Workshop Manual, 340/ 345/ 346 XP/ 350

For Husqvarna Parts Call 606-678-9623 or 606-561-4983
Workshop manual
340 345 346XP
350 351 353
English
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Workshop manual
Husqvarna 340/345/346XP/350/351/353
Contents
Introduction ........................................................... 2
Safety regulations ................................................. 3
General instructions ........................................... 3
Special instructions ............................................ 3
Special tools .......................................................... 4
Technical data ....................................................... 6
Construction and function ................................... 8
Carburettor ......................................................... 8
Troubleshooting .................................................. 10
Repair instructions ............................................. 12
Chain brake ...................................................... 12
Silencer ............................................................ 14
Chain catcher ................................................... 14
Stop switch ....................................................... 15
Stop switch – resistance measurement ........... 15
Choke control ................................................... 16
Throttle trigger .................................................. 17
Hand grip heater .............................................. 18
Starter assembly .............................................. 21
Starter cord ...................................................... 21
Recoil spring .................................................... 22
Ignition module – testing .................................. 23
Ignition module and flywheel ............................ 23
Generator ......................................................... 24
Centrifugal clutch ............................................. 26
Oil pump ........................................................... 27
Carburettor ....................................................... 30
Carburettor – pressure testing ......................... 33
Carburettor heater ............................................ 34
Air intake system .............................................. 35
Carburettor – adjustment ................................. 37
Fuel tank .......................................................... 38
Fuel filter .......................................................... 39
Fuel hose ......................................................... 39
Piston and cylinder ........................................... 41
Decompression valve – pressure testing ......... 42
Cylinder – pressure testing .............................. 44
Crankcase and crankshaft ............................... 45
Crankshaft bearings ......................................... 46
Repairing damaged threads ............................. 49
Thread insert .................................................... 49
Guide bar bolts ................................................. 49
Appendix A, Carburettor – EPA models ........... 50
English – 1
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Introduction
Arrangement of the manual
Troubleshooting
This workshop manual can be used in two different
ways.
These pages describe the most common faults that
affect a chainsaw. They are divided into four
different groups with the most likely faults described first.
• To repair a specific sub-assembly on a chainsaw.
• To dismantle and reassemble a complete
chainsaw.
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 subassembly.
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/
Dismantling”.
Repair instructions
The section that describes how to repair the
chainsaw 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:
340
345
346XP
350
351
353
Work through the manual and follow the instructions given in each section under the heading
“Removal/Dismantling”.
Then follow all the “Cleaning and inspection”
instructions in each section.
Working from the back of the manual, follow all the
instructions under the headings “Refitting/
Reassembly” in reverse order.
Each of the sections covering removal/dismantling
and refitting/reassembly include the relevant
lubrication 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.
2 – English
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Safety regulations
General instructions
Special instructions
This workshop manual gives detailed instructions
on how to troubleshoot, repair and test a chainsaw.
This section also describes the various safety
precautions that should be taken when carrying out
repairs.
The fuel that is used in a chainsaw poses the
following hazards:
The workshop manual has been written for personnel who are assumed to have general experience
of repairing and servicing chainsaws.
• May cause breathing difficulties.
Workshops where chainsaws are repaired must be
equipped with safety equipment that meets local
regulations.
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.
No-one should carry out repairs on a chainsaw
until they have read and understood the contents
of this workshop manual.
Wear ear protection when testing saws.
Chainsaws are type-approved to meet the relevant
safety legislation, but this only applies when the
saw is fitted with the cutting equipment specified 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
indicate where caution should be taken.
WARNING!
The warning text warns of the risk
of personal injury if the instructions are not followed.
NOTE!
The warning text warns of the risk of
material damage if the instructions are
not followed.
• The fuel and its fumes are toxic.
• May cause irritation to skin or eyes.
• Highly flammable.
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.
English – 3
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Special tools
2
1
4
3
6
5
8
7
10
13
9
11
14
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Special tools
15
16
17
19
18
20 b
20 c
Item Description
Used for
Order no.
1
Clutch tool
Centrifugal clutch
502 54 16-01
2
Piston stop
Locking crankshaft
502 54 15-01
3
Stop plate
Locating intake gaiter
502 54 17-01
4
Fuel filter hook
Withdrawing the fuel filter
502 50 83-01
5
Allen key
For M5 bolts
502 50 18-01
6
Puller
Frame bearing
504 90 90-02
7
Removal tool
Remove seal from clutch side
502 50 55-01
8
Mandrel, sealing ring Removing crankshaft
9
Cover plate
Sealing during pressure testing 502 54 11-02
10
Pressure tester
Connection to cylinder
503 84 40-02
11
Feeler gauge
Adjusting ignition module
502 51 34-02
12
Clamp stand
Clamping the saw
502 51 02-01
13
Pressure gauge
Pressurisation during testing
502 50 38-01
14
Piston fitting kit
Fitting piston
502 50 70-01
15
Test plug
Checking ignition module
502 71 13-01
16
Rev counter
Adjusting carburettor
502 71 14-01
17
Removal tool
Removing crankshaft
502 51 61-01
18
Vacuum gauge
Vacuum test
502 50 37-01
19
Assembly pliers
Fitting spark plug guard
502 50 06-01
20a Sleeve
Fitting crankshaft
502 50 30-18
20b Shaft extension
Flywheel side
502 50 30-18
20c Shaft extension
Clutch side
502 50 30-18
21
Stop plate
Removing crankshaft
502 54 18-01
22
Assembly tool
Assembling spring, chain brake 502 50 67-01
23
Crankshaft tool
Fitting crankshaft seal
20 a
21
502 54 21-01
22
23
502 50 30-16
English – 5
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Technical data
340:
345:
346XP/G:
350:
350 EPA:
351/G:
353/G:
Displacement
cm3/cubic inches
Cylinder bore
Ø mm/Ø inches
Stroke
mm/inches
Max power/speed
kW/hp/rpm
40,8 / 2,44
45,0 / 2,75
45,0 / 2,75
49,4 / 3,01
51,7 / 3,15
49,4 / 3,01
51,7 / 3,15
40 / 1,57"
42 / 1,65"
42 / 1,65"
44 / 1,73"
45 / 1,77"
44 / 1,73"
45 / 1,77"
32 / 1,28"
32 / 1,28"
32 / 1,28"
32 / 1,28"
32 / 1,28"
32 / 1,28"
32 / 1,28"
2,0 / 2,7 / 9 000
2,2 / 3,0 / 9 000
2,5 / 3,4 / 9 600
2,3 / 3,1 / 9 000
2,3 / 3,1 / 9 000
2,3 / 3,1 / 9 000
2,4 / 3,3 / 9 000
Spark plug gap
mm/inches
Ignition system
Air gap
mm/inches
Carburettor type
0,5 / 0,02"
0,5 / 0,02"
0,5 / 0,02"
0,5 / 0,02"
0,5 / 0,02"
0,5 / 0,02"
0,5 / 0,02"
SEM CD
SEM CD
SEM CD
SEM CD
SEM CD
SEM CD
SEM CD
0,3 / 0,012"
0,3 / 0,012"
0,3 / 0,012"
0,3 / 0,012"
0,3 / 0,012"
0,3 / 0,012"
0,3 / 0,012"
Walbro HDA 195
Walbro HDA 195
Zama C3-EL17
Walbro HDA 195
Zama C3-EL18
Zama C3-EL17
Zama C3-EL17
Effective cutting length
cm/inches
Chain speed at
max power – revs
m/s – rpm
Chain pitch
mm/inches
Drive link
mm/inches
17,3 / 9 000
17,3 / 9 000
18,5 / 9 600
17,3 / 9 000
17,3 / 9 000
17,3 / 9 000
17,3 / 9 000
8,25 / 0,325"
8,25 / 0,325"
8,25 / 0,325"
8,25 / 0,325"
8,25 / 0,325"
8,25 / 0,325"
8,25 / 0,325"
1,3 / 0,050" - 1,5 / 0,058"
1,3 / 0,050" - 1,5 / 0,058"
1,3 / 0,050" - 1,5 / 0,058"
1,3 / 0,050" - 1,5 / 0,058"
1,3 / 0,050" - 1,5 / 0,058"
1,3 / 0,050" - 1,5 / 0,058"
1,3 / 0,050" - 1,5 / 0,058"
340:
345:
346XP/G:
350:
350 EPA:
351/G:
353/G:
340:
345:
346XP/G:
350:
350 EPA:
351/G:
353/G:
30-48 / 12"-19"
30-48 / 12"-19"
30-48 / 12"-19"
30-48 / 12"-19"
30-48 / 12"-19"
30-48 / 12"-19"
30-48 / 12"-19"
6 – English
