STIHL 029, 039 User manual

STIHL 029, 039 1

STIHl

STIHlSTIHl

STIHl

Service Manual

029 and 039

Chain Saws

As the design concept of these two

models is almost identical, the

descriptions and servicing pro-

cedures in this manual generally

apply to both. Differences are

described in detail.

You should make use of the

illustrated parts lists while carrying

out repair work. They show the

installed positions of the individual

components and assemblies.

Microfilmed parts list are always

more up to date than printed lists.

A fault on the machine may have

several causes. Consult the

"Troubleshooting Charts" when

tracing faults.

Refer to the "Technical Informa-

tion" bulletins for engineering

changes which have been intro-

duced since publication of this

service manual.

Service manuals and technical

information bulletins describing

engineering changes are intended

exclusively for the use of STIHL

servicing dealers and staff and

must not be passed on to third

parties.

Chain saw on assembly stand

The STIHL Special Tools manual

lists all special servicing tools

currently available from STIHL.

Always use original STIHL

replacement parts.

Original STIHL parts can be

identified by the STIHL part

number, the

STIHl

STIHlSTIHl

STIHl

logo and

the STIHL parts symbol

(

The

symbol may appear alone on small

parts.

Servicing and repairs are made

considerably easier if the saw is

mounted on assembly stand 5910

850 3100 or 5910 890 3100. This

enables the saw to be swivelled to

the best position for the ongoing

repair and leaves both hands free.

The saw can be quickly secured to

the stand by means of the bar

mounting studs and nuts (after

removing the sprocket cover).

