Technical Information · issue 39 of 2003
Carburetor; Muffler and seal; Summary
IssueTI 39/2003
Engine family 1128
Part changes (1)
| Was | Becomes | What the bulletin says |
|---|---|---|
| 1128 120 0625 | 1128 120 0622 | The previous carburetor 1128 120 0625 is replaced by version 1128 120 0622. |
Full text
Page 1 of 5
STIH)
Technical Information
39.2003
STIHL MS 440 chainsaw – Series 1128
Contents
1. Carburetor
2. Muffler and seal
3. Summary
The modifications outlined below ensure that 1.1 Supply of spare parts
tomorrow's European emission standards are The previous carburetor 1128 120 0625 without
already met today. limiter caps remains available for older machines
and other models. Spare parts for the new
1. Carburetor carburetor are listed in the current spare parts
documentation.
The previous carburetor 1128 120 0625 is replaced
by version 1128 120 0622.
1.2 Service note
If the carburetor 1128 120 0622 with limiter caps
has to be replaced for servicing in a model
MS 440 C with catalytic converter, the high speed
screw (H) must be turned 1/8 of a turn clockwise
(leaner setting); cf. 1.3.3. Basic setting without
limiter caps.
175TI004 KN
Left: previous carburetor 1128 120 0625 without
limiter caps
Right: new carburetor 1128 120 0622 with limiter
caps
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)m~ge 2 Technical Information 39.2003
1.3 Carburetor adjustment 1.3.2 Maintenance / repair
H L
175TI006 KN
178TI005 KN
With the new carburetor, the high speed adjusting The limiter caps must be removed in order to
screw H and the low speed adjusting screw L can replace a defective adjusting screw or to clean the
only be adjusted by the user within a range of 258° carburetor.
(approx. 3/4 turn). This ensures that the full-throttle,
. Turn the limiter cap on the high speed adjusting
partial-throttle and idle settings always remain
screw H anticlockwise as far as possible – the
optimally set for the engine.
ridge on the limiter cap must line up with the
In this way, the carburetor setting can be adjusted to groove in the carburetor housing
different working conditions, e.g. change of altitude
(mountain country or sea level).
.
Turn the limiter cap on the low speed adjusting
screw (L) clockwise – as far as possible – then
back off 1/4 turn – the ridge on the limiter cap
1.3.1 Mechanical design must line up with the groove in the carburetor
housing – the ridge on the limiter cap is
perpendicular to the slit in the screw
. Turn extractor 5910 890 4500 anticlockwise
until the limiter cap is pulled off the head of the
adjusting screw.
3 The limiter cap may twist when the extractor is
1 turned in – ensure that the ridge on the limiter
cap is lined up with the groove in the carburetor
housing when it is pulled off.
175TI005 KN
4 2 Adjustment after maintenance / repair
. Limiter caps (1) . Check the air filter – clean or replace it if
necessary
. High speed adjusting screw with seal (2)
. Check the spark arresting screen (if fitted) –
. Low speed adjusting screw with seal (3) clean or replace it if necessary
. Idle speed adjusting screw (4)
The limiter caps are fitted over the knurled head of
the adjusting screws. The stops on the carburetor
housing serve as limiters.
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Technical Information 39.2003 Page 3
1.3.3 Basic setting without limiter caps 1.3.4 Securing the limiter caps
The carburetor can be set to its basic setting more
easily with the aid of setting disk 5910 893 6600.
H L
146TI014 KN
146TI013 KN
Limiter caps must not be reused.
. Insert new limiter caps in the hole as
. Starting from the tight position of the adjusting illustrated – ensure that the ridges are correctly
screw: positioned (see arrows)
on MS 440: . Press the limiter caps onto the adjusting
H = Back off 1 turn screws until they are flush with the carburetor
L = Back off 1 turn
on MS 440 C with catalytic converter:
housing (1)
1.3.5 Standard setting with limiter caps
H = Back off 7/8 turn
L = Back off 1 turn The limiter caps must not be removed when making
the standard setting.
. Switch off the engine
Set the specified speeds within the tolerance
. Check the air filter – clean or replace it if
range of +/– 200 rpm necessary
1. Set speed to 3300 rpm with the idle speed . Check the spark arresting screen in the muffler
adjusting screw (LA) (if fitted) – clean or replace it if necessary
2. Turn the low speed adjusting screw (L)
clockwise or anticlockwise to set the highest
speed
H
If this speed is greater than 3700 rpm, stop and H L
start again with step 1
3. Set the speed to 3300 rpm again with the idle LA
178TI008 KN
speed adjusting screw (LA)
4. Set the speed to 2500 rpm with the low speed
adjusting screw (L) . Turn the high speed adjusting screw (H)
anticlockwise as far as possible (max. 3/4 turn)
5. Set the maximum speed of 13,500 rpm with . Turn the low speed adjusting screw (L)
the high speed adjusting screw (H) clockwise as far as possible, then back off
1/4 turn
If the setting is too lean, the engine may be
damaged by overheating and a shortage of
lubricant.
6. Continue with 1.3.4 "Securing the limiter
caps"
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)m~ge 4 Technical Information 39.2003
Idle speed adjustment 2. Muffler and seal
Engine stops when idling The seal 1128 149 0500 is fitted between the upper
. Set the low speed adjusting screw (L) so that it and lower mouldings of the muffler 1128 140 0600
is 1/4 turn open in future.
. Turn the idle speed adjusting screw (LA) 1
clockwise until the saw chain begins to run –
then back off 1/4 turn
Chain runs when idling
. Set the low speed adjusting screw (L) so that it
is 1/4 turn open
. Turn the idle speed adjusting screw (LA)
anticlockwise until the saw chain stops – then
175TI003 KN
give it another 1/4 turn in the same direction
Speed varies when idling; poor acceleration
(although low speed adjusting screw (L) is 1/4 turn
open) Muffler 1128 140 0600 with seal (1) 1128 149 0500
. Idle setting too lean – turn the low speed
adjusting screw (L) anticlockwise until the Supply of spare parts
engine runs uniformly and accelerates
correctly – max. up to the stop
Seal 1128 149 0500 is not included in muffler
1128 140 0600 and must be ordered separately.
. Whenever the low speed adjusting screw (L)
has been adjusted, at least one adjustment is
usually required on the idle speed adjusting
screw (LA)
Adjustment for use in mountain country
A marginal adjustment may be necessary if the
engine does not run satisfactorily:
. Check the standard setting
. Let the engine warm up
. Turn the high speed adjusting screw (H)
cockwise (leaner) – max. up to the stop
If the setting is too lean, the engine may be
damaged by overheating and a shortage of
lubricant.
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Technical Information 39.2003 Page 5
3. Summary
Item Part name Previous New Remarks
1 Carburetor HD-15B 1128 120 0625 --- 1)
2 Carburetor HD-17A; ---
including Item 3 1128 120 0622 2)
3 Cap --- 4203 121 2700
4 Seal --- 1128 149 0500
Modification to be introduced continuously
Remarks
1) Previous version of part remains available for older machines and other models
2) The new spare parts are listed in the current spare parts list
Last Technical Information on STIHL MS 440: 28.2002
© ANDREAS STIHL AG & Co. KG, 2003 Technical Documentation
D1/MTK-bl 7953
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