Technical Information · issue 21 of 2005
Limiter cap; Segment; Spare parts; Removal of the limiter caps; Summary
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STIH)
Technical Information 21.2005
Chainsaws STIHL MS 260 – Series 1121
Chainsaws STIHL MS 270, 280 – Series 1133
Chainsaws STIHL MS 290, 310, 390 – Series 1127
Chainsaws STIHL MS 361 – Series 1135
Chainsaws STIHL MS 440, 460 – Series 1128
Chainsaws STIHL MS 650, 660 – Series 1122
Blowers STIHL BR 320, 340, 400, 420 – Series 4203
Mistblowers STIHL SR 320, 340, 400, 420 – Series 4203
Clearing saws STIHL FS 550 – Series 4116
Contents
1. Limiter cap
2. Segment
3. Spare parts
4. Removal of the limiter caps
5. Summary
Carburetor: limiter cap
The limiter caps 4203 121 2700 and segment on the
carburetor have been modified for easier alignment.
1. Limiter cap
The upper detent has been eliminated.
Left: previous version of limiter cap with upper
detent (arrow)
Right: new version without upper detent
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)m~ge 2 Technical Information 21.2005
The limiter cap now features a mark and the lug has 2. Segment
been moved so that the limiter cap can be aligned
more easily. The groove width is increased approx. 0.01 in to
0.05 in (0.3 mm to 1.5 mm). Marks are provided on
the segment for chainsaw models MS 270, 280,
290, 310, 361, 390, 440, 460, 650 and 660.
The mark on the segment of these carburetors
makes it easier to align the limiter cap on the low
speed adjusting screw L before pulling it off.
The limiter cap on the low speed adjusting screw L
cannot be lined up against the stop and pulled off,
but is instead pulled off when offset a quarter-turn
from the stop – the marks on the limiter cap and
segment line up
(cf. 4.1 low speed adjusting screw L).
Left: previous version of the limiter cap – lug (1) is at
90° to the slot in the screw head (2)
Right: new version with mark (3), the lug (4) now
forms a continuation of the slot in the screw head (5)
Left: previous version of the segment with groove
width a = 0.047 in (1.19 mm)
Right: new version with groove width b = 0.059 in
(1.50 mm) and marks c
3. Spare parts
The part numbers for the limiter cap and carburetor
remain unchanged.
4. Removal of the limiter caps
The limiter caps must be removed in order to
replace a damaged adjusting screw or to clean the
carburetor.
Caps which have been removed must not be
reused, as they are damaged during removal!
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Technical Information 21.2005 Page 3
4.1 Low speed adjusting screw L
. Pull off the limiter cap
. Screw the puller 5910 890 4500 (special tool)
counterclockwise (left-hand thread) onto the
limiter cap approx. five turns. 4.2 High speed adjusting screw H
. Turn the limiter cap on the low speed adjusting . Screw the puller 5910 890 4500 (special tool)
screw L clockwise with the puller – until the stop counterclockwise (left-hand thread) onto the
on the limiter cap is reached – then back off the limiter cap approx. five turns.
limiter cap a quarter-turn so that the slot in the
screw head (1) of the limiter cap is lined up with
the groove (2) in the carburetor housing. The lug
on the limiter cap must be visible through the
groove in the insert in the carburetor housing.
. Line up the marks on the limiter cap and
segment (see arrows) – only on chainsaw
models MS 270, 280, 290, 310, 361, 390, 440,
460, 650, 660.
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Check the alignment of the limiter cap: . Pull off the limiter cap.
. The slot in the screw head (1) of the limiter cap
forms the continuation of the groove (2) in the
carburetor housing. The lug on the limiter cap
must be visible through the groove in the insert
in the carburetor housing.
. Line up the marks on the limiter cap and
segment (see arrows) – only on chainsaw
models MS 270, 280, 290, 310, 361, 390, 440,
460, 650, 660.
. Correct the limiter cap alignment if necessary,
turning the limiter cap with the puller.
5. Summary
Item Part name Previous New Remark
1 Cap 4203 121 2700 4203 121 2700 1)
Modification to be introduced continuously
Remark
1) Only modified version of part is available from factory
Last Technical Information on the STIHL MS 260: 40.2004
STIHL MS 270, 280: 28.2003
STIHL MS 290, 310, 390: 36.2004
STIHL MS 361: 16.2005
STIHL MS 440: 30.2004
STIHL MS 460: 40.2003
STIHL MS 650: 10.2005
STIHL MS 660: 15.2005
STIHL BR 320, 340, 400, 420: 53.2003
STIHL SR 320, 340, 400, 420: 53.2003
STIHL FS 550: 29.2002
© ANDREAS STIHL AG & Co. KG, 2005 Technical Documentation
D1/MTK-bl
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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.