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Technical data
rpm
340:
345:
346XP/G:
350:
350 EPA:
351/G:
353/G:
Idling speed
rpm
Engagement speed
rpm
Max. speed
rpm
Spark plug
2 700
2 700
2 700
2 700
2 700
2 700
2 700
3 800
3 800
3 800
3 800
3 800
3 800
3 800
12 500
12 500
14 200
13 000
13 000
13 000
13 000
NGK BPMR 7A, Champion RCJ 7Y
NGK BPMR 7A, Champion RCJ 7Y
NGK BPMR 7A, Champion RCJ 7Y
NGK BPMR 7A, Champion RCJ 7Y
NGK BPMR 7A, Champion RCJ 7Y
NGK BPMR 7A, Champion RCJ 7Y
NGK BPMR 7A, Champion RCJ 7Y
GAS
340:
345:
346XP/G:
350:
350 EPA:
351/G:
353/G:
340:
345:
346XP:
346XPG:
350:
350 EPA:
351:
351G:
353:
353G:
OIL
Fuel tank capacity
Litres/US pints
Oil pump capacity at
8,500 rpm,
ml/min
Oil tank capacity
Litres/US pints
Automatic oil pump
0,5 / 1,05
0,5 / 1,05
0,5 / 1,05
0,5 / 1,05
0,5 / 1,05
0,5 / 1,05
0,5 / 1,06
9
9
5 - 12
5 - 12
5 - 12
5 - 12
5 - 12
0,25 / 0,53
0,25 / 0,53
0,28 / 0,59
0,26 / 0,55
0,26 / 0,55
0,28 / 0,59
0,28 / 0,59
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Weight without bar and chain
kg / lbs
Weight with bar and chain
kg / lbs
Heated hand grips
4,7 / 10,3
4,7 / 10,3
4,8 / 10,6
4,9 / 10,8
4,8 / 10,6
4,8 / 10,6
4,8 / 10,6
4,9 / 10,8
5,0 / 11,0
5,1 / 11,2
5,5 / 12,1
5,5 / 12,1
5,6 / 12,2
5,7 / 12,4
5,6 / 12,2
5,6 / 12,2
5,6 / 12,2
5,7 / 12,4
5,8 / 12,6
5,9 / 13,0
Yes
Yes
Yes
English – 7
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Construction and function
Carburettor
The carburettor consists of three sub-systems:
The carburettor works in different ways depending
on the setting:
• Cold start mode
• Idling mode
• Part throttle mode
• Full throttle mode
• The metering unit (A) which contains the jets
and the fuel control mechanism. This measures
out the right amount of fuel to suit the speed of
the saw and the power demand.
• The mixing unit (B) consists of the choke,
diffuser jets and throttle valve. This is where the
air and fuel are mixed to create a flammable
mixture.
In the cold start mode the choke valve (D) is
completely closed. This increases the vacuum in
the carburettor so that fuel is sucked through the
diffuser jets faster (E).
• The pump unit (C) pumps fuel from the tank to
the metering system inside the carburettor. One
side of the pump diaphragm is connected to the
crankcase and pulses as a result of pressure
changes in the crankcase. The other side of the
diaphragm sucks in the fuel.
In idling mode the throttle valve (F) is closed. Air is
sucked through an aperture in the throttle valve
and a small amount of fuel is supplied through the
diffuser jet (E).
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Construction and function
In part throttle mode the throttle valve (F) is partially open. Fuel is supplied through the diffuser jets
(E).
In full throttle mode both valves are open and fuel
is supplied through all the diffuser jets (E).
English – 9
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Troubleshooting
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) (cont.)
Starting
Difficulty starting
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
Carburettor
leaking fuel
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
Flooding when
engine not
running
Worn needle valve
Needle valve set too high
Needle valve assembly sticking
Idles when L
screw closed
Worn needle valve
Leaking control diaphragm/
cover plate
Needle valve assembly sticking
Worn needle valve lever
Faulty diffuser jet
Idling uneven
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
L screw requires
constant
adjustment
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
Too much fuel at
idling
Needle valve set too high
Needle valve assembly sticking
Metering system damaged
Worn needle valve
Leaking control diaphragm/
cover plate
Metering system incorrectly
assembled
Idling (low rpm)
Will not idle
Idling too rich
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
10 – English
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Troubleshooting
High rpm
Acceleration and retardation
Will not run at Adjust H screw
full throttle
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
Does not
accelerate
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
Engine stalls
when throttle
released
Adjust L screw
Adjust H screw
Faulty pump diaphragm
Needle valve set too high
Needle valve assembly sticking
Faulty diffuser jets
Over rich
acceleration
Adjust L screw
Adjust H screw
Blocked air filter
Faulty pump diaphragm
Faulty diffuser jets
Low power
Will not “fourstroke”
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
Troubleshooting methods
In addition to the faults described in the above
table, 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
English – 11
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Repair instructions
Chain brake – dismantling
3
1
WARNING!
Make sure the spring does not fly
out and cause injury. Wear eye
protection.
Disengage the brake by pushing the kickback
guard backwards. Unscrew the guide bar bolts and
remove the clutch cover, chain and guide bar.
Remove the screws and carefully remove the cover
from the chain brake spring.
4
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 mechanism and turn anticlockwise to activate the brake.
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
upwards so that it slides onto the screwdriver shaft.
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
12 – English
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Repair instructions
Chain brake – reassembly
4
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
WARNING!
Make sure the spring does not fly
out and cause injury. Wear eye
protection.
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.
5
Turn the chain tensioner anticlockwise as far as it
will go.
Refit:
• guide bar
• chain
• clutch cover
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.
Grip the clutch cover in a vice. Compress the
spring with special tool 502 50 67-01 and push it
down with your thumb.
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.
3
• 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.
Fit the cover over the chain brake spring, tightening
the screws to a torque of 1–1.5 Nm.
English – 13
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Repair instructions
Silencer – removal
Silencer – refitting
WARNING!
Do not touch the silencer until it
has cooled down, otherwise you
may burn yourself.
1
1
If the saw is equipped with a spark arrestor mesh
this should be fitted first.
2
Refit
• cooling plate
• gasket
• silencer, tighten bolts to a torque of 8–10 Nm.
• silencer support
• cylinder cover
3
Run the saw for at least 1 minute, then retighten
the silencer bolts to 8–10 Nm.
Chain catcher – replacement
If the chain catcher is worn it must be replaced with
a new one.
Remove the cylinder cover, silencer support,
silencer, gasket and cooling plate.
2
If the saw is fitted with a spark arrestor mesh this
must also be removed.
1
Release the brake by pushing the kickback guard
backwards. Undo the guide bar bolts and remove
the clutch cover, chain and guide bar.
2
Cleaning and inspection
Clean and inspect all parts carefully. If there are
any cracks or other defects replace the damaged
parts with new ones.
The spark arrestor mesh is best cleaned with a
wire brush. If the mesh is damaged it must be
replaced.
If the mesh is blocked the saw will overheat and
this will cause damage to cylinder and piston.
Never use the saw with a silencer that is in poor
condition. Always use original parts.
Remove the chain catcher and replace it with a
new one. Check that the vibration damping spring
locates correctly against the crankcase when you
bolt the new chain catcher in position.
A worn (damaged) chain catcher on 340, 345 or
350 can be replaced with the same chain catcher
as 346XP, 351 and 353 (see figure above).
3
Turn the chain tensioner anticlockwise as far as it
will go.
Refit:
• guide bar
• chain
• clutch cover
14 – English
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Repair instructions
Stop switch – removal
Cleaning and inspection
1
Remove the cylinder cover and air filter.
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.
2
Stop switch – resistance measurement
Clean the mating surfaces and check the resistance as follows:
Disconnect both leads from the stop plate and stop
switch. Remove the stop plate by carefully sliding it
over the lug on the front mounting.
3
Measure the resistance by connecting a multimeter
to the ignition coil. NOTE! The switch must be in
the “on” position to give the correct reading.
The resistance must not be higher than 0.2 ohm
when the switch is in the on position.
Carefully prise the carburettor assembly off the lefthand rubber mounting using a small screwdriver.
4
Carefully prise the stop switch’s upper mounting off
the air filter holder while lifting the switch to release
it from the lower mounting.
English – 15
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Repair instructions
Stop switch – refitting
Choke control – removal
1
1
Remove the cylinder cover, air filter and stop
switch. Disconnect the fuel hose from the carburettor.
NOTE!
