Technical Information · issue 27 of 2003
Carburetor; Grommet; Muffler and Gasket; Cylinder with Piston; Summary
Model MS 660 Chainsaw – Series 1122
IssueTI 27/2003
Engine family 1122
Part changes (3)
| Was | Becomes | What the bulletin says |
|---|---|---|
| 1122 120 0621 | 1122 120 0618 | The previous carburetor 1122 120 0621 has been replaced by carburetor 1122 120 0618. |
| 1122 140 0602 | 1122 140 0604 | The previous muffler 1122 140 0602 has been Gasket 1122 149 0500 is not included in muffler replaced by muffler 1122 140 0604 with gasket 1122 140 0604 and must be ordered separately. |
| 1122 020 1209 | 1122 020 1211 | Cylinder with Piston The previous cylinder with piston 1122 020 1209 will be replaced by version 1122 020 1211. |
Full text
Page 1 of 5
STIH)
Technical Information
27.2003
Model MS 660 Chainsaw – Series 1122
Contents
1.
2.
Carburetor
Grommet
3. Muffler and Gasket
4. Cylinder with Piston
5. Summary
The engineering changes described below ensure 1.1 Parts availability
compliance with future emission standards in The previous carburetor 1122 120 0621 without
Europe. limiter caps remains available as a spare for older
machines and other models.
1. Carburetor
The previous carburetor 1122 120 0621 has been
replaced by carburetor 1122 120 0618.
178TI004 KN
Left: Previous carburetor 1122 120 0621 without
limiter caps
Right: New carburetor 1122 120 0618 with limiter
caps
TI_27_2003_01_01_02.fm englisch / english
)m~ge 2 Technical Information 27.2003
1.2 Adjusting the carburetor 1.2.2 Servicing / Repairs
H L
178TI005 KN
178TI007 KN
On the new carburetor the user is may make The caps have to be removed to replace a damaged
corrections to the setting of the high speed adjusting screw or clean the carburetor.
screw (H) and low speed screw (L) only within a
. Rotate limiter cap on high speed screw (H)
range of about 270 degrees (3/4 turn). This ensures
counterclockwise as far as stop – lug on limiter
that the full load, part load and idle settings remain
cap must line up with the slot in the carburetor
within a favorable engine rpm range.
body.
It is still possible to fine-tune the carburetor to suit
changes in working and site conditions, e.g. a
change in altitude (mountains, sea level).
. fo
Rotate limiter cap on low speed screw (L)
clockwise as far as stop. Then turn it back a
quarter turn. Lug on limiter cap must line up with
slot in the carburetor body. Lug on limiter cap is
1.2.1 Construction at a right angle to the screw slot.
. Screw home puller 5910 890 4500
counterclockwise until the limiter cap is pulled
off the adjusting screw.
3 Adjustment after servicing / repairs
1 . Check the air filter and clean or replace as
necessary.
. Check the spark arresting screw (where
178TI006 KN
applicable) and clean or replace as necessary.
4 2
. Limiter caps (1)
. High speed screw with sealing ring (2)
. Low speed screw with sealing ring (3)
. Idle speed screw (4)
The limiter caps are pushed over the heads of the
adjusting screws and on to knurling. The stops on
the carburetor body limit screw rotation.
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Technical Information 27.2003 Page 3
1.2.3 Standard setting without limiter caps 1.2.4 Securing the limiter caps
H L 1
146TI013 KN
146TI014 KN
. Starting with the adjusting screws against their Do not re-install used caps
seats:Open H screw one full turnOpen L screw
. Fit the new limiter caps in the holes as shown in
one full turn
the illustration, making sure the lugs are
correctly positioned (see arrows).
Adjust the specified engine speeds within a . Push the caps on to the adjusting screws until
tolerance range of +/- 200 rpm. their are flush with the carburetor body (1).
1. Use idle speed screw (LA) to set engine
1.2.5 Standard setting with limiter caps
speed to 3,300 rpm. The limiter caps must not be removed for the
standard setting.
