Technical Information · issue 46 of 1995
New chainsaw
IssueTI 46/1995
Engine family 1128
Full text
Page 1 of 12
Technical Information
46.95
New STIHL 046 Chainsaws - Series 1128
The STIHL 046 is a new high-performance profes- The new lightweight flywheel with polymer fan and
sional chainsaw. It has been developed on the small, low weight high-power magnets increases
basis of the STIHL 044. cooling air throughput by 30 %. Its lower weight
also improves engine acceleration from idle to
maximum speed and enhances operator control of
The engine delivers ample power and high torque the saw.
at relatively low revs and is characterized by
outstanding reliability and a long service life.
The decompression valve releases the compres-
sion in the combustion chamber during starts and
A new longlife air filter system with easily changed thus reduces the effort required to pull the starter
filter elements and optimized sealing helps reduce rope. This helps minimize physical effort during
maintenance and increases operational reliability. starts and greatly improves operator comfort.
)Technical Information 46.95 - Page 2
&RQWHQWV
1. Technical Description
2. Specifications
3. Special Accessories for User
4. Service Accessories
5. Repairs
6. Spare Parts
1.=Technical Description
Comparisons made in this chapter describe the
differences between the STIHL 046 and STIHL
044.
1.1=====Air Filter System
The new air filter system is characterized by
excellent filtering efficiency, long periods between
cleanings and ease of maintenance. Cleaning is
necessary only when there is a noticeable drop in
engine power. No tools are required to remove the
filter element.
Carburetor box cover, filter element and filter base
are pulled together when the carburetor box
cover’s mounting screw is tightened.
The peripheral sealing lips on the filter element
provide a seal against dirt and dust.
The STIHL 046 can be adapted to suit different
operating conditions by installing different filter
145TI002 SC
elements. Conversions are simple and require
no tools:
• Remove the carburetor box cover.
• Change the filter element.
• Refit the carburetor box cover.
The following filter elements are available:
1.1.1====Mesh Filter
Green, with mesh for snow conditions and winter 1
operation. 2
1.1.2=HD Filter
Black, for dry and very dusty operating sites.
145TI003 SC
The filter element is protected from coarse dirt
by a dry felt prefilter (1).
Left: Mesh filter
Right: HD filter
)Technical Information 46.95 - Page 3
The fabric of the HD filter element (2) must be
impregnated with STIHL HD filter oil before it is
used for the first time. Filter efficiency is severely
impaired in the dry condition. The saw comes with a
100 ml (3.5 fl.oz) bottle of filter oil.
In order to avoid the risk of icing up, the HD filter
should be replaced by a mesh filter in winter
operating conditions.
1.2====Compensator
The compensator keeps the fuel/air mixture con-
stant at all times, irrespective of how dirty the air
filter is. It is not necessary to change the setting of
the high speed screw as contamination of the air 1
filter builds up. This system greatly extends the
intervals between cleanings.
For detailed description of compensator see
TI 07.91 (STIHL 066).
145TI004 SC
1.3====Intake Air Flow
The flow of intake air has been optimized by the 2
new flange (1) and the baffle (2). This results in
improved volumetric efficiency and higher torque.
1
145TI005 SC
1.4====Engine
The crankshaft has a wider big-end bearing to
suit the higher engine power output of 4.4 kW
(5.9 bhp). The crankcase has been strengthened.
1.5==== Cooling
Cylinder cooling surface area has been increased
by 10%. The volume of cooling air has been
upped approx. 30% as a result of the new light-
weight flywheel.
Control of cooling air flow has been improved by
a modified shroud and an additional plate in the
outlet area.
)Technical Information 46.95 - Page 4
1.6=Decompression Valve
1.6.1= Construction
3
The main components of the decompression valve
are the body (1) and plunger (2). 1
The plunger (2) moves axially in the valve body.
The bottom end of the plunger is cone-shaped.
Three spring-loaded balls (3), hold the plunger (2) in 2
137TI006 KN
its upper or lower position. The complete valve is
screwed into the cylinder.
