Husqvarna 455 Rancher Instruction manual

Workshop manual
English
455 Rancher 460

2– English
Workshop manual
Husqvarna 455 Rancher and 460
Contents
Introduction ........................................................... 3
Safety regulations ................................................ 4
General instructions ........................................... 4
Special instructions ............................................ 4
Special tools ......................................................... 5
Technical data ....................................................... 7
Carburettor ............................................................ 9
Carburettor ........................................................ 9
Carburettor - pressure testing .......................... 14
Carburettor - adjustment .................................. 15
Troubleshooting ................................................. 17
Repair instructions ............................................. 19
Chain brake ...................................................... 19
Silencer ............................................................ 21
Chain catcher ................................................... 21
Stop switch ....................................................... 22
Stop switch – resistance measurement............ 22
Choke control ................................................... 23
Throttle trigger .................................................. 24
Starter assembly .............................................. 25
Starter cord....................................................... 25
Recoil spring..................................................... 26
Ignition module – testing .................................. 27
Ignition module and flywheel ............................ 27
Centrifugal clutch.............................................. 29
Oil pump ........................................................... 30
Air intake system ............................................. 32
Fuel filter........................................................... 33
Fuel hose.......................................................... 33
Fuel tank........................................................... 34
Piston and cylinder ........................................... 34
Decompression valve – pressure testing ......... 35
Cylinder – pressure testing............................... 37
Crankshaft complete ........................................ 37
Crankshaft bearings ......................................... 38
Thread insert .................................................... 39
Guide bar bolts ................................................. 39

English – 3
Arrangement of the manual
This workshop manual can be used in two different
ways.
• To repair a specific sub-assembly on a chainsaw.
• To dismantle and reassemble a complete chain-
saw.
Repairing a specific sub-assembly
If a specific sub-assembly on the chainsaw needs
to be repaired:
1. Look up the page referring to the relevant sub-
assembly.
2. Follow the instructions under the headings:
• Removal/Dismantling
• Cleaning and inspection
• Refitting/Reassembly
Dismantling and reassembling the entire chainsaw
If the entire chainsaw is to be dismantled, follow
the instructions under the heading “Removal/Dis-
mantling”.
Work through the manual and follow the instruc-
tions given in each section under the heading
“Removal/Dismantling”.
Then follow all the “Cleaning and inspection” ins-
tructions in each section.
Working from the back of the manual, follow all the
instructions under the headings “Refitting/Reas-
sembly” in reverse order.
Each of the sections covering removal/dismantling
and refitting/reassembly include the relevant lubri-
cation instructions and bolt torques for each stage
of repair.
Construction and function
This chapter gives a simple description of the
chainsaw carburettor and its various parts.
Introduction
Troubleshooting
These pages describe the most common faults that
affect a chainsaw. They are divided into four dif-
ferent groups with the most likely faults described
first.
Repair instructions
The section that describes how to repair the chain-
saw consists of detailed, step-by-step instructions.
It explains in detail the special tools, lubricants
and bolt torques that are needed when working on
each component.
This workshop manual covers the following
chainsaw models: 455 Rancher
460