Do not use knurled pliers to disconnect or
reconnect the fuel hose. This could
damage the hose and lead to leakage or
fracture.
A
2
C
Carefully press the new stop switch into place.
Check that the switch’s upper mounting clips over
the air filter holder.
B
2
Disconnect the pushrod from the carburettor by first
carefully prising up the spring over the end of the
rod, where it connects to the throttle lever (A). Then
press the throttle lever forwards (B) while pressing
the throttle pushrod backwards (C) and lifting it off
the lever. Withdraw the throttle pushrod from the
tank and lift it upwards without pulling it through the
rubber inlet manifold. Carefully release the carburettor assembly from the right-hand rubber mounting and lift it upwards.
Refit the stop plate. Engage the stop plate in the
front slot first then lift the rear edge onto the stop
switch. Slide the stop plate in as far as it will go.
3
3
Refit:
• the leads to the stop plate and stop switch
• air filter
• cylinder
Compress the clip that holds the choke control to
the carburettor while pulling it out at the same time.
Disconnect the choke control from the air filter
holder.
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Repair instructions
Choke control – refitting
Cleaning and inspection
First reattach the choke control to the air filter, then
press it onto the carburettor so that the clips engage.
• 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.
Then refit:
• Lubricate the throttle lock with oil.
• stop switch
• Check that the spring is not broken and has not
lost its tension.
• carburettor into its rubber mountings
• throttle pushrod into the fuel tank and connect to
throttle lever.
• lift the spring arm over the throttle pushrod
Throttle lock, throttle trigger and return
spring – refitting
• fuel hose to the carburettor
1
• air filter and cylinder cover
Throttle lock, throttle trigger and return
spring – removal
A
1
B
A
C
Remove the throttle lock by pressing it to the left
(A) and carefully levering it up with a screwdriver
on the clutch side (B) of the saw to disengage the
lugs on either side of the throttle lock from the fuel
tank. When both lugs are clear of the tank, pull the
lock backwards (C).
Refit the return spring to the throttle trigger as
shown. Make sure the spring is correctly positioned
by engaging one end in the slot in the throttle
trigger (A).
2
First insert the rear edge of the throttle trigger into
the tank. Then push/clip the front edge into the two
clips on the tank with the aid of a combination tool,
for example. Drive in the steel pin from the clutch
side. Use a 2.5 mm/0.1" diameter drift.
2
A
B
C
Drive out the steel pin using a 2.5 mm/0.1" diameter drift (A). Push it out from the flywheel side of
the saw. Remove the throttle trigger by first pressing it towards the clutch side of the saw (B) until it
clicks, then towards the flywheel side until it clicks
again. Remove it from the tank and lift out the
return spring.
3
Then press down the return spring while pressing
the throttle lock forwards/upwards into the retaining
clip in the fuel tank until you hear a click. Release
the return spring in the throttle lock, then press the
lock down onto the tank.
4
Check the operation of the throttle lock by trying to
press the throttle trigger without pressing down the
throttle lock. Also check that the throttle lock and
throttle trigger return freely to their original positions when released.
English – 17
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Repair instructions
Hand grip heater on model 346XPG,
351G, 353G – removal
2
Reconnect the lead and refit the hand grip cover
and cylinder cover.
No heating or heating only in front hand grip
• Switch – troubleshooting
• Front hand grip – troubleshooting
1
Carefully free the switch and frame from the front
hand grip using a screwdriver.
1
2
Disconnect the leads from the switch and connect
a multimeter to it. The meter should read over
1000 ohm when the switch is in the “0” position.
The meter should read no higher than 0.1 ohm with
the switch in the “1” position. Replace the meter if
the readings are outside these limits.
Rear hand grip heater not working
• Rear hand grip heater – troubleshooting
Remove the three bolts that secure the cover over
the front hand grip. Disconnect the leads from the
switch and generator and measure the resistance of
the hand grip heater, which should be 3–4 ohm.
Replace the front hand grip if the resistance is higher.
2
1
Remove the cylinder cover, air filter and cover from
the rear hand grip.
2
Disconnect the red lead from the heater and
connect a multimeter between it and the black
earth lead that is bolted to the bottom of the
carburettor on the clutch side of the saw. The
meter should read 0.7–1.2 ohm. If the reading is
higher replace the heater element.
3
Remove the air filter, throttle pushrod, rubber
diaphragm and carburettor, see “Carburettor –
removal”.
4
Remove the bolt from the plate at the base of the
carburettor to release the lead for the heater
element.
5
Reconnect the leads and refit the cover.
3
Push the switch back into place and reconnect the
leads.
4
Bolt the cover back onto the hand grip.
• Generator – troubleshooting
1
Remove the cylinder cover and cover from the
front hand grip. Disconnect the black lead from the
generator and connect a multimeter between it and
a clean area on the cylinder. The multimeter should
show a resistance of 0.9–1.3 ohm. If the reading is
higher or lower, replace the generator, see “Replacing the generator”.
Unscrew the three bolts from the front hand grip
and remove the cover to reveal the leads. Disconnect the red lead.
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Repair instructions
Rear handle heater
Measure the resistance between F and Z. It should
be 1 ± 0.5 ohm.
If not, replace the rear handle heater.
6
Generator
Measure the resistance between G and H. It
should be between 0.3–1.3 ohm.
If not, replace the generator.
Carburettor heater
Disconnect the lead at X and clean the connectors.
Measure the resistance between X and G.
The reading should be between 3–10 ohms. If not,
disconnect the lead at Y and clean the connectors.
Measure the resistance between X and Y, if the
reading is not between 3–7 ohms – replace the
carburettor heater.
Unscrew the two bolts from the right side of the
rear hand grip. Remove the throttle lock and
throttle handle, see “Throttle trigger”. Pull out the
heater element with the leads still connected.
Troubleshooting carburettor heater
(346XPG, 351G, 353G)
Operation
The carburettor temperature is controlled by an
electronic thermostat to eliminate the risk of ice
formation in the carburettor. The thermostat
switches on/off at 12°C/54F. This means that the
saw operator does not need to remember to switch
the carburettor heater on or off.
O
O
Z
Z
5
5
NN
GG
F
F
33
K
KV
V
• Troubleshooting
Front handle heater
Remove the side cover from the handle. Disconnect the leads at F and G (see diagram).
Clean the connectors. Turn the switch ”on”.
Measure the resistance between F and G.
The reading should be 4±1 ohms. If not, disconnect the lead at O and remove the switch.
Measure the resistance between O and F. The
reading should be 4±1 ohms. If the resistance is
incorrect, replace the front handle.
Disconnect the lead at N and G and measure the
resistance between these points. The reading
should be no higher than 0.1 ohm. If it is too high,
replace the lead.
XX
44
YY
11
H
H
Switch
Measure the resistance between N and O with the
switch turned off. The reading should be 1 000
ohms or higher.
Repeat the measurement with the switch turned
on. The reading should be no higher than 0.1 ohm.
If it is too high, replace the switch.
English – 19
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Repair instructions
Heater element and rear hand grip –
removal
Hand grip heater on model 346XPG,
351G, 353G – refitting
1
Remove the cylinder cover, hand grip cover, hand
grip and right-hand stop.
1
Feed the leads into the rear hand grip and insert
the heater element in the hand grip. Screw in the
two bolts through the right side of the hand grip to
secure the heater.
Then remove:
• throttle lock, throttle trigger and recoil spring,
see “Throttle trigger”.
2
• fuel hose and throttle pushrod from the carburettor
Unbolt the rear tank mounting from the crankcase,
i.e. the rear vibration damping spring, and both
stops. Lower the tank as far as it will go to allow
access to the heater lead where it is connected to
the tank.
Refit:
• fuel tank with both stops and the rear vibration
damping spring
• throttle lock, throttle trigger and recoil spring,
see “Throttle trigger”.
• fuel hose and throttle pushrod to the carburettor
(check that the hose is not trapped between the
tank and crankcase, measurement 43 mm/1.69
inches)
• hand grip cover, air filter and cylinder cover
Heater element and rear hand grip –
removal
Press the black lead into the base of the carburettor and connect it with the bolt.
Tighten to a torque of 3–4 Nm.
3
Run the red lead to the front hand grip and connect
it.
4
Press the throttle trigger and throttle lock into
position and check that they work correctly, see
“Throttle trigger”.
5
1
Screw the heater element into place using the two
screws and feed the leads through the rear hand
grip. Secure the red lead in the clip on the tank and
connect it. Feed the black lead through crankcase
and secure/earth it to the base of the carburettor
using the bolt at the front on the clutch side of the
saw. Tighten to a torque of 3–4 Nm.