1.6.2=Function
Before starting, the plunger (2) is pushed into its
lower position. The cone moves away from the 3
body (1), the decompression valve is open. 1
The crankshaft is rotated via the rewind starter.
The upward stroke of the piston causes the 2
mixture in the cylinder to be compressed. A small fo
137TI007 KN
amount of the mixture in the cylinder is pushed out
through the bore in the valve body (see arrow).
The remaining mixture in the cylinder is com-
pressed. Only after the mixture is ignited does the
pressure in the cylinder exceed the decompression
valve’s closing pressure.
The plunger (2) is then pushed upwards and the
cone closes the bore.
The shroud now has an opening to accommodate
the decompression valve.
The area around the opening is raised (see
arrow) to protect the decompression valve from
accidental contact.
A cover 1122 084 1405 is fitted between the
cylinder and shroud to help prevent entry of dust
and dirt.
145TI006 SC
)Technical Information 46.95 - Page 5
1.7= Tank Vent
The STIHL 046 is equipped with an optimized fuel
tank vent valve.
3
2
1
145TI007 SC
Air enters the fuel tank when there is a slight
vacuum of approx. 0.05 bar (0.725 psi), and is
expelled from the tank when pressure reaches
approx. 0.1 bar (1.45 psi). 3 2
Equalization of pressure is controlled via the cap
(3), sintered filter (2) and the valve (2).
The cap protects the sintered filter from surface
icing and ensures good air circulation (see arrow)
145TI008 KN
in a low-dust zone of the carburetor box. 1
The sintered filter helps prevent contamination
entering the valve.
Top right: Air out
Bottom right: Air in
1.8===Antivibration System
The rubber buffers of the STIHL 046 have been
designed to reduce vibrations.
1.9===Lightweight Flywheel
The new lightweight flywheel consists of
1 Steel hub
2 Polymer fan
3 High-power magnets
4 Magnesium bushing for pawl of
rewind starter
2
Using a composite method of construction it was
possible to reduce component weight by
approx. 30 % and increase cooling air throughput 1
by 30 %. An aluminium flywheel with the same
cooling air capacity would weigh almost twice as
4
much as the lightweight flywheel.
3
The lower mass of the lightweight flywheel
allows faster engine acceleration and simplifies
control of the saw.
145TI009 KN
1.10=Cutting Attachment
The STIHL 046 can be equipped with the same
cutting attachments as the STIHL 044.
)Technical Information 46.95 - Page 6
1.11=Crankcase/Cylinder Assembly
This assembly uses 6 mm mounting screws and a
sheet steel cylinder gasket.
See also service note.
2.=====Specifications
2.1====Engine
STIHL single-cylinder two-stroke engine with special impregnated cylinder bore
Displacement: 76.5 cm3 (4.67 cu.in)
Bore: 52 mm (2.05 in)
Stroke: 36 mm (1.42 in)
Compression ratio: 9.6 : 1
Engine power: 4.4 kW (5.9 bhp) at 9,500 rpm
Max. torque: 4.8 Nm (3.54 lb.ft) at 6,500 rpm
Max. permissible engine speed
with Rollomatic bar and chain 13,500 rpm
Mean idle speed: 2,500 rpm
Crankshaft:
Main bearings:
Three-part, drop forged
Two deep-groove ball bearings
Big end bearing: Needle cage
Connecting rod length: 62 mm (2.44 in)
Piston pin diameter: 12 mm (0.47 in)
Small end bearing: Needle cage
Clutch: Centrifugal clutch without linings
Diameter: 76 mm (3.0 in)
Clutch engages at: approx. 3,500 rpm
Rewind starter: Pawl engagement with automatic starter rope rewind mechanism,
ElastoStart
Starter rope diameter: 3.5 mm (0.14 in)
2.2====Fuel System
Carburetor: All position diaphragm carburetor with integral fuel pump
Standard setting;
- High speed screw H: Open 1 turn
- Low speed screw L: Open 1 turn
Fuel tank capacity: 0.94 l (2 US pt)
Fuel mixture: Regular brand-name gasoline and two-stroke engine oil
Octane number: min. pump octane 89 unleaded
Mix ratio: 50:1 with STIHL 50:1 two-stroke engine oil
25:1 with other brand-name two-stroke, air-cooled engine oils
Compensator: Allows constant pressure at clean air side of air filter and metering
diaphraghm, irrespective of degree of filter contamination
Air filters
- Mesh filter Wire mesh for winter operation
- HD filter For dry, very dusty operating sites
2.3====Ignition System
Type: Electronic magneto ignition (breakerless)
Flywheel: Lightweight polymer flywheel with steel hub and
magnesium bushing for pawl engagement
Air gap: 0.15 - 0.30 mm (0.006-0.012 in)
Ignition timing: 2.0 - 3.0 mm (0.080-0.12 in) B.T.D.C.