4– English
General instructions
This workshop manual gives detailed instructions
on how to troubleshoot, repair and test a chain-
saw. This section also describes the various safety
precautions that should be taken when carrying out
repairs.
The workshop manual has been written for person-
nel who are assumed to have general experience
of repairing and servicing chainsaws.
Workshops where chainsaws are repaired must be
equipped with safety equipment that meets local
regulations.
No-one should carry out repairs on a chainsaw
until they have read and understood the contents
of this workshop manual.
Chainsaws are type-approved to meet the rele-
vant safety legislation, but this only applies when
the saw is fitted with the cutting equipment speci-
fied in the user’s manual. The fitting of any other
equipment, or of accessories or parts that are not
approved by Jonsered, could mean that the saw
no longer meets these safety requirements and
the person who carried out the work may be held
responsible for its non-conformance.
In this workshop manual the following boxes indi-
cate where caution should be taken.
Special instructions
The fuel that is used in a chainsaw poses the fol-
lowing hazards:
• The fuel and its fumes are toxic.
• May cause irritation to skin or eyes.
• May cause breathing difficulties.
• Highly flammable.
When using compressed air the air jet should
never be pointed at the body. Air can be forced into
the bloodstream and cause fatal injury.
Wear ear protection when testing saws.
After testing a saw do not touch the silencer until
it has cooled down. The silencer gets very hot and
you may burn yourself. Wear protective gloves
when working on the silencer.
The guide bar, chain and clutch cover (chain
brake) must be fitted before the saw is started. If
not, the clutch may come loose and cause injury.
Poor chain lubrication can result in failure of the
chain, which could cause serious or fatal injury.
Take care to ensure that the spring inside the
starter assembly does not fly out and cause injury.
Wear eye protection. If the spring is under
compression when the pulley is removed it could
fly out and cause injury.
Before removing the tensioning spring from the
chain brake, ensure that the brake is in the on
position, otherwise the spring may fly out and
cause injury.
After completing the repair the chain brake must be
tested, see “Chain brake – reassembly \ Operating
test”.
Always consider the fire risk. A chainsaw can
produce sparks that could start a fire.
Inspect the chain catcher and replace it if it is
damaged.
WARNING!
The warning text warns of the risk
of personal injury if the instruc-
tions are not followed.
NOTE!
The warning text warns of the risk of ma-
terial damage if the instructions are not
followed.
Safety regulations
Safety regulations

English – 5
10
Special tools
45
8
123
6
7
9
Special tools

6– English
Item Description Used for Order no.
1 Clutch tool Centrifugal clutch 502 54 16-01
2 Piston stop Locking the crankshaft 504 91 06-05
3 Fuel filter hook Withdrawing the fuel filter 502 50 83-01
4 Allen key For M5 bolts 502 50 18-01
5 Pressure tester Pressure testing cylinder 503 84 40-02
6 Feeler gauge Adjusting ignition module 502 51 34-02
7 Assembly fixture Assembling chain saw 502 51 02-01
8 Pressure gauge Pressurisation during testing 531 03 06-23
9 Test spark plug Checking the ignition module 502 71 13-01
10 Rev counter Adjusting carburettor 502 71 14-01
11 Assembly pliers Fitting spark plug guard 502 50 06-01
12a Cover plate, exhaust Sealing the exhaust port 502 54 11-02
12b Cover plates, inlet Sealing the intake manifold 502 52 48-02
13 Assembly tool Assembling spring, chain brake 502 50 67-01
14 Puller Pulling bearing of crankshaft 504 90 90-01
15a Sleeve Fitting crankshaft 502 50 30-18
15b Shaft extension Flywheel side 502 50 30-18
15c Shaft extension Cluch side 502 50 30-18
16 Punch Dismantling the flywheel 502 51 94-01
11 12a
13 14
12b
15a
15c
15b
16
Special tools

English – 7
Displacement Cylinder bore Stroke Max power/speed
cm3/cubic inches Ø mm/Ø inches mm/inches kW/hp/rpm
455: 55,5 / 3,38 47 / 1,85 32 / 1,28 2,6 / 3,5 / 9 000
460: 60,3 / 3,68 49 / 1,93 32 / 1,28 2,7 / 3,7 / 9 000
Spark plug gap Ignition system Air gap Carburettor type
mm/inches mm/inches
455: 0,5 / 0,02 SEM CD 0,3 / 0,012 Walbro WTA 29
460: 0,5 / 0,02 SEM CD 0,3 / 0,012 Walbro WTA 29
Effective cutting length Chain speed at Chain pitch Drive link
cm/inches max power – revs mm/inches mm/inches
m/s – rpm
455: 31-50 / 13-20 20,0 / 9 000 9,52 / 3/8 1,3 / 0,050 - 1,5 / 0,058
460: 31-50 / 13-20 20,0 / 9 000 8,25 / 0,325 1,3 / 0,050 - 1,5 / 0,058
Technical data
Technical data