2
Refit:
• fuel tank with both stops and the rear vibration
damping spring
• throttle lock, throttle trigger and recoil spring,
see “Throttle trigger”.
Bolt the vibration damping springs that hold the
tank unit back in place and refit the cover over the
front hand grip.
• fuel hose and throttle pushrod to the carburettor
(check that the hose is not trapped between the
tank and crankcase, measurement 43 mm/1.69
inches)
• hand grip cover, air filter and cylinder cover
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Repair instructions
Starter assembly – removal
Replacing a broken or worn starter cord
1
1
Before replacing a worn starter cord the tension in the
recoil spring must be released. Pull the starter cord out
through the notch in the pulley rim and wind the pulley
anti-clockwise to release the tension in the spring.
Undo the four bolts that fasten the starter assembly
to the crankcase and lift off the starter assembly.
2
Pull out about 30 cm of the cord and fasten it in the
notch in the pulley rim. Release the tension in the
return spring by letting the pulley wind backwards
slowly.
2
Remove the bolt from the centre of the pulley and
lift off the pulley.
3
3
WARNING!
If the recoil spring is still under
tension when the pulley is removed it can fly out and cause injury. Wear eye protection.
Remove the bolt from the centre of the pulley and
lift off the pulley.
Cleaning and inspection
Clean the parts and check the following:
• The starter cord.
• The teeth on the pulley, lubricate with oil.
Fit a new cord through the hole in the pulley and tie
a knot to secure it. Feed the other end of the cord
through the hole in the starter housing and through
the starter handle, then tie a double knot in the
end. Wind about 3 turns of the starter cord onto the
pulley. Fit the bolt through the centre of the pulley
and tighten to a torque of 2–3 Nm.
• That the pawls on the flywheel are undamaged,
i.e. that they spring back towards the centre and
move freely.
• Lubricate the return spring with light oil.
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Repair instructions
Replacing a worn recoil spring
WARNING!
Make sure the recoil spring does
not fly out and cause injury. Wear
eye protection.
1
Remove the bolt from the centre of the pulley and
lift off the pulley and spring.
2
Remove the broken recoil spring.
Cleaning and inspection:
• Clean and inspect all parts carefully. If there are
any cracks or other defects replace the damaged parts with new ones. Lubricate the return
spring with light oil.
Tensioning the recoil spring
1
Fasten the starter cord in the notch in the pulley
rim and wind the pulley about 2 turns clockwise.
Check that the pulley is free to rotate at least
another half turn when the starter cord is fully
extended.
3
Fit the bolt through the centre of the pulley and
tighten to a torque of 2–3 Nm.
Tension the recoil spring, see “Tensioning the recoil
spring”.
Starter assembly – refitting
1
Position the starter assembly on the crankcase and
tighten the bolts to a torque of 2.5–3.5 Nm.
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Repair instructions
Ignition module – testing
2
If there is a fault in the ignition system the ignition
module must be tested before the ignition system
is removed.
If replacing the ignition module, disconnect its leads
and unscrew it. The ignition module can be left in
place if you are simply removing the flywheel.
3
Test the ignition module as follows:
• Connect a test spark plug 502 71 13-01 to the
ignition lead and clip the test spark plug onto the
cylinder.
• Turn the engine over using the starter cord.
• If the test spark plug produces a spark the
ignition module is OK.
Ignition module/flywheel – removal
1
Loosen the flywheel nut using a suitable socket and
unscrew it until it is flush with the end of the shaft.
4
Remove the cylinder cover. Disconnect the HT lead,
remove the spark plug and fit piston stop 502 54 1501 in its place. Take off the starter assembly, release
the leads from the cable guide and remove it.
Model 346XP, 351, 353:
Remove the cover from the hand grip.
Position puller 504 90 90-02 over the magnets and
counterweight on the flywheel. Tighten 2–3 turns
and tap the head of the puller with a metal mallet to
release the flywheel. Remove the puller, nut and
washer. Lift off the flywheel.
Cleaning and inspection
• Clean all parts, especially the tapers on the
flywheel and shaft.
• Check that the flywheel is not cracked or damaged in any other way.
English – 23
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Repair instructions
Replacing the generator, model 346XP,
351, 353
1
Remove the cylinder cover. Disconnect the HT lead,
remove the spark plug and fit piston stop 502 54 1501 in its place. Take off the starter assembly, release
the leads from the cable guide and remove it.
Remove the cover from the hand grip.
4
Remove the fuel hose and throttle pushrod from
the carburettor.
Unbolt the rear tank mounting from the crankcase,
i.e. the rear vibration damping spring, and both
stops. Lower the tank as far as it will go to allow
access to the heater lead where it is connected to
the tank.
5
Disconnect the generator lead from the hand grip
and unclip it from the tank. Remove the generator
and lead.
2
Generator – refitting
1
Feed the generator lead through the holes in the
crankcase and hand grip. Bolt the generator in
position, tightening the bolts to a torque of 5 Nm.
Clip the lead to the tank.
NOTE! The lead connector must be positioned on
the right of the clip, see diagram. Connect the lead
to the connector on the hand grip.
Loosen the flywheel nut using a suitable socket
and unscrew it until it is flush with the end of the
shaft.
Position puller 504 90 90-02 over the magnets and
counterweight on the flywheel. Tighten 2–3 turns
and tap the head of the puller with a metal mallet to
release the flywheel. Remove the puller, nut and
washer. Lift off the flywheel.
2
Refit:
• fuel tank with both stops and rear vibration
damping spring
• fuel hose to carburettor, hose length between
tank and crankcase: 43 mm/1.69 inches and
between crankcase and carburettor: 53 mm/2.09
inches
• throttle pushrod to carburettor
3
• flywheel with nut and washer
• cable guide, leads and starter assembly
Remove the piston stop and reconnect the HT lead
and cylinder cover.
Unscrew the two bolts from the generator but leave
the generator in place.
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Repair instructions
Ignition module and flywheel – refitting
3
1
Place the flywheel on the crankshaft. Turn the
flywheel so that the key lines up with the keyway in
the shaft.
Fit the washer and nut on the shaft and tighten to a
torque of 25-30 Nm.
Then refit:
• cable guide and press the leads into position
• HT lead
• starter assembly, tighten to a torque of 2.5–3.5
Nm
2
• cylinder cover
0,3 mm
To refit the ignition module proceed as follows:
Turn the flywheel so that the magnets are in line
with the ignition module. Fit the ignition module
with the plastic feeler gauge (502 51 34-01) held in
position at the same time, without tightening the
bolts. Connect the black earth lead to the front
screw on the ignition module. Adjust the gap
between the ignition module and magnet to 0.3 +/0.1 mm. The gap must be measured at either of
the two lowest pegs on the ignition module.
Tighten the bolts to 4.5–6 Nm. Connect the blue
lead to the ignition module.
English – 25
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Repair instructions
Centrifugal clutch – removal
Inspection and cleaning
1
Remove the cylinder cover. Disengage the chain
brake by pushing the kickback guard backwards.
Undo the guide bar bolts and remove the clutch
cover, chain and guide bar.
• 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.
2
Min 65mm
• Check the thickness of the clutch shoes by
using vernier callipers to measure the diameter
of the clutch. If the diameter is less than 65 mm
the clutch assembly must be replaced.
Disconnect the HT lead. Remove the spark plug
and fit piston stop 502 54 15-01 in its place.
Centrifugal clutch – refitting
3
1
NOTE!
Handle the clutch springs carefully. If they
are opened up too much they could
damage the saw.
Unbolt the clutch using tool 502 54 16-01 and a
suitable socket or combination spanner. Turn the
nut clockwise to remove it.
4
NOTE!
Handle the clutch springs carefully. If they
are opened up too much they could
damage the saw.
Insert the clutch springs in the shoes using circlip
pliers.
Carefully prise out the clutch springs with a screwdriver.
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Repair instructions
2
3
D
C
B
A
Fit the clutch onto the crankshaft and tighten
anticlockwise as far as it will go. Then tighten to a
torque of at least 20 Nm using tool 502 54 16-01
and a suitable socket or combination spanner.
3
Remove the piston stop. Fit the spark plug, tightening
it to a torque of 15 Nm, then connect the HT lead.
Unbolt and remove the clutch drum (A), RIM chain
sprocket (B) if fitted, needle bearing (C) and pump
drive wheel (D).
Model 350:
Remove the bolts on the anti-vibration elements on
the same side.
4
Then refit:
• cylinder cover
• guide bar
• chain
• clutch cover
Oil pump – removal 346XP, 350, 351,
353
1
Empty and clean the oil tank.
