Husqvarna 390 XP W Instruction manual

English - 1
English
390XP
Workshop manual

2 - English
Workshop Manual
390XP
Contents
1 Introduction and safety regulations ........................ 3
2 Technical data ............................................................ 6
3 Service tools .............................................................. 8
4 Service data ............................................................. 10
5 Chain brake............................................................. 12
6 Chain catcher.......................................................... 15
7 Muffler...................................................................... 16
8 Start/stop switch..................................................... 17
9 Throttle trigger,lockout and spring ....................... 18
10 Starter.................................................................... 19
11 Electrical system .................................................. 21
12 Centrifugal clutch ................................................. 26
13 Lubrication system............................................... 28
14 Carburettor............................................................ 32
15 Tank unit ................................................................ 39
16 Anti-vibration system........................................... 41
17 Piston and cylinder ............................................... 42
18 Crankcase and crankshaft................................... 46
19 Bar bolts................................................................ 51
20 Troubleshooting..................................................... 52

English - 3
1.1 General
This Workshop Manual provides a comprehensive
description of how to troubleshoot, repair and test the
chainsaw. A description of different safety measures that
should be taken during repair work is also given.
1.2 Safety
Note! The section dealing with safety should be read
and understood by all who do repair and service
work on the chainsaw.
Warning symbols and decals can be found in this
Workshop Manual and on the chainsaw. If a warning
symbol or decal on the chainsaw has been damaged or
is missing, replace it as soon as possible to make sure
the greatest possible safety when using the chainsaw.
1.3 Target Group
Personnel using this manual must have general
knowledge of the repair and service of small engines.
The Workshop Manual must be read and understood by
personnel who are to carry out repair work and service
on the chainsaw. The Manual is also suitable for use
when training new employees.
1.4 Modifications
In case of modifications made after the publication
of this Workshop manual the Manual should be read
together with all service information issued concerning
the chainsaw in question.
1.5 Layout
This Workshop Manual can be used in two different
ways:
• For the repair of a particular system on the
chainsaw.
• Disassembly and Assembly of the entire chainsaw.
Repair of a particular system
When a particular system on the chainsaw is to be
repaired, proceed as follows:
1. Look up the page for the system in question.
2. Do the steps:
• Disassembly
• Cleaning and inspection
• Assembly
Disassembly and Assembly of the entire chainsaw
1. Find the starter chapter and do the steps in
Disassemble.
2. Do the steps in Cleaning and inspection.
3. Make sure you have the required spare parts.
4. Find the Crankcase chapter do the steps in
Assembly.
To help with understanding, some chapters provide
a Description. Some chapters also have specific
instructions that explain how to repair or replace a
certain component.
Introduction and safety regulations
1 Introduction and safety regulations

4 - English
WARNING! The warning text warns of
the risk of personal injury if the
instructions are not followed.
1.1 General instructions
The workshop where chainsaw repairs are to be done
must be equipped with safety equipment as set out in
local regulations.
To be allowed to do repair the chainsaw you must have
read and understood the contents of this Workshop
Manual.
This Workshop Manual contains the following types of
warning texts. Warning texts are positioned before the
procedures they refer to.
1.2 Special instructions
NOTE! This text warns of material damage if
the instructions are not followed.
CAUTION! The caution text warns of
the risk of machine damage if the
instructions are not followed.
Introduction and safety regulations
WARNING! Read and understand the
following instructions to avoid personal
injury
The fuel used in the chainsaw has the following
hazardous properties:
• The fluid and its fumes are poisonous.
• Can cause skin irritation.
• Is highly inflammable.
The bar, chain and clutch cover (chain brake) must be
fitted before the saw is started otherwise the clutch can
come loose and cause personal injury.
Wear hearing protection when test running.
Do not use the saw until it has been adjusted so that
the chain remains still when idling.
After test running, do not touch the muffler until it has
cooled. Risk of burn injuries.
Insufficient lubrication of the chain can result in the
chain breaking, which can cause serious or even life-
threatening injury.
Make sure that the spring in the starter does not fly out
and cause personal injury.
If the spring tension is activated on the starter pulley
when it is to be taken up, the spring can fly out and
cause personal injury.
Make sure that the brake is applied when removing
the pressure spring on the chain brake. Otherwise the
pressure spring can fly out and cause personal injury.
After repair, the chain brake must be examined in
accordance with the instructions in the chain brake
chapter.
When replacing the crankshaft bearings note that the
crankcase halves are hot. Wear protective gloves
Do not direct the compressed air jet towards your body
or any person when using compressed air. Air can go
through the skin into the blood and result in mortal
danger.

