BG85 Shop Manual

STIH)

STIHL Series 4140 Components BG, SH

2005-01

Contents

1.

2.

3. 3.1 3.2

Introduction

Safety Precautions

Specifications Fuel System Tightening Torques

2

8.

Throttle Control

18

Throttle Trigger Setting Lever (BG 85, SH 85 only) Stop Switch Vers Versio ion n up to 2001 2001 Vers Versio ion n from from 2001 2001 Short Circuit Wire/ Ground Wire Throttle Cable Throttle Rod

18

3

8.1 8.2

4 4 5

8.3 8.3.1 .3.1 8.3.2 .3.2 8.4 8.5 8.6

4.

Troubleshooting

4.1 4.2 4.3

Rewind Starter Fuel System Engine

7 8 10

Housing

11

5.1 5.2

Handle Molding Handle and Feet (BG (BG 85, 85, SH 85) 85)

11

9. 9.1 9.1.1 9.1.2 9.2 9.2.1 9.2.2

11

12

Removing and Installing Muffler/Spark Arresting Screen Without Cat Muffler with Catalytic Converter

13

7.

Rewind Starter

14

9.4

7.1 7.2

General Removing and Installing Starter Cup Rope Rotor Replacing the Rewind Spring Tensioning th the Rewind Spring Starter Rope Pawl

14

9.4.1

6.2 6.2.1 6.2.2

7.3 7.4 7.5 7.5.1 7.6 7.7

20 21 21

12 13 13

14 15 15

9.3.2

9.3.3 .3.3 9.3.4 9.3.5 9.3.6

9.4.2

9.4.3 16 17 17 18

10.5

Fuel System

9.5 9.5.1 9.5.2 9.6 9.6.1 9.6.2 9.6.3

Air Filter Removing and Installing Choke Shu Shutter Carburetor Leakage Test Removing and Installing Spac Space er Flange nge Servicing the Carburetor Manua nual Fuel Pum Pump with Oval End Cover Manua nual Fuel Pum Pump with Square End Cover Meter eterin ing g Diap Diaphr hrag agm m Inlet Need eedle Fixed Jet Pump Di Diaphragm and Fuel Strainer Adjusting the Carburetor Carburetor with LD Screw User Ad Adjustment of of Carburetor with H, L and LA Screws Basic Set Settin ting on Carburetor with H, L and LA Srews Tank Vent General Replacing Fuel Tank General Pickup Body Fuel Hoses

Blower and Vacuum Attachment Fanwheel Protective Screen (all except BG 45) Protective Screen (BG 45 only) only) Blower Tube (BG only) Suction Tu Tube (SH only) Elbow (SH only)

35 35 35 35 36 36 36

21 11.

9.3.1 6.1

10.3

10.6

9.2.3 9.3 Engine

10.1 10.2

10.4

7

5.

6.

19 19 19 20

10.

21 22 22 23 23

12.

Special Servicing Tools

37

Servicing Aids

38

24 24 25 25

26 26 27 28 28 29 29

29

31 32 32 33 33 33 34 34

q © ANDREAS STIHL AG & Co. KG, KG, 2005

Series 4140 Components BG, SH

1

1.

Introduction

This service manual contains detailed descriptions of all typical repair and servicing procedures for models BG 45, 46, 55, 55, 65, 85, 85, SH 55, 85, which are based on the series 4140 powerhead. powerhead. You will find detailed descriptions de scriptions of procedures for servicing and repairing engine components in the service manual for the “Series 4140 Powerhead“. 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 of any replacement parts. A fault on the machine may have several causes. To help locate the fault, consult the chapter on "Troubleshooting" in this manual and the "STIHL Service Training System" for all assemblies. Refer to the "Technical "Technical Information" 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.

2

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

Always use original STIHL replacement parts. They can be identified by the STIHL part number, the STIH) logo and the STIHL parts symbol ( This symbol may appear alone on small parts.

Symbols are included in the text and pictures for grea ter clarity. The meanings are as follows: In the descriptions: :

= Action to be taken as shown in the illustration (above the text)

– = Action Action to to be take taken n that that is not shown in the illustration (above the text) 4.2 Reference to another chapter, i.e. chapter 4.2 in this example. In the illustrations: A

Pointer

a Direction

of movement

Service manuals and technical information bulletins are intended exclusively for the use of properly equipped repair shops. They must not be passed to third parties.


2.

Safety Precautions

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 instruction 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 bring any fire, flame, spark or other source of heat near the fuel. All work with fuel must be performed outdoors only. Spilled fuel must be wiped away immediately.


3

3.

3.1

Specifications

Fuel System

Carburetor: Carburetor leakage test at gauge pressure: Operation of tank vent at gauge pressure: under vacuum: Fuel: Octane number: Fuel mixture:

Mix ratio:

Diaphragm carburetor 0.8 bar (8 kPa) 0.3 bar (3 kPa) 0.05 bar (0.5 kPa) see instruction manual min. 90 RON Regular brand-name gasoline and STIHL 50:1 two-stroke engine oil or brand-name two-stroke engine oil 50:1 with STIHL 50:1 two-stroke engine oil Fuel mix for units with catalytic converter: Use only STIHL 50:1 twostroke engine oil with unleaded gasoline.

