Stihl 034 Series, 036 Series, 036 QS Series User Manual

1034, 036, 036 QS

Contents

1 Introduction 2

2 Safety Precautions 3

3 Specifications 4

3.1 Engine 4

3.2 Fuel System 4

3.3 Ignition System 5

3.4 Cutting Attachment 5

3.5 Tightening Torques 6

3.6 Special Accessories 7

3.6.1 For User 7

3.6.2 For Service 7

4 Clutch, Chain Drive,

Chain Brake and Chain Tensioner 8

4.1 Clutch Drum and Chain Sprocket 8

4.2 Replacing the Chain Catcher 9

4.3 Clutch 9

4.4 Chain Brake (034, 036)10

4.4.1 Removing 10

4.4.2 Installing 11

4.5 Chain Brake (036 QS) 12

4.5.1 Removing 12

4.5.2 Installing 14

4.5.3 Checking Play 15

4.5.4 Adjusting Play 16

4.5.5 Checking Operation of Chain Brake 17

4.6 Chain Tensioner 17

4.7 Bar Mounting Studs 18

5Engine 19

5.1 Removing and Installing Muffler 19

5.2 Exposing the Cylinder 20

5.3 Cylinder and Piston 20

5.3.1 Removing 20

5.3.2 Installing 21

5.4 Piston Rings 24

5.5 Crankcase 24

5.5.1 Removing the Crankshaft 24

5.5.2 Installing the Crankshaft 26

5.6 Crankcase Leakage Test 31

5.6.1 Preparations 31

5.6.2 Pressure Test 32

5.6.3 Vacuum Test 33

5.7 Replacing the Oil Seals 33

6 Ignition System 34

6.1 Ignition Lead/ Spark Plug Boot 34

6.2 Short Circuit Wire/ Ground Wire 35

6.3 STOP Contact 37

6.4 Flywheel 38

6.4.1 Removing 38

6.4.2 Installing 38

6.5 Ignition Module 39

6.5.1 Removing and Installing 39

6.5.2 Ignition Timing 40

7 Rewind Starter 40

7.1 Routine Maintenance 40

7.2 Rope Rotor, Pawls, Starter Rope, Rope Guide Bush 40

7.3 Rewind Spring 41

7.3.1 Replacing the Rewind Spring (034) 41

7.3.2 Replacing the Rewind Spring (036, 036 QS) 41

7.4 Tensioning the Rewind Spring 42

8 AV Handle System 42

8.1 Repair 42

9Master Control 43

9.1 Construction and Function 43

9.2 Throttle Trigger/Interlock Lever (034, 036) 44

9.3 Throttle Trigger/Interlock Lever/Switch Lever (036 QS) 45

9.4 Switch Shaft 46

10 Electric Handle Heating

System (034, 036) 47

10.1 Troubleshooting 47

10.1.1 Troubleshooting Chart 49

10.1.2 Test Connections and Test Values 50

10.2 Heater Switch 51

10.3 Heating Element in Rear Handle 51

10.4 Heating Element in Front Handle 53

10.5 Generator 54

10.5.1 Removing 54

10.5.2 Installing 55

11 Chain Lubrication 55

11.1 Pickup Body 55

11.2 Suction Hose 56

11.3 Vent Valve 56

11.4 Removing and Installing the Oil Pump 57

11.5 Servicing the Oil Pump 58

12 Fuel System 59

12.1 Air Filter 59

12.2 Leakage Testing the Carburetor 60

12.3 Removing and Installing the Carburetor 61

12.4 Servicing the Carburetor 62

12.5 Adjusting the Carburetor 66

12.6 Tank Vent 67

12.7 Fuel Filter and Fuel Hose 68

12.8 Tank Hous ing 69

12.8.1 Removing and Installing 69

13 Special Servicing

Tools and Aids 71

13.1 Special Servicing Tools 71

13.2 Servicing Aids 72

2 034, 036, 036 QS

This service manual contains detailed descriptions of all the repair and servicing procedures specific to this series of chain saws.

