Husqvarna 555FX Instruction manual

Workshop manual
555FX 555FXT
555RXT 555FRM
English

1
Workshop Manual
Brushcutter, Trimmer
Model 555FX, 555FXT, 555RXT, 555FRM
Contents
General recommendations ____________________ 2
1. Starter ___________________________________ 3
2. Electrical system __________________________ 7
3. Fuel system _____________________________ 15
4. Centrifugal clutch ________________________ 31
5. Angle gear ______________________________ 37
6. Cylinder and piston _______________________ 41
7. Crankshaft and crankcase _________________ 51
8. Tools ___________________________________ 57
9. Technical Data ___________________________ 61
©Copyright Husqvarna AB, Sweden 2013

2
502 51 03-01
General recommendations
Remember:
Never start the engine without the clutch and clutch drum
mounted.
Do not grasp hot elements such as the muffler or the clutch
before they have cooled sufficiently to avoid burn injuries.
Avoid getting petrol on you skin or in your mouth. Use
protective cream on your hands. This lowers the risk of
infection and makes dirt easier to wash off. Long-term contact
with engine oil can be damaging to your health.
Never run the engine indoors. The engine exhaust is poisonous!
Wipe up any spilled oil from the floor immediately in order to
avoid injuries from slipping.
Do not use tools that are worn or fit poorly on nuts and bolts
and so on.
Fire risk
Handle petrol with respect, since it is highly flammable.
Do not smoke and ensure that there are no open flames or sparks
in the vicinity.
Make sure that there is a functioning fire extinguisher in the
vicinity.
Do not try to extinguish a petrol fire with water.
Poisonous fumes
When using cleaning fluids, read the instructions carefully.
Make sure that ventilation is good when handling petrol,
trichloroethylene and other highly volatile liquids.
The engine exhaust is poisonous. Test run the engine only if
ventilation is good. Preferably outside.
Special tools
Certain tasks in this handbook require the use of special tools.
In sections where this is applicable, an image of the tool with
an ordering number is provided.
We recommend using special tools in order to avoid personal
injury and to eliminate expensive damage to the components
in question.
Sealing faces and gaskets
Make sure that all sealing faces are clean and free from old
gasket remnants. Use a tool that will not damage the sealing
face when it is cleaned. Any scratches and irregularities
should be removed with a fine, float-cut file.
Sealing rings
Always change a sealing ring once it has been dismounted.
The sensitive sealing lips can be easily damaged with poor
sealing ability as a result. The surfaces that the seal is to
tighten against must also be completely free from damage.
Lubricate the sealing lip with grease before it is attached
and make sure that it is not damaged by such things as the
collars and splines on an axle. Use tape or a conical bushing
as protection. It is important that the sealing ring is turned
correctly in order for it to function as intended.
WARNING!
Risk of personal injury if the instructions are not
followed.
NOTE!
Material damage may occur if the instructions are not
followed.
!
!
!
!
!
!
!
+ Always work on a clean work surface.
+ Always work in a logical manner in order to be sure that all
components are correctly attached and that nuts and bolts are
tightened.
+ Use special tools where recommended in order to work
correctly.

3
1
Contents
Dismantling _________________________________ 4
Assembly___________________________________ 5
Replacing the drive dogs_______________________ 6
Starter

4
1 Starter
WARNING!
Protective glasses should be worn when working on the starter to avoid injury to the eyes if, for
some reason, the return spring should fly out.
!
Remove the bolt in the centre of the
starter pulley and remove the starter
pulley.
Remove the bolt in the centre of the
starter pulley. Lift the starter pulley
carefully from the starter cover.
Loosen the spring tension. Loosen the spring tension.
Pull out the starter cord about 30 cm.
Brake the starter pulley with your thumb
and lift the cord as illustrated.
Let the starter pulley rotate backwards
slowly.
Dismantling
Remove the starter from the engine.
Dismantling
Remove the 4 bolts and lift off the
starter.
The cylinder cover does not need to be
loosened or detached.
NOTE!
Ensure that the reinforcement
sleeves in the starter cover’s
securing holes are not lost.