4


3.2

Tightening Torques

DG and P (Plastoform) screws are used in polymer and light metal 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

Nm Screw

IS-DG5x60

Muffler/cylinder

9.0

Screw

IS-DG5x24

9.0 10.0 6.0

1) 2)

Screw

IS-DG5x24

Muffler/cylinder (version with catalytic converter) Stub/muffler (version with spark arresting screen in muffler) Spacer flange/cylinder

Collar screw Screw

P6x15/49 IS-DG5x24

Collar screw/inner blower housing Inner blower housing/crankcase

4.0 8.0

Screw Screw Nut

IS-DG5x24 IS-P6x26.5 M8x1LH-06

8.0 5.0 17.0

Screw Screw Screw

IS-P6x19 IS-P6x19 IS-P6x19

Inner blower housing/engine pan Outer/inner blower housings Fanwheel/crankshaft (SH with shredder blade) Handle/inner blower housing Handle molding/inner blower housing Fan housing/inner blower housing

Screw Screw

IS-DG5x20Z Fan housing/spiral housing IS-DG5x24 Spiral housing/crankcase

6.0 6.0

Screw Screw

IS-DG5x24 IS-P6x19 M14x1.25

6.0 5.0 20.0

M14x7

Spiral housing/engine pan Protective screen/outer blower housing Spark plug

5.0 4.0 6.0

3) 4)

5)

Remarks: 1) with binding head 2) SH 55, 85 only 3) BG 85, SH 85 only 4) BG 65, 85, SH 85 only 5) BG 45 only


5

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.

Power screwdriver settings for polymer:

Plastoform screws

max. 600 rpm

DG screws

max. 500 rpm

Important: Do not mix up screws with and without binding head

6


4. 4.1

Troubleshooting Rewind Starter

Condition

Cause

Remedy

Starter rope broken

Rope pulled out too vigorously as far as stop or over edge, i.e. not vertically

Fit new starter rope

Normal wear

Fit new starter rope

Spring overtensioned – no reserve when rope is fully extended

Fit new rewind spring

Very dirty or corroded

Fit new rewind spring

Guide peg on pawl or pawl itself is worn

Fit new pawl

Spring clip fatigued

Fit new spring clip

Starter mechanism very dirty (dusty conditions)

Thoroughly clean complete starter mechanism

Lubricating oil on rewind spring becomes viscous at very low outside temperatures (spring windings stick together)

Coat rewind spring with a standard solvent-based degreasant (containing no chlorinated or halogenated hydrocarbons). Then pull rope carefully as often as necessary until normal action is restored

Rewind spring broken

Starter rope can be pulled out almost without resistance (crankshaft does not turn)

Starter rope is difficult to pull and rewinds very slowly


7

4.2

Fuel System

Condition

Cause

Remedy

Engine stalls at idle speed

Idle jet bores or ports blocked

Clean jet bores and ports and blow clear with compressed air

Idle jet too rich or too lean

Reset low speed screw (L) correctly

Setting of idle speed screw (LA) incorrect – throttle shutter completely closed

Reset idle speed screw (LA) correctly

Air filter plugged

Clean the air filter or replace if necessary

Tank vent faulty

Fit new tank vent

Leak in fuel line between tank and fuel pump

Seal or renew connections and fuel line

Pump diaphragm damaged or fatigued

Fit new pump diaphragm

Main jet bores or ports blocked

Clean the bores and ports

Fuel pickup body dirty

Install new pickup body

Setting of high speed screw (H) too rich

Reset high speed screw (H) correctly

Throttle shutter not opened fully

Check linkage

Engine speed drops quickly under load – low power

8


Condition

Cause

Remedy

Poor acceleration

Idle jet too lean

Turn low speed screw (L) counterclockwise (richer), no further than stop

Main jet too lean

Turn high speed screw (H) counterclockwise (richer), no further than stop

Inlet control lever too low (relative to correct installed position)

Set inlet control lever flush with top of carburetor body

Inlet needle sticking to valve seat

Remove inlet needle, clean and refit

Connecting bore to atmosphere blocked

Clean the bore

Diaphragm gasket leaking

Fit new diaphragm gasket

Metering diaphragm damaged or shrunk

Fit new metering diaphragm

Engine will not idle – idle speed too high

Throttle shutter opened too wide by idle speed screw (LA)

Reset idle speed screw (LA) correctly

Carburetor floods, engine stalls

Inlet needle not sealing. Foreign matter in valve seat or cone damaged

Remove and clean or replace inlet needle, clean fuel tank, pickup body and fuel line if necessary

Inlet control lever sticking on spindle

Free off inlet control lever

Helical spring not located on nipple of inlet control lever

Remove inlet control lever and refit correctly

Perforated disc on diaphragm is deformed and presses constantly against inlet control lever

Fit new metering diaphragm

Inlet control lever too low (relative to correct installed position)

Fit new inlet control lever


9

4.3

Engine

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

Air filter Fuel system Carburetor Ignition system 1)

Condition

Cause

Remedy

Engine does not start easily, stalls at idle speed, but operates normally at full throttle

Oil seals in crankcase faulty

Install new oil seals 1)

Crankcase leaking / damaged (cracks)

Seal / replace the crankcase 1)

Muffler leaking

Seal / replace the muffler

Piston rings worn or broken

Install new piston rings 1)

Muffler / spark arresting screen carbonized

Clean muffler (inlet and exhaust openings), replace spark arresting screen

Air filter element dirty

Fit new air filter element

Fuel / impulse line kinked or cracked

Fit new lines or position without kinks

Insufficient cylinder cooling. Air inlets in fan housing blocked or cooling fins on cylinder very dirty

Thoroughly clean all cooling air passages and cooling fins

Engine does not deliver full power or runs erratically

Engine overheating

1)

10

see "Series 4140 Powerhead" service manual


5. 5.1

Housing Handle Molding

5.2

Remove fan housing with rewind starter, 7.2

Handle and Feet (BG 85, SH 85)

2

– Remove the spark plug. 1

A V 2 7 1 A R 2 3 9

:

If necessary, replace the setting lever (1), 8.2

:

If necessary, remove the grip molding (2) as follows:

A V 2 6 2 A R 2 3 9

:

Take out the screws (arrows).

– Remove the handle.

2

1

1 1

1

A V 0 7 1 A R 2 3 9

:

BG 45, 55, SH 55 only :

Take out the screws (1) and remove the handle molding (2).

2

A V 1 6 2 A R 2 3 9

Pull the grip molding (1) out of the guides (arrows) and lift it away.

Install in the reverse sequence.

1 :

A V 3 6 2 A R 2 3 9

Pull the feet (1) upwards and out of the handle.