There are separate handbooks for servicing procedures on standardized parts and assemblies that are installed in several STIHL power tool models. Reference is made to these handbooks in the appropriate chapters of this manual

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.

Refer to the latest edition of the relevant parts list to check the part numbers or any replacement parts. Parts lists on microfiche and CDROM are always more up to date than printed lists.

A fault on the machine may have several causes. To help locat e the fault, consult the troubleshooting charts for all assemblies in the "Standard Repairs, Troubleshooting" handbook.

Refer to the "Technical Info rmation" bulletins for engineering changes which have been introduced since publication of this service manual. Technical information bulletins also supplement the parts list until a revised edition is issued.

The special servicing tools mentioned in the descriptions are listed in the last chapter of this manual. Use the part numbers to identify the tools in the "STIHL Special Tools" manual. The manual lists all special servicing tools currently available from STIHL.

Symbols are included in the text and pictures for greater clarity. The meanings are as follows:

In the descriptions:  = Action to be taken as

shown in the illustration (above the text)

– = Action to be taken that is

not shown in the illustration (above the text)

= Situation applies from

serial number

= Situation applies up to

serial number

In the illustrations:

Pointer Direction of movement

Service manuals and all technical Information bulletins are intended exclusively for the use of STIHL servicing dealers. They must not be passed to third parties.

Servicing and repairs are made considerably easier if the powerhead is mounted on assembly stand (1) 5910 890 3100. Remove the chain sprocket cover, bar and chain first. The powerhead can then be swivelled to the best position for the

138RA001

ongoing repair. This leaves both hands free.

Always use original STIHL replacement parts.

They can be identified by the STIHL part number, the

67,+logo and the

STIHL parts symbol This symbol may appear alone on small parts.

1 Introduction

3034, 036, 036 QS

If the engine is started up in the course of repairs or maintenance work, observe all local and countryspecific safety regulations as well as the safety precautions and warnings in the owner’s manual.

Gasoline is an extremely flammable fuel and can be explosive in certain conditions.

Improper handling may result in burns or other serious injuries.

Warning!

Do not smoke or bring any fire, flame or other source of heat near the fuel. All work with fuel must be performed outdoors only. Spilled fuel must be wiped away immediately.

2 Safety Precautions

4 034, 036, 036 QS

3 Specifications

3.1 Engine

STIHL single cylinder two-stroke engine with special impregnated cylinder bore

034 036, 036 QS

Displacement: Bore: Stroke: Compression ratio: Engine power to ISO 8893:

Max. torque: Max. permissible engine speed with

bar and chain: Mean idle speed: Crankshaft: Main bearings: Crankshaft journal diameter: Big end bearing: Piston pin diameter: Small end bearing: Connecting rod length: Rewind starter:

Starter rope: Clutch: Diameter: Clutch engages at: Crankcase leakage test at gauge pressure: under vacuum:

56.5 cm

46 mm 34 mm

9.5:1

3.0 kW (4.1 bhp) at 9,500 rpm

3.5 Nm at 6,500 rpm

13,000 rpm 2,700 rpm Two-part, drop forged Two deep-groove ball bearings

14.4 mm Needle cage 10 mm Needle cage 58 mm Pawl engagement with automatic starter rope rewind mechanism

3.5 mm dia., 960 mm Centrifugal clutch without linings 76 mm approx. 3,500 rpm

0.5 bar

61.5 cm

48 mm 34 mm

9.5:1

3.4 kW (4.6 bhp) at 9,500 rpm

3.7 Nm at 6,500 rpm

13,000 rpm 2,700 rpm Two-part, drop forged Two deep-groove ball bearings

14.4 mm Needle cage 10 mm Needle cage 58 mm Pawl engagement with automatic starter rope rewind mechanism

3.5 mm dia., 960 mm Centrifugal clutch without linings 76 mm approx. 3,500 rpm

0.5 bar

3.2 Fuel System 034, 036, 036 QS

Carburetor: Standard setting

High speed screw H: Low speed screw L: Idle setting:

Carburetor leakage test at gauge pressure: Fuel tank capacity: Fuel mixture:

Mix ratio:

Air filter:

All positon diaphragm carburetor with integral fuel pump

approx. 1 turn open approx. 1 turn open (starting with screws firmly against their seats)

0.4 bar 625 cm

Regular brand-name gasoline and brand-name two-stroke engine oil 50:1 with STIHL two-stroke engine oil 25:1 with other brand-name twostroke, air-cooled engine oils Large area, bisectional box filter with wire mesh

5034, 036, 036 QS

3.3 Ignition System

Type: Air gap:

Spark plug (suppressed): Electrode gap: Spark plug thread: Thread length: Heat range:

034, 036, 036 QS

Transistorized magneto ignition (breakerless)

0.2 - 0.3 mm Bosch WSR 6 F

0.5 mm M14x1.25

9.5 mm 200

3.4 Cutting Attachment

Guide bars:

Cutting lengths: Oilomatic chain:

Chain sprockets: Chain speed:

Chain lubrication:

Oil delivery rate: Oil tank capacity:

STlHL Rollomatic S bars with nose sprocket. STlHL Duromatic bars with stellitetipped nose. Both types with corrosion-resistant finish and induction hardened rails. Rollomatic 37, 40, 45 and 50 cm Duromatic 37, 40, 45 and 50 cm

9.32 mm (3/8") Rapid-Micro, Rapid-Super (Options: 8.25 mm (0.325") Rapid-Micro, Rapid-Super, Topic-Micro and Topic-Super) 7-tooth, 3/8" rim sprocket

20.7 m/s at 9,500 rpm (with 7-toot h, 3/8" sprocket) Fully automatic, speed-controlled reciprocating oil pump; no oil feed at idle speed. Additional manual oil flow control Adjustable 5.5 - 15.5 cm

/min at 10,000 rpm 320 cm

6 034, 036, 036 QS

3.5 Tightening Torques

DG and P (Plastoform) screws are used in polymer and lightmetal components. These screws form a permanent thread when they are installed for the first time. They can be removed and installed as often as necessary without impairing the strength of the screwed assembly, providing the specified tightening torque is observed. For this reason it is essential to use a torque wrench.

Fastener Thread size For component Torque

Remarks

Pan head screw M4x8 Chain tensioner cover plate 3.0

M7x12.5 Starter post to fan housing 12.0 1)

Screw M8x22 Brake band/crankcase

(036 QS II) 10.0 2) Self-tapping screw B3.9x13 Brake cable retainer/tank housing (036 QS II) 1.5 Collar screw M8x21.5 Guide bar 23.0 2) Spline screw IS-M4x12 Cover, chain brake/crankcase 3.0

M10x1 Decompression valve (036, 036 QS) 14.0 Spline screw M3.5x12 Generator (W version) 2.0 3) Spline screw IS-P6x21.5 Front handle/tank housing, top right

(W version) 7.0 3)

Spline screw IS-P6x19 Front ha nd le /ta nk housing, bottom

(W version) 7.0 3) Spline screw IS-P6x32,5 Front handle/tank housing, top right, polymer 5.0 3) Spline screw IS-P6x21,5 Front handle/tank housing, bottom, polymer 5.0 3) Spline screw IS-P4x19 Handle mo ldin g 1.6 Screw assembly M5x30 Hand guard, left 7.0 2) Spline screw IS-P6x19 Chain catcher 2.8 Spline screw IS-M5x12 Spiked bumber 7.5 Spline screw IS-M5x20 Crankcase 9.0 Spline screw IS-M5x20 Fan housing/crankcase 7.0

M12x1 L Carrier 50.0 Screw HL6x18.5 Annular buffer to rear left/right of tank housing 5.0 Spline screw IS-P6x19 Annular buffer to front right of tank housing 5.0 Spline screw IS-M5x6 Muffler, upper/lower casing 6.5 2) Spline screw IS-M5x25 Muffler/crankcase 10.0 2) Spline screw IS-M5x16 Muffler/cylinder (036, 036 QS) 10.0 2) Spline screw IS-M5x25 Muffler/crankcase (034) 10.0 4) Spline screw IS-M5x20 Muffler/cylinder (034) 10.0 4) Spline screw IS-M5x22 Muffler/cylinder (034/Z version) 10.0 4) Slotted nut M5 Shroud 3.3 Slotted nut M5 Air filter 2.0