STIHL 029, 039 2

CONTENTS

1. Specifications 35. Ignition System 37 11. Fuel System 58

1.1 Engine 3 5.1 Repairing Component 11.1 Air Filter 58

1.2 Fuel System 4 Parts 37 11.2 Removing and Installing

1.3 Ignition System 4 5.1.1 Spark Plug 37 the Carburetor 59

1.4 Cutting Attachment 5 5.1.2 Ignition Module 39 11.3 Leakage Testing

1.5 Special Accessories 5 5.1.2.1 Ignition Timing 39 the Carburetor 60

1.5.1 For User 5 5.1.2.2 Removing and Installing 39 11.4 Servicing the

1.5.2 For Service 5 5.1.3 Spark Plug Terminal 41 Carburetor 60

1.6 Tightening Torques 6 5.1.4 Ignition Lead 42 11.5 Carburetor Adjustment 66

5.1.5 Flywheel 42 11.6 Automatic Choke 68

2. Troubleshooting 5.1.6 Short Circuit Wire/ 11.6.1 Description of Operation 68

Charts 7 Ground Wire 44 11.6.2 Troubleshooting Chart 69

5.1.7 Contact Spring 44 11.6.3 Testing Automatic

2.1 Clutch, Chain Drive, Choke 70

Chain Brake and 6. Rewind Starter 45 11.6.4 Leakage Testing

Chain Tensioner 7 Engine Housing

2.2 Engine 8 6.1 Routine Maintenance 45 and Control Valve 70

2.3 Ignition System 9 6.2 Rope Rotor/Pawl 45 11.6.5 Testing Control Valve

2.4 Rewind Starter 10 6.3 Replacing the (removed from machine) 71

2.5 Chain Lubrication 11 Starter Rope 46 11.6.6 Leakage Testing

2.6 Fuel System 12 6.4 Replacing the the Bellows 72

Rewind Spring 47 11.6.7 Foam Filter/

3. Clutch, Chain Drive, 6.5 Tensioning the Polymer Sintered Filter 72

Chain Brake and Rewind Spring 47 11.6.8 Removing and Installing

Chain Tensioner 14 6.6 Replacing Starter the Carburetor 73

Rope Guide Bush 48 11.6.9 Removing and Installing

3.1 Clutch Drum and Lever System on

Chain Sprocket 14 7. AV Handle System 49 Carburetor 73

3.2 Clutch 15 11.6.10 Throttle Shaft/

3.3 Chain Brake 17 7.1 Repair 49 Choke Shaft 76

3.3.1 Disassembly 17 11.6.11 Hose/Connector 77

3.3.2 Assembly 19 11.6.12 Control Valve 77

3.4 Front Chain 8. Handle Housing 50 11.6.13 Bellows 78

Tensioner 21 11.7 Tank Vent 79

3.5 Side Chain 8.1 Front Handle 50 11.8 Fuel Pickup Body and

Tensioner 21 8.1.1 Removing and Installing Fuel Hose 79

3.6 Bar Mounting Studs 22 Handle Housing 50 11.9 Replacing the

FuelTank 80

4. Engine 23 9. Master Control 53

12. Special Servicing 82

4.1 Removing and Refitting 9.1 Switch Shaft 53 Tools and Aids

Exhaust Muffler 23 9.2 Interlock Lever/

4.2 Leakage Testing Throttle Trigger 54 12.1 Special Servicing Tools 82

the Engine 24 12.2 Servicing Aids 83

4.2.1 Preparations 24 10. Chain Lubrication 55

4.2.2 Pressure Test 25

4.2.3 Vacuum Test 26 10.1 Suction Hose/

4.3 Replacing the Pickup Body 55

Oil Seals 27 10.2 Vent Valve 56

4.4 Removing and Installing 10.3 Removing and Installing

the Engine 29 the Oil Pump 56

4.5 Cylinder 30 10.4 Servicing the

4.6 Piston 33 Oil Pump 57

4.7 Piston Rings 35

4.8 Crankshaft 36

STIHL 029, 039 3

1. SPECIFICATIONS

1.1 Engine 029 039

STIHL single-cylinder two-stroke engine with special

impregnated cylinder bore

Displacement: 54.1 cm

3

(3.3 cu.in) 64.1 cm

3

(3.9 cu. in)

Bore: 45 mm (1.77 in) 49 mm (1.93 in)

Stroke: 34 mm (1.34 in) 34 mm (1.34 in)

Compression ratio: 9.5:1 10:1

Power output: 2.70 kW (3.7 bhp) 3.20 kW (4.4 bhp)

Max. torque: 2.8 Nm (2.1 lb. ft) 3.4 Nm (2.5 Ib. ft)

at 6,500 r.p.m. at 6,500 r.p.m.

Max. permissible engine

speed with bar and chain: 13,000 r.p.m. 13,000 r.p.m.

Mean idle speed: 2,700 r.p.m. 2,700 r.p.m.

Crankshaft: Three-part, Three-part,

drop forged drop forged

Crankshaft bearings: 2 ball bearings 2 ball bearings

Crankpin dia.: 14.4 mm (0.55 in) 14.4 mm (0.55 in)

Big-end bearing: Needle cage Needle cage

Conrod length: 58 mm (2.28 in) 58 mm (2.28 in)

Piston pin diameter: 10 mm (0.39 in) 10 mm (0.39 in)

Small-end bearing: Needle cage Needle cage

Rewind starter: Pawl system with Pawl system with

automatic rope automatic rope

rewind mechanism rewind mechanism

Starter rope: 3.5 mm (0.14 in) dia., 3.5 mm (0.14 in) dia.,

960 mm (37.8 in) long 960 mm (37.8 in) long

Clutch: Centrifugal clutch Centrifugal clutch

without linings, without linings,

76 mm (3.0 in) dia. 76 mm (3.0 in) dia.

Clutch engages at: approx. 3,500 r.p.m. approx. 3,500 r.p.m.

