Technical Information · issue 16 of 1994
Crank drive; carburetor; fuel filler cap; rewind s
Part changes (3)
| Was | Becomes | What the bulletin says |
|---|---|---|
| 1128 030 0401 | 1128 030 0405 | The original crankshaft 1128 030 0401 will be replaced by crankshaft 1128 030 0405. |
| 1128 020 2106 | 1128 020 2112 | The original crankcase 1128 020 2106 will be replaced by the new version 1128 020 2112. |
| 1128 029 2300 | 1128 029 2301 | original cylinder gasket 1128 029 2300 will be replaced by the gasket 1128 029 2301 that was introduced with the automatic choke. |
Full text
Page 1 of 7
Technical Information
16.94
Engineering Changes on Model 044 Chain Saws - Series 1128
Contents
1. Crank gear (crankshaft/related parts)
2. Carburetors (idle system, pump diaphragm, valve jet)
3. Ignition module mounting (screws with captive washer)
4. Fuel pickup body (standardization)
5. Filler cap (hook on cap retainer deleted on production line)
6. Rewind starter (rewind spring with sheetmetal holder)
7. Starter post in fan housing (revised tightening torque)
8. Cylinder gasket (standardization) fo
1. Crank gear
The big-end and small-end bearings will be
enlarged from machine number X 29 382 283
Modification of these bearings has necessitated
changes to the crankshaft, crankcase, connecting
rod, piston, piston pin, snap ring and needle cage.
The component parts of the original and new crank
gears are not interchangeable.
The following detail changes were made:
1.1. Crankshaft
The original crankshaft 1128 030 0401 will be
replaced by crankshaft 1128 030 0405. 1
The big-end bearing (1) of the new crankshaft is
wider and has a larger diameter. Furthermore,
the size of the small end has been increased.
The diameter of the small end is an easy way of
identifying the crankshafts:
Original crankshaft: a = Ø 14 mm (0.55 in)
New crankshaft: a = Ø 15 mm (0.59 in)
1.2. Crankcase
The original crankcase 1128 020 2106 will be
replaced by the new version 1128 020 2112.
The crank chamber of the new crankcase has been
adapted to suit the larger crankshaft radius (r). Page 2 of 7
Technical Information 16.94 - Page 2
Radius "r" has been increased as a result of the
larger diameter of the crankpin. The extra size of
the crank chamber ensures that there is sufficient
clearance between the connecting rod and crank-
case.
1.3 Piston, piston pin, snap rings and
needle cage
The diameters of the piston boss and piston pin
have been increased and the snap rings and
needle cage modified accordingly. (see summary).
1.4 Service note
The new crankshaft must not be installed in the
original crankcases 1128 020 2106 and
1128 020 2103.
1.5 Summary
Part Name Original New Key Rem. MOQ
version version H
Crankcase 1128 020 2106 1128 020 2112 1) 1
Crankshaft 1128 030 0401 1128 030 0405 2) 1
Cylinder with piston Ø 50 mm; 1128 020 1201 --- 2) 1
including items 1, 3, 5:
Cylinder with piston Ø 50 mm; --- 1128 020 1211
including items 2, 4, 6:
Cylinder with piston Ø 50 mm, (auto. choke); 1128 020 1204 --- 2) 1
including items 1, 3, 5:
Cylinder with piston Ø 50 mm, (auto. choke); --- 1128 020 1212 1
including items 2, 4, 6:
Piston Ø 50 mm 1128 030 2000 --- 1 2)
Piston Ø 50 mm --- 1128 030 2001 2 1
Piston pin 10x6x35 1128 034 1500 --- 3 2)
Piston pin 12x8x35 --- 1128 034 1501 4 1
Snap ring C10 (2x) 9463 650 1000 --- 5 2)
Snap ring C12 (2x) --- 9463 650 1200 6 10
Needle cage 10x14x13 9512 535 2340 --- 2)
Needle cage 12x15x15 --- 9512 003 3061 1
Modification to be introduced from machine number X 29 382 283
Remarks
1) Original version of part will be supplied from factory only as long as existing stocks last
2) Original version of part remains available for older machines Page 3 of 7
Technical Information 16.94 - Page 3
2. Carburetors
The following table shows all carburetors
used in model 044 saws according to serial
numbers and versions.