)Technical Information 46.95 - Page 7
Spark plug (suppressed): Bosch WSR 6 F
Electrode gap: 0.5 mm (0.020 in)
Spark plug thread: M14 x 1.25
Length of thread: 9.5 mm (0.37 in)
Heat range: 200
2.4===Weights
Powerhead without cutting
attachment: 6.5 kg (14.3 lb)
Power to weight ratio 2.55 lbs/bhp
3.====Special Accessories for User
STIHL repair kit 046 1128 900 5001
3/8", 7-tooth rim sprocket kit*1128 007 1000
3/8", 8-tooth rim sprocket kit 1128 007 1001
3/8", 7-tooth spur sprocket* 1128 640 2000
3/8", 8-tooth spur sprocket 1128 640 2005
Chain scabbard extension 0000 792 9132
*) Part may be standard equipment in some
markets
4.====Service Accessories
4.1===Special Servicing Tools
Part Name Part No. Application Rem.
Locking strip 0000 893 5903 Blocking the crankshaft
Sealing plate 0000 855 8106 Sealing exhaust port for
leakage test
Wooden assembly block 1108 893 4800 Fitting piston
Clamping strap 0000 893 2600 Compressing piston rings
Test flange 1128 850 4200 Leakage test
- Sleeves 0000 963 1008
)Technical Information 46.95 - Page 8
Part Name Part No. Application Rem.
Carburetor and 1106 850 2905 Testing carburetor and
crankcase tester crankcase for leaks
Vacuum pump 0000 850 3501 Testing crankcase for
leaks
- Nipple 0000 855 9200
- Fuel line 1110 141 8600
Plug 1122 025 2200 Replaces decompression valve for
pressure test
Puller 0000 890 4400 Removing oil seals
- Jaws (No. 3.1) 0000 893 3706
- Jaws (No. 1) 0000 893 3700
Press sleeve 1115 893 4600 Installing oil seal (starter side)
Press sleeve 1118 893 4602 Installing oil seal (clutch side)
Guide 1123 894 7700 Protecting oil seal at
starter side
Assembly drift 1111 893 4700 Fitting piston pin
Installing tool 12 5910 890 2212 Fitting hookless snap rings in piston
Assembly tube 1117 890 0900 Attaching brake spring
Stud puller M8 5910 893 0501 Removing bar mounting studs
Setting gauge 1111 890 6400 Setting air gap between
Assembly tool 1116 893 4800
ignition module and flywheel
Installing rewind spring
Assembly hook 5910 893 8800 Removing fuel pickup body
Assembly stand 5910 890 3100 Holding saw for repairs
- Clamping bar 5910 890 2005 Mounting saw to assembly stand
Assembly tube 1117 890 0900 Attaching clutch springs
Service tool AS 5910 007 2205 Removing crankshaft (clutch side)
- Screw sleeve 5910 893 2420 Installing crankshaft
Service tool ZS 5910 007 2220 Removing crankshaft (starter side)
- Screw sleeve 5910 893 2409 Pulling crankcase halves together
Torque wrench 5910 890 0301 0.5 to 18 Nm (0.325 to 13.5 lbf.ft) 1)
5910 890 0302 2)
Torque wrench 5910 890 0311 6 to 80 Nm (4.5 to 60 lbf.ft) 1)
5910 890 0312 2)
T-handle screwdriver 5910 890 2400 For all IS screws 3)
QI-T27x150
Crimping tool 5910 890 8210 Attaching connectors to electrical wires