M8x1 Flywheel 33.0 6) Setscrew M5x8.5 Setscrew, l/h side of cylinder 1.4 5) Setscrew M5x8.5 Setscrew, r/h side of cylinder 1.4

7034, 036, 036 QS

Hexagon nut M5 Carburetor (initial) 2.0 Hexagon nut M5 Carburetor (final) 3.5 Spline screw IS-M5x20 Cylinder/crankcase (036, 036 QS) 11.5 Spline screw IS-M5x20 Cylinder/crankcase (034) 10.5

M14x1.25 Spark plug 25.0 Spline screw IS-M5x20 Ignition module (with washer) 8.0 2) Spline screw IS-M4x12 Oil pump/crankcase 3.5

1) Micro-encapsulated

2) Threadlocking method: medium strength adhesive (e.g . LOCTITE 243)

3) Threadlocking method: high strength adhesive (e.g. LOCTITE 649)

4) Threadlocking method: high strength adhesive up to 250 °C (e.g. LOCTITE 272)

5) Threadlocking method: high strength adhesive (e.g. LOCTITE 270)

6) Degrease taper with cleaning agent (e.g. Somentor 33)

Use the following procedure when refitting a DG or P 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 and weaken the assembly.

Note:

Power screwdriver settings for polymer:

– Plastoform screws max. 600 rpm – DG screws max. 500 rpm

3.6 Special Accessories

3.6.1 For User

3.6.2 For Service

Intake air preheating kit Intake air preheating kit .325", 8-tooth rim sprocket kit .325", 7-tooth rim sprocket kit 3/8", 7-tooth rim sprocket kit 3/8", 7-tooth spur sprocket .325", 7-tooth spur sprocket

Gasket set Carburetor parts kit Gasket panel

034, 036, 036 QS

1125 007 1035 (036) 1125 007 1004 (034/034S) 1125 007 1000 1125 007 1001 1125 007 1002 1125 640 2000 1125 640 2005

1125 007 1050 1128 007 1065 0457 281 0604

Fastener Thread size For component Torque

Remarks

8 034, 036, 036 QS

Troubleshooting chart - see "Standard Repairs, Troubleshooting" handbook.

 Unscrew nuts (1) from chain

sprocket cover (2). Remove the sprocket cover , bar and chain (3).

138RA002

 Disengage the chain brake by

pulling the hand guard toward the front handle.

143RA004

 Remove the E-clip (1) and

washer (2). If a rim sprocket (3) is fitted, pull it off.

148RA061

036 QS

 Disengage the additional brake

by pressing down the throttle trigger and interlock lever. Remove the clutch drum (1) and needle cage (2).

148RA062

034, 036

 Pull off the chain sprocket (1) or

clutch drum (2).

– Take out the needle cage.

138RA003

 Inspect the clutch drum (1).

There should be no scores or signs of excessive wear.

Important:

If there are signs of serious wear on the inside diameter of the clutch drum (1), check the remaining wall

148RA101

80%

100%

thickness. If it is less than about 80% of the original thickness, fit a new clutch drum.

Note:

Clean stub of crankshaft. Wash needle cage, examine it for damage and replace if necessary. Lubricate needle cage with STIHL multipurpose grease - see 13.2.

Reassemble in the reverse sequence - start by fitting the ne edle cage on the crankshaft stub.

4 Clutch, Chain Drive,

Chain Brake and Chain Tensioner

4.1 Clutch Drum and Chain Sprocket

9034, 036, 036 QS

– Remove chain sprocket cover -

see 4.1.

 Take out screw (1 ) an d re m ove

the inner side plate (2).

 Take out screw (3 ) an d re m ove

the chain catcher (4).