8– English
Idling speed Engagement speed Spark plug
rpm rpm
455: 2 700 3 800 NGK BPMR 7A
Champion RCJ 7Y
460: 2 700 3 800 NGK BPMR 7A,
Champion RCJ 7Y
Fuel tank capacity Oil pump capacity at Oil tank capacity Automatic oil pump
Litres/US pints 8,500 rpm, Litres/US pints
ml/min
455: 0,44 / 0,93 9 0,32 / 0,68 Yes
460: 0,44 / 0,93 9 0,32 / 0,68 Yes
Weight without Weight with
bar and chain bar and chain
kg / lbs kg / lbs
455: 5,8 / 12,8 6,2 / 13,6
460: 5,8 / 12,8 6,2 / 13,6
rpm
GAS
OIL
Technical data

English – 9
Carburettor
WARNING!
The fuel used in the chainsaw has
the following hazardous properties:
1. The fluid and its fumes are
poisonous.
2. Can cause skin irritation.
3. Is highly inflammable.
Carburettor
Description
The drawings accompanying this description do
not correspond with the carburettor on the chain-
saw. They only show the principle for the design
and function.
Design
The carburettor is based on three sub-systems:
• The metering unit, A.
• The mixing venturi, B.
• The pump unit, C.
The jets and the fuel’s control functions are located
in the metering unit (A). Here the correct quantity
of fuel is adjusted for the actual speed and power
output.
A
B
C
The mixing venturi (B) houses the choke, throttle
valve and diffuser jets. Here air is mixed with the
fuel to give a fuel/air mixture that can be ignited by
the ignition spark.
In the pump unit (C), fuel is pumped from the fuel
tank to the metering unit. One side of the pump di-
aphragm is connected to the crankcase and pulses
in time with the pressure changes in the crankcase.
The other side of the diaphragm pumps the fuel.
Carburettor

10 – English
Function
The carburettor operates differently in the following
modes:
• Cold start mode
• Idling mode
• Part throttle mode
• Full throttle mode
In the cold start mode (see figure below) the choke
valve (H) is fully closed. This increases the vacuum
in the carburettor so that fuel is sucked more easily
from all the diffuser jets (D, E and F). The throttle
valve (I) is partly open. Extra air inlet (J) is closed.
I
H
G
DF
E
J
In the idling mode (see figure below) the throttle
valve (I and J) is closed and the choke valve (H) is
open.
Air is sucked in through an aperture in the throttle
valve and a small amount of fuel is supplied th-
rough the diffuser jet (D).
In the part throttle mode (see figure below) the th-
rottle valve (I) is partially open and the choke valve
(H) is open. Fuel is supplied through the diffuser
jets (D and E).
In full throttle mode (se figure below) all valves
are open and fuel is supplied through all diffuser
jets (D, E, F and G). Extra air inlet (J) is also fully
opened.
I
D
H
E
IH
D
G
DF
E
H
I
J
Carburettor

English – 11
Carburettor – removal
1
Remove the cylinder cover and air filter. Discon-
nect the leads from the stop switch and the short
circuit spring, and the fuel hoses from the carburet-
tor.
NOTE!
Do not use knurled pliers to disconnect or
reconnect the fuel hose. This could damage
the hose and lead to leakage or fracture.
5
Remove the cover (A) over the metering unit and
carefully remove the metering diaphragm (B) and
gasket. See figure below.
6
Remove the screw (E) and take out the needle
valve (D) with lever (C), pin and spring. See figure
below.
2
Dismantle the throttle actuator rod by pulling out
and lifting up C from its seating. Remove the
throttle actuator rod from the lever and then from
the handle.
C
B
B
3
Loosen the carburettor’s rubber mountings (B).
A
B
C
D
E
4
Loosen the screws (x4,D) on the carburettor. Lift
the carburettor out of the carburettor compartment.
D
DD
D
Carburettor