Reassemble in the reverse sequence.

1

1

A V 1 7 1 A R 2 3 9

BG 65, 85, SH 85 only :

Take out the screws (1) and remove the handle molding (2).

Note: BG 65 has no setting lever.


11

6. 6.1

Engine Removing and Installing

– Remove fan housing with rewind starter, 7.2 – Remove the fanwheel,

2

10.1

1

– Remove the filter housing, 9.1 A V 5 7 1 A R 2 3 9

– Remove the handle molding, 5.1

:

3 1

On machines with a throttle cable, disconnect the throttle cable (1) from slotted pin (2) on the throttle lever and push the throttle cable out of the tensioner (arrow). If necessary, remove the carburetor first. Avoid kinking the throttle cable in this process.

A V 6 7 1 A R 2 3 9

:

Remove the engine.

– On machines with a throttle rod, remove the throttle rod, 8.6

2

A V 7 7 1 A R 2 3 9

A V 3 7 1 A R 2 3 9

:

Disconnect the short circuit wire (1) and ground wire (2) from the ignition module.

Install in the reverse sequence. Observe correct tightening torques, 3.2.

:

Remove the retainers (3).

:

1

2 A V 4 7 1 A R 2 3 9

A V 2 9 0 A R 2 3 9

: :

12

When installing the engine in the inner fan housing, check that the gasket (arrow) is in front of the inner fan housing.

Pull the fuel hoses (1 and 2) off the elbow connectors on the carburetor.

Take engine mounting screws (arrows) out of inner fan housing.


6.2

Muffler/Spark Arresting Screen 6.2.1 Without Cat Troubleshooting, 4.3

6.2.2


Troubleshooting,

– Remove the fan housing with rewind starter, 7.2

– Clean the sealing faces before installation.

The catalytic converter integrated in the muffler is a device that helps reduce the amount of noxious emissions in the exhaust gas by initiating chemical reactions without being consumed in the process. The catalytic converter is maintenance-free. Never attempt to carry out repairs on the catalytic converter.

– Install a new exhaust gasket. – Apply sealant to the underside of the screw head, 12. – Tighten down the screws firmly, 3.2

1

4.3

1

A V 5 0 2 A R 2 3 9

Muffler :

Muffler with Catalytic Converter

1

A V 7 0 2 A R 2 3 9

Spark arresting screen

Take out the screws (1).

:

On machines with a removable stub (1) (with and without spark arresting screen), use a 15 mm wrench to unscrew the stub.

A V 8 0 2 A R 2 3 9

Muffler – Remove the fan housing with the rewind starter, 7.2 :

Take the screws (1) out of the muffler.

– Clean the spark arresting screen or install a new stub if necessary.

2

2

– Clean the thread of the stub and coat it with sealant, 12. 1

Follow the sealant manufacturer’s instructions.

1 :

Remove the muffler (1) and exhaust gasket (2).


A V 1 0 2 A R 2 3 9

– Screw home the stub and tighten it down firmly, 3.2

3 :

A V 9 0 2 A R 2 3 9

Remove the muffler (1) with exhaust gaskets (2) and flange (3).

13

7. 7.1

Rewind Starter General


Troubleshooting,

– Clean the sealing faces before installation.

If the action of the starter rope becomes very stiff and the rope rewinds very slowly or not completely, it can be assumed that the starter mechanism is in order but plugged with dirt. At very low outside temperatures the lubricating oil on the rewind spring may thicken and cause the spring windings to stick together. This has a detrimental effect on the function of the starter mechanism. In such a case it is sufficient to apply a few drops of a standard solvent-based degreasant (containing no chlorinated or halogenated hydrocarbons) to the rewind spring. Carefully pull out the starter rope several times and allow it to rewind until its normal smooth action is restored.

– Install new exhaust gaskets.

1

2 A V 0 1 2 A R 2 3 9

Spark arresting screen – Remove the fan housing with rewind starter, 7.2 :

Take out the screw (1).

:

Pull the spark arresting screen (2) out of the muffler.

7.2

Removing and Installing

4.1

:

Take out the screws (1+2).

– Remove the fan housing with rewind starter. :

If necessary, remove the antistatic wire (arrow).

If clogged with dirt or pitch, the entire starter mechanism, including the rewind spring, must be removed and disassembled. Take particular care when removing the spring. Clean all parts,

12.

Lubricate the rewind spring and starter post with STIHL special lubricant, 12, before installing.

– Clean the spark arresting screen, replace it if necessary. Install in the reverse sequence.

14


7.3

Starter Cup

Machines with starter cup integrated in flywheel: For servicing information see the chapter on “Flywheel” in the “Series 4140 Powerhead” service manual.

7.4

Rope Rotor

Remove the rewind starter, 7.2 3

Relieving tension of rewind spring

1 2

The rewind spring will not be under tension if the starter rope is broken.

A V 1 8 1 A R 2 3 9

– Pull out the starter rope about 10 cm and hold the rope rotor steady. Removing – While still holding the rotor steady, take three turns of the rope off the rotor. – Pull out the starter rope a little further and then let go of the rotor. The rotor spins back so that the rewind spring is no longer under tension.

The rewind spring must not be under tension. :

Remove the spring clip (1) from the starter post.

:

Remove the washer (2) and pawl (3).

– Carefully pull the rope rotor off the starter post. – Replace the broken or worn starter rope, 7.6 Installing – Coat the bore in the rope rotor with STIHL special lubricant, 12.

1 2 A V 2 8 1 A R 2 3 9

:


Fit the rotor on the starter post so that the driver (1) on the rope rotor slips behind the inner spring loop (2).

15

7.5

– Check that the spring loop has engaged by turning the rope rotor a little and letting it go. It must spring back. – Coat pawl with special lubricant and install, 12.

2

Replacing the Rewind Spring

– Remove the rope rotor,

7.4

– Remove the pieces of broken spring from the rope rotor and starter cover. – Before installing, lubricate the new spring with a few drops of STIHL special lubricant, 12.