English - 5
1.3 Symbols on the chainsaw
The following symbols are found on the chainsaw
casing.
1.4 Symbols in this Workshop Manual
This symbol indicates a risk of personal
injury if instructions are not followed.
Choke
Switch for hand grip heater
Fuel filler
Stop switch
Screw to adjust chain lubrication
Chain oil filler
Decompression valve
Chain brake
Use protective gloves.
Use protective goggles.
Introduction and safety regulations

6 - English
Displacement Bore Stroke Max. power/rpm
cm3/ cubic inch Ømm/Øinch mm/inch kW/hp / rpm
390 88 cm3/5.4 55mm/2.2” 3,7/1,5 4,8kW, 9600rpm
Guide bar length Maximum chain speed Chain pitch Drive link
cm/inch at maximum power, m/s mm/inch mm/inch
390 46-90/18-36 21,4 m/s at 9600 rpm 9,52/3,8 1,5/0,058
Spark plug gap Ignition system Air gap Carburettor type
mm/inch mm/inch
390 0,5/0,02 AM50 0.30mm/X WJ-116
2 Technical data
Technical data

English - 7
Idling speed Engage speed Max. speed Spark plug
rpm rpm rpm
390XP 2 700 3500 13000 NKG BPMR7A
Fuel tank volume Oil pump capacity Oil tank volume Automatic oil pump
Litres/US pint Litres/US pint
390XP 0,90/1,9 4 - 20 cm3/min 0,50/1,1 YES
Weight without Weight with Hand grip heater Electric carburettor
bar and chain bar and chain Watts/rpm heater
kg/lbs kg/lbs Watts/rpm
390XP XP 7.1/15.6 XP20” 8.5kg/18.6 65/10000 YES
rpm
OIL
Technical data

8 - English
10
8
3
11 12 13
14
9
12a
456
7
3 Service tools
Service tools
2b

English - 9
The tools listed here are service tools intended for use on the chainsaw in question. In addition to these tools, a
standard set of hand tools is required.
15
19
18
16
Service tools
Item Description Used for Article number
1 Piston stop Locking the crankshaft 502 54 15-01
2a Cover plate, exhaust Sealing the exhaust port 502 71 39-01
2b Cover plate, inlet Sealing the intake system 502 54 05-01
3 Pressure testing device Produce pressure when leakage testing 531 03 06-23
4 Puller Pulling bearing of crankshaft 531 00 48-67
5 Flywheel puller kit Dismantling of the flywheel 502 51 49-02
6 Piston assembly kit Assembling the piston 502 50 70-01
7 Seal ring extractor (flywheel side) Pulling of seal ring 504 91 40-01
8 Feeler gauges ignition gap Air gap tool 502 51 34-02
9 Tachometer Checking engine rpm 502 71 14-01
10 Test spark plug Checking the ignition module 502 71 13-01
11 Assembly pliers Assembly of spark plug cap 502 50 06-01
12 Hook for fuel filter Removing fuel filter 502 50 83-01
13 Assembly fixture Dismantling/assembling of the chainsaw 502 51 02-01
14 Clutch tool Removing the clutch 502 52 22-01
15 T-handle Torx T10 Dismantling/assembling of the chainsaw 588 52 41-01
15 T-handle Torx T20 Dismantling/assembling of the chainsaw 588 59 27-01
15 T-handle Torx T25 Dismantling/assembling of the chainsaw 502 71 27-01
15 T-handle Torx T27 Dismantling/assembling of the chainsaw 502 71 27-03
15 T-handle Torx T30 Dismantling/assembling of the chainsaw 502 71 31-01
16 T-handle Allen key For M4 bolts 502 50 18-01
16 T-handle Allen key For M5 bolts 502 50 18-01
17 Special tool clutch Removing the clutch 504 00 23-01
18 Crankshaft/crankcase splitter Dismantling of the crankcase 502 51 61-01
19 Crankshaft installation tool Installing the crankshaft 502 50 30-17
17

