7
13
8
249TI037 KN
9
4.3 Summary
Item Part Name Previous New Remarks
Handlebar support; --- 4134 790 3200
including items 1 to 9:
1 Wing bolt --- 4128 790 7500
2 Washer --- 0000 958 0609
3 Clamp, top --- 4128 791 0900
4 Compression spring --- 0000 997 1304
5 Clamp, base --- 4128 791 0905
6 Compression spring --- 0000 997 1701
7 Support --- 4134 790 7600
8 Clamp --- 4134 791 0900
9 Spline screw IS-M6x30-10.9 --- 9022 341 1370
10 Handlebar --- 4128 790 1701
11 Clamp 4137 791 0900 --- 1)
12 Clamp 4137 791 6800 --- 1)
13 Clamp 4130 791 0606 --- 1)
14 Spline screw IS-M6x35-10.9 9022 341 1380 --- 1)
15 Handlebar 4137 790 1701 --- 1)
Modification to be introduced: in progress
Remarks
1) Previous version of part remains available for older machines and other models
TI_09_2003_02_01_02.fm
)qechnic~l=fnform~tion=MVKOMMP====================================================================================m~ge=ON
5. Clutch
Service note
The washers 0000 958 1000 must not be installed
in the previous version of the clutch. For
dimensional reasons, the carriers and shoes of the
previous and new clutches must not be combined.
Recommendation: instead of replacing individual
parts of the previous clutch, it is advisable to fit the
new clutch assembly 4128 160 2001.
256TI017 KN
Parts availability
Only the new clutch 4128 160 2001 is available from
The previous clutch 4128 160 2000 has been
the factory.
modified for quieter operation. The new version
4128 160 2001 has 16x10x0.5 washers (arrows) at
the two bearing points between the carrier and the
clutch shoes.
Summary
Item Part Name Previous New Remarks
1 Clutch; including: 4128 160 2000 4128 160 2001 1)
2 Washer 16x10x0.5 (2 x) --- 0000 958 1000
All other parts as before
Modification to be introduced:
USA production from serial number 2 52 747 650
Remarks
1) Previous version of part is no longer available from factory
6. Oil Seals (crankshaft)
To facilitate installation, the 7 mm wide oil seals
9640 003 1200 (arrow) have been replaced by the
new, 5 mm wide versions 9640 003 1195.
The new oil seals can also be used in older
machines.
The oil seals are installed in the same way as
before.
250TI058 KN
TI_09_2003_02_01_02.fm
)m~ge 22 Technical Information 09.2003
Summary
Item Part Name Previous New Remarks
1 Oil seal DIN3760-BS12x22x7 9640 003 1200 --- 1)
2 Oil seal DIN3760-BS12x22x5 --- 9640 003 1195
Modification to be introduced in progress
Remarks
1) Previous version of part is no longer available from factory
7. Crankshaft
(FS 120, 200, 250, BT 120 only)
These washers are not required for the 3-part
crankshaft supplied as a replacement part. This
should be borne in mind when doing repairs in the
crankcase area.
Service notes
The 3-part crankshaft 4134 030 0400 should be
installed without the washers 4140 036 0300! Any
washers remaining in the crankcase must be
250TI059 KN
removed before installing the crankshaft.
If a 5-part crankshaft is reinstalled following a repair
5-part crankshaft with washers in the crankcase area, then two new washers
4140 036 0300 must be fitted on either side of the
crank web.
The 3-part crankshaft 4134 030 0400 was replaced
in the line by a 5-part version some time ago.
Together with the new, 5-part crankshaft, washers
(arrows) are fitted on either side of the crank web.
Summary
Item Part Name Previous New Remarks
1 Washers (2 x) --- 4140 036 0300
Modification to be introduced: in progress
TI_09_2003_02_01_02.fm Page 11 of 23
Technical Information 09.2003 Page 23
8. Rewind Starter / Spring Housing
Fastening
The plastoform screw 9104 003 0410 has for some
time been used instead of the self-tapping screw
9099 021 2330 (arrow) to fasten the spring housing
inside the fan housing.
The plastoform screw can also be used in older
250TI060 KN
machines.
Last Technical Information on the STIHL FS 120, 200, 250: 42.2002
STIHL FS 350: 05.2003
STIHL BT 120 C: 42.2002
© ANDREAS STIHL AG & Co. KG, 2003 Technical Documentation
D1/MTK-na 7995
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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.