2
Unbolt the oil pump from the crankcase.
5
C
A
D
Remove the cylinder cover. Disengage the chain
brake by pushing the kickback guard backwards.
Undo the guide bar bolts and remove the clutch
cover, chain and guide bar. Disconnect the HT
lead. Remove the spark plug and fit piston stop
502 54 15-01 in its place. Unscrew the clutch
(clockwise) using clutch tool 502 54 16-01 and a
suitable socket spanner or combination spanner.
B
Remove the oil hose and filter (A).
Model 350:
Push the housing up a little from the fuel tank and
remove the filter (A) from underneath, see the
diagram under “Oil pump – removal 340, 345”.
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Repair instructions
6
Remove the pin (B) from the adjuster screw, using
a small drift to press it out.
Oil pump –refitting 346XP, 350, 351, 353
1
C
7
Press in the pump piston (C) so that the adjuster
screw (D) can be removed. Remove the pump
piston.
A
Oil pump – removal 340, 345
D
1-4
See ”Oil pump – removal, models 346XP, 350,
351, 353”, points 1-4.
Remove the bolts on the anti-vibration elements on
the same side.
B
Lubricate the pump piston (C) with chain oil and fit
the pump piston and washers.
5
2
Press down the pump piston (C). Fit the adjuster
screw and spring so that the pin (B) can be
pressed into position.
3
Reconnect the oil hose and filter (A).
Carefully lift out the oil pump from the crankcase.
6
Model 350:
Push the crankcase up a little from the fuel tank
and screw on the filter (A) from underneath.
WARNING!
Poor chain lubrication can result
in failure of the chain, which could
cause serious or fatal injury.
4
Push the crankcase up a little from the fuel tank
and remove the filter (A) from underneath.
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.
Bolt the oil pump to the crankcase. The adjustable
oil pump must be bolted to torque of 2–3 Nm.
• Lubricate all moving parts with chain oil.
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Repair instructions
Oil pump –refitting 340, 345
5
1
Lubricate the piston pump (C) with chain oil and fit
the pump piston.
2
Fit the pump. A round pin secures its position.
Fit the chain guard plate, tightening the bolts to a
torque of 2–3 Nm.
Model 350:
Fit the bolts on the anti-vibration elements on the
same side.
6
D
C
B
A
Push the crankcase up a little from the fuel tank
and screw on the filter (A) from underneath.
Lubricate the needle bearing with grease. Fit the
pump drive wheel (D), needle bearing (C), chain
sprocket (B), if fitted, and clutch drum (A).
7
Fit the clutch onto the crankshaft and tighten
anticlockwise as far as it will go. Then tighten to a
torque of at least 20 Nm using tool 502 54 16-01
and a suitable socket spanner or combination
spanner.
3
Fit the chain guide plate (one bolt), tightening
torque 2-3 Nm.
NOTE! Check that the chain tensioner is in position. Fit the bolts on the anti-vibration elements.
Note.
Models 340 and 345 have another type of chain
tensioner, which is adjusted from the side.
4
See ”Oil pump – Refitting, models 346XP, 350,
351, 353” pos. 6-9.
8
Remove the piston stop. Fit the spark plug, tightening it to a torque of 15 Nm, then connect the HT
lead. Then refit the cylinder cover, guide bar, chain
and clutch cover.
9
Refill the tank with oil. For more information see
the user instructions for this model for the recommended grade of oil.
English – 29
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Repair instructions
Adjustable oil pump – adjustment
346XP, 350, 351, 353
2
A
Use a screwdriver or adjustable spanner to turn the
adjuster screw on the pump. Turning the screw
clockwise decreases the oil flow and turning it anticlockwise increases the oil flow.
2
3
1
+ –
Recommended setting:
13–15" bar Min. setting
15–18" bar Midway setting
18–20" bar Max. setting
C
B
Disconnect the pushrod from the carburettor by
first carefully prising up the spring over the end of
the rod, where it connects to the throttle lever (A).
Then press the throttle lever forwards (B) while
pressing the throttle pushrod backwards (C) and
lifting it off the lever. Withdraw the throttle pushrod
from the tank and lift it upwards without pulling it
through the rubber inlet manifold. Carefully release
the carburettor assembly from the right-hand
rubber mounting and lift it upwards.
3
Carburettor – removal
1
Open the spring lock on the rubber bellows.
4
NOTE!
Do not use knurled pliers to disconnect or
reconnect the fuel hose. This could
damage the hose and lead to leakage or
fracture.
Remove the cylinder and air filter. Disconnect the
leads from the stop switch and the fuel hose from
the carburettor.
Undo and remove the carburettor bolts. Lift off the
carburettor.
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Repair instructions
On saws with a carburettor heater 346XPG,
351G, 353G
Heating element
Carburettor – dismantling
Remove the bracket’s two bolts above the carburettor. Disconnect the cable connections to the
carburettor heater and remove the heating element.
O
O
Z
Z
5
N
N
G
G
5
F
The item numbers in the diagram refer to the steps
below (1–7).
3
F
3
KV
X
KV
X
1
Remove the cover from the metering unit and
carefully remove the metering diaphragm and
gasket.
4
4
2
Undo the screw and take out the needle valve,
together with the lever arm, spindle and spring.
Y
Y
1
1
H
H
When replacing the thermostat: Disconnect the
cable from X and V. Trouble shooting, see page
20.
On saws with carburettor 346XPG, 351G, 353G
Replacing the heating element: Lower the rear
section of the tank by removing the bolt between
the hand grip cover and vibration damping springs.
Remove the starter and then loosen the stop
screws on both sides (one is located under the
starter and this must be removed first). Now
disconnect the cable from X and Y.
Dismantling the carburettor: Loosen the high, low
and idling jet screws.
3
Remove the cover from the pump unit and carefully
remove the gasket and pump diaphragm.
4
Remove the fuel filter.
5
Remove the high, low and idling jet screws. (HDA
159A high and low jet screws are protected by
plastic caps which can be prised off with a screwdriver. Only on EPA, see appendix A.)
6
Remove the plug by first drilling a hole in it and
then prising it out with a screwdriver or the like.
7
If necessary remove the throttle and choke valves,
and remove the spindles together with the lever
arms and springs.
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Repair instructions
Cleaning and inspection
Clean all the carburettor components in petrol. Use
an airline to dry off the petrol from all components.
Blow through all the channels in the carburettor
body and check that they are not blocked.
Check that:
• The gasket, pump diaphragm and metering
diaphragm are undamaged.
• There is no play in the throttle and choke valves.
• The needle valve and its lever arm are not worn.
• The fuel filter is undamaged.
• The tips of the high and low speed jet screws
are not damaged.
• The air intake duct is not cracked.
1
If the throttle and choke butterflies and their
spindles were removed, these must be refitted.
Lubricate the spindle bearings with light oil.
2
Insert the plug in the hole with the convex side
upwards and expand it by pressing downwards
with a drift.
3
Refit the high and low speed jet screws and
springs, plus the idling screw. Fit the plastic caps
over the high and low speed screws.
4
Fit the fuel filter, using the handle of a small screwdriver.
5
Fit the pump diaphragm, gasket and cover to the
pump unit.
6
Carburettor – reassembly
NOTE!
Cleanliness is very important when
reassembling the carburettor. Tiny particles of dirt can cause operating problems.
Fit the needle valve with lever arm, spindle and
spring and tighten the screw.
Use a rule to check that the lever arm is level with
the cover face. If necessary, the lever arm can be
bent slightly.
7
Fit the metering diaphragm with its gasket and refit
the cover to the metering unit.
8
Carry out pressure testing.
The item numbers in the diagram refer to the steps
below (1–8).
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Repair instructions
Carburettor – pressure testing
Carburettor – refitting
Pressure testing should be carried out with the
carburettor fully assembled. Testing should always
be carried out after the carburettor has been
repaired, but can also be performed for troubleshooting before dismantling.
Carry out the test as follows:
NOTE!
Cleanliness is very important when reassembling the carburettor. Tiny particles of
dirt can cause operating problems.
1
• Screw in the high and low speed jet screws and
back them off one turn.
• Connect pressure tester 502 50 38-01 to the
carburettor fuel inlet.
Fit stop plate 502 54 17-01 between the carburettor flange and the insulating plate.
• Lower the carburettor into a beaker of water.
• Pump up the pressure to 50 kPa (0.5 bar) and
clamp the pump tube.
On saws with a carburettor heater
346XPG, 351G, 353G
• There should be no leakage. If leakage occurs,
refer to the table below.