12 – English
WARNING!
Never direct the compressed air jet
towards the body. Air can penetrate
into the blood circulation, which
means mortal danger.
WARNING!
Fuel has the following hazardous
properties:
1. The fluid and its fumes are poi-
sonous.
2. Can cause skin irritation.
3. Is highly inflammable.
Cleaning and inspection
See figures on previous page and check the fol-
lowing:
1
That gaskets, pump and control diaphragms are
undamaged.
2
That there is no play on the throttle and choke valve
shafts.
3
The needle valve and lever are not worn at C and D in
figure on previous page.
4
The fuel filter is undamaged.
5
The tips of the high and low speed needles are not
damaged.
8
Use a needle or the like to carefully remove the
fuel filter (F). See figure below.
9
Remove caps with the high and low speed screws.
See figure below number 10.
10
If necessary, remove the throttle and choke valves
and remove the shafts together with levers and
springs. See figure below.
6
The intake manifold is undamaged.
7
The carburettor has an extra air shutter connected
in parallel with the ordinary throttle valve. The shut-
ter housing with shaft is secured in the carburettor
using two screws.
Clean all units in clean petrol.
Use compressed air to dry the petrol on the com-
ponents. Direct the air through all channels in the
carburettor housing and make sure that they are
not blocked.
F
G
I
J
Carburettor
7
Remove the cover (J) over the pump unit and
carefully remove the gasket (I) and pump diaphragm
(G). See figure below number 8.

English – 13
Assembly
Where no figure is referred to, see figure on the
previous page.
Maintain a high level of cleanliness when assem-
bling the carburettor. The slightest contamination
can result in running problems.
1
If the throttle and choke valves, together with
levers and springs were removed, they should be
refitted. Lubricate the shaft bearings with light oil.
2
Fit the high and low speed needles and springs.
Note! Do not fully tighten the screws. This will da-
mage the seats and needle tips.
3
Fit the fuel filter (F) by using the handle of a small
screwdriver. See figure below.
4
Fit the pump diaphragm (G), gasket (I) and cover
(J) on the pump unit. See figure below.
F
G
I
J
7
Fit the control diaphragm (B) with gasket and cover
(A) on the metering unit. See figure below.
A
B
5
Fit the needle valve (D) with lever (C), pin and
spring and tighten the screw (E). Fit welch plug (K).
See figure below.
6
Check with a ruler or the like that the lever is level
1.65 mm below plane. See figure below. If neces-
sary, the lever can be bent slightly.
C
D
E
K
Carburettor

14 – English
Pressure testing
Pressure testing should be carried out with the car-
burettor fully assembled. Testing should always be
carried out after the carburettor has been repaired,
but it can also be carried out as trouble shooting
before dismantling the carburettor.
See figure below and carry out the test as follows:
Leakage at Fault with
Diffuser jets Needle valve
Leakage in impulse tube Pump diaphragm
Ventilation hole
on metering unit. Control diaphragm
9
Carry out a pressure test.
1
Unscrew the high and low speed screws one turn
from closed position.
2
Connect pressure tester to the carburettor’s fuel
intake.
3
Lower the carburettor into a beaker of water.
4
Pump the pressure up to 50 kPa (0.5 bar).
5
No leakage is permitted. If a leakage occurs refer
to the table below.
Carburettor – refitting
NOTE!
Cleanliness is very important when reas-
sembling the carburettor. Tiny particles of
dirt can cause operating problems.
2
Tighten the carburettor screws (x4,C) with a torque
of 1-1.5 Nm. Fit the fuel hoses (x2,D). Fit the
throttle actuator rod and press down its lock.
1
Position the carburettor in the carburettor compart-
ment. Fit the carburettor in the rubber mountings (B).
B
B
A
L
A
A
P
A
N
P
3
Connect the leads to the stop switch and the short
curcuit spring. Fit the air filter and cylinder cover.
Carburettor
8
Fit the air shutter blade on the shaft (L) and con-
nect the throttle actuator rod (N) in parallel with the
ordinary throttle valve. The valve housing (P) is
secured in the carburettor using two screws.
C
CC
C
D
D