A B C
Serial No. up to X 26 452 475 from X 26 452 476 from X 28 047 978
up to X 28 047 977
Standard C3M - S5 E; C3M - S20; C3M - S5 G;
1128 120 0601 1128 120 0608 1128 120 0617
Automatic choke C3M - S12 A; C3M - S21; C3M - S12 B;
1128 120 0603 1128 120 0609 1128 120 0615
(see note)
Carburetor heating --- C3M - S22; C3M - S23;
1128 120 0611 1128 120 0616
Column A shows the carburetors installed at the 2.1. Pump diaphragm
time the saw version was launched.
All carburetors in column B are equipped with a
The original pump diaphragm 1125 121 4802 will
compensator (see TI 54.92). These carburetors be replaced by version 1128 121 4802. The new
were also equipped with a modified idle system. pump diaphragm is made of a different material
This idle system is not used on current production and will also be included in the carburetor parts kit
carburetors. 1128 007 1065.
Column C shows the current carburetors.
2.2. Valve jet, throttle shaft and lever,
Note to column C low speed and high speed adjusting screws
Saws with an automatic choke will still be built for a
while with the C3M - S21 carburetor; 1128 120 0609. The valve jet, throttle shaft and lever, low speed
The C3M - S12 B carburetor 1128 120 0615 and high speed adjusting screws of carburetors
is already being shipped as a replacement unit. C3M - S5G, C3M - S12B und C3M - S23 have
The idle systems of the carburetors in columns A been modified (see summary).
and C are, therefore, identical. This means that
the replacement parts for the carburetors in column
A are once again applicable for the carburetors in
column C (see summary).
Some carburetors are marked C3M-S20 A.
These are carburetors that have been upgraded to
the same level as the C3M-S5 G.
Service note
(only for models with automatic choke)
If carburetor 1128 120 0615 (C3M - S12B) is used to
replace carburetor 1128 120 0603 (C3M - S12A),
it is necessary to either install an air filter with a
connection for the compensator or replace the end
cover which comes with the carburetor (for compen-
sator) with end cover 1125 121 0803 (no connection
for compensator). Note that end cover
1125 121 0803 must be ordered separately. Page 4 of 7
Technical Information 16.94 - Page 4
2.3. Summary
The following summary shows the changes that
have taken place from column B to column C in
the table on page 3. The changes made between
columns A and B are explained in TI 54.92.
Part Name Original New Key Rem. MOQ
version version H
1128 120 0608 --- 1)
Carburetor C3M-S20 (standard);
including items1 to 4, 5:
Carburetor C3M-S5G (standard); --- 1128 120 0617 1
including items1 to 4, 5:
Carburetor C3M-S22 (carb heating); 1128 120 0611 --- 1)
including items1 to 4, 5:
Carburetor C3M-S23 (carb heating); --- 1128 120 0616 1
including items1 to 4, 5:
Carburetor C3M-S21 (automatic choke); 1128 120 0609
fo --- 1)
including items1 to 3, 4, 6:
Carburetor C3M-S12B (automatic choke); --- 1128 120 0615 1
including items1 to 3, 4, 6:
Carburetor parts kit 034S, 036, 044; 1128 007 1065 1128 007 1065 2)
including item 1:
Pump diaphragm 1125 121 4802 1128 121 4802 1 1) 1
Valve jet 1128 121 5401 1128 121 5400 2 3)
High speed adjusting screw 1125 122 6701 1125 122 6700 3 3)
Low speed adjusting screw 1128 122 6802 1128 122 6800 4 3)
Throttle shaft with lever 1128 120 7103 1128 120 7100 5 3)
Throttle shaft with lever 1128 120 7104 1128 120 7102 6 3)
All other parts as before
Modification to be introduced from machine number X 28 047 978
Remarks
1) Original version of part no longer available from factory
2) Unmodified version of part will be supplied until existing factory stocks are exhausted
3) Original version of part remains available as spare Page 5 of 7
Technical Information 16.94 - Page 5
3. Ignition module mounting
In future the two original IS-M5x20 spline screws
and A5.3 washers (2x) will be replaced by two
IS-M5x20 screws with captive washers.
