Zenoah GZ4350 Instruction manual

Workshop Manual
English
GZ4350

English - 2
Workshop Manual
GZ4350
Contents
Index ................................................................................................ 3
Introduction and safety instructions .................................... 6
Technical data................................................................................ 9
Service tools ................................................................................11
Service data..................................................................................13
Safety equipment ......................................................................15
Repair instructions.....................................................................23
Troubleshooting .........................................................................57
Contents
Husqvarna AB has a policy of continuous product development and therefore reserves the right to modify
the design and appearance of products without prior notice.

3- English
Index
Index
C
Carburettor 34
Adjustment 42
Assembly 38
Cleaning and inspection 38
Design 34
Dismantling 36
Function 35
Pressure testing 40
Centrifugal clutch 30
Assembly of centrifugal clutch 31
Cleaning and inspection 30
Dismantling the centrifugal clutch 30
Chain brake 17
Assembling the chain brake 18
Cleaning and inspection 17
Dismantling the chain brake 17
Functional inspection 19
Chain catcher 20
Replacing the chain catcher 20
Crankshaft and crankcase 53
Assembling a complete crankshaft 54
Bearings and oil seals 55
Cleaning and inspection 54
Dismantling the crankcase and crankshaft 53
Cylinder cover 22
Removing cylinder cover 22
Replacing cylinder cover 22
F
Fuel system 46
Replacing the fuel lter 46
Replacing the fuel hose 46
Replcing the primer bulb 46
H
Handle heating system 47
I
Ignition module and ywheel 28
Assembling the ignition module and ywheel 29
Cleaning and inspection 28
Dismantling the ignition module and ywheel 28
Intake system 32
Assembling the intake system 33
Cleaning and inspection 32
Dismantling the intake system 32
Introduction and safety instructions 7
General 7
General Instructions 8
Modications 7
Safety 7
Special Instructions 8
Structure 7
Target group 7
Tools 7
M
Muer 19
Assembling the muer 20
Cleaning and inspection 19
Dismantling the muer 19
O
Oil pump and screen 31
Assembling the oil pump and screen 32
Cleaning and inspection 31
Dismantling the oil pump and screen 31
P
Piston and cylinder 49
Assembling the piston and cylinder 51
Dismantling the piston and cylinder 49
Faults and causes 50
Leakage testing the the cylinder 50
S
Service data 14
Service tools 12
Starter 25
Cleaning and inspection 25
Dismantling the starter 25
Replacing a broken or worn starter cord 26
Tensioning the return spring 26
Replacing a broken return spring 27
Starter assembly 27
Stop switch 20
Dismantling the stop switch 20
Resistance test - stop switch 21
Symbols
Symbols in the Workshop Manual 9
Symbols on the chain saw 9
T
Tank unit 44
Assembly 44
Dismantling 44
Technical Data 10
Throttle trigger lockout, throttle trigger and
spring 22
Assembling the throttle trigger lockout, throttle
trigger and spring 23
Cleaning and inspection 22
Dismantling the throttle trigger lockout, throttle
trigger and spring 22
Troubleshooting 58
Troubleshooting methods 59
V
Vibration damping system 45
Assembly 45
Cleaning and inspection 45
Dismantling 45

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Index

5- English
Introduction and safety instructions
2 Introduction and safety regulations
Contents
2.1 General ..........................................................................................................................................................................6
2.2 Safety .............................................................................................................................................................................6
2.3 Target group ................................................................................................................................................................6
2.4 Modications...............................................................................................................................................................6
2.5 Tools ...............................................................................................................................................................................6
2.6 Structure .......................................................................................................................................................................6
2.7 Numbering ..................................................................................................................................................................6
2.8 General instructions .................................................................................................................................................7
2.9 Special instructions ..................................................................................................................................................7
2.10 Symbols on the saw .................................................................................................................................................8
2.11 Symbols in the Workshop Manual ......................................................................................................................8