Then grip the rewind spring with pointed nose pliers about 10 mm from the end of the outer loop and place it in the starter.

:

Check the distance of the inner spring loop from the hub and correct if necessary. Dimension "A" must not be more than 2 mm.

1

A V 4 8 1 A R 2 3 9

A V 3 8 1 A R 2 3 9

:

Fit the washer and engage the spring clip (1) in the groove in the starter post.

:

:

Make sure the spring clip (1) den engages the guide peg (arrow) on the pawl (2) and points clockwise.

The rewind spring may pop out and uncoil if the rope rotor is not installed very carefully.

Handle the spring clip with care. The rewind starter may not function properly if the spring clip is deformed. – Tension the rewind spring, 7.5.1

:

Position the rewind spring in the starter and press the outer spring loop over the lug (arrow).

If the rewind spring has popped out, refit it as follows:

– Install the rope rotor,

7.4

– Tension the rewind spring, 7.5.1

– Hold the spring in your hand and wind from the inside outwards and tension it to a diameter of 55 mm.

– Install the rewind starter, 7.2

16


7.5.1

Tensioning the Rewind Spring

7.6

Starter Rope

– Remove the rewind starter, 7.2 – If the starter rope is broken, remove the remaining rope from the rope rotor and starter grip. A V 9 8 1 A R 2 3 9

A V 7 8 1 A R 2 3 9

:

Make a loop in the unwound starter rope. Grip the rope close to the rotor and use it to turn the rotor six full turns clockwise.

The starter grip must sit firmly in the rope guide bush without drooping to one side. If this is not the case, tension the spring by one additional turn.

– If the starter rope is worn, relieve tension of rewind spring, 7.4. Pull the end of the rope out of the rotor and undo the knot. Then pull the worn rope out of the starter grip, housing and rotor.

When the starter rope is fully extended, it must still be possible to rotate the rope rotor at least another half turn before maximum spring tension is reached. If this is not the case, pull the rope out, hold the rope rotor steady and take off one turn of the rope. A V 8 8 1 A R 2 3 9

:

Hold the rope rotor steady.

:

Pull out the rope with the starter grip and straighten it out.

– Hold the starter grip firmly to keep the rope tensioned. – Let go of the rope rotor and slowly release the starter grip so that the rope winds itself onto the rotor.


Do not overtension the rewind spring as this will cause it to break. – Place the rewind starter in position, insert the screws and tighten them down firmly, 3.2

A V 0 9 1 A R 2 3 9

:

Thread one end of the new rope through the rotor and housing. Tie a simple overhand knot in the end of the rope.

– Pull the rope back into the rotor until the knot locates in the recess. – Thread the other end of the rope through the starter grip. Tie a simple overhand knot in the end of the rope.

17

7.7

Pawl

8. 8.1

Throttle Control Throttle Trigger

3

2

1

:

2

A V 5 6 0 A R 0 8 3

On machines with "ElastoStart": Thread end of new starter rope through the grip (1) and the spring element (2). Tie a simple overhand knot in the end of the rope. Pull the rope and spring element into the grip and then fit the cap (3).

– Tension the rewind spring, 7.5.1 – Install the rewind starter, 7.2

1

A V 3 8 1 A R 2 3 9

– Remove the rewind starter, 7.2 :

Ease the spring clip (1) off the starter post and pull the pawl (2) out of the rope rotor.

– Remove the handle molding, 5.1 :

On machines with a throttle cable, remove the throttle trigger (1) and disconnect it from the throttle cable.

Do not pull the rope rotor off the starter post. – Coat the new pawl with special lubricant, 12, and fit it in position. :

:

Push the spring clip (1) into the groove in the starter post.

2

1 A V 8 6 2 A R 2 3 9

Make sure the spring clip (1) engages the guide peg (arrow) on the pawl (2). :

The spring clip must point clockwise. Handle the spring clip with care. The rewind starter may not function properly if the spring clip is deformed.

On machines with a throttle rod (1), remove the throttle trigger (2) and disconnect it from the throttle rod.


– Install the rewind starter, 7.2

18


8.2

8

Setting Lever (BG 85, SH 85 only) 7

8.3 8.3.1

Stop Switch Version up to 2001

1

6 4

3 1 2

2

5 4 3 2

1

A V 6 2 2 A R 2 3 9

– Remove the handle molding, 5.1 :

:

Ease the E-clip (8) off the setting lever’s stub. :

:

Remove the cam (7).

:

Pull the setting lever (1) with washers (2, 5) and cup springs (3, 4) out of the handle molding (6).

A V 3 7 0 A R 2 3 9

A V 7 2 2 A R 2 3 9

Fit the cam (1) on the setting lever’s stub so that it lines up with the marking on the handle housing. Push the E-clip (2) in the groove on the setting lever’s stub.

Assemble all other parts in the reverse sequence.

:

Use a flat screwdriver to ease the stop switch (1) out of the handle molding.

:

Pull the connectors (2) (short circuit and ground wires) off the stop switch.

Install in the reverse sequence. Check correct positions of wires.

Reassemble in the reverse sequence. – Slip the washers (2, 5) and cup springs (3, 4) over the stub of the setting lever (1) and push it into the handle molding (6). Note the correct installed position of the two cup springs (3 and 4).


19

8.3.2

Version from 2001

8.4

Short Circuit Wire/ Ground Wire 1

2 1 3 1 A V 3 2 2 A R 2 3 9


2

A V 1 0 1 A R 2 3 9


A V 5 2 2 A R 2 3 9

BG 65, 85, SH 85 from 2001 only :

:

Use a flat screwdriver to ease the stop switch (1) and protective cap (2) out of the handle molding.

– Remove the stop switch, 8.3 :

:

Pull the connectors (3) (short circuit and ground wires) off the stop switch.

Remove the wire (1) from the housing peg.

Pull the connectors of the short circuit wire (1) and ground wire (2) off the ignition module.

Install in the reverse sequence. Check correct positions of wires.