10 - English
Key to diagrams
The figures next to parts screwed on indicate
the tightening torque Nm.
= Lubricate with two-stroke oil.
= Lubricate with chain oil.
= Lubricate with grease.
4 Service data
Service data
●
●
●
■
▲
▲
●
●
4 mm8 ~ 9 Nm
4 mm8 ~ 10 Nm
4 mm8 ~ 10 Nm
4 mm4.5 ~ 5.5 Nm
4 mm4.5 ~ 5.5 Nm
1 ~ 1.5 Nm
4 mm4.5 ~ 5.5 Nm
4 mm4.5 ~ 5.5 Nm
13 mm15 Nm
4 mm8 ~ 10 Nm
5 mm12 ~ 14 Nm
4 mm8 ~ 10 Nm
20 Nm
1 ~ 1.5 Nm
1 ~ 2 Nm
1 ~ 2 Nm
1 ~ 2 Nm
1 ~ 2 Nm
3 ~ 4 Nm
1 ~ 2 Nm

English - 11
Service data
3 mm3 ~ 4 Nm
13 mm22 ~ 25 Nm
4 mm6 ~ 8 Nm
4 mm8 ~ 10 Nm
13 mm
12 ~ 14 Nm
19 mm15 Nm
4 mm8 ~ 10 Nm
4 mm
4.5 ~ 5.5 Nm
4 mm4.5 ~ 5.5 Nm
4 mm2 ~ 5.5 Nm
4 mm4.5 ~ 5.5 Nm
4 mm4.5 ~ 5.5 Nm
3 mm1 ~ 1.5 Nm
T276 ~ 7 Nm
4 mm4.5 ~ 5.5 Nm
4 mm4 ~ 5 Nm
4 mm3.5 ~ 4.5 Nm
4 mm6 ~ 8 Nm
0.5 ~ 1 Nm
0.5 ~ 1 Nm
▲
▲
●

12 - English
WARNING!
Make sure the spring does not fly out
and cause injury. Wear eye protection
5 Chain brake
Chain brake
Fig 1
Fig 2
Fig. 1
A
B
Fig. 2
C
G
FE
D
5.1 Disassembly
1. Disassemble the chain and bar. Refer to the
Operator’s manual.
2. Disassemble the centrifugal clutch. Refer to chapter
Centrifugal clutch in the Workshop manual.
3. Push the hand guard forward so that the chain brake
is engaged. See fig. 1.
4. Remove the hand guard, two screws. Note the
sleeve on the starter side. See fig. 2.
5. Remove the chain guide-plate (A). See fig. 1.
6. Remove the locking ring (C) with washer (D) and lift
up the clutch drum (E) with needle bearing (F) and
chain drive sprocket (G). See fig. 3.
Fig 3

English - 13
Chain brake
Fig. 1
A
B
Fig 8
Fig 5
Fig 7
Fig 6
Fig. 4
I
H
Fig. 5
Fig. 6
J
Fig 9
Fig. 7
Min. 0.8 mm
7. Remove the spark plug and fit the piston stop.
Remove the clutch with the clutch tool. Note the
left-hand thread. Screw in the direction of the arrow.
See fig. 5.
8. Remove the four screws (B) and the cover over the
chain brake mechanism. See fig. 6.
9. Press down the retaining bush (H) while releasing
the lever (I) with a screwdriver. See Fig 7.
10. Remove the pressure spring by freeing the back end
with a screw driver. See fig. 8.
11. Remove the toggle joint (J) with attached brake
strap. See fig. 8.
12. Remove the brake strap from the toggle joint.
13. Take out the retaining bush (H) with spring. See fig.
5.
• Carefully clean and examine all parts. 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 0.8 mm at any point. See
Figure 9.
• Lubricate the knee joint with grease.
5.2 Cleaning and inspection