English – 15
Basic adjustment for EPA II saws with capsed
carburettors
Model 455 and 460 are equipped with capsed
carburettors. A slightly different adjustment proce-
dure is necessary when replacing the carburettor
or needles.
Capsed carburettor
This means that this chain saw is equipped with
movement limiters on the carburettor’s adjuster
screws. These limit the adjustment range to a
maximum of 1/2 turn.
1/2
1/2
HL
Replacement of the H-needle or complete car-
burettor
1. Carefully screw the new H-needle to the bottom
and turn it anticlockwise ”A” turns.
455 A = 2 1/2
460 A = 2 1/2
2. Check that:
The H-cap is adjusted to its richest setting (tur-
ned counterclockwise to stop).
The cap is not fixed to the needle, it should
rotate independently.
Adjust the L-cap to a center position (1/4 turn coun-
terclockwise = minimum, 1/4 turn clockwise = maxi-
mum).
3. Start the engine. If necessary, adjust the idling
speed with the T-screw until the chain stops.
4. Adjust the H-needle to give a top speed of ”B”
rpm. Use a tachometer.
455 B = 12 500
460 B = 12 500
Use a narrow blade screwdriver (ref.no. 531 00 48-
63) and insert it through the hole in the cap (max.
blade width 2 mm/0,08 inch).
After replacing the carburettor or high speed and/or
low speed needle on an EPA (The US Environme-
ntal Protection Agency) certified product, a basic
adjustment must be carried out as described below
in order to meet the EPA-requirements. This to
achieve as low emissions as possible. This instruc-
tion is made for EPA certified products only.
On EPA carburettors both the H- and L-needles are
fitted with caps to prevent the chain saw operator
from changing the adjustment above EPA stan-
dard. The caps can be removed to achieve richer
or leaner adjustments. To set the needles correctly
an adjustment sleeve is fitted from the factory over
the caps to lock them in maximum allowed set-
tings.
When correctly set the caps must be fixed on the
needles. The adjustment sleeve then can be remo-
ved. Over the caps on complete sparepart carbu-
rettor, there is a plastic sleeve which is intended to
lock the caps at the richest position (anticlockwise
towards stop) during the time that the needles
are adjusted. When the adjustment is complete
and the caps have been fixed on the needles, the
sleeve is no longer of any function and can be
removed.
Conditions
• The air filter should be clean and the cylinder
cover fitted when adjustments are made. Adjus-
ting the carburettor with a dirty air filter will give
a too lean fuel mixture the next time the air filter
is cleaned. This can result in serious damage to
the engine.
• Mount, for this model, approved bar and
chain combination (see Technical data in the
Operator's Manual).
455 16"
460 16"
• The chain should not be tensioned more than
that it remains ~ 0,2 inches to the bar.
Carburettor

16 – English
5. Let the engine run at ”B” rpm ~ 1 minute, until
warm.
6. Close the H-needle to a top speed of ”C” rpm.
455 C = 13 500
460 C = 13 500
7. Check that the H-cap is still adjusted to its
richest setting (turned counterclockwise to stop).
Note! The H-needle must not rotate!
8. Gently knock the H-cap into position. Use a
5 mm/0,2 inch mandrel (for example the locking
pin for the bevel gear ref. no. 502 02 61-03).
This is a basic carburettor adjustment. Further
fine adjustments, within the limits the caps allow,
may be necessary to achieve optimum perfor-
mance. See the Operator's Manual.
Replacement of the L-needle
1. Take off the cap from the L-needle using a pair
of cutting pliers and unscrew the needle.
2. Screw the new L-needle to the bottom and then
turn it counterclockwise ”D” turns.
455 D = 1 1/2
460 D = 1 1/2
3. Press a new L-cap on the L-needle to the first
stop, which means that the cap is not fixed to
the needle, it should rotate independently.
4. Adjust the L-cap to the richest position (turned
counterclockwise to stop) without turning the
needle.
5. Let the engine run at ~ ”E” app. 1 minute until
warm and then let it run on idle.
455 E = 12 500
460 E = 12 500
6. Adjust the idle speed to ”F” rpm.
455 F = 2700
460 F = 2700
7. Adjust the L-needle until the highest possible
idling speed is achieved and then turn the L-
needle 1/2 turn counterclockwise. Use a narrow
blade screwdriver (ref.no. 531 00 48-63) and
insert through the hole in the cap (max. blade
width 2 mm/0,08 inch). Note! If the chain rotates,
turn the idling speed screw (T) counterclockwise
until the chain stops.
8. Check that the L-cap is still adjusted to its ri-
chest position (turned counterclockwise to stop).
Note! The L-needle must not rotate!
9. Gently knock the L-cap into position. Use a
5 mm/0,2 inch mandrel (for example the locking
pin for the bevel gear ref.no. 502 02 61-03). This
is a basic carburettor adjustment. Further fine
adjustments, within the limits the caps allow,
may be necessary to achieve optimum perfor-
mance. See the Operator's Manual.
Carburettor