148RA063

2 1

Reassemble in the reverse sequence.

Troubleshooting chart - see "Standard Repairs, Troubleshooting" handbook.

– Remove clutch drum/chain

sprocket - see 4.1.

 Release twist lock (1) on

carburetor box cover (2) and lift cover off vertically.

148RA064

Note:

 When reassembling, check

correct position of groove and guide.

148RA065

 Unscrew the slotted nut (1). – Pull boot off the spark plug.  Remove the shroud (2).

148RA066

 On powerheads with a

decompression valve (1), remove the cover and unscrew the decompression valve.

 Unscrew the spark plug (2).

148RA067

 Push the locking strip (1)

0000 893 5903 into the cylinder so that the words "OBEN - TOP" face upward.

148RA069

4.2 Replacing the

Chain Catcher

4.3 Clutch

10 034, 036, 036 QS

 Unscrew the clutch clockwise

from the crankshaft (left-hand thread).

On 036, 036 QS:

Remove cover washer from the crankshaft stub.

148RA068

– Disassemble and reassemble the

clutch - see "Standard Repairs, Troubleshooting" handbook.

– Reassemble in the reverse

sequence.

Note:

Observe tightening torque for clutch (see "Tightening Torques").

Troubleshooting chart - see "Standard Repairs, Tro ubleshooting" handbook.

– Remove the chain sprocket cover

and cutting attachment - see 4.1.

– Remove the clutch drum/chain

sprocket - see 4.1

 Remove mounting screw (1 ) from

inner side plate (2) and lift side plate away.

– Engage the chain brake by

pushing the hand guard away from the front handle.

138RA004

 Remove mounting screws (1)

from cover (2) and lift the cover away.

138RA005

 Carefully pry the brake spring (1)

off the anchor pin and disconnect it from the lever (2).

138RA006

 Ease the brake band (1) out of

its seat in the crankcase and disconnect it from the lever (2).

138RA007

 Remove screw with captive

washer from the hand guard.

Note:

When installing, tighten down the screw with captive washer firmly (see "Tightening Torques").

138RA008

4.4 Chain Brake (034, 036)

4.4.1 Removing

11034, 036, 036 QS

 Remove the E-clip from the pivot

pin.

– Pull the hand guard and lever

from the pivot pins.

138RA009

– Pull the lever out of the hand

guard.

 Remove the E-clip (3) from pivot

pin of lever (2) and detach the spring (1).

 Remove the cam lever and

138RA010

2 3

spring.

– Clean all disassembled parts in

white spirit. Replace any worn or damaged parts.

 Fit the cam lever (2) and

spring (1).

– Fit the E-clip.

138RA011

 Insert lever in th e side of the hand

guard so that short arm of lever points up.

Note:

Check correct installed position of lever.

138RA012

 Position the hand guard (1)

against the pivot pin and fit the other side of the hand guard over the fan housing.

138RA013

 Press the cam lever slightly

downward and push the hand guard and lever onto the pivot pins.

– Secure lever with E-clip. – Insert hand guard mounting

138RA014

screw with captive washer at fan side and tighten down firmly (see "Tightening Torques")

Important:

Coat all sliding and bearing points with STIHL multipurpose grease,

see 13.2, or (better) with

molybdenum grease (e.g. Molykote), see 13.2. Do not lubricate the brake band.

 First att ach the brake band (1) to

the lever (2) and then push it into the crankcase recess (arrow).

138RA007

4.4.2 Installing

12 034, 036, 036 QS

 Check that protective tube is

correctly positioned: a = 20 mm b = 33 mm

138RA016

 Hook the brake sp ring to the

lever.

138RA017

 Use the assembly tool

1117 890 090 0 to at tach the brake spring (1) to the anchor pin.

– Fit cover over the chain brake.

138RA015

– Fit the inner side plate - see 4.1. – Install the clutch drum/chain

sprocket - see 4.1.

– Fit the cutting attachment and

chain sprocket cover - see 4.1.

Troubleshooting chart - see "Standard Repairs, Troubleshooting" handbook.

