Technical Information · issue 18 of 1997
Tank housing /tank vent; Carburetor; Electric hand
Model 024, 026 Chainsaws============- Series 1121
Full text
Page 1 of 4
Technical Information
18.97
Model 024, 026 Chainsaws============- Series 1121
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1. Tank housing (tank vent, fuel pickup hose, cover, shutter, stop buffer)
2. Carburetor (sealing ring for high speed and low speed screws, valve jet)
3. Seal on spark plug boot deleted
1.=Tank housing
Modified tank housings with different part numbers
will be installed in all saw versions from machine
number X 36 348 620K=qhe changes are described
below.
1.1=Tank vent
The original two-way valve for equalizing pressure
in the fuel tank has been deleted and will be
replaced by mushroom valve 1110 353 1600.
The new valve only allows air to enter the fuel tank.
145TI016 KN
Left: Original valve
Right: New valve
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Fuel consumption during saw operation causes a
low pressure to occur in the tank. This opens the
mushroom valve, allows air to flow into the tank
and equalize pressure.
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Pressure may build up in the tank while the engine
is stopped (e.g. due to radiated heat from engine
145TI017 KN
or sun).
Always open the fuel filler cap slowly so that any
excess pressure built up after unit is turned off is
released gradually and fuel does not escape
unexpectedly.
)Technical Information 18.97 - Page 2
1.2=Fuel pickup hose
The S-shaped fuel pickup hose 1129 358 7700 will
be installed on the production line instead of the
original straight hose 1121 358 7705. The new
hose requires a larger opening in the tank housing.
In this connection the replacement tank housings
will also have the same size opening. In order to
ensure easy changeovers, replacement tank
housings will be supplied together with the new
pickup hose for about the next 2 years (see
Summary).
1.3=Cover =026=, shutter =024
When the air filter system with compensator was
introduced on the 026 (see TI 31.95) the
combustion air intake was moved from the top to
the bottom (between carburetor box cover and
tank housing). As the air flow has been changed,
the cut-out (see arrow) in the tank housings of all
saw versions is no longer required and has been
deleted. Similarly, the cover E1F=~nd shutter E2F
(depending on model and version) previously fitted
in this cut-out have been deleted.
Service note
The cut-out is now closed with a molding skin
(cross-hatched in illustration). It can be re-opened
for use on 026 saws with the original air filter
system and 024 saws. The cover or shutter can
then be fitted.
Carry out the work carefully (with a drill and file) so
that the cover or shutter is an exact fit.
)Technical Information 18.97 - Page 3
1.4=Stop buffer
A stop buffer 1121 791 2800 (arrow) is installed
in the left carburetor box cover wall to further
enhance the anti-vibration system. It helps limit
the AV system’s buffer travel under extremely
high loads.
The stop buffer is included in the scope of supply
of the new replacement tank housing.
133TI029 KN
1.5=Summary
Item Part Name Original New Rem.
version version
1 Tank housing (standard); 1121 350 0804 1121 350 0821 1)
includes items 2 to 8:
2
3
Shutter
Valve
1121 791 1300
4114 353 1600
---
1110 353 1600
2)
3)
4 Hose --- 1129 358 7700
5 Stop buffer --- 1121 791 2800
6 Hose 1121 358 7705 --- 2)
7 Cover 1121 791 7500 --- 2)
8 Plug 1121 791 1400 --- 2)
All other parts as before
Modification to be introduced from machine number X 36 348 620
5HPDUNV
1) Original version of part will be supplied by factory only as long as existing stocks last
2) Part remains available for older machines
3) Original version of part remains available for older machines and other models
)Technical Information 18.97 - Page 4
2.=Carburetor
New carburetor versions will be installed from
machine number X 36 348 620.
The differences between the new and original
carburetors are:
• Valve jet E1F=with orifice (semi-fixed jet)
• New H and L screws sealed with 0-ring E2F
133TI030 KN
and washer E3F
1 2 3
Approximately 75% of the fuel required is fed
through a calibrated orifice (0.48 mm dia.)
irrespective of the position of the H screw.
This means that machines can be tuned more
accurately and are less sensitive to incorrect
adjustment.
The carburetor type designations have been
changed from WT 394 to WT 426.
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Item Part Name Original New Rem.
version version
1 Carburetor WT 394; 1121 120 0650 --- 1)
2 Carburetor WT 426; --- 1121 120 0650
above includes:
3 Valve jet 1120 121 5405 1121 121 5400 2)
4 High speed screw 1118 122 6700 1121 122 6700 2)
5 Low speed screw 1120 122 6805 1121 122 6802 2)
6 O-ring --- 4130 122 3600
7 Washer --- 4130 121 8601
All other parts as before
Modification to be introduced: from machine number X 36 348 620
5HPDUNV
1) Only modified version of part is available from factory
2) Original version of part remains available for original carburetor and other models
3.=Seal on spark plug boot
The seal 1121 084 1410=on the spark plug boot
will be discontinued on the production line in the
near future, but it will remain available as a
replacement part.
Last Technical Information on models 024, 026: 38.96
1997 Andreas Stihl Andreas Stihl - D1/MTK-sc
Technical Documentation 6045 Page 2 of 4
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