English – 17
Troubleshooting
Worn needle valve
Leaking control diaphragm/cover
plate
Needle valve assembly sticking
Worn needle valve lever
Faulty diffuser jet
Fuel filter blocked
Fuel line blocked
Leaking air intake hose (rubber)
Loose carburettor mounting
bolts
Worn throttle valve pivot
Loose throttle valve screw
Worn throttle valve
Needle valve assembly sticking
Leak in metering system (air
or fuel)
Metering system centre knob
is worn
Hole in diaphragm
Leaking control diaphragm/cover
plate
Crankcase leaking
Fuel line blocked
Needle valve set too high
Needle valve assembly sticking
Leak in metering system (air
or fuel)
Leaking control diaphragm/cover
plate
Faulty diffuser jets
Crankcase leaking
Needle valve set too high
Needle valve assembly sticking
Metering system damaged
Worn needle valve
Leaking control diaphragm/cover
plate
Metering system incorrectly
assembled
Adjust L screw
Air filter blocked
Choke not working
Worn choke pivot
Worn choke valve
Fuel filter blocked
Fuel line blocked
Piston ring seized
Blocked impulse channel
Loose or faulty fuel pipe
Hole in diaphragm
Worn needle valve
Needle valve assembly sticking
Needle valve set too high
Leak in metering system (air
or fuel)
Loose cover on carburettor
pump side
Worn needle valve
Needle valve set too high
Needle valve assembly sticking
Difficulty starting
Carburettor
leaking fuel
Flooding when
engine not
running
Starting
The various faults that can affect a chainsaw are divided into four groups. In each group the likely
symptoms are given on the left and possible causes are listed on the right. The most likely faults are
given first, and so on.
Idling (low rpm)
Idles when L
screw closed
Idling uneven
L screw requires
constant adjust-
ment
Too much fuel at
idling
Idling (low rpm) (cont.)
Adjust L screw
Leaking air intake hose (rubber)
Loose carburettor mounting
bolts
Loose or faulty fuel hose
Fuel filter blocked
Fuel line blocked
Fuel tank vent blocked
Throttle valve pivot stiff
Throttle pushrod sticking
Defective throttle return spring
Bent throttle stop
Faulty diffuser jet
Adjust L screw
Worn needle valve
Needle valve set too high
Worn needle valve lever
Leaking control diaphragm/cover
plate
Needle valve assembly sticking
Will not idle
Idling too rich
Troubleshooting