Crankcage leakage test

at gauge pressure: 0.4 bar (5.8 psi) 0.4 bar (5.8 psi)

under vacuum: 0.4 bar (5.8 psi) 0.4 bar (5.8 psi)

STIHL 029, 039 4

1.2 Fuel System 029 / 039

Carburetor: All position diaphragm

carburetor with integral fuel

pump

Standard setting

High speed adjusting screw H: Back off approx. 1 turn

Low speed adjusting screw L: Back off approx. 1 turn

(starting with screws tight

against their seats)

Carburetor leakage test

at gauge pressure: 0.4 bar (5.8 psi)

Fuel tank capacity: 0.56 L (1 .2 US pt)

Fuel mixture: Regular brand-name gasoline

and brand-name two-stroke

engine oil

Mix ratio: 50:1 with Stihl two-stroke

engine oil

25:1 with other brand-name

two-stroke brand-name,

air-cooled engine oils

Air filter: Prefilter (coarse filter)

bisectional box filter

1.3 Ignition System

Type: Electronic magneto ignition

(breakerless) with integral

trigger unit

Air gap: 0.15-0.3 mm (0.006-0.012 in)

Ignition timing: 2.0-2.8 mm (0.08-0.10 in) B.T.D.C.

at 8,000 r.p.m.

Advance angle: 24.5-29.5° B.T.D.C.

at 8,000 r.p.m.

Spark plug (suppressed): Bosch WSR 6 F or

NGK BPMR 7 A

Electrode gap: 0.5 mm (0.020 in)

Spark plug thread: M14x1.25

Length of thread: 9.5 mm (0.37 in)

Heat range: 200

STIHL 029, 039 5

1.4 Cutting Attachment

Guide bars: Rollomatic with sprocket nose

Duromatic with stellite-tipped nose

Bar tail: 3003

Bar lengths: (32, 37, 40, 45, 50 and 63 cm)

(13, 15, 16, 18 and 25 in)

Oilomatic chain: 9.32 mm (3/8") Rapid-Micro,

Rapid-Super

8.25 mm (0.325") Rapid-Micro,

Rapid-Super

Chain sprockets: 7-tooth 3/8" spur sprocket

7-tooth 0.325" spur sprocket

7-tooth 0.325" rim sprocket

8-tooth 0.325" rim sprocket

Chain speed: 21.7 m/s (71 ft/s) at 10,000 r.p.m.

Chain lubrication: Fully automatic, speed-controlled

reciprocating oil pump, no feed at

idle speed. Additional manual oil flow

control

Oil feed rate (adjustable): 6-15 cm³/min (0.2 - 0.5 fl.oz/min)

at 10,000 r.p.m.

Oil tank capacity: 0.33 L (0.7 US pt)

1.5 Special Accessories

1.5.1 For user STIHL repair kit 1127 900 5000

Starter rope ∅ 3.5x30.5 m 0000 930 2203

7-tooth 3/8" rim sprocket kit 1125 007 1002

7-tooth 0.325" rim sprocket kit 1125 007 1001

8-tooth 0.325" rim sprocket kit 1125 007 1000

7-tooth 3/8" spur sprocket 1125 640 2000

7-tooth 0.325" spur sprocket 1125 640 2005

Spur gear/tensioning screw kit 1127 007 1003

Elastostart 1128 190 3400

1.5.2 For service shop Carburetor parts kit (Walbro) 1127 007 1060

Carburetor parts kit

(automatic choke) 1127 007 1061

STIHL 029, 039 6

1.6 Tightening Torques

"DG" screws are used in the polymer and light-alloy components of models 029 and 039. When screwed in for the

first time, DG screws form a permanent thread in the parts concerned. They can be released and retightened as often

as necessary without affecting the strength of the screwed assembly. However, it is essential to always use a torque

wrench to tighten the screws to the specified torques.

Fastener Thread For component Torque Remarks

size Nm (Ibf.ft)

Spline screw IS-DG4x15 Chain tensioner cover/

engine housing 3.2 (2.4)

Spline screw IS-DG4x15 Chain brake cover/

engine housing 3.2 (2.4)

Spline screw IS-DG4x15 Handle housing/handle molding 1.6 (1.2)

Spline screw IS-DG4x15 Oil pump 4.0 (3.0)

Spline screw IS-DG4x15 Shroud/engine housing 3.2 (2.4)

Spline screw IS-DG4x15 Ground wire to cylinder 4.0 (3.0)

Spline screw IS-DG5x16 Chain catcher/engine housing 3.5 (2.6)