Puller 1110 893 4500 Removing flywheel
Socket, 13 mm 5910 893 5608 Flywheel nut
Socket, 19 mm 5910 893 5613 Clutch
Screwdriver T 27x125 0812 542 2104 IS screws
Press arbor 1118 893 7200 Installing ball bearing at clutch side
Press arbor 1120 893 7200 Installing ball bearing at starter side
Pliers A 19 DIN 5254 0811 611 8380 Retaining ring on crankshaft
5HPDUNV
1) Always use torque wrench to tighten Plastoform screws
2) Wrench has optical/acoustic signal
3) On Plastoform screws, use for releasing only
)Technical Information 46.95 - Page
4.2====Servicing Aids
Part Name Part No. Application
Lubricating grease 0781 120 1111 Oil seals, oil pump drive,
chain sprocket bearing
Cleaning crankshaft stub
STIHL special lubricant 0781 417 1315 Bearing bore in rope rotor,
rewind spring in starter cover
Electrician’s repair kit 0000 007 1013
STIHL multipurpose grease 0781 120 1109 High voltage output on ignition module
Medium-strength threadlocking, Securing screws
(Loctite 242)
High-strength threadlocking, Securing screws
(Loctite 270)
High-strength threadlocking, Securing screws
(Loctite 649)
Gasket panel 044/046 0457 281 1704
5.=Repairs
If the saw is started up in the course of repairs or
maintenance work, always observe all local
regulations and the safety precautions outlined in
the owner’s manual.
5.1====Service Notes
5.1.1=Use locking strip only when
======decompression valve is closed
Locking strip 0000 893 5903 (for blocking crank-
shaft) must not be inserted in the spark plug hole
until the decompression valve is
closed. If the decompression valve is open,
it may be bent by the force of the piston and
locking strip.
)Technical Information 46.95 - Page 10
5.1.2=Removing the Cylinder
In order to avoid the risk of damage to the
piston (i.e. piston snagging on edge of gasket),
use a knife to separate the gasket from the base of
the cylinder before taking the cylinder off the piston.
137TI002
5.1.3=HD Filter Assembly 0000 120 1650
The HD filter used in the STIHL 046 has already
been introduced on the STIHL 044 (TI 20.95),
STIHL 066 (TI 10.95) and STIHL 084 (TI 18.95).
Foam element 1124 124 0804 is necessary for the
use of the HD filter on these models.
This foam element is not required in the STIHL
046. However, it remains in the scope of supply for
reasons of interchangeability. An instruction sheet
describes how the filter element is used in the indi-
vidual models.
5.1.4=Leakage Test
Plug 1122 025 2200 must be installed in place of
the decompression valve before carrying out the
leakage test (see service manual).
The decompression valve can be removed and
installed with a standard commercial deep well
13-mm socket.
Tightening torque 14 Nm (10.3 lbf.ft).