5
1
A
A
!
Starter
Assembly
Clean requisite parts and assemble
in the reverse order as set out for
dismantling.
Assembly
Clean all components before assembly:
Change return springs, starter pulley
and starter cord as needed.
NOTE!
Be careful when opening the packaging with the return spring so that the
spring does not fly out.
Attach the spring cassette.
Attach the starter pulley.
Attach the new starter cord.
Attach the spring cassette and tighten
the two bolts (A).
Lubricate the bearing journal with a little
grease and attach the starter pulley.
Place the washer in place and tighten
the bolt.
Attach the new starter cord. Push it in to
the starter pulley’s track as illustrated and
then out through the cord guide in the
starter cover. Make sure that the knot at
the end of the cord is as small as possible!
NOTE!
New starter cords can be attached without dismantling the starter!
Anchor the cord in the starter handle. Thread the cord through the starter
handle and anchor it with a knot.
Fold down the free end and pull the knot
well into the handle.
Remove the spring cassette. Remove the two bolts holding the spring
cassette and remove the cassette for
replacement if necessary.
WARNING!
Wear protective glasses. The return spring can fly out
and cause personal injury if improperly handled.

6
1
Make sure that the tongue on the starter
housing comes inside the filter holder.
Tighten the bolts.
Check that the drive dogs grip the
starter pulley in the correct way.
Make sure that the tongue on the starter
housing comes inside the filter holder.
Tighten the bolts.
Starter
Replacing the drive
dogs
See chapter 2 Ignition system.
Replacing the drive
dogs
See chapter 2 Ignition system.
Tighten the return spring.
Check the spring tension.
Check that the reinforcement sleeves in
the starter cover’s securing holes are in
position.
Tighten the return spring.
Lift up the starter cord when the return
spring is completely loose and the cord
pulled out completely.
Then turn the starter pulley anti-
clockwise 7 revolutions.
Check the spring tension. With the cord
completely pulled out the cord pulley
should be able to be turned at least
another half revolution.
Check that the reinforcement sleeves in
the starter cover’s securing holes are in
position.
Mount the starter onto the engine. Mount the starter onto the engine.
Pull out the starter cord a little.
Place the starter in position and release
the starter cord at the same time.
Check that the air guide plate between
the starter and the flywheel is positioned
correctly.

7
2
Electrical system
Contents
Checking the ignition spark _____________________ 8
Replacing the spark plug cover _________________ 10
Dismantling ________________________________ 11
Drive dogs _________________________________ 12
Assembly__________________________________ 12
Heated handles _____________________________ 12

8
2
502 71 13-01
Electrical system
The engine is equipped with an electronic ignition system completely without moving parts. Consequently,
a faulty component cannot be repaired, but must be replaced by a new component.
The spark in an electronic ignition system has a very short burn time and can therefore be interpreted as
weak and can be difficult to see while troubleshooting.
Checking the ignition
spark
Clean the electrodes and check the
electrode gap.
Checking the ignition
spark
Remove the spark plug and clean it
from soot deposits with the help of a
steel brush.
Check the electrode gap. It should be
0.6 mm.
Adjust the gap as needed to the correct
value with the side electrode.
If the electrodes are worn more than
50% the spark plug should be changed.
If the engine does not start or misfires
despite the spark plug showing no signs
of wear, try with a new spark plug.
If the electrodes are worn more than
50% the spark plug should be changed.
Too large a spark gap entails a great
deal of stress on the ignition module and
risk for short-circuiting.
If the engine does not start or misfires
despite the spark plug showing no signs
of wear, try with a new spark plug.
Earth the spark plug and check whether
there is a spark when attempting to
start.
Test with test spark plug no. 502 71 13-01
if no spark is seen.
Earth the spark plug by connecting it
with a starter screw using a steel wire as
illustrated.
Pull the starter handle sharply.
A spark should be seen between the
electrodes.
If no spark is seen test with test spark
plug no. 502 71 13-01.
If a spark then occurs, the spark plug is
faulty.

9
2
Electrical system
Still no spark?
Check the ignition cable’s connection to
the spark plug cover.
Still no spark?
Check the spark plug connection.
Remove the spark plug cover and
make sure the ignition cable is not
damaged. Remove a segment of cable
if required to get sufficient contact at the
connection coil.
If no spark occurs even now, remove the
short-circuit cable from the stop switch.
Remove the screw A and lift off the
cover B to make the stop switch
accessible.
If the plug now sparks, the fault is either
in the stop switch or the short-circuit
cable.
Change the switch as needed and
check to see if the cable insulation is
damaged.
Still no spark?
Check other cables and connections.
Still no spark?
Check other cables and connections
for poor contacts (dirt, corrosion, cable
breakage and damaged insulation).
Make sure that the cables are correctly
drawn and lie in the cable grooves.
Do not forget to check the cables in the
throttle too.
See chapter 3 “Throttle”.
Tip!
Use an Ohmmeter in order to easily
check if cable breakage has occurred,
due to pinching, for example.
The stop switch can be easily detached
with a screwdriver.
Use a screwdriver pinch the switch’s
snap fastener inside the throttle.
NOTE!
The stop switch has a non
locking design and must be
replaced with one of the same
type.