English - 6
2 Introduction and safety instructions
Introduction and safety instructions
2.1 General
This Workshop Manual describes in detail how
to be troubleshoot, repair and test the chain saw.
Adescription of dierent safety steps that must be
taken during repair work is also given.
2.2 Safety
Note: The section dealing with safety must be
read and understood by all those carrying out
repair work or service on the chain saw.
Warning symbols can be found in this Workshop
Manual and on the chain saw. See “Symbols on
the saw” and“Symbols in the Workshop Manual”.
A new warning symbol decal must be applied as
soon as possible if a warning symbol on the chain
saw has been damaged or is missing so that the
greatest level of safety can be maintained when
using the chain saw.
2.3 Target group
This Workshop Manual is written for personnel who
are assumed to have general knowledge of repair-
ing and servicing chain saws.
The Workshop Manual must be read and under-
stood by personnel who will carry out repair work
and service on the chain saw. The Manual is also
suitable for use when training new employees.
2.4 Modications
Any modications to the chain saw will be gradu-
ally introduced into ongoing production. As these
modications aect service and/or spare parts,
specic service information will be sent out on
each occasion. This means that in time this Work-
shop Manual will become out of date. In order to
prevent this, the Manual should be read together
with all service information concerning the chain
saw in question.
2.5 Tools
Special tools are required for some stages. All
service tools are listed in the Workshop Manual.
Usage is made apparent in each section.
Always use Husqvarna’s original:
• Spare parts
• Service tools
• Accessories
2.6 Structure
This Workshop Manual can be used in two dier-
ent ways:
• Repair of a specic system on the chain saw.
• Dismantling and assembly of the entire chain saw.
Repair of a specic system
When a particular system on the chain saw is to be
repaired, proceed as follows:
1. Look up the page for the system in question.
2. Carry out the following steps:
Dismantling
Cleaning and inspection
Assembly
Dismantling and assembling the chain saw.
Proceed as follows when the chain saw is to be
dismantled and assembled:
1. Open the “Repair instructions” chapter which
deals with the Starter and carry out the in-
structions outlined under the Dismantling
heading.
2. Work forward in the Manual and carry out Dis-
mantling in the order set out in the sections.
3. Go back to the Starter and carry out the in-
structions under Cleaning and Inspection.
4. Work forward in the Manual and carry out
Cleaning and Inspection in the order set out
in the sections.
5. Order or collect all requisite spare parts from
the stores.
6. Look up the“Repair instructions”chapter which
deals with the Crankcase and carry out the
instructions outlined in Assembling.
7. Work back in the Manual and carry out Assem-
bling in the order set out in the sections.
Some sections include an introductory Descrip-
tion of the actual unit in order to increase the basic
understanding.
2.7 Numbering
Position references to components inside the g-
ures are designated A, B, etc.
The gures are numbered 1, 2 etc.
The position references and gure numbers restart
in each new section.

7- English
2.8 General Instructions
The workshop where the chain saw is to be re-
paired must be equipped with safety equipment in
accordance with local regulations.
No one may repair the chain saw unless they have
read and understood the content of this Workshop
Manual.
This workshop manual contains the following warn-
ing boxes in relevant places.
2.9 Special Instructions
The fuel used in the chain saw has the following
hazardous properties:
• The uid and its vapour are poisonous.
• Can cause eye and skin irritation.
• Can cause breathing problems.
• Is highly inammable.
When using compressed air, do not direct the jet
towards your body. Air can penetrate into the blood
stream, which can endanger life.
Wear protective earplugs or earmus when test
running.
After test running, do not touch the muer until it
has cooled down. Risk of burns. Use protective
gloves when working with the muer.
Do not start the chain saw unless the guide bar,
saw chain and clutch cover (chain brake) are tted,
otherwise the clutch may loosen and cause per-
sonal injury.
Insucient saw chain lubrication can result in saw
chain breakage, which can cause serious or even
life-threatening injury.
Exercise care to ensure the starter spring does not
y out and cause personal injury. Wear protective
glasses. If the spring tension is activated on the
starter pulley when it is to be taken up, the spring
can y out and cause personal injury.
Check that the brake is applied when removing
the pressure spring on the chain brake. Otherwise
the pressure spring can y out and cause personal
injury.
After repairing, check the chain brake, see “As-
sembling chain brake \ Function check”.
Keep in mind the re risk. The chain saw may emit
sparks, which cause ignition.
Check the chain catcher and replace it if it is dam-
aged.
WARNING!
The warning box warns of the risk
of personal injury if the instruc-
tions are not followed.
NOTE!
This box warns of material damage if the
instructions are not followed.
Introduction and safety instructions

English - 8
Introduction and safety instructions
2.10 Symbols on the chain saw
The symbols below are embedded on the chain
saw.
Choke Lever
Refuelling
Stop switch
Chain oil ll
Chain brake
Primer bulb
Adjusting the oil pump
Heated handles
2.11 Symbols in the Workshop Manual
This symbol warns of personal injury
when the instructions are not followed.
Wear protective gloves.
Wear protective goggle.