1

A V 5 7 0 A R 2 3 9

All BG/SH units :

Pull the retainers (1) off the ignition lead.

:

Take the wires out of the guides (arrows) in the inner fan housing.


1

– Push home the wires so that they are properly seated in the guides in the inner fan housing. 2 A V 4 2 2 A R 2 3 9

BG 45, 55, SH 55 only, from 2001 – Remove the throttle trigger, 8.1 :

20

Remove the wire (1) from the throttle trigger’s pivot pin (2).


8.5

Throttle Cable

8.6

Throttle Rod

9. 9.1

2

A V 8 6 2 A R 2 3 9


:

Disconnect the throttle cable (1) from the throttle trigger (2), 8.1

:

Remove the throttle trigger (2) and disconnect the throttle rod (1).

:

Take the throttle cable out of the guides (arrows) in the inner fan housing.

:

Disconnect the throttle rod (1) from the carburetor.

Install in the reverse sequence. – Remove the carburetor,

9.2.2

Dirty air filters reduce engine power, increase fuel consumption and make starting more difficult. If there is a noticeable loss of engine power, check to see if the air filter is plugged with dirt.

1


Fuel System Air Filter

– Before removing the air filter, close the choke shutter and remove all loose dirt from around the filter. – Wash the foam filter in a standard solvent-based degreasant containing no chlorinated or halogenated hydrocarbons and then dry. Replace if necessary. – Replace the felt filter. As a temporary measure, knock the filter out on the palm of your hand or blow clear with compressed air. Do not wash. – Replace multi-ply felt filter. As a temporary measure, knock the filter out on the palm of your hand or blow clear with compressed air. Do not wash If a felt filter is replaced by a multiply filter, do not re-install the foam filter. Always replace a damaged air filter immediately.

:

Push the throttle cable (1) out of the tensioner (2). Remove the throttle cable.



21

9.1.1


9.1.2

– Knock the filter out on the palm of your hand or blow clear with compressed air. Do not wash. Replace if heavily loaded.

Choke Shutter

3 1 2

Always replace a damaged air filter immediately. A V 1 1 2 A R 2 3 9

:

A V 9 2 2 A R 2 3 9

Squeeze retainers together.

– Remove the air filter,

9.1.1

:

Remove the push nut (1).

:

Pull the choke shutter (2) out of the lever (3).

– When installing, make sure the choke shutter is properly located in the lever’s guide. 1

Use a new push nut. 2

A V 2 1 2 A R 2 3 9

1 :

Swing the filter cover (1) to the side and pull the lugs out of the guides (arrows).


A V 6 1 2 A R 2 3 9

Machines with catalytic converter :

Remove the gasket (1) and heat shield (2).

Use new gaskets. Install in the reverse sequence. 2 1

3

A V 7 1 2 A R 2 3 9

:

Pull the filter (1) out of the filter housing (3).

:

Unscrew the nuts (2) and remove the filter housing.

22


9.2 9.2.1

Carburetor Leakage Test

If you suspect a fault in the fuel system, see 4.2. In the case of problems with the carburetor or fuel supply system, also check or clean the tank vent, 9.5 The carburetor can be tested for leaks with the carburetor and crankcase tester 1106 850 2905. – Remove the air filter,

If this pressure remains constant, the carburetor is airtight. However, if it drops, there are two possible causes:

A V 2 8 0 A R 2 3 2

9.1.1

1. The inlet needle is not sealing (foreign matter in valve seat or sealing cone of inlet needle is damaged or inlet control lever sticking). 2. Metering diaphragm is damaged.

:

Push the fuel line with nipple onto the carburetor’s elbow connector (arrow).

In either of these cases the carburetor has to be serviced. – After completing the test, open the vent screw and pull the fuel line off the carburetor. – Push the fuel hose onto the carburetor’s elbow connector. Assemble all other parts in the reverse sequence. Always install a new gasket.

A V 3 8 0 A R 2 3 2

A V 5 1 2 A R 2 3 9

:

Disconnect the fuel hose from the carburetor’s elbow connector.

2

:

Connect the tester's pressure hose to the nipple.

1

3

2 A V 2 7 1 A R 3 4 1

:

Push the fuel line (1) 1110 141 8600 onto the nipple (2) 0000 855 9200.


1

:

A V 4 8 0 A R 2 3 2

Close the vent screw (1) on the rubber bulb (2) and pump air into the carburetor until the pressure gauge (3) shows a reading of approx. 0.8 bar.

23

9.2.2


Remove the air filter,

9.2.3

Spacer Flange

9.1.1

1 2 A V 4 3 2 A R 2 3 9

:

Remove the carburetor (1) and gasket (2).

– Remove the carburetor, :


9.1.1

On machines with throttle cable, pull the throttle cable (1) out of the spacer flange (2).

Always install the carburetor with new gaskets. Position the fuel hoses so that they are not kinked. Observe tightening torques,

3.2 1

2 A V 3 5 2 A R 2 3 9

A V 3 3 2 A R 2 3 9

:

Disconnect the fuel hoses from from the elbow connectors on the carburetor.

:

On machines with throttle cable, take out the screws (1) and remove the spacer flange together with the hex head screws (2).

2 2 1 1

A V 9 3 2 A R 2 3 9

:

On machines with throttle cable (1), disconnect throttle cable from slotted pin (2) on carburetor’s throttle lever.

A V 2 5 2 A R 2 3 9

:

On machines with throttle rod, take out the screws (1) and remove the spacer flange together with the hex head screws (2).

– On machines with throttle rod, remove the throttle rod, 8.6

24


9.3 9.3.1

Servicing the Carburetor Manual Fuel Pump with Oval End Cover

– Carry out leakage test,

9.2

– Remove the carburetor,

9.2.2

A V 4 5 2 A R 2 3 9

:

A V 8 5 2 A R 6 3 9

:

Pull the gasket (1) out of the guides (arrows) on the spiral housing.

Take the cap out of the end cover.