10
2
502 50 06-01
502 51 34-02
Electrical system
Replacing the spark
plug cover
1. Insert the ignition cable through the
spark plug cover.
2. Make a hole in the ignition cable for
the ignition coil.
Replacing the spark
plug cover
1. Lubricate the ignition cable with a
little grease and thread it through the
spark plug cover.
2. Cut off a bit of the ignition cable
(approx. 5 mm) and make a hole in
the cable for the ignition coil with
the aid of a pair of no. 502 50 06-01
pliers.
3. Attach the ignition coil to the ignition
cable.
3. Attach the ignition coil to the ignition
cable and ensure that the wire is
folded along the cable.
4. Pull the ignition coil into the spark
plug cover.
NOTE!
It is important that the tip of the ignition coil hits the centre of the ignition
cable to prevent sparking.
Adjust the air gap. Adjust the air gap as needed to the
correct value.
• Loosen the bolts.
• Position the feeler gauge and press
the ignition module against the
flywheel.
• Tighten the bolts and check the air
gap again.
If the spark plug still does not fire, the
ignition system should be replaced.
Still no spark?
Check the air gap.
Still no spark?
Dismantle the starter, air guide plate
and the guard over the muffler.
Check the air gap between the flywheel
magnet and the ignition module. The
gap should be 0.3 mm.
Use a 502 51 34-02 feeler gauge.

11
2
502 51 94-01
502 54 15-01
502 50 18-01
A
B
B
C
502 51 49-01
Electrical system
Remove the nut holding the flywheel.
Remove the flywheel.
Dismantle the alternator if necessary.
Remove the nut holding the flywheel.
Remove the flywheel from the
crankshaft using punch no. 502 51 94-
01.
Leave a gap of approx. 2 mm between
the punch and the flywheel.
Gently knock the punch with a hammer
while holding the flywheel with your
other hand.
Heat the flywheel using a hot air gun
if necessary or use puller no 502 51
49-01.
Remove the alternator that supplies
power to the heated handles.
Dismantling
Dismantle the starter, air guide plate,
cylinder cover, muffler guard and the
spark plug.
Attach piston stop no. 502 54 15-01.
Dismantling
Dismantle the starter, air guide plate,
cylinder cover, muffler guard and the
spark plug.
Fit piston stop no. 502 54 15-01 in the
spark plug hole.
NOTE!
Place the piston stop so it is
caught between the piston and
the cylinder head. Not so it sticks
out into the exhaust port.
Dismantle the ignition module. Dismantle the ignition module.
Remove the ignition cable from cable
channel (A).
Remove both bolts (B).
Loosen the short-circuit cable (C) from
the ignition module.

12
2
502 51 34-02
502 50 18-01
502 50 18-01
Assembly
Assemble the alternator if necessary.
Check the key groove in the crankshaft
and key in the flywheel. If damaged the
components must be replaced.
Fit the flywheel and then the ignition
module.
Check the air gap, see page 10.
Assembly
Assemble the alternator if neces-
sary.
Check that the key groove in the
crankshaft is not damaged. If it is, the
crankshaft must be replaced.
Check that the key in the flywheel is not
damaged. If it is, the flywheel must be
replaced.
Attach the flywheel.
Attach the ignition module and make
sure the short-circuit cable is not
trapped.
Check the air gap, see page 10.
Remove the throttle from the handle.
In order to have access, the bolt that
holds the throttle and the cover with
the circuit breaker must be removed to
reach the electrical cables.
Drive dogs
Remove the bolts.
Remove the hooks and the springs to
replace them.
Mind the washer (A) so as not to lose it.
Replace damaged parts.
Assemble in the reverse order.
Drive dogs
The drive dogs can be easily replaced if
they are damaged.
Remove the bolts, the hooks and the
springs.
Mind the washer (A) so as not to lose it.
Replace damaged parts.
Assemble in the reverse order.
Check that the hooks can be turned
freely when the bolts are tight.
Electrical system
NOTE!
Do not pry off the heating element
before the locking catch has been
removed. The element can be
damaged.
The heating element in the throttle
is accessed when the throttle lock is
pushed out of the throttle.
Pry off the locking catch and lift out the
heating element.
A heating element is placed in the
throttle lock for involuntary throttling.
Press the locking catch from the throttle,
making sure not to lose the spring (A).
Pry off the locking catch (B) and lift out
the heating element (C).
Remove the throttle from the handle.
See also chapter 3 “Throttle”.
In order to remove the heating element
the bolt (A) that holds the throttle and
cover (B) and the heater switch must
first be removed (2 bolts).
Heated handles
The heating element in the handles consists of ceramic plates. These are self-regulating
with regard to temperature. When temperature increases, the resistance in the elements
lowers and so does the temperature. So no separate thermostat is needed.