14 - English
Chain brake
Fig. 12
H
L
Fig 10
Fig 11
Fig. 8
C
E
F
Fig. 9
Assemble the chain brake:
1. Fit the toggle joint and brake strap. See fig. 9.
2. Grease the moving parts of the toggle joint (J) and fit
the unit on the chain saw. See fig. 10.
Compress the spring and press it in place.
3. Grease and fit the lever (I). See fig. 7.
4. Grease and fit the retaining bush (H) withspring. See
fig. 7.
5. Fit the cover over the chain brake mechanism. Four
bolts (B).Tighten the bolts to 4 Nm. See fig. 1.
6. Fit the chain guide-plate with bolt (A). See fig. 1.
7. Fit the hand guard with the sleeve on the starter side.
See fig. 2.
8. Push back the hand guard so that the chain brake is
in the off position.
9. Check that the brake strap is correctly positioned in
the recess (K) in the crankcase. See fig. 10.
10. Fit the clutch hub on the crankshaft and tighten with
the clutch tool. Note – left-hand thread! See fig. 11.
11. Remove the piston stop and fit the spark plug and
put on the ignition cable.
12. Grease in the needle bearing before fitting. Fit the
clutch drum (E) with needle bearing (F) and chain
drive sprocket (G). See fig. 3.
13. Fit the washer (D) and locking ring (C). See fig. 4.
14. Fit the cylinder cover, chain and bar. See Operators
Manual.
For this test, the engine must not be running. Check that
the chain brake engages as follows:
Hold the chainsaw over a stable surface as shown in fig
12. The distance between the bar and surface is given in
the table below.
Bar length, L Height, H
15 - 20 Inches
21 - 28 Inches
29 - 32 Inches
50 cm
70 cm
80 cm
Let go of the front handle and let the chainsaw pivot
round on the rear handle.
1. When the bar hits the surface the chain brake
should engage..
WARNING!
Make sure the spring does not fly out
and cause injury. Wear eye protection
5.3 Assembly
5.4 Function test
NOTE!
After repair of the chain brake.The chain brake
must be tested as described in Function check.

English - 15
Chain catcher
Fig. 1
6 Chain catcher
6.1 Disassemble the chain catcher
1. Remove the clutch cover.
2. Disassemble the bar and chain.
6.2 Cleaning and inspection
Inspect the chain catcher and replace it if it is damaged.
See figure 1.
6.3 Assembly
1. Fit the bar and chain.
2. Adjust the tension of the chain.
3. Fit the clutch cover. See “4 Service data” on page
10.
Fig. 10
L
H
Fig. 11

16 - English
Fig. 1
7 Muffler
Muffler
7.1 Disassembly
WARNING!
Do not touch the muffler until it has
become cool. Risk of burn injuries.
1. Remove the two lower M5 bolts and the two M6 bolts
on the muffler. See fig. 1
2. Remove the gasket and cooling plate. See fig. 1
3. If the saw is fitted with a spark-arrester, remove it.
See fig. 1.
Fig. 9
Fig. 10
Fig. 11
stop
CAUTION!
Replace the gasket if it is damaged.The
gasket has to be fitted correctly against
the muffler.
7.2 Cleaning and inspection
Clean all components and do a check of:
1. That the spark-arrester is intact.
2. That the muffler and muffler mounting are not
cracked or in any way defect.
3. That the gasket is undamaged.
7.3 Assembly
1. Clean the contact surfaces of the gasket, cooling
plate and cylinder.
2. If the chainsaw is fitted with a spark-arrester, refit it.
See fig 1.
3. Fit the cooling plate, gasket and muffler to the cylin-
der. See fig 1.
4. Tighten the two bolts to the cylinder and tighten the
four bolts.
Retighten the screws after warm running.

English - 17
Start/stop switch
Fig. 1
Fig. 2
Fig. 9
Fig. 10
Fig. 11
stop
Fig. 9
Fig. 10
Fig. 11
stop
8 Start/stop switch
8.1 Disassembly
1. Remove the stop switch with a screwdriver and
detach the leads. See fig. 1.
8.2 Cleaning and inspection
Carefully clean and check all components. Parts must
be replaced if cracked or if they show signs of other
defects. Always use original spare parts.
Measure the resistance by connecting an ohmmeter to
the stop switch. See fig. 2. The resistance should be as
follows:
”0” pressed in - less than 0.1 ohm.
”1” pressed in - more than 1000 ohm.
8.3 Assembly
The symbol/stop marking should be mounted to the
rear hand grip during assembly. The earth lead is fitted
in the upper or lower connection. See fig. 2.
8.4 Function check
Clean the mating surfaces and do a check of the resis-
tance as follows:
Measure the resistance by connecting a multimeter to
the blue cable and the cylinder (earth).
NOTE! The switch must be in the “on” position to give
the correct reading.
The resistance must not be higher than 0.5 Ωwhen the
switch is in the on position.
The stop switch is in the ON-position when the button is
held down and in the OFF-position the button is neutral.