Spline screw IS-DG5x16 Spiked bumper/engine housing 3.5 (2.6)

Spline screw IS-DG5x24 Front handle/handle housing 3.5 (2.6)

Spline screw IS-DG5x24 Hand guard (I/h) with sleeve 3.5 (2.6)

Spline screw IS-DG5x24 Fan housing/engine housing 3.5 (2.6)

Spline screw IS-DG5x24 Buffer/front handle 3.5 (2.6)

Spline screw IS-DG5x24 Buffer/engine housing 3.5 (2.6)

Spline screw IS-DG5x24 Ignition module/engine housing 4.8 (3.5)

Spline screw IS-DG6x52 Engine housing/cylinder 11.0 (8.1)

M12x1L Carrier (clutch) 50.0 (37.0)

Collar stud DG8x24 Guide bar 16.0 (11.8)

Collar stud M10x21 Guide bar/engine pan 30.0 (22.0) 1)

M14x1.25 Spark plug 25.0 (18.5)

Hexagon nut M5 Muffler 9.0 (6.6)

Hexagon nut M5 Box filter/carburetor 2.0 (1.5)

Hexagon nut M5 Carburetor with box filter 3.2 (2.4)

Hexagon nut M8x1 Flywheel 27.5 (20.3)

Use the following procedure to fit a DG screw in an existing thread:

- Place the DG 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.

Remarks:

1) Screw must be secured with adhesive 0786 110 0126 (Loctite 649).

Note: Screws secured with adhesive are easier to release if the adhesive is heated first with a hot air blower (hair

dryer). Exercise caution on polymer components.

STIHL 029, 039 7

Condition Cause Remedy

Saw chain turns at idle speed Engine idle speed too high Readjust at idle speed

adjusting screw

(counterclockwise)

Spring hooks broken Fit new springs

Loud noises Clutch springs stretched or Replace all clutch springs

fatigued

Needle cage damaged Fit new needle cage

Clutch shoe retainer broken Fit new retainer

Clutch shoes and carrier Fit new clutch

worn

Chain sprocket wears Chain not properly Tension chain as specified

rapidly tensioned

Chain wears rapidly Chain not properly Tension chain as specified

tensioned

Poor chain lubrication Check chain lubrication and

rectify problem

Worn chain sprocket Fit new sprocket

Chain does not stop Brake spring broken Fit new brake spring

immediately when brake is

activated Brake band stretched or Fit new brake band

broken

2. TROUBLESHOOTING

CHARTS

2.1 Clutch,

Chain Drive,

Chain Brake and

Chain Tensioner

STIHL 029, 039 8

2.2 Engine

Always check and, if necessary, repair the following parts before looking for faults on the engine:

- Air filter

- Fuel system

- Carburetor

- Ignition system

Condition Cause Remedy

Engine does not start easily, Oil seals between cylinder Replace oil seals

stalls at idle speed, but operates and engine pan damaged

normally at full throttle

Manifold leaking Seal or replace manifold

Engine pan leaking Seal engine pan

Engine pan damaged (cracks) Replace engine pan

Engine does not deliver full Secondary air seepage through Mount manifold correctly or

power or runs erratically poorly mounted or faulty replace

manifold

Piston rings leaking or Fit new piston rings

broken

Muffler carbonized Clean muffler (inlet

and exhaust), replace spark

arresting screen (if fitted)

Engine overheating Insufficient cylinder Thoroughly clean all cooling

cooling. Air inlets in fan air openings

housing blocked or cooling fins

on cylinder very dirty

Intake air preheating being Move shutter to

used at too high an outside summer position

temperature

STIHL 029, 039 9

2.3 Ignition System

Warning: Exercise extreme caution while carrying out maintenance and repair work on the ignition system.

The high voltages which occur can cause serious or fatal accidents!

Ignition system in order.

Look for fault in fuel system and

carburetor.

yes

Replace ignition module. Does engine

now run after positive spark test?

Fit new flywheel.

Is spark test positive?