9- English
Displacement Cylinder diameter Stroke length Max. output/speed
cm3/cubic inch Ø mm/Ø inch mm/inch kW/hp/rpm
GZ4350 43,1 / 2.63 42 / 1.65 31,1 / 1.22 2,2 / 2.95 / 9 600
Electrode gap Ignition system Air gap Carburettor type
mm/inch mm/inch
GZ4350 0,65 / 0.025 IKEDA UK-09701 0,4 / 0.016 Walbro HD-54B
Usable cutting length Chain speed at 133% of Chain pitch Drive link
cm/inchmaximum engine power speed mm/inch mm/inch
ft/s / m/s
GZ4350 31-43 / 12-17 80.7 / 24,6 8,25 / 0.325 1,3 / 0.050 - 1,5 / 0.058
3 Technical data
Technical data

English - 10
Engage speed Spark plug Type of oil pump
rpm
GZ4350 4100 (+/- 250) NGK CMR7H Adjustable
Volume fuel tank Capacity oil pump at Volume oil tank
Litre/US. pint 9,000 rpm, Litre/US. pint
ml/min
GZ4350 0,42 / 0.87 3-13 0,27 / 0.57
Technical data
Weight without bar and chain Heated handles
kg / lbs
GZ4350 4,5 / 9.92 -

11 - English
11 12
9
4 Service tools
Service tools
4
3
8
12
7
10
56
13
14
15 16
17

English - 12
Pos. Description Used for Order No.
1 Air gap tool, ignition Setting ignition module 514 24 41-01
2 Piston stopper Locking the crank shaft 581 40 85-01
3 Wrench Clutch out or in 513 63 60-01
4 Puller assy Rotor out 510 13 89-01
5 Rod assy Piston pin out or in 521 53 35-01
6 Wrench Clutch spring in 513 63 65-01
7 Guide Brake spring out or in 513 63 70-01
8 Guide Crankshaft in 513 70 59-01
9 Tachometer Engine speed meter 502 71 14-01
10 Torx wrench T20/T25/T27 578 28 90-01
11 Ignition checker Spark strength check 501 97 64-01
12 Guide Setting heating coil (543XPG) 512 41 31-01
13 Spark plug adapter Pressure testing 503 84 40-03
14 Cover plate, inlet Pressure testing 574 71 14-01
15 Rubber wedge, outlet Pressure testing 502 54 11-02
16 Bearing/oil seal, kit MAG side 584 14 05-01
17 Bearing/oil seal, kit PTO side 584 14 05-02
18 Pressure/vacuum gauge Pressure testing 531 03 06-23
19 Compression tester Compression testing 531 03 16-86
19b Adapter Size: 10mm 583 84 98-01
20 Assembly xture Securing the chain saw 502 51 02-01
21 Crankshaft assembly kit Assembling crankshaft 502 50 30-22
(MAG side only)
22 Hook for fuel lter Withdrawing the fuel lter 502 50 83-01
23 Assembly kit, piston Assembling the piston 502 50 70-01
24 Adjustment screwdriver Adjustment of the carburettor 513 63 56-01
25 Adjustment screwdriver Adjustment of the carburettor 530 03 55-60
Service tools
20
19
18
21 22 23
19b
24
25
The tools listed here are
the service tools required
for this model of chain
saw. In addition to these
tools, a normal kit of hand
tools is required.

13 - English
5 Service data
Service data
Key
The numbers by bolted components represent the tightening torque in Nm.
Lubricate with two-stroke oil.
Lubricate with grease.
Apply thread lock: Three bond #1322 or Loctite #262.
Apply thread lock: Three bond #1342 or Loctite #242.
o
m
n
Apply liquid gasket: #1217F.

English - 14
Service data

15 - English
6 Safety equipment
Safety equipment
Contents
6.1 Dismantling the chain brake .................................................................................................................................16
6.2 Assembling the chain brake ..................................................................................................................................17
6.3 Dismantling the muer ..........................................................................................................................................18
6.4 Assembling the muer ..........................................................................................................................................19
6.5 Replacing the chain catcher ..................................................................................................................................19
6.6 Dismantling the stop switch .................................................................................................................................19
6.7 Assembling the stop switch ..................................................................................................................................19
6.8 Resistance test - stop function .............................................................................................................................20
6.9 Dismantling the throttle trigger lockout, throttle trigger and spring ...................................................21
6.10 Assembling the throttle trigger lockout, throttle trigger and spring ....................................................22