– Remove the chain sprocket cover

and cutting attachment - see 4.1.

– Remove clutch drum/chain

sprocket - see 4.1.

 Remove mounting screw (1) from

inner side plate (2) and lift side plate away.

 Remove mounting screws (3)

from cover (4) and lift the cover away.

148RA070

– Engage the chain brake by

pushing the hand guard away from the front handle.

4.5 Chain Brake (036 QS)

4.5.1 Removing

13034, 036, 036 QS

 Carefully pry the brake spring (1)

off the anchor pin and disconnect it from the lever (2).

148RA071

 Remove the screw (1).  Ease the brake band ( 2) out of

its seat in the crankcase and disconnect it from the lever (3).

148RA072

 Remove screw with captive

washer from the hand guard.

Note:

When installing, tighten down the screw with captive washer firmly (see "Tightening Torques").

138RA008

 Carefully pry spring (1) off the

pivot pin.

148RA073

 Pull the hand guard (2) and brake

lever (1) off the pivot pins.

148RA074

 Disconnect brake cable ( 1) from

the brake lever (2).

– Take the brake lever out of the

hand guard.

148RA075

 Disconnect spring (1) from

lever (2).

 Pry the E-clip (3) off the pivot pin

and remove the lever with spring.

Clean all disassembled parts in

148RA076

2 3

white spirit. Replace any worn or damaged parts.

14 034, 036, 036 QS

 Fit the lever (2) and spring (1).  Fit the E-clip (3).

148RA076

2 3

 Insert lever in the side of the hand

guard as shown.

148RA077

 Attach brake cable (1) to hole

(arrow) in brake lever (2).

148RA075

 Position the hand guard (1)

against the pivot pin and fit the other side of the hand guard over the fan housing.

 Press the lever (1) slightly

downward and push the hand guard and brake lever (2) onto

148RA078

the pivot pins.

– Insert screw with captive washer

for hand guard and tighten down firmly (see "Tightening Torques").

Important:

Coat all sliding and bearing points with STIHL multipurpose grease,

see 13.2, or (better) with

molybdenum grease (e.g. Molykote), see 13.2. Do not lubricate the brake band.

 Attach spring (1) to the pivot pin.

148RA073

 First att ach the brake band (2) to

the brake lever (3) and then pu sh it into the slot in the crankcase.

 Install screw (1) with LOCTITE

243 and tighten down firmly (see "Tightening Torques")

148RA072

 Hook the brake spring (1) to the

brake lever (2).

148RA071

4.5.2 Installing

15034, 036, 036 QS

 Use the assembly tool

1117 890 090 0 to at tach the brake spring (1) to the anchor pin.

– Fit cover over the chain brake -

see 4.5.1.

– Fit inner side plate - see 4.5.1.

148RA098

– Install the clutch drum/chain

sprocket - see 4.1.

– Fit the cutting attachment and

chain sprocket cover - see 4.1.

– Pull hand guard toward front

handle.

– Unscrew nut from chain sprocket

cover and remove the cover - see

4.1.

– Remove the cutting att a chment -

see 4.1.

 Take out screw (1) and remove

the side plate (2).

 Take out screws (3) an d re m ove

the cover (4).

148RA070

 The brake cable (1) must hang

loosely in the crankcase when the brake is disengaged.

148RA079

 Press down interlock lever (1) all

the way and hold it in that position.

148RA080

 The brake band (1) must locate

without any play against the points (A) in the crankcase.

148RA081

 Let go of the interlock lever (1).  Check free travel by slowly

squeezing the interlock lever (1). Play must be within the mark (B) at the front end of the interlock lever.

148RA082

4.5.3 Checking Play

16 034, 036, 036 QS

The brake lever must not move. If it does, adjust play - see 4.5.4

Reassemble in the reverse sequence.

 Open twist lock (1) and lift away

the carburetor box cover (2) vertically.

148RA064

 Release and unscrew slotted

nuts (1).

 Remove the air filter (2).

148RA084

 Loosen the self-tapping

screw (1).