Leakage
Fault lies in
Diffuser jets
In impulse tube
Ventilation hole above
metering unit
Needle valve
Pump diaphragm
Control diaphragm
Insert the heating element between the air filter
connection and carburettor as well as above the
carburettor. Route the cable as illustrated above.
Tighten the bracket above the carburettor with the
two bolts.
Connect the cables to the carburettor heater.
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Repair instructions
5
2
Connect the leads to the stop switch.
Fit the carburettor. Screw in the carburettor bolts
directly from behind, without lifting the carburettor
assembly. Tighten to a torque of 1–1.5 Nm. It is
important to hold the carburettor flange while
tightening the bolts to prevent the inlet manifold
from moving.
Carburettor heater 346XP, 351, 353 –
Refitting
Heating element
3
Push the rear carburettor mounting into its rubber
bushing using a small screwdriver. Remove stop
plate 502 54 17-01.
4
1
Fit the heating element between the air filter
connection and the carburettor as well as above
the carburettor.
2
Tighten the bracket above the carburettor using the
two bolts.
3
Connect the leads to the carburettor heater.
Refit:
• carburettor
Connect the fuel hose to the carburettor. Refit the
throttle pushrod at the same time as the rubber
inlet manifold, press in the throttle pushrod so that
it engages in the carburettor and fit the spring.
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Repair instructions
Air intake system – removal
4
The air intake system comprises:
• inlet manifold
• insulating plate with clip
• carburettor flange
• impulse hose
• support ring
1
Remove:
Unscrew the four cylinder bolts. Lift up the cylinder
so that the intake system insulating plate is free of
the crankcase.
• cylinder cover
• air filter
• carburettor
• HT lead
• starter assembly (340, 345)
• Fuel tank (340, 345)
2
On models 340 and 345 there are cylinder bolts on
the underside.
5
Unbolt the vibration damping spring between the
cylinder and hand grip.
3
Free the insulating plate from the cylinder by
releasing the clamp using pliers. Remove the
complete air intake system.
6
Remove:
• support ring
• carburettor flange from the inlet manifold
• insulating plate
Cleaning and inspection
Unscrew and remove the bolt from the silencer
support.
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.
NOTE! When replacing the impulse hose it must
not be lubricated with oil or grease.
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Repair instructions
Air intake system – refitting
4
1
A
B
Fit the inlet manifold (A) through the insulating
plate in the carburettor flange cut-out (B), and
check that the insulating plate’s impulse tube sits
correctly in the inlet manifold. Fit the perforated
brass support ring in the inlet manifold.
2
Refit the carburettor. Screw in the carburettor bolts
directly from behind without lifting the carburettor
assembly, tightening to a torque of 1–1.5 Nm. It is
important to hold the carburettor flange securely
when tightening the bolts to prevent the inlet
manifold from moving.
4
Fit the air intake system on the cylinder and snap
the insulating plate into position. Check carefully
that the impulse tube is correctly seated against
the cylinder’s impulse channel.
3
Push down the rear carburettor mounting into the
rubber bushings using a small screwdriver. Remove tool 502 54 17-01.
5
Refit:
• cylinder, see special instructions
• silencer support (does not apply to 340, 345,
350)
• air filter
• HT lead
• cylinder cover
• after the test run retighten the silencer bolts to a
torque of 8–10 Nm
Position tool 502 54 17-01 between the carburettor
flange and the insulating plate.
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Repair instructions
Carburettor – adjustment
For instructions on adjusting the EPA carburettor
see appendix A.
Adjusting the carburettor involves adjusting the
engine to the local conditions e.g. climate, altitude, fuel and type of two-stroke oil.
If it is not possible to check the maximum speed
with a tachometer then the H jet should not be set
to a weaker mixture than the basic factory setting.
The recommended maximum speed must not be
exceeded.
NOTE!
The carburettor is equipped with three adjustment
options.
L = Low speed jet
H = High speed jet
T = Idling adjustment screw
If the chain turns at idling speed, the T
screw should be turned anti-clockwise
until the chain stops.
Fine adjustment
Once the chainsaw is “run in” the carburettor should
be readjusted. First adjust the L jet screw, then the
idling screw T and finally the H jet screw.
The recommended engine speeds are as follows:
The L and H jets adjust the fuel flow to match the
airflow that the throttle valve opening allows.
Turning them clockwise makes the fuel/air mixture
weaker (less fuel in relation to the amount of air)
and turning them anti-clockwise makes the fuel/air
mixture richer. A weak mixture increases the
engine speed and a rich mixture decreases the
engine speed.
The T screw controls the throttle position when
idling. Turning the T screw clockwise gives faster
idling; turning it anti-clockwise lowers idling
speed.
WARNING!
The guide bar, chain and clutch
cover must be fitted before the
saw is started, otherwise the
clutch may fly off and cause injury.
Basic settings and running in
During testing at the factory the carburettor is
adjusted to the basic factory settings.
The factory settings are H = 1 turn and L = 1
turn.
To ensure that engine components receive
adequate lubrication (running in) the carburettor should be set to a somewhat richer fuel
mixture for the chainsaw’s first 3-4 running
hours. This is done by adjusting the maximum
speed to 6-700 rpm less than the recommended maximum speed.
Model
340
345
346XP/G
350
350 EPA
351
353
Max revs
12,500 rpm
12,500 rpm
14,200 rpm
13,000 rpm
13,000 rpm
13,000 rpm
13,000 rpm
Idle revs
2,700 rpm
2,700 rpm
2,700 rpm
2,700 rpm
2,700 rpm
2,700 rpm
2,700 rpm
Basic requirements
• Before making any adjustments the air filter
should be clean and the cylinder cover should be
in place. If the carburettor is adjusted with a dirty
air filter, the mixture will be too weak next time
the air filter is cleaned. This can cause serious
engine damage.
• Carefully screw in the L and H jets fully, then
back them off 1 turn. The carburettor now has the
settings H = 1 and L = 1.
• Start the chainsaw and allow it to warm up for 10
minutes.
• Place the saw on a flat surface so that the guide
bar is pointing away from you and the guide bar
and chain are not touching the surface.
Low speed jet L
• Find the highest idling speed by slowly screwing
the L screw in and then out again.
• When the highest speed has been found, screw
out the L screw 1/8 - 1/4 turn.
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Repair instructions
Fine adjustment of idling speed T
Fuel tank – removal
• The idling speed is adjusted using the screw
marked T.
WARNING!
The fuel used in chainsaws is
harmful if inhaled, may cause
skin irritation and is highly flammable.
• If adjustment is necessary, screw in the idling
screw T until the chain starts to turn. Then screw it
out until the chain stops moving.
• The idling speed is correctly set when the engine
runs smoothly in all positions and there is a clear
margin to the speed at which the chain starts to
move.
High speed jet H
• The high speed jet H influences the saw power
output and engine speed. If the H jet is set too
weak the saw will over-rev, which could cause
engine damage.
• Run the saw at full throttle for about 10 seconds.
H=1.
1
Empty the fuel tank.
2
Remove the following:
• cylinder cover
• air filter
• clutch cover
• chain and guide bar
• starter assembly
• Then screw out the H screw 1/4 turn. H=1 1/4.
• cable guide
• Run the saw again at full throttle for about 10
seconds and listen to the difference in the engine
note. Repeat this procedure again with the H
screw screwed out another 1/4 turn. H=1 1/2.
3
Disconnect the fuel hose from the carburettor.
• You have now run the saw at settings H ± 0, H =
+1/4 and H = +1/2 from the factory setting. At full
throttle the engine will sound different at each
setting.
• The H screw is correctly adjusted when the saw
“burbles” a little at full throttle without any load.
4
A
C
B
• If there is a lot of smoke from the silencer and the
saw does not run smoothly then the setting is too
rich.
• Screw in the H screw to the setting that sounds
right.
NOTE!
For optimum adjustment, a tachometer
should be used. The recommended maximum speed should not be exceeded.
Carburettor – correct adjustment
• When the carburettor is correctly adjusted the saw
should accelerate without hesitation and the
engine will burble a little at full throttle without any
load.
Disconnect the pushrod from the carburettor by
first carefully prising up the spring over the end of
the rod, where it connects to the throttle lever (A).
Then press the throttle lever forwards (B) while
pressing the throttle pushrod backwards (C) and
lifting it off the lever. Withdraw the throttle pushrod
from the tank and lift it upwards without pulling it
through the rubber inlet manifold.
• The chain must not turn when idling.
• If the L screw is set too weak this can make the
saw difficult to start and cause poor acceleration.
• If the H screw is set too weak the saw will produce
less power, poor acceleration and there is a risk of
engine damage.