Use ohmmeter to check ignition lead

for break. If break is detected, replace

ignition lead. Does spark test now

produce sparkover?

Does flywheel appear to be

in good condition?

Fit new spark plug.Is air gap correct?

Adjust air gap (0.15 - 0.3 mm).

Is spark test positive?

Insert screwdriver in place of spark plug in spark plug

terminal and hold about 4 mm (1/8") away from

ground. Sparkover?

Replace faulty ignition lead of short circuit wire.

Repair contact spring or switch shaft.

Faulty insulation on ignition

lead or short circuit wire?

Is connector sleeve touching short circuit

contact?

Clean spark plug and reset electrode gap.

Does spark test produce powerful spark?

Press terminal firmly onto spark

plug and fit spring if necessary.

Spark plug terminal firmly seated on spark plug?

Remove spark plug.

Is it in good condition?

no

yes

no

yes

no

yes

STIHL 029, 039 10

Condition Cause Remed

y

Starter rope broken Rope pulled out too vigorously as Fit new starter rope

far as stop or over edge - i.e.

not vertically

Normal wear Fit new starter rope

Rewind spring broken Spring overtensioned - Fit new rewind spring

no reserve when rope is fully

extended

Very dirty or corroded Fit new rewind spring

Starter rope can be pulled out Guide peg on pawl or pawl Fit new pawls

almost without resistance itself worn

(crankshaft does not turn)

Spring clip fatigued Fit new spring clip

Starter rope is difficult to Starter mechanism is very Thoroughly clean complete

pull and rewinds very slowly dirty (dusty conditions) starter mechanism

Lubricating oil on rewind spring Apply a few drops of kerosine

becomes viscous at very low (paraffin) to spring, then pull

outside temperatures (spring rope carefully several times

windings stick together) until normal action is

restored

2.4 Rewind Starter

STIHL 029, 039 11

Important: In the event of trouble with the chain lubrication system, always investigate the other possible sources

of faults before disassembling the oil pump.

Condition Cause Remedy

Chain receives no oil Oil tank empty Fill up with oil

Oil inlet hole in guide bar Clean oil inlet hole

is blocked

Intake hose or pickup body Wash intake hose and pickup

(strainer) clogged or intake body (strainer) in white spirit

hose ruptured and blow out with compressed air;

replace if necessary

Valve in oil tank blocked Clean or replace valve

Teeth on pump piston and/or Fit new oil pump and/or

worm worn new worm

Machine losing chain oil Bore in pump Fit new pump housing

housing worn

Oil pump delivers too Control screw and/or Fit new control screw and/or

little oil control edge on pump piston pump piston

worn

Bore in pump housing Fit new pump housing

worn

2.5 Chain Lubrication

STIHL 029, 039 12

Note: For machines with automatic choke see 11.6.2.

Condition Cause Remedy

Carburetor floods; Inlet needle not sealing. Remove and clean or replace

engine stalls Foreign matter in valve seat or inlet needle,

cone damaged clean fuel tank, pickup body and

fuel line if necessary

Inlet control lever sticking on Free off inlet control lever

spindle

Helical spring not located on Remove inlet control lever

nipple of inlet control lever and refit correctly

Perforated disc on diaphragm Fit new metering diaphragm

is deformed and presses constantly

against inlet control lever

Inlet control lever too high Set inlet control lever flush

(relative to design position) with bottom of metering chamber

Poor acceleration Idle jet "too lean" Back off low speed adjusting

screw slightly

(see Carburetor Adjustment)

Main jet "too lean" Back off high speed adjusting

screw slightly

(see Carburetor Adjustment)

Inlet control lever too low Set inlet control lever flush

(relative to design position) with bottom of metering chamber

Inlet needle sticking to valve Remove inlet needle, clean

seat and refit

Connecting bore to atmosphere Clean bore

blocked

Diaphragm gasket leaking Fit new diaphragm gasket

Metering diaphragm damaged Fit new metering diaphragm

or shrunk

Engine will not idle, Throttle shutter opened too wide Reset idle speed adjusting screw

idle speed too high by idle speed adjusting screw correctly

2.6 Fuel System

STIHL 029, 039 13

Condition Cause Remedy

Engine stalls at idle speed Idle jet bores or ports Clean jet bores and ports

blocked with compressed air

Idle jet "too rich" Screw down low speed adjusting

screw slightly

(see Carburetor Adjustment)