Summary
Part Name Original New Key Rem. MOQ
version version H
Spline screw IS-M5x20 9022 371 1020 --- 1)
Washer A 5.3 991 021 0120 --- 1)
Screw with captive washer IS-M5x20 (2x) --- 9022 371 1022 20
Modification to be introduced: in progress
Remarks
1) Original version of part remains available as spare for other models
4. Fuel pickup body
The new pickup body 0000 350 3500 will be installed
from machine number X 29 382 309 in order to
further improve performance and standardize parts 1
with other models.
Compared to the original pickup body 1115 350 3503, 2
the new version has a larger filter area. 3
This helps prolong service life and also improves dirt
retention.
Summary
Part Name Original New Key Rem. MOQ
version version H
Pickup body; 1115 350 3503 0000 350 3500 1) 1
including:
Filter 1110 358 1800 -*- 1 2)3)
Weight 1115 358 8200 --- 2 4)
Cap 1115 358 2500 --- 3 4)
Modification to be introduced from machine number X 29 382 309
Remarks
1) Original version of part no longer available from factory
2) Original version of part remains available for older machines
3) New version of part is not available as separate item
4) Original version of part will be supplied from factory only as long as existing stocks last Page 6 of 7
Technical Information 16.94 - Page 6
5. Filler cap
The cord (1) of the cap retainer will be clipped
directly to an eye in the tank housing from machine
number X 28 030 485. The hook (2) is no longer
installed on the production line.
Suitable eyes are provided in the fuel and oil tanks.
The part number remains as before
Service note
A filler cap with hook will continue to be supplied
for replacement purposes.
• The
hook has to be removed before fitting the
filler cap in a crankcase with eyes.
6. Rewind starter
6.1 Rewind spring fo
The spring housing was deleted in January 1994.
The rewind spring is now supplied in a sheetmetal
holder which can be scrapped after the spring is
installed. The part number of the rewind spring
remains unchanged.
Benefits:
• Lower
weight compared to spring housing
• Spring
housing deleted - one less part to wear
• Improved service friendliness
6.2 Starter post
The tightening torque of the starter post in the fan
housing has been increased from 9.5 Nm to
11.5 Nm (7.0 lbf.ft to 8.5 lbf.ft). Page 7 of 7
Technical Information 16.94 - Page 7
6.3 Summary
Part Name Original New Key Rem. MOQ
version version H
Fan housing with rewind starter; 1128 080 2104 1128 080 2104 1)
including:
Rewind spring 1128 190 0600 1129 190 0600 1) 1
Modification to be introduced: in progress
Remarks
1) Unmodified version of part will be supplied until existing factory stocks are exhausted
7. Cylinder gasket
In the interests of further standardizing parts the
original cylinder gasket 1128 029 2300 will be
replaced by the gasket 1128 029 2301 that was
introduced with the automatic choke.
Left: Original cylinder gasket
Right: New cylinder gasket
Summary
Part Name Original New Key Rem. MOQ
version version H
Cylinder gasket 1128 029 2300 1128 029 2301 1) 1
Modification to be introduced: in progress
Remarks
1) Original version of part no longer available from factory
Last Technical Information on model 044 : 54.92
Waiblingen, March 21, 1994 Andreas Stihl
D1/MTK-st Technical Documentation 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.