18 - English
9 Throttle trigger lockout, throttle trigger and spring
Throttle trigger lockout, throttle trigger and spring
Fig. 2
Fig. 3
Fig. 1
Fig. 12
Fig. 15
A
B
Fig. 13
Fig. 14
B
C
Fig. 12
Fig. 15
A
B
Fig. 13
Fig. 14
B
C
Fig. 12
Fig. 15
A
B
Fig. 13
Fig. 14
B
C
Fig. 3
Fig. 12
Fig. 15
A
B
Fig. 13
Fig. 14
B
C
9.1 Disassembly
1. Remove the hand grip insert (C). See fig. 1.
2. Remove the throttle lock pivot (A) with the help of a
driver. See fig. 1.
3. Press apart with a screwdriver or the like the throttle
lock/control and take out the throttle lock from the
recess in the hand grip. Now remove the spring. See
fig. 2.
4. Remove the stop switch. Press out the throttle lever
pivot (B) with a driver. See fig. 1 and 4.
5. Remove the throttle cable and lever. See fig. 4.
9.2 Cleaning and inspection
Clean all components and do a check of the following:
1. That the throttle cable and lever are undamaged and
run easily.
2. That the lock activation mechanism is not worn. See
fig. 2.
9.3 Replace a defect throttle cable
Attach the wire to the throttle trigger. Pull the wire
through the handle.
9.4 Assembly
1. Fit the throttle cable and lever. Fit the throttle lever
with pivot (B). See fig. 1 and 4.
2. Fit the spring in the recess in the throttle lock. Hold
the spring in place and locate the throttle lock in the
recess in the hand grip.
3. Fitting of the throttle lock is simplified by using a
screwdriver or the like to lock the spring. See fig. 3.
4. Fit the throttle lock pivot (A) with the help of a
driver. See fig. 1.
5. Fit the switch and hang grip insert.

English - 19
10 Starter
Fig. 1
Starter
Fig. 2
Fig. 3
Fig. 1
Fig. 2
Fig. 3
10.1 Disassembly
WARNING!
Make sure the the spring is released on
the starter pulley. it can come loose and
cause personal injury.
1. Remove the four bolts holding the starter to the
crankcase and remove the starter. See fig. 1.
2. Pull out the handle 20-30 cm and take out the cord
from the slot in the starter pulley. See fig. 2.
3. Rotate the starter pulley anticlockwise until the
tension on the pulley is released.
4. Remove the central bolt and take out the washer and
starter pulley. See fig. 3.
5. If the starter cord is to be replaced, cut it off and pull
out the ends from the handle and starter pulley with
pointed pliers.
6. If the spring is to be replaced, remove the old spring.
10.2 Cleaning and inspection
1. Clean all components.
2. Do a check of the following:
- Starter cord is not damaged.
- The dogs on the starter pulley is not damaged .
- That the pawls on the flywheel are intact and that
the spring is back towards the centre and moves
freely.
3. Grease the spring in the starter pulley

20 - English
Starter
10.3 Assembly
1. If a new spring is to be fitted, place the new spring
with steel wire so that the end loop comes over the
peg (A) in starter pulley. See fig. 4.
2. Press the spring down in the starter pulley and
remove the wire.
Fig. 5
Fig. 4
Fig. 4
A
Fig. 5
Fig. 6
Fig. 4
A
Fig. 5
Fig. 6
Fig. 6
10.4 Cord tension check
1. Pull out the cord completely.
2. In this position it should be possible to turn the pul-
ley by hand an additional 1/2 - 3/4 turn.
3. Put the starter on the crankcase and tighten the
bolts. See fig. 1.
7. Wind the cord onto the starter pulley and rotate the
pulley clockwise until the cord is correctly tensioned.
See fig. 6.
3. If a new cord is to be fitted, push the free end in the
hole in the starter pulley.Take hold of the end with
pointed pliers inside the pulley and pull up the cord.
See fig. 5.
4. Grease the starter pulley bearing and spring, and fit
the pulley on the spindle.Turn gently backwards and
forwards until the spring catches on the stop in the
housing.
5. Fit the washer and bolt (See fig. 3. ) and tighten it
with the coorect torque (Refer to ”4 Service data” on
page 10).
6. Pull out the cord through its hole in the housing and
fit the handle and secure it with a double knot. See
fig. 5