Setting of idle speed Set idle speed adjusting

adjusting screw incorrect screw correctly

- throttle shutter completely

closed

Small plastic plate in valve Clean or renew valve jet

jet does not close

Engine speed drops quickly under Air filter plugged Clean air filter

load - low power

Tank vent faulty Clean or replace tank vent

if necessary

Leak in fuel line between tank Seal or renew connections

and fuel pump and fuel line

Pump diaphragm damaged or Fit new pump diaphragm

fatigued

Main jet bores or ports Clean bores and ports

blocked

Fuel pickup body dirty Clean pickup body, fit new

filter

Fuel strainers dirty Clean fuel strainers

See also 2.2

STIHL 029, 039 14

3. CLUTCH, CHAIN DRIVE

CHAIN BRAKE AND

CHAIN TENSIONER

3.1 Clutch Drum and

Chain Sprocket

Top:

Removing needle cage

Bottom:

Assembly sequence of chain drive

1 = Spur sprocket

Top: Top: 2 = Needle cage

Sprocket cover mounting nuts Removing E-clip 3 = Washer

4 = E-clip

Bottom: Bottom: 5 = Clutch drum (for rim sprocket)

Disengaging chain brake Removing chain sprocket 6 = Rim sprocket

- Unscrew sprocket cover nuts - Remove the washer from the Note: Clean stub of crankshaft.

and remove the sprocket cover. clutch drum or chain sprocket. Replace the needle cage or wash

it in clean white spirit and lubricate

- Disengage the chain brake by - Remove the spur sprocket or rim with STIHL multipurpose grease,

pulling the hand guard back sprocket with clutch drum. see 12.2.

toward the front handle.

- Take the needle cage out of the Push clutch drum/chain sprocket

- Pry the E-clip off the crankshaft. clutch drum or chain sprocket. onto crankshaft and rotate it until

tang of spring on oil pump worm

Reassemble in the reverse engages the notch in the clutch

sequence. drum.

Important: Rim sprocket must be

fitted with the chip ejector cavities

facing outward.

STIHL 029, 039 15

3.2 Clutch

Top:

Removing prefilter Top: Top:

Locking strip 0000 893 5902 Unscrewing the clutch

Bottom:

1 = Spark plug terminal Bottom: Bottom:

2 = Spark plug Locking strip in position Assembly hook 5910 890 2800

Removing and disassembling - Push the locking strip into the - Remove the clutch drum or chain

clutch: spark plug hole so that "TOP" or sprocket, see 3.1.

"OBEN" is facing upward.

Troubleshooting chart - see 2.1. - Unscrew the clutch from the

Important: To avoid the risk of stub of the crankshaft.

- Remove air filter - see 11.1. piston damage, use only the

specified locking strip. Caution: Clutch has a left-hand

- Pull the prefilter out of the handle thread.

housing.

- Pull terminal off the spark plug.

Unscrew the spark plug.

STIHL 029, 039 16

Top:

Fitting retainer on

Top: clutch shoe Top:

Removing a clutch spring Clutch clamped in a vise

Bottom:

Bottom: Pushing clutch shoe Bottom:

Component parts of clutch onto carrier Attaching clutch springs

- Use assembly hook to remove all Assembling and installing - Clamp the clutch, e.g. one shoe,

the clutch springs. the clutch: in a vise.

- Pull the clutch shoes off the - Slip the retainers onto the clutch - Attach one end of each spring to

carrier. shoes so that the narrow side is the clutch shoes by hand.

next to the series number, e.g.