• If either the L or H screws are set too rich it will
cause acceleration problems or too low working
speed.
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Repair instructions
5
Cleaning and inspection
Carefully check that:
• there are no leaks from the fuel tank
• there are no leaks from the tank filler cap
• the fuel hose is undamaged and free from wear
• the fuel filter is not clogged
• the tank vent is not blocked or leaking
• the vibration damping springs and stops are not
damaged
Replacing the fuel filter
NOTE!
Do not use knurled pliers to disconnect or
reconnect the fuel hose. This could
damage the hose and lead to leakage or
fracture.
1
First remove the old fuel filter from the tank unit
using special tool 502 50 83-01.
2
Pull the fuel hose out of the tank and pull off the
filter.
Unscrew both stops and the three vibration damping springs from the flywheel side and clutch side
of the engine.
3
Fit the new fuel filter and feed the fuel hose back
into position.
6
Replacing the fuel hose
NOTE!
Do not use knurled pliers to disconnect or
reconnect the fuel hose. This could
damage the hose.
1
Disconnect and remove the fuel hose from the
crankcase.
Before replacing the fuel hose, measure the length
of hose between the crankcase and carburettor
and between the tank and crankcase. The correct
hose length between the tank and crankcase is 43
mm (1.69 inches). The correct hose length between the crankcase and carburettor is 53 mm
(2.09 inches).
2
Remove the fuel hose from the fuel tank using tool
502 50 83-01. Trim off 5 mm (0.20 inches) from the
mitred end of the hose. Fit the fuel filter and
reinsert the hose in the tank.
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Repair instructions
3
Tank vent – testing
1
Connect pressure gauge 502 50 38-01 to the fuel
hose. Pump the pressure up to 50 kPa (0.5 bar).
The pressure should drop to 20 kPa (0.2 bar)
within 60 seconds.
Fit the throttle pushrod in the tank and connect it to
the carburettor. Refit the spring.
A
4
C
2
B
Use gauge 502 50 37-01 to measure vacuum.
Readings should be as follows: the vacuum should
increase from 30 to 15 within 30 seconds. If
readings are outside this range the vyon plugs
must be replaced.
Connect the fuel hose to the carburettor. Check
that the hose is not kinked or too long to be
clamped between the crankcase and tank. The
correct hose length between the tank and crankcase is 43 mm (1.69 inches). The correct hose
length between the crankcase and carburettor is
53 mm (2.09 inches) excluding the mitred section.
5
Fuel tank – refitting
1
Insert the fuel hose into the carburettor chamber.
Refit the fuel tank.
2
Connect the fuel hose to the carburettor.
Bolt the front vibration damping spring into position, followed by both stops and the remaining two
vibration damping springs. Tighten to a torque of
2–3 Nm. Check that both vibration damping
springs and the stops are correctly seated on the
crankcase. Incorrect fitting may result in higher
vibration levels.
6
Then refit:
• cable guide
• starter assembly (2.5–3 Nm)
• chain and guide bar
• clutch cover
• air filter
• cylinder cover
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Repair instructions
Piston and cylinder – removal
1
Remove:
4
Cover the opening in the crankcase.
5
• cylinder cover
• carburettor (see “Carburettor – removal”)
• silencer
• spark plug
• fuel tank (applies to 340, 345)
2
Remove the circlips from the ends of the gudgeon
pin and press it out. Then lift off the piston.
6
Unbolt the vibration damping spring from the hand
grip.
3
Remove the bearing from the little end of the
connecting rod.
7
Undo the four cylinder bolts and lift the cylinder off
carefully.
Models 340, 345
If replacing the cylinder:
Unscrew the decompression valve. Remove the
intake system, see “Air intake system – removal”.
Undo the four cylinder bolts from the underside
and lift the cylinder off carefully.
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Repair instructions
8
When replacing the cylinder 340, 345:
Unscrew the decompression valve. (345)
Remove the intake system, see “Air intake system
– removal”.
Model 350 is fitted with a spacer, which is secured
using four bolts from the underside. The spacer
does not however need to be removed when
removing the cylinder.
• Measure piston ring wear. This should not
exceed 1 mm. Use the piston to push down the
piston ring.
• The needle roller bearing is undamaged.
• The inlet manifold is undamaged.
• Pressure test the decompression valve.
• Also refer to Jonsered’s Analysis guide for piston
failures, art. no. 108 07 01-01.
Decompression valve – pressure
testing
1
Cleaning and inspection
Clean all the components, scraping off all traces of
old gasket and carbon from the following places:
• Piston crown
• Top of the cylinder bore
• Cylinder exhaust port
• Decompression valve channel (340, 346XP,
350, 351, 353)
Connect tool 502 50 38-01 to the decompression
valve.
• Cylinder base and/or crankcase
2
Pump up the pressure to 80 kPa (0.8 bar).
Check the following:
• The surface coating of the cylinder is not worn
through, especially in the upper part of the
cylinder.
• The cylinder is free from score marks and areas
of wear.
3
Wait 30 seconds.
4
The pressure should not be less than 60 kPa
(0.6 bar).
• The piston is free from score marks. Small
scratches can be polished out with fine emery
paper.
• The piston ring is not burnt into its groove.
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Repair instructions
Piston and cylinder – refitting 346XP,
350, 351, 353
4
1
Press the insulating plate 503 86 62-01 onto the
cylinder. Check that the impulse tube connected to
the insulating plate is seated correctly in the inlet
manifold and lock the clamp over the manifold.
Lubricate the little end bearing with two-stroke oil
and insert it in the connecting rod.
2
5
Lubricate the piston ring and piston with two-stroke
oil.
6
Fit the piston with the arrow pointing towards the
exhaust port. Push in the gudgeon pin and fit the
circlips. If replacing the cylinder, fit the decompression valve, tightening to a torque of 12–14 Nm.
3
Fit a new cylinder base gasket. Compress the
piston ring with tool 502 50 70-01 and lower the
cylinder over it carefully.
7
1
Fit the inlet manifold 503 86 63-01 to the cylinder.
Check that the impulse tube is correctly seated in
the impulse channel.
4
3
2
NOTE!
It is very important that there are no leaks
in the inlet system, otherwise the engine
may seize.
Fit the cylinder bolts, tightening them in diagonal
pairs to a torque of 8–10 Nm.
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Repair instructions
Piston and cylinder – refitting 340, 345
Cylinder – pressure testing
1-5
See Piston and cylinder 346XP, 350, 351, 353 –
Refitting points 1-5.
6
Apply silicone adhesive/sealing compound (037062) to the crankcase’s contact surfaces with the
cylinder.
Carefully slide the cylinder down over the piston
towards the big end bearing.
Note!
Work is facilitated if the crankshaft complete with
bearing and piston is released from the crankcase
and the piston is pushed into the cylinder. The unit
is then refitted in the crankcase.
7
• Loosen the carburettor bolts so that the carburettor can be moved back about 4 mm. Insert
cover plate 502 54 11-02 between the carburettor and the carburettor flange. Tighten the
carburettor bolts to a torque of 1–1.5 Nm.
• Loosen the silencer bolts so that the silencer
can be moved back about 4 mm. Insert cover
plate 502 54 11-02 between the silencer and the
exhaust flange on the cylinder flange. Tighten
the silencer bolts to a torque of 8–10 Nm.
Fit the cylinder bolts, tightening crosswise to a
torque of 13–15 Nm.
8
Pressure test the cylinder.
• Unscrew and remove the spark plug. Screw in
pressure test nipple 503 84 40-02. Connect tool
502 50 38-01 to the nipple. The decompression
valve must be closed. The decompression valve
must be closed. To check the decompression
valve itself, see “Decompression valve – pressure testing”.
• Pump up the pressure to 80 kPa (0.8 bar).
9
Refit:
• Wait 30 seconds.
• spark plug, tighten to a torque of 15 Nm
• carburettor, see “Carburettor – refitting”,
• silencer, tighten to a torque of 8–10 Nm
• cylinder cover
NOTE!
If a new piston or cylinder has been fitted
the saw must be run for the first 3–4
hours with carburettor adjusted to the
factory settings.
• The pressure should not be less than 60 kPa
(0.6 bar).
• Remove the cover plates from the silencer and
carburettor, tighten the bolts to the specified
torque. Remove the pressure test nipple 503 84
40-02 and refit the spark plug.
WARNING!
After pressure testing the cylinder, check that the inlet manifold
is seated correctly, otherwise the
saw may be damaged.