18 – English
Acceleration and retardation
Does not
accelerate
Engine stalls
when throttle
released
Over rich
acceleration
Adjust L screw
Adjust H screw
Blocked air filter
Blocked fuel tank vent
Blocked fuel filter
Fuel line blocked
Loose or damaged fuel hose
Impulse channel blocked
Loose cover on carburettor pump
side
Faulty pump diaphragm
Leaking air intake hose (rubber)
Loose carburettor mounting bolts
Needle valve set too low
Metering system incorrectly
assembled
Needle valve assembly sticking
Faulty diffuser jets
Blocked silencer
Adjust L screw
Adjust H screw
Faulty pump diaphragm
Needle valve set too high
Needle valve assembly sticking
Faulty diffuser jets
Adjust L screw
Adjust H screw
Blocked air filter
Faulty pump diaphragm
Faulty diffuser jets
Troubleshooting methods
In addition to the faults described in the above ta-
ble, trouble shooting can be carried out on specific
components or sub-systems of the chainsaw. The
various procedures are described in the relevant
chapters, see the contents page, as follows:
• Checking the operation of the chain brake
• Measuring the resistance of the stop plate
• Pressure testing the carburettor
• Pressure testing the decompression valve
• Pressure testing the cylinder
Adjust H screw
Blocked air filter
Blocked fuel tank vent
Blocked fuel filter
Fuel line blocked
Loose or damaged fuel hose
Impulse channel leaking
Impulse channel blocked
Loose cover on carburettor pump
side
Faulty pump diaphragm
Leaking air intake hose (rubber)
Loose carburettor mounting bolts
Needle valve set too low
Metering system damaged
Metering system incorrectly
assembled
Leaking control diaphragm/cover
plate
Needle valve assembly sticking
Blocked silencer
Adjust H screw
Blocked fuel tank vent
Blocked fuel filter
Impulse channel leaking
Impulse channel blocked
Loose cover on carburettor pump
side
Faulty pump diaphragm
Blocked air filter
Needle valve assembly sticking
Leak in metering system (air or
fuel)
Metering system incorrectly
assembled
Loose diaphragm rivet
Hole in diaphragm
Leaking control diaphragm/cover
plate
Blocked fuel tank vent
Blocked fuel filter
Fuel line blocked
Loose or damaged fuel hose
Impulse channel leaking
Impulse channel blocked
Loose cover on carburettor pump
side
Faulty pump diaphragm
Leaking air intake hose (rubber)
Loose carburettor mounting bolts
Needle valve set too low
Leak in metering system (air or fuel)
Metering unit incorrectly assembled
Loose diaphragm rivet
Hole in diaphragm
Leaking control diaphragm/cover
plate
Will not run at
full throttle
Low power
Will not “four-
stroke”
High rpm
Troubleshooting

English – 19
3
WARNING!
Make sure the spring does not fly
out and cause injury. Wear eye
protection.
Repair instructions
Chain brake – dismantling
1
Disengage the brake by pushing the kickback
guard backwards. Unscrew the guide bar bolts and
remove the clutch cover, chain and guide bar.
2
Grip the clutch cover carefully in a vice. Release
the brake spring by using the kickback guard from
the saw as a tool. Engage it with the brake mecha-
nism and turn anticlockwise to activate the brake.
Cleaning and inspection
• Clean and inspect all parts carefully. If there are
any cracks or other defects replace the damaged
parts with new ones. Always use original parts.
•Measure the thickness of the chain brake band.
It must be no less than 0.6 mm at any point.
•Lubricate the elbow joint with grease.
min 0,6 mm
Remove the screws and carefully remove the cover
from the chain brake spring.
4
Place one hand over the spring and insert a small
screwdriver between the bottom end of the spring
and the clutch cover. Carefully prise the spring up-
wards so that it slides onto the screwdriver shaft.
Repair instructions

20 – English
NOTE!
After completing the repair the chain
brake must be tested as described below.
Operating test:
The engine must not be running during the test.
Guide bar length Height
38cm/15" 50 cm/20"
• Hold the chainsaw over a firm surface. The
height of the guide bar above the surface is
given in the table above.
• Let go of the front handle and let the chainsaw
fall towards the surface.
• When the guide bar hits the surface the chain
brake must engage.
Chain brake – reassembly
1
Bolt the elbow joint to the brake band and tighten
to a torque of 1–1.5 Nm.
Locate the elbow joint and connected brake band
in their recesses in the clutch cover. Lubricate the
recess for the spring with grease.
2
Grip the clutch cover in a vice. Compress the
spring with special tool 502 50 67-01 and push it
down with your thumb.
3
Fit the cover over the chain brake spring, tighte-
ning the screws to a torque of 1–1.5 Nm.
5
Turn the chain tensioner anticlockwise as far as it
will go.
Refit:
• guide bar
• chain
• clutch cover
WARNING!
Make sure the spring does not fly
out and cause injury. Wear eye
protection.
4
Tension the brake spring by using the kickback
guard from the saw as a tool. Engage it with the
brake mechanism and turn clockwise to release the
brake.
Repair instructions