Install in the reverse sequence. Always install new gaskets. Observe tightening torques, 3.2

1

2

A V 3 2 2 A R 6 3 9

:

Take out the M3x12 screws (1).

:

Remove the end cover with cap (2).

A V 5 2 0 A R 6 3 9

:

Inspect the metering diaphragm and gasket and replace if necessary, 9.3.3

Reassemble in the reverse sequence. Additional holes in the gasket and diaphragm (if there are any) must line up with those in the carburetor and flange.

1

2

A V 4 2 2 A R 6 3 9


:

Take out the M3x8 screws (1).

:

Remove the flange (2).

25

9.3.2

Manual Fuel Pump with Square End Cover

9.3.3

1

Metering Diaphragm

1 2

A V 3 2 0 A R 6 3 9

:

A V 5 2 0 A R 6 3 9

:


– Remove the end cover with cap.

Inspect the metering diaphragm and gasket and replace if necessary, 9.3.3


A V 6 2 0 A R 6 3 9

– Remove flange from manual fuel pump with oval end cover, 9.3.1 – Remove flange from manual fuel pump with square end cover, 9.3.2 :

Remove the metering diaphragm (1) and gasket (2) from the carburetor body.

If the gasket and diaphragm are stuck together, remove and separate them very carefully. A V 5 8 2 A R 2 3 9

:

Take the cap out of the end cover.

:

Inspect the diaphragm and gasket and replace if necessary.

The diaphragm is a very delicate component. As a result of the alternating stresses the material eventually shows signs of fatigue, i.e. the diaphragm distorts and swells and has to be replaced. Reassemble in the reverse sequence.

A V 4 2 0 A R 6 3 9

:

26

Remove the flange.


9.3.4

Inlet Needle


1

1

– Engage clevis in annular groove on head of the inlet needle.

2

A V 7 2 0 A R 6 3 9

:

Fit the gasket (1) on the carburetor body.

A V 9 2 0 A R 6 3 9

– Remove the metering diaphragm, 9.3.3 :

Line up the hole in the gasket (2) with the compensating bore in the carburetor.

Make sure the helical spring locates on the control lever’s nipple. – Check that inlet control lever moves freely. Important: The upper edge of the inlet control lever must be flush with the top of the carburetor body.


– Install the metering diaphragm, 9.3.3 4 3

1

1

A V 8 2 0 A R 6 3 9

:

Place metering diaphragm (1) on the gasket.

Line up the hole in the metering diaphragm (1) with the compensating bore in the carburetor and gasket.

2 :

A V 0 6 2 A R 2 3 9

Remove the inlet control lever (4), spindle (3), spring (2) and inlet needle (1).

Take care with the spring (2) because it may pop out during disassembly.

Assemble all other parts, 9.3.1 and 9.3.2.

A V 0 2 1 A R 2 7 3

:


If there is an annular indentation (arrow) on the sealing cone of the inlet needle, it will be necessary to replace the inlet needle because it will no longer seal properly.

27

9.3.5

Fixed Jet

9.3.6

Take care not to damage the fixed jet when removing.

Pump Diaphragm and Fuel Strainer 1

– Remove the metering diaphragm, 9.3.3

2

A V 2 3 0 A R 6 3 9

– Remove the carburetor, :


:

Remove the end cover (2).

The diaphragm is a very delicate component. As a result of the alternating stresses the material eventually shows signs of fatigue, i.e. the diaphragm distorts and swells and has to be replaced. – Inspect the diaphragm and gasket and replace if necessary.

9.2.2

1

1

1 A V 5 2 2 A R 6 3 9

:

C1Q-S48, C1Q-S50, C1Q-S55 carburetors only :

A V 3 3 0 A R 6 3 9

A V 6 8 0 A R 6 3 9

:

Remove the gasket (1).

Examine the fuel strainer (1) for contamination and damage and replace if necessary.

Unscrew the fixed jet (1).

3 1

1

A V 4 3 0 A R 6 3 9

A V 1 3 0 A R 6 3 9

C1Q-S64, C1Q-S73 carburetors only

:

:

If the gasket and pump diaphragm are stuck together, remove and separate them very carefully.

Unscrew the fixed jet (1).


28

2

Remove the pump diaphragm (1).

1

A V 9 5 2 A R 2 3 9

Reassemble in the reverse sequence. :

The pump diaphragm (1) and gasket (2) are held in position by the pegs (arrows) on the end cover (3).


9.4 9.4.1

Adjusting the Carburetor Carburetor with LD Screw The carburetor with idle speed screw (LD) has no adjusting screws for maximum engine (H screw) or idle mixture (L screw).

9.4.2

User Adjustment of Carburetor with H, L and LA Screws L

LD

The carburetor is tuned so that the engine receives an optimum fuel-air mixture under all operating conditions.

H A V 0 9 0 A R 2 3 2

Standard setting When adjusting from scratch, first carry out the standard setting.

Adjusting idle speed

Standard setting

– Carry out standard setting.

The limiter cap must not be removed from the high speed screw (H) to carry out the standard setting.

– Start the engine and warm it up.

Engine stops while idling: :

Turn the idle speed screw (LD) (arrow) slowly clockwise until the engine runs smoothly.

LD

Erratic idling behavior, poor acceleration: A V 0 9 0 A R 2 3 2

:

Carefully turn the idle speed screw (LD) (arrow) counterclockwise (left-hand thread) down onto its seat.

:

Then turn the idle speed screw (LD) two full turns clockwise.

LA

A V 3 0 3 A R 2 3 9

:

Turn the idle speed screw (LD) slowly no more than half a turn counterclockwise.

With this carburetor it is only possible to correct the setting of the high speed screw (H) within fine limits. – Check the air filter and replace if necessary, 9.1.1 – Check the spark arresting screen, clean or replace it if necessary, 6.2

– Check the air filter and replace if necessary, 9.1 – Check the spark arresting screen, clean or replace as necessary, 7.2


29

– At high altitude (mountains): Turn the high speed screw (H) clockwise (leaner), but no further than stop, until there is no noticeable increase in engine speed.

