Technical Information · issue 20 of 2011
Carburetors, Limiter Cap; Accelerator Pump; Summary
IssueTI 20/2011
Engine family 1141
Part changes (1)
| Was | Becomes | What the bulletin says |
|---|---|---|
| 1141 121 2702 | 1141 121 2704 | Carburetors, Limiter Cap The previous carburetors with limiter cap 1141 121 2702 will be replaced by the new versions with limiter cap 1141 121 2704. |
Full text
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STIH)
Technical Information 20.2011
STIHL MS 261, MS 271, MS 291 Chain Saws – Series 1141
Contents
1. Carburetors, Limiter Cap
2. Accelerator Pump
3. Summary
1. Carburetors, Limiter Cap
The previous carburetors with limiter cap
1141 121 2702 will be replaced by the new versions
with limiter cap 1141 121 2704.
The new carburetor body features a guide pin, while
the limiter cap has a guide slot.
The pin and slot simplify preassembly of the limiter
cap. Furthermore, the limiter cap is held in the
specified position (rich stop) during the basic 1
setting. This makes the procedure of checking the
position of the limiter cap after the basic setting
unnecessary. 2
Once the limiter cap is fixed in position, corrections
to the high speed screw (H) are possible within a
range of about three quarters of a turn – as before.
5902TI024 KN
Top: Previous carburetor with limiter cap
1141 121 2702
Bottom: New carburetor with guide pin (1) and
new limiter cap 1141 121 2704 with guide
slot (2)
TI_20_2011_30_01_01.fm englisch / English
)m~ge 2 Technical Information 20.2011
1.2 Removing the Limiter Cap
5902TI028 KN
5902TI025 KN
Left: Previous limiter cap 1141 121 2702
Right: New limiter cap 1141 121 2704 with guide . Line up the limiter cap (1) so that the
slot notch (arrow) points vertically upwards.
The following carburetors have been standardized
by modifications to the throttle shutter:
Previous carburetor Replace by 3
carburetor 1
1141 120 0601 1141 120 0600 2
C1Q-S181A
(MS 271, MS 291) C1Q-S178B (C)
1141 120 0603 1141 120 0602
5902TI026 KN
C1Q-S182A
(MS 271 C, MS 291 C) C1Q-S179B (C)
. Screw the puller (2) 5910 890 4502 (special
tool) about five turns counterclockwise (left-
1.1 Parts Availability / Service Note hand thread) into the limiter cap (1).
Only carburetors with the new limiter cap . Pull off the limiter cap.
1141 121 2704 will be supplied as replacements in
future. The new carburetor can also be used in older . Use screwdriver (5910 890 2306) to unscrew
machines. the high speed screw (3) with polymer segment.
The previous limiter cap 1141 121 2702 remains
available for older carburetors without guide pin.
The previous carburetors (1141 120 0601 and
1141 120 0603) are no longer available from the
factory.
TI_20_2011_30_01_01.fm Page 2 of 4
Technical Information 20.2011 Page 3
1.3 Basic and Standard Settings 1.4 Preassembling Limiter Cap on High
The settings on the carburetors remain unchanged. Speed Screw
1
2
1.3.1 Basic setting without limiter cap on high
speed screw (in service shop)
Low speed screw L: Open 1full turn
High speed screw H: Open 11/2 turns
5902TI027 KN
1.3.2 Standard setting with limiter cap on the
high speed screw: . Line up the new limiter cap (1141 121 2704) so
Low speed screw L: Open 1 full turn that the guide pin (1) engages the guide slot (2).
. Press the limiter cap onto the high speed
High speed screw H: Open 3/4 turn screw (H) as far as first stop – almost flush with
(no further than stop) the boss (arrow) – do not push fully home.
Limiter cap is now preassembled and is held in this
position (rich stop) while the basic setting is carried
out.
. Basic setting and fixing the limiter cap on the
high speed screw are performed as before.
2. Accelerator Pump
In the foreseeable future the previous carburetors,
i.e. C1Q-S178C (1141 120 0600), C1Q-S179C
(1141 120 0602) and C1Q-S180 C
(1141 120 0604) will be renamed
C1Q-S178D, C1Q-S179D and C1Q-S180D. These
carburetors feature a modified spring for the
accelerator pump. The replacement parts remain
unchanged.
TI_20_2011_30_01_01.fm
)m~ge 4 Technical Information 20.2011
3. Summary
Item Part Name Previous New Rem.
1 C1Q-S181A carburetor; including item 7 1141 120 0601 --- 1)
2 C1Q-S178A carburetor; including item 7 1141 120 0600 --- 1)
3 C1Q-S182A carburetor; including item 7 1141 120 0603 --- 1)
4 C1Q-S179A carburetor; including item 7 1141 120 0602 --- 1)
5 C1Q-S178B ... D carburetor; including item 7 --- 1141 120 0600 2) 3)
6 C1Q-S179 ... D carburetor; including item 7 --- 1141 120 0602 2) 3)
7 Limiter cap 1141 121 2702 1141 121 2704 4)
Modification to be introduced: in progress
Remarks
1) Previous version of part no longer available from factory
2) Only modified version of part is available from factory
3) New version of part can also be used for older machines
4) Previous version of part remains available for older carburetors
© ANDREAS STIHL AG & Co. KG, 2011 Technical Documentation
D1/MTK-bl
TI_20_2011_30_01_01.fm Page 3 of 4
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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.