 Use a 6mm open-end wrench to

adjust play with nut (2).

148RA085

Turn wrench to right to reduce play.

Turn wrench to left to increase play.

 Lock the setting with se lf-tapping

screw (1).

Reassemble in the reverse sequence.

4.5.4 Adjusting Play

17034, 036, 036 QS

Check operation of the chain brake with the bar and chain mounted.

Note:

When starting the machine observe local safety regulations and the safety precautions in the owner’s manual.

– With the engine running, open

the throttle wide. – Release the rear handle. The chain must come to a standstill

in less than one second.

If the brake does not operate properly, service the sliding and bearing points shown in the illustrations as follows:

If lightly contaminated:

– Clean all parts with a brush and

white spirit.

If heavily contaminated or clogged with resin:

– Remove the parts concerned and

clean in white spirit or a resin

solvent.

– Replace worn or damaged parts. – Before re-installing parts, the

machine recesses and seats.

 Lubricate bearing points with

Mobilplex grease (see 13.2).

148RA047

 Lubricate these points (1) with

Mobilplex grease (see 13.2).

 Coat outside diam eter of clutch

drum (2) with chain oil.

Note:

If a biological chain oil is preferred,

148RA048

STIHL recommends the use of rapidly biodegradable STIHL Bioplus. To guarantee t roublefree oper ation, use only original STIHL replacement parts as per the latest parts list.

– Remove chain sprocket cover

and cutting attachment - see 4.1.

 Remove mounting scre w (1) from

inner side plate (2) and lift side plate away.

138RA004

 Use a screwdriver to turn the spur

gear clockwise until tensioner slide butts against the thrust pad.

Note:

Older machines are equipped wi th a front chain tensioner - see 5.5.2.

148RA086

4.5.5 Checking Operation of Chain Brake 4.6 Chain Tensioner

18 034, 036, 036 QS

 Take out the cover plate

mounting screw (1).

 Remove the cover plate (2) with

retainer (3) from the spur gear.

148RA087

1 2

 Pull out the spur gear (1).  Take out the tensio ne r slid e (3 )

with adjusting screw (4) and thrust pad (2).

– Inspect the teeth on the spur gear

and adjusting screw, remove

4 3

148RA088

thrust pad if necessary.

– Take the adjusting screw out of

the tensioner slide and replace the parts.

Install in the reverse sequence.

 Check that O-ring is fit ted in spur

gear.

– Lubricate O-ring with a little oil

before fitting the spur gear.

Note:

Coat teeth of adjusting screw and

138RA018

spur gear with grease, see 13.2, before refitting.

The adjusting screw and spur gear must be replaced as a matching pair.

– Remove chain sprocket cover

and cutting attachment - see 4.1.

 Push stud puller 5910 893 0501

over the collar stud as far as it will go. Use a 15 mm wrench to unscrew the collar stud counterclockwise.

138RA019

– Before installing, coat thread of

collar stud with LOCTITE - see

13.2.

– Install and tighten down t he collar

studs (see "Tightening Torques").

4.7 Bar Mounting Studs

19034, 036, 036 QS

Always check and, if necessary, repair the fuel system, carburetor, air filter and ignition system before looking for faults on the engine.

Troubleshooting chart - see "Standard Repairs, Troubleshooting" handbook.

(034)

 Take out the screws and remove

the upper casing.

138 RA 219

(036, 036 QS)

 Take out screws and remove the

upper casing.

138 RA 220

 Take out the screws and remove

the lower casing.

138 RA 020

(034)

 Remove exhaust gasket (1) and

flange.

138RA021

(036, 036 QS)

 Remove heat shield (1) and

gasket (2) from the upper casing (3).

138RA022

 Install new gasket (1) so that its

bead points toward the muffler.

Note:

If the bores of the lower casing are not reinforced, fit washers under the heads of the mounting screws.

138RA021

– Coat threads of mounting screws

with LOCTITE - see 13.2.

– Insert and tighten down the

mounting screws firmly (see "Tightening Torques").