English - 16
0.6 mm
2
Release the tension in the brake spring by press-
ing down on the lever. See gure 2.
Loosen the screws and carefully remove the cov-
ers over the brake spring. See gure 2b.
WARNING!
Exercise care to ensure the spring
does not y out and cause personal
injury. Wear protective goggles.
6.1 Dismantling the chain brake
Cleaning and inspection
• Clean and check all components carefully. Parts
must be replaced if cracked or show signs of
other defects. Always use original spare parts.
• Measure the thickness of the chain brake band.
It must not be less than 0,6 mm in any place.
See gure 4.
• Lubricate the knee joint with grease.
3
Hold one hand on top of the brake spring and
press in a small screwdriver (or special tool 513 63
70-01) into the spring. Carefully bend upwards until
the spring is released and it slides onto the screw-
driver, see gure 3.
Safety equipment
6 Safety equipment
1
Release the brake by moving the front hand guard
backward. Loosen the bar nuts and remove the
clutch cover, guide bar and saw chain.
See gure 1.
Fig 1
Fig 3
Fig 4
Fig 2
Fig 2b

17 - English
6.2 Assembling the chain brake
1
Fit the knee joint and the brake band together (see
gure 5). Place the knee joint with the tted chain
brake band in the opening in the clutch cover. The
space for the spring in the cover must be lubricated
with grease, see gure 5.
2
Compress the spring with a wide screwdriver (or
special tool 513 63 70-01) and press it down with
your thumb, see gure 6.
3
Fit the two covers using 0,7-1,5 Nm tightening
torque, see gure 7.
WARNING!
Exercise care to ensure the spring
does not y out and cause personal
injury. Wear protective goggles.
4
Tension the spring by pressing down on the lever.
See gure 8.
5
Fit the guide bar, saw chain and clutch cover.
See gure 9.
Safety equipment
Fig 5
Fig 6
Fig 7
Fig 8
Fig 9

English - 18
NOTE!
After repairing, the chain brake must be in-
spected in line with the instruction below.
Functional inspection:
Do not turn on the engine when carrying out this
inspection.
Guide bar length Height
13”-18” 45 cm/18"
• Hold the chain saw over a stable surface. The
distance between the guide bar and the sur-
face is shown in the table above.
• Let go of the front handle and let the chain saw
drop toward the surface underneath.
• When the guide bar hits the surface the chain
brake must trigger.
Safety equipment
Fig 10
WARNING!
Do not touch the muer until it
has cooled. Risk of burns.
6.3 Dismantling the muer
1
Remove the cylinder cover, muer and gasket.
See gure 11.
2
If the muer is tted with a spark arrestor mesh,
this is removed. If necessary, use the combination
spanner to push down the plate edge and remove
the spark arrestor mesh, See gure 11.
Cleaning and inspection
• Clean and check all components carefully. Parts
must be replaced if cracked or show signs of
other defects. Always use original spare parts.
• The spark arrestor mesh is best cleaned with a
wire brush.
• The mesh must be replaced, if damaged. The
chain saw will overheat if the mesh is clogged
resulting in damage to the cylinder and piston.
• Never use a chain saw with a clogged or defec-
tive muer.
Fig 11

19 - English
6.5 Replacing the chain catcher
A worn chain catcher must always be replaced with
a new one. Always use original spare parts.
1
Release the chain brake by moving the front hand
guard backward.
Loosen the bar nuts and remove the clutch cover,
saw chain and guide bar.
2
Remove the chain catcher and replace it with a
new one. Tightening torque 3,4-4,9 Nm.
Safety equipment
6.6 Dismantling the stop switch
1
Carefully remove the stop switch using a at
screwdriver or similar tool. See gure 14.
2
Disconnect the cables.
Cleaning and inspection
• Clean and check the power switch carefully.
Parts must be replaced if cracked or show
signs of other defects. Always use original
spare parts.
Fig 13
Fig 14
6.4 Assembling the muer
1
If the muer is tted with a spark arrestor mesh,
put it in place rst. When tting the mesh, make
sure that the mesh is inserted in the right position.
If necessary, use the combination spanner to insert
the mesh.
2
Fit the:
• gasket
• muer, tightening torque of 5,9- 6,9 Nm.
• cylinder cover
3
Warm up the chain saw for at least one minute and
retighten the screws on the muer to 5,9 - 6,9 Nm.
Fig 12
6.7 Assembling the stop switch
1
Connect the cables. See g 14.
2
Fit the stop switch.