- Pull the retainers off the clutch 1127. - Use the assembly hook to attach

shoes. the other ends of the springs and

- Fit the clutch shoes over the press them firmly into the clutch

- Clean all parts and stub of arms of the clutch carrier so that shoes with one finger.

crankshaft in white spirit. the series number, e.g. 1127, is

Replace any damaged or worn on the same side as the carrier's

parts. hexagon.

STIHL 029, 039 17

Top: Top: Top:

Tightening the clutch Bumper strip Detaching brake spring

Bottom: Bottom: Bottom:

Fitting the prefilter Cover mounting screws Removing the brake band

- Screw clutch onto crankshaft - Remove the clutch drum or spur - Carefully remove the brake

and torque down to 50 Nm sprocket - see 3.1. spring from the anchor pin.

(37 Ibf.ft).

- Engage the chain brake. - Ease the brake band out of its

- Install clutch drum or spur seat in the engine housing.

sprocket - see 3.1 - Remove the upper bumper strip

from its seat.

- Remove locking strip from

cylinder. Install spark plug - Remove mounting screws from

and torque down to 25 Nm cover and lift cover away.

(18.5 Ibf.ft).

- Install the air filter - see 11.1.

- Fit the prefilter so that its tabs

engage the recesses in the

handle housing.

3.3 Chain Brake

3.3.1 Disassembly

STIHL 029, 039 18

Top:

Removing the Top:

brake band Top: Washer on pivot pin

E-clip on bell crank pivot pin

Bottom: Bottom:

Hand guard mounting Bottom: 1 = Hand guard

screw Removin

g

the link

(

stra

p)

2 = Bell crank

- Remove the brake band from the - Pry the E-clip off the bell crank - Remove washer from bell crank

retaining lug and disconnect it pivot pin. pivot pin.

from the bell crank.

- Remove the link (strap) from the - Carefully pull the hand guard and

- Take out the hand guard moun- bell crank pivot pin. bell crank off their pivot pins and

ting screw. lift them away together.

- Slide the link up and take it off

the hand guard pivot pin.

STIHL 029, 039 19

3.3.2

A

ssembly

Top:

1 = Spring Top:

2 = Cam lever Pressing cam lever

3 = E-clip downward

Bottom: Bottom:

Fitting bell crank in Correct installed position

Disconnecting the spring hand guard of hand guard

- Remove the E-clip from the cam

lever pivot pin.

- Disconnect spring from the cam

lever. Pull the cam lever off the

pivot pin.

- Remove the spring.

- Clean all disassembled parts in

white spirit. Replace any worn or

damaged parts.

- Push the cam lever onto the pivot - Position bearing boss of hand

pin and secure it with the E-clip. guard against the pivot pin and fit

the other side of the hand guard

- Attach the spring to the cam over the handle housing.

lever, from behind, and push it

over the pivot pin. - Press the cam lever downward

and push the hand guard and

- Insert the bell crank in the side of bell crank onto the pivot pins.

the hand guard so that the short

arm of the bell crank points up.

STIHL 029, 039 20

Top: Top:

Fitting the link Top: Assembly tube 1117 890 0900

Fitting the brake band

Bottom: Bottom:

Attaching brake band to bell Bottom: Attaching brake spring to

crank Attaching the brake spring anchor pin

- Fit the washer on the bell crank Important: Coat sliding and - Slip the bush over the hand

pivot pin. bearing points with Molykote guard mounting screw. Fit screw

grease - see 12.2. Do not and tighten to 3.5 Nm (2.6 Ibf.ft).

- Position the link on the hand lubricate the brake band.

guard pivot pin and slide it down - Fit cover for brake band.

until it engages the groove on the - Attach the brake spring to the

end of the pivot pin. Then push bell crank. - Fit bumper strip in its seat.

link over the bell crank pivot pin

and secure it with the E-clip. - Use the assembly tool and a - Install the clutch drum or chain

screwdriver to attach the brake sprocket - see 3.1.

- First attach brake band to bell spring to the anchor pin.

crank and then push it into the

engine housing recess.

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STIHL 029, 039 User manual

STIHL 029, 039 User manual

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