L

H

LA

A V 3 0 3 A R 2 3 9

Now make the following adjustments: :

Turn the high speed screw (H) counterclockwise as far as stop (no more than 3/4 turn)

– At sea level: Turn the high speed screw (H) counterclockwise (richer), but no further than stop, until there is no noticeable increase in engine speed.

Erratic idling behavior – Idle setting is too rich. Turn the low speed screw (L) clockwise (about a quarter turn) until the engine runs and accelerates smoothly. It is usually necessary to change the setting of the idle speed screw (LA) after every correction to the low speed screw (L).

It is possible that the standard setting produces the highest engine rpm in both the above cases.

Adjusting idle speed :

Carefully turn the low speed screw (L) clockwise until it is against its seat, then open it one full turn counterclockwise.

– Open the low speed screw (L) one full turn. – Allow the engine to warm up.

– Start the engine and allow it to warm up. Engine stops while idling Fine tuning A minor correction may be necessary when operating at high altitude or at sea level. Note that even very slight corrections to the high speed screw (H) produce a noticeable change in engine running behavior. – Carry out the standard setting. – Start the engine and allow it to warm up.

– Turn the idle speed screw (LA) slowly clockwise until the engine runs smoothly.

Erratic idling behavior, poor acceleration – Idle setting is too lean. Turn the low speed screw (L) counterclockwise (about a quarter turn) until the engine runs and accelerates smoothly.

– Open the throttle wide.

30


9.4.3

Basic Setting on Carburetor with H, L and LA Srews The limiter cap has to be removed from the high speed screw (H) only if it is necessary to replace the high speed screw (H), clean the carburetor or adjust it from scratch.

Adjusting idle speed – Check the air filter and clean or replace as necessary. – Warm up the engine.

1

After removing the limiter cap it is necessary to carry out the basic setting.

A V 5 1 3 A R 2 3 9

:

On carburetors with a long limiter cap (1): Use suitable pliers to pull off the limiter cap.

– Screw down both adjusting screw (H and L) clockwise until they are against their seats. Now make the following adjustments:

Adjust idle speed with a tachometer. Adjust specified engine speeds within a tolerance of +/- 200 rpm. 1. Adjust engine speed with idle speed screw (LA) to 3,300 rpm. 2.Turn low speed screw (L) clockwise or counterclockwise to obtain maximum engine speed. If this speed is higher than 3,700 rpm, abort the procedure and start again with step 1. 3. Use the idle speed screw (LA) to set engine speed again to 3,300 rpm

2 :

1

4. Set the engine speed to 2,800 rpm with the low speed screw (L).

A V 6 1 3 A R 2 3 9

5. Set maximum engine speed to 10,500 rpm with the high speed screw (H).

On carburetors with a short limiter cap (1): Push the puller (2) 5910 890 4501, with the groove facing you, between the limiter cap (1) and carburetor body and pry the cap off. If the l imiter cap is stuck on the screw, turn the puller over so that its groove faces the carburetor body. Pry off the limiter cap.

Do not re-install used caps because they may be damaged during the removal process. Always install a new limiter cap.

H

L

A V 7 1 3 A R 2 3 9

– Open the high speed screw (H) 1 1/2 turns counterclockwise. – Open the low speed screw (L) one full turn counterclockwise.


31

9.5 9.5.1

270°

270 A V 9 2 1 A R 9 4 2

A V 8 1 3 A R 2 9 3

Tank Vent General

Correct operation of the carburetor is only possible if atmospheric pressure and internal fuel tank pressure are equal at all times. This is ensured by the tank vent. In the event of trouble with the carburetor or the fuel supply system, always check the tank vent and replace it if necessary.

Testing the tank vent :

On carburetors with a short limiter cap: Line up the new cap for the high speed screw (H) against the rich stop and press it on only as far as the second noticeable detent position.

:

The stop limits the adjustment range of the high speed screw (H) to a 3/4 turn. Do not press the cap against the carburetor body as it will otherwise be damage.

:

– Carry out standard setting, 9.4.2

On carburetors with a long limiter cap: Line up the new cap for the high speed screw (H) against the rich stop so that the high speed screw (H) can only be rotated a 3/4 turn clockwise. Push on the limiter cap until it butts against the carburetor body.

Carry out standard setting,

9.4.2

– Open the tank cap slowly and drain the tank. Refit the tank cap, making sure it is tight. – Disconnect the fuel hoses from the carburetor, 9.2.2 – Seal one of the fuel hoses with a suitable plug. – Connect vacuum pump 0000 850 3501 to the other fuel hose and produce a vacuum in the fuel tank by operating the pump quickly. – If the vacuum remains unchanged, install a new tank vent, 9.5.2 If the vacuum slowly disappears, the tank vent is in order.

32


9.5.2

Replacing

9.6 9.6.1

If no equalization of pressures takes place, replace the tank vent. – Remove the filter housing, 9.1.1 Note installed position of tank vent.

Fuel Tank General

Always use a new sealing ring.

Fuel tank


The fuel tank is part of the inner fan housing and cannot be replaced separately. If the fuel tank is damaged, replace the complete inner fan housing. The diaphragm pump draws fuel out of the tank and into the carburetor via the fuel hose. Any impurities mixed with the fuel are retained by the pickup body (filter). The fine pores of the filter eventually become clogged with minute particles of dirt. This restricts the passage of fuel and results in fuel starvation. Always observe all safety precautions when working on the fuel system, 2.

1 A V 6 9 0 A R 2 3 9

2

In the event of trouble with the fuel supply system, always check the fuel tank and the pickup body first. Clean the fuel tank if necessary.

Cleaning the fuel tank – Unscrew the fuel filler cap and drain the tank.

Machines up to 2002 :

Pull out the tank vent (1).

:

Pull out the grommet (2).