5.2===Test Data
5.2.1=Leakage Test
5.2.1.1
Pressure test 0.4 bar (5.8 psi)
Vacuum test 0.4 bar (5.8 psi)
5.2.1.2
Pressure test: 0.4 bar (5.8 psi)
)Technical Information 46.95 - Page 11
5.3=====Tightening Torques
Fastener Thread For component Torque lbf.ft Rem.
size Nm
Screw B 2.9 x 9,5 Switch housing 1.0 0.75
Screw B 3.9 x 19 Handle molding 1.6 1.2
Spline screw IS-M4x12 Generator 3.5 2.6 1)
Spline screw IS-M4 x 8 Chain tensioner cover plate 3.0 2.2
Spline screw IS-M4x12 Cover on oil pump,
sprocket side 3.0 2.2
Spline screw IS-M4x12 Brake band/crankcase 3.0 2.2 2)
Spline screw IS-M4x12 Oil pump 3.5 2.6
Spline screw IS-M4x12 Segment/fan housing 2.5 1.8
Spline screw IS-M4x12 Cover on crankcase,
sprocket side 3.0 2.2
Spline screw IS M4 x 16 Buffer/crankcase 5.0 3.7 2)
Collar nut M5 SK6 Carburetor, filter base, flange 6.0 4.4 3)
Spline screw IS-M5 x 6 Muffler (top) 6.5 4.8 2)
Spline screw IS-M5 x 12 Spiked bumper (top, with nut) 7.5 5.5
Spline screw IS-M5 x 16 Spiked bumper (bottom,
chain catcher) 7.5 5.5
Spline screw IS-M5 x 16 Muffler/cylinder 11.5 8.5 2)
Spline screw
Spline screw
IS-M5 x 16
IS-M5 x 20
Shroud/crankcase
Wrap-around handle with bracket
7.0
7.0
5.2
5.2
Spline screw IS-M5 x 20 Crankcase 11.5 8.5
Spline screw IS-M5 x 20 Fan housing 7.0 5.2
Spline screw IS-M5 x 20 Ignition module/crankcase 7.0 5.2 2), 4)
Spline screw IS-M5 x 30 Hand guard, left 7.0 5.2
Spline screw IS-M5 x 30 Muffler, top (Kat) 6.5 4.8 2)
Spline screw IS-M6 x 18 Muffler/cylinder (Kat) 15.0 11.0 2)
Spline screw IS-M6 x 18 Muffler/crankcase 15.0 11.0
Spline screw IS-M6 x 25 Cylinder/crankcase 15.0 11.0
Nut M 8x1 Flywheel 32.5 24.0
Collar nut M8 x 21.5 For guide bar 23.0 17.0 2)
M10 x 1 Decompression valve in cylinder 14.0 10.3
Carrier M12 x 1 L Clutch 50.0 37.0
M14 x 1.25 Spark plug 25.0 18.5
Spline screw IS-P6 x 19 Front handle, top/bottom 8.0 5.9 1)
Spline screw IS-P6 x 19 Buffer/tank housing, front 5.5 4.0
Spline screw IS-P6 x 19 Buffer/tank housing, rear 5.5 4.0
Spline screw IS-P6 x 32,5 Buffer/tank housing, rear left 5.5 4.0
Nut (self-locking) M5 Spiked bumper 7.5 5.5
Nut (self-locking) M5 Chain catcher/spiked bumper 6.0 4.4
5HPDUNV
1) Screw must be secured with LOCTITE 649
2) Screw must be secured with LOCTITE 242
3) Screw must be secured with LOCTITE 270
4) A washer must be fitted under the screw head
)Technical Information 46.95 - Page 12
Use the following procedure when refitting a
Plastoform screw in an existing thread:
• Place the screw in the hole and rotate it
counterclockwise until it drops down slightly.
• Tighten the screw clockwise to the specified
torque.
This procedure ensures that the screw engages
properly in the existing thread and does not form
a new thread.
1RWH
Screws secured with adhesive (Loctite) are easier
to release if they are heated with a hot air blower
(hair dryer).
Take care on polymer components.
5.4=Repair Times
The repair times for the STIHL 044 also apply to the
STIHL 046.
6.=Spare Parts
The clutch, rewind starter and chain brake have
been taken from the STIHL 044. All other parts
have been revised and are available as new spare
parts. See illustrated parts list.
Waiblingen, September 5, 1995 Andreas Stihl - D1/MTK-st
1995 Andreas Stihl Technical Documentation Page 2 of 12
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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.