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Repair instructions
Crankcase and crankshaft –
dismantling 346XP, 351, 353
3
1
Remove the following:
• guide bar and chain
• clutch cover
• cylinder cover
• starter assembly*
• ignition system*
• generator*
• centrifugal clutch*
• oil pump*
Split the crankcase with the aid of tool 502 51 6101 (A) and stop plate 502 54 18-01 (B), working
from the flywheel side of the saw.
• bark rest
• chain tensioner
• throttle pushrod
4
• carburettor*
• carburettor base
• silencer*
• piston and cylinder*
• fuel tank*
* See special instructions.
NOTE!
Take care to prevent dirt or foreign particles getting into the bearings.
2
Press the crankshaft out of the flywheel side of the
crankcase using tool 502 51 61-01.
5
Do the same on the clutch side without using stop
plate 502 54 18-01.
Unscrew the 6 bolts that hold the crankcase
together.
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Repair instructions
Crankshaft complete - dismantling
340, 345, 350
Crankshaft bearings – replacement
346XP, 351, 353
If the crankshaft bearings are to be replaced, tap
them out gently using drift 502 70 84-01.
1
Remove the following:
• chain and bar
• clutch cover
• cylinder cover
• starter assembly*
• ignition system*
• generator
• centrifugal clutch*
• throttle pushrod
The new bearings must be shrunk-fit into the
crankcase using a hot air gun.
• carburettor*
Cleaning and inspection
• silencer*
Clean and inspect all parts carefully.
• piston and cylinder*
Sealing ring – replacement
• fuel tank*
Remove the sealing ring from the magnet side
using tool 502 50 55-01.
* See special instructions.
2
Sealing ring replacement - drive side
Remove the oil pump.
1
Lift the crankshaft completely out of the crankcase.
350:
Unbolt the four bolts from underneath and lift off
the spacer.
Lift the crankshaft completely out of the crankcase.
Pry up the sealing ring from the bearing by using a
small screwdriver or the like.
Note. The sealing ring can be replaced without the
need of removing the bearing.
2
Press the new sealing ring into the bearing.
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Repair instructions
Cleaning and inspection
Clean and inspect all parts carefully.
Crankcase and crankshaft –
reassembly 346XP, 351, 353
1
Sealing ring – replacement
Remove the sealing ring from the crankcase using
a small screwdriver.
NOTE!
Take care to avoid damaging the crankcase.
To fit the sealing ring use the sleeve that is supplied with 502 50 30-16.
The end with the half moon is used for the sealing
ring on the clutch side, which must be fitted flush
with the surface of the crankcase.
The other end of the sleeve is used to fit the
sealing ring on the flywheel side and ensures that
the sleeve is fitted at the correct depth, 1.8 mm.
Lubricate the sealing rings with oil.
Crankshaft bearings 340, 345, 350 –
replacement
Remove:
• The crankshaft complete from the crankcase,
see page 47.
1
Pull off the crankshaft bearing from crankshaft.
2
Fit a new bearing on the crankshaft.
Hold the clutch side of the crankcase in a vice. Pull
the crankshaft into its bearing using assembly tools
502 70 84-01 and 502 70 45-07.
2
Check that the guide pins are in place. Fit a new
gasket to the mating surface of the clutch side of
the crankcase.
3
Place the flywheel side of the crankcase over the
crankshaft and pull the two crankcase halves
together using assembly tools 502 70 84-01 and
502 70 45-06.
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Repair instructions
4
Crankshaft complete 340, 345, 350 –
reassembly
Fit and tighten the six crankcase bolts to a torque
of 8–10 Nm. Check that the crankshaft rotates
freely.
1
Fit the crankshaft complete in the crankcase.
5
Refit the following parts:
• chain tensioner
350:
Fit and tighten the four bolts holding the spacer
from underneath and fit the crankshaft complete in
the crankcase.
• centrifugal clutch*
Refit the following parts:
• fuel tank*
• piston and cylinder*
• piston and cylinder*
• fuel tank*
• generator*
• silencer*
• carburettor base
• carburettor*
• carburettor*
• throttle pushrod
• throttle pushrod
• centrifugal clutch*
• silencer*
• generator*
• ignition system*
• ignition system*
• starter assembly*
• starter assembly*
• cylinder cover
• cylinder cover
• clutch cover
• clutch cover
• guide bar and chain
• chain and bar
* See special instructions.
* See special instructions.
• bark rest
• oil pump*
NOTE!
If a new crankshaft has been fitted the
saw must be run in for 3-4 hours with the
carburettor adjusted to the factory settings.
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Repair instructions
Repairing damaged threads
Guide bar bolts – replacement
A repair kit, 503 27 33-01, is available for repairing
damaged threads.
1
Drain the oil tank.
First drill out the hole using:
6.1 mm drill bit for magnesium crankcase
2
Knock through the old guide bar bolt so that it falls
into the oil tank.
Then screw in the thread insert using a suitable
bolt and spanner.
3
Remove the bolt from the oil tank.
4
Thread insert
A damaged thread can be repaired using a thread
insert. The slotted part of the thread insert is
screwed in first, as this is the cutting part.
To repair a thread that was originally designed for a
PL5 screw: first drill out with a 6.1 mm diameter
drill bit, then screw in the thread insert using a
suitable screw and spanner.
To repair a thread that was originally designed for a
MT6 screw: first drill out with a 7.1 mm diameter
drill bit, then screw in the thread insert using a
suitable screw and spanner.
This type of thread insert is best suited for use in
plastic and magnesium, but not for repairing
threads in aluminium. In that case use a helicoil
insert with metric screw.
New part no.
503 27 39-01
503 27 40-01
Fasten a steel wire to the thread of the new bolt,
feed the steel wire into the oil tank and out through
the bolt hole in the crankcase.
5
Pull the steel wire until the bolt comes out through
its hole.
6
Pull through the bolt with its nut. Place a spacer
between the nut and crankcase.
7
Check that the square shoulder of the bolt is
correctly seated in the recess in the crankcase.
8
Refill with chain oil.
Description
PL5
MT6
English – 49
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Repair instructions
Appendix A
Basic adjustment for EPA II carburetors
5. Let the engine run at ”B” rpm ~ 1 minute, until warm.
After replacing the carburetor or high speed and/or low
speed needle on an EPA (The US Environmental
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 instruction is made for USA & Canada
only. On EPA carburetors both the H- and L-needles are
fitted with caps to prevent the chain saw operator from
changing the adjustment above EPA standard. 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 settings.
6. Adjust the H-needle to a top speed of ”C” rpm.
When correctly set the caps must be fixed on the needles. The adjustment sleeve then can be removed. Over
the caps on complete sparepart carburetor, 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.
NOTE! On the complete spare part carburetor, the Lneedle is adjusted from the factory.
Model
340/345/350/351
346XP
C = 13 700
C = 14 300
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 ex. the locking pin for the bevel gear
ref.no. 502 02 61-03). This is a basic carburetor
adjustment. Further fine adjustments, within the limits
the caps allow, may be necessary to achieve optimum
performance. See the Operator’s manual.
Replacement of the L-needle
1. Take off the cap from the L-needle using e.g. 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.
Model
340/345/350
346XP/351
D = 1 1/2
D = 1 1/2
NOTE! Before making any adjustments the following
must be done!
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.
• Mount, for this model, approved bar & chain combination (See Technical data in the Operator’s manual).
4. Adjust the L-cap to the richest position (turned
counterclockwise to stop) without turning the needle.
Model
340/345/350
346XP/351
5. Let the engine run at ~ ”E” app.1 minute until warm
and then let it run on idle.
16”
16”
• The chain should not be tensioned more than that it
remains ~0,2 inches to the bar.
Model
340/345/350/351
346XP
• Mount a new air filter.
6. Adjust the idle speed to ”F” rpm.
Replacement of the H-needle or complete carburetor
1. Screw the new H-needle to the bottom and turn it
counterclockwise ”A” turns.
Model
340/345/350
346XP/351
Model
340/345/350
346XP/351
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 w. ref.no. 531 00 48-63 and insert
through the hole in the cap (max. blade width 2 mm/
0.08 inch) .
A = 3/4
A = 3/4
2. Check that:
The H-cap is adjusted to its richest setting. (Turned
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 counterclockwise =
minimum, 1/4 turn clockwise = maximum).
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.
Model
340/345/350/351
346XP
B = 12 000
B = 13 000
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).
E = 12 000
E = 13 000
F = 2 700
F = 2 700
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 richest
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 ex. the locking pin for the bevel gear
ref.no. 502 02 61-03).
This is a basic carburetor adjustment. Further fine
adjustments, within the limits the caps allow, may be
necessary to achieve optimum performance. See the
Operator’s manual.
50 – English
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114 01 47-26
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