– Pour a small amount of clean gasoline into the tank. – Close the tank and shake the machine vigorously.

Install in the reverse sequence. – Open the tank again and drain it. Dispose of fuel properly.

1

2

A V 1 2 3 A R 2 3 9

Machines from 2002 :

Carefully pry out the tank vent (1) with sealing ring (2).


33

9.6.2

Pickup Body

9.6.3

Fuel Hoses

– Unscrew the fuel filler cap and drain the tank. – Remove the fan housing with rewind starter, 7.2 – Remove the carburetor,

9.2.2

– Unscrew the spark plug. – Use locking strip 4221 893 5900 to block the piston. – Remove the blower tube and elbow, 10.4 and 10.6

– Remove the pickup body.

– Unscrew the fuel filler cap and drain the tank. :

– Pull off the tank vent, 9.5.2

Use hook (1) 5910 893 8800 to pull the pickup body out of the fuel tank.

A V 4 6 1 A R 2 3 9

:

Pull the pickup body (1) off the fuel hose and check it for contamination, replace if necessary.

:

Pull out the fuel hoses (arrow).

Note installed position.

BG 55, 65, 85 only :

Take out the screws and lift away the outer fan housing.

Install in the reverse sequence. Install in the reverse sequence.

A V 2 6 1 A R 2 3 9

:

34

On BG 45, take out the screws and lift away the outer fan housing.


10. 10.1

Blower and Vacuum Attachment Fanwheel

10.2

Protective Screen (all except BG 45)

10.3

Protective Screen (BG 45 only)

1

1

1

2 A V 3 6 1 A R 2 3 9

SH 55, 85 only :

A V 1 6 1 A R 2 3 9

SH units only

Unscrew the star nut (1), take out the screws and lift away the outer fan housing.

– Remove suction tube, :

10.5

A V 6 6 1 A R 2 3 9

:


:

Lift the right-hand side of the protective screen so that it comes out of the guide (2)

Press down the retaining tab (1) on the protective screen and swing the screen open.

1

1

3

2

4 A V 5 6 1 A R 2 3 9

:

Unscrew the nut (1) clockwise (left-hand thread).

:

On SH 55, 85, remove the shredder blade (2).

:

Remove the washer (3), fanwheel (4) and the washer behind it.

A V 7 6 1 A R 2 3 9

:

Use a screwdriver or similar tool to press down the retaining tabs (1) on the outer fan housing and lift away the protective screen (2).

– Remove the protective screen. :

Before reinstalling, check the seal (1) for damage and make sure it is properly seated.

Install in the reverse sequence. – Make sure the protective screen engages in the guide.

– Inspect all blades and replace fanwheel if necessary. Install in the reverse sequence.

:

Remove the torsion spring (arrow).



35

10.4

Blower Tube (BG only)

10.5

Suction Tube (SH only)

10.6

Elbow (SH only)

1

A V 4 9 0 A R 2 3 9

:

Insert a screwdriver or similar tool in the recess (arrow) on the blower stub and push the retaining tab up.

:

Turn the suction tube counterclockwise as far as stop (1/4 turn).

A V 8 6 1 A R 2 3 9

:

Loosen the star nut (1).

:

Insert a screwdriver or similar tool in the recess (arrow) on the blower stub and push the retaining tab up.

– Pull the suction tube off the stub. – At the same time, turn the blower tube counterclockwise as far as stop (1/4 turn).

To fit, open the protective screen. – At the same time, turn the elbow counterclockwise as far as stop (1/4 turn).

– Pull the blower tube off the stub. – Fit by inserting blower tube with lug in the stub.

– Pull the elbow off the stub. – Fit by inserting blower tube with lug in the stub.

– Rotate the blower tube clockwise until the bayonet coupling engages.

A V 9 6 1 A R 2 3 9

:

Insert suction tube so that its guide slots (arrow) engage the lugs (arrow) on the stub.

– Rotate the suction tube clockwise until the bayonet coupling engages.

36

:

Check that rubber sealing ring (arrow) is properly seated.

– Rotate elbow clockwise until the bayonet coupling engages.


11.

Special Servicing Tools

No.

Part Name

Part No.

Application

1 2

Locking strip Socket

4221 893 5900 0812 540 1112

3

Vacuum pump

0000 850 3501

4

Carburetor and crankcase tester

1106 850 2905

5 6 7

Nipple Hose for leakage test Screwdriver Q-SW 8 x 200

0000 855 9200 1110 141 8600 5910 890 2420

Blocking crankshaft Installing and removing spline socket head screws with electric or pneumatic screwdrivers Testing crankcase and carburetor for leaks, testing tank vent Testing crankcase and carburetor for leaks Testing carburetor for leaks Testing carburetor for leaks Carburetor nuts

8 9 10 11

Crimping tool Torque wrench Torque wrench Socket, T 27 x 125

5910 890 8210 5910 890 0301 5910 890 0311 0812 524 2104

12

T-handle screwdriver Q-T27x150 Hook

5910 890 2400

Attaching connectors to electrical wires 0.5 to 18 Nm 6 to 80 Nm Installing and removing spline socket head screws with electric or pneumatic screwdrivers, tightening with torque wrench IS screws

5910 893 8800

Removing pickup body

13

Rem.

1) 2) 1) 3)

4)

Remarks: 1)

Always use torque wrench for tightening DG or P screws.

2) 3)

Alternative: Torque wrench 5910 890 0302 with optical/acoustic signal. Alternative: Torque wrench 5910 890 0312 with optical/acoustic signal.

4)

Only use for releasing/removing DG or P screws.


37

12.

Servicing Aids

No.

Part Name

Part No.

Application

1

Dirko gray sealant (100 g tube)

0783 830 2120

Guard on muffler

2

STIHL special lubricating oil

0781 417 1315

Bearing bore in rope rotor, rewind spring

3

Standard commercial, solventbased degreasant containing no chlorinated or halogenated hydrocarbons

38

Cleaning sealing faces



39

40


BG85 Shop Manual

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