5Engine

5.1 Removing and Installing Muffler

20 034, 036, 036 QS

Always check and, if necessary, repair the fuel system, carburetor, air filter and ignition system before looking for faults on the engine.

Troubleshooting chart - see "Standard Repairs, Troubleshooting" handbook.

– Drain the fuel and oil tanks. – Remove the air filter - see 12.1 – Remove the carburetor - see 12.3

 Pull the washer (1) off the studs

and remove the sleeve (2) from the manifold.

– Remove the shroud, spark plug

and, if fitted, the decompression valve - see 4.3.

138RA023

– Remove the muffler - see 5.1 Reassemble in the reverse

sequence.

– Preparations - see 5.2  Take out the four cylinder base

screws.

148RA089

 Pull the cylinder off the piston

and, at the same time, push the manifold through the tank housing opening.

Caution:

Do not use pointed or sharp-edged tools for this job.

138RA024

 Remove the cylinder gasket.

138RA025

 Release the hose clamp (1) on

the manifold (2). Pull the manifold off the intake port.

– Inspect the cylinder and replace it

if necessary.

Note:

138RA026

If a new cylinder has to be installed, always fit the matching piston. New cylinders are only supplied complete with piston for this reason.

5.2 Exposing the Cylinder 5.3 Cylinder and Piston

5.3.1 Removing

21034, 036, 036 QS

Important:

Before removing the piston, decide whether or not the crankshaft has to be removed as well.

 To remove the flywheel and

clutch, block the crankshaft by

sliding the wooden assembly

138RA027

block (1) 1 108 893 4800 between

the piston and crankcase.  Use a scriber or similar tool to

ease the hookless snap rings out

of the grooves in the piston.

 Use the assembly drift (2)

1 1 10 893 4700 to push the pist on

pin (1) out of the piston.

Note:

– If the piston pin is stuck, tap the

end of the drift lightly with a

hammer if necessary.

138RA028

Important: Hold the piston

steady during this process to ensure that no jolts are transmitted to the connecting rod.

– Remove piston and take the

needle cage out of the connecting rod.

 Inspect piston r ings and replace if

necessary - see 5.4.

138RA029

– Thoroughly clean the gasket

seating surface on the cylinder.

 Lubricate the need le cage with oil

and fit it in the small end.

138RA030

 Install a snap ring in the front

piston boss (2), i.e. the piston boss facing you when the arrow (1) on the piston head is pointing to the right.

Note:

Use installing tool 5510 890 2210 to

138RA031

fit the snap ring - see "S tandard Repairs, Troubleshooting" handbook.

– Heat the piston on an electric

heating plate to about 60°C.

5.3.2 Installing

22 034, 036, 036 QS

 Slip the piston over the

connecting rod so that arrow on piston crown points to exhaust port.

138RA032

– Push the assembly drift

1110 893 4700, sma ll dia m et er first from the clutch side, through the piston and small end (needle cage) and line up the piston.

 Fit piston pin on the end of the

assembly drift and push it into the

138RA033

piston.

– Use installing tool 5910 890 2210

to fit the snap ring - see "S tandard Repairs, Troubleshooting" handbook.

– Fit new cylinder gasket on the

crankcase.

– Lubricate piston and piston rings

with oil.

 Slide the wooden assembly

block between the piston and crankcase.

 Rest the piston on the wooden

assembly block.

138RA034

 Position the piston rings so that

the radii at the ring gap meet at the fixing pin in the piston groove when the rings are compressed.

138RA035

 Push the manifold on to the

intake port so that its tab lines up with the rib on the cylinder.

138RA036

 Slide the hose clamp on to the

manifold. The screw head must point to the right.

 The screw on the hose clamp

must be below the manifold and at a right angle to the cylinder axis.

138RA037

 Tighten the screw until the gap

"a" between the two ends of the hose clamp is 3.5 to 4.5 mm.

Note:

If a new cylinder is installed in an older machine, it is necessary to shorten the seventh cylinder fin. Use the edge of the eighth fin as a guide for the modification (see arrow in illustration).

138RA038

10mm

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