13
2
Electrical system
Separate the contacts (A-A) and (B-B).
Then extend the cables (A) and (B) with
approx. 90 cm long steel wires attached
to the contacts.
Separate the contacts (A-A) and (B-B).
Then extend the cables (A) and (B) with
approx. 90 cm long steel wires attached
to the contacts.
This is to make it easier to draw the
cables to the new heating element back
through the handle.
1 = black
2 = blue
Remove the bolt and pull off the left grip
from the handle.
Pull one cable at a time from the handle.
Remove the heating element from the
handle with a pair of flat nosed pliers.
Remove the bolt that holds the left grip
on the handle.
Pull out handle from the handlebars and
then the cables, carefully and one at
a time, so that the steel wire does not
loosen from the cables.
The heating element is located in a
pocket in the outside of the handle.
Use flat nose pliers to pull out the
heating element from the handle.
NOTE!
Do not pull the cables or their
connections. Connections can be
easily broken.
Assemble in the reverse order as set
out for dismantling.
Wiring diagram
LH = Left handle
RH = Throttle
HC = Heater switch
TT = Triple contact
IM = Ignition module
SC = Short-circuit switch
Gen = Generator
Blu = blue
Bl = black
Re = red
Bl/Blu = black/blue
Use a universal tool when checking
wiring and heating elements. Set the
instrument to measure resistance to
check for open circuits.

14
2Electrical system

15
3
Contents
Air filter ___________________________________ 16
Tank venting _______________________________ 16
Fuel pump, Fuel filter_________________________ 17
Carburettor ________________________________ 18
Assembly__________________________________ 24
Carburettor settings__________________________ 25
Throttle ___________________________________ 27
Fuel system

16
3
531 03 06-23
505 69 85-70
NOTE!
The dirty flock filter must be
replaced with a new filter.
Fuel system
In addition to the fuel tank and carburettor, the fuel system consists of the air filter, fuel filter and tank venting.
All these components interact so that the engine receives the optimal mixture of fuel and air to make it as efficient as
possible. Very small deviations in the carburettor setting or a blocked air filter have a large effect on the running and
efficiency of the engine.
The carburettor can come from several different manufacturers on our models, but the function and repair methods are
essentially the same.
Air filter
Remove the air filter holder.
Air filter
Dismantle the cover (A) and remove the
air filter (B).
The nylon filter comes in two models.
The standard filter has a mesh size of
44μ. There is also a 80μunit available.
There is also a flock filter.
WARNING!
Do not clean not the filter with petrol. Hazardous!
!
Clean the nylon filter in tepid soapy
water or use cleaning agent 55 69
85-70 Active Cleaner. If the filter fabric
is damaged the entire filter should be
changed.
Clean the nylon filter in tepid soapy
water or use cleaning agent 55 69
85-70 Active Cleaner. If the filter fabric
is damaged the entire filter should be
changed.
Tank venting
Check that the tank venting valve works
correctly.
Replace the fuel cap if the valve is
faulty.
Tank venting
Tank venting takes place through the
fuel cap and needs to be functional for
the engine to work.
• Remove the cover over the fuel
pump and the fuel hose from the
carburettor. Drain the fuel from the
tank.
• Connect the fuel hose to pressure
tester no. 531 03 06-23.
• Pump up a pressure in the tank. It
must not exceed 65 kPa (