2. Rotate the low speed screw (L) clockwise or . Shut off the engine
counterclockwise to obtain maximum engine
. Check the air filter and clean or replace as
speed.
necessary.
If this engine speed is higher than 3,700 rpm, abort . Check the spark arresting screen (if fitted) in
the adjustment and start again from the beginning must and clean or replace as necessary.
(step 1).
3. Use idle speed screw (LA) to set engine
speed to 3,300 rpm once again.
H
4. Use low speed screw (L) to set engine speed H L
to 2500 rpm.
5. Use high speed screw (H) to set maximum LA
engine speed to 13,000 rpm.
178TI008 KN
If the setting is too lean, there is a risk of damaging
the engine as a result of insufficient lubrication and . Rotate the high speed screw (H)
overheating. counterclockwise as far as stop (max. 3/4 turn).
6. Go to "Securing the limiter caps" . Rotate the low speed screw (L) clockwise as far
as stop. Then turn it back a quarter turn.
TI_27_2003_01_01_02.fm
)m~ge 4 Technical Information 27.2003
Adjusting engine idle speed 2. Grommet
Engine stops while idling The previous grommet 1122 123 0621 has been
. Open the low speed screw (L) a quarter turn. replaced by grommet 1122 123 0618.
. Turn the idle speed screw (LA) clockwise until
the chain begins to run, then turn the screw back
a quarter turn from that position.
Chain runs when engine is idling
. Open the low speed screw (L) a quarter turn.
L L
. Turn the idle speed screw (LA) H H
counterclockwise until the chain
stops running – then turn screw another quarter LA LA
178TI009 KN
turn in the same direction.
Erratic idling behavior, poor acceleration
(even though low speed screw = 1/4)
Left: Previous grommet 1122 123 7503
. Idle setting is too lean. Turn the low speed screw Right: New grommet 1122 123 7501 with bead and
(L) counterclockwise (no further than stop) until chamfer
the engine runs and accelerates smoothly.
The new grommet may only be used with carburetor
. It is usually necessary to change the setting of
the idle speed screw (LA) after every correction
1122 120 0618.
Parts availability
to the low speed screw (L).
Fine tuning for operation at high altitude The previous grommet 1122 123 7503 remains
available as a spare for machines with carburetor
A slight correction of the setting may be necessary 1122 120 0621 (without limiter caps).
if engine power is not satisfactory.
. Check the standard setting.
. Warm up the engine.
. Turn the high speed screw (H) clockwise
(leaner), but no further than stop.
If the setting is too lean, there is a risk of damaging
the engine as a result of insufficient lubrication and
overheating.
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Technical Information 27.2003 Page 5
3. Muffler and Gasket Parts availability
The previous muffler 1122 140 0602 has been Gasket 1122 149 0500 is not included in muffler
replaced by muffler 1122 140 0604 with gasket 1122 140 0604 and must be ordered separately.
1122 149 0500. The previous carburetor 1122 140 0621 without
limiter caps remains available as a spare for older
1 machines and other models.
2
4. Cylinder with Piston
The previous cylinder with piston 1122 020 1209 will
be replaced by version 1122 020 1211.
Port timing has been optimized on the new cylinder.
Parts availability
178TI010 KN
The previous cylinder with piston 1122 020 1209
remains available as a spare for older machines and
other models.
New muffler 1122 140 0604 with gasket (1)
1122 149 0500 and upper casing (2) 1122 145 0801
5. Summary
Item Part Name Previous New Remarks
1 Carburetor 1122 120 0621 1122 120 0618 1)
2 Grommet 1122 123 7503 1122 123 7501 1)
3 Muffler 1122 140 0602 1122 140 0604 1)
4 Gasket --- 1122 149 0500
5 Cylinder with piston 1122 020 1209 1122 020 1211 1)
Modification to be introduced: in progress
Remarks
1) Previous version of part remains available for older machines and other models
Last Technical Information on model MS 660: 53.2002
© ANDREAS STIHL AG & Co. KG, 2003 Technical Documentation
D1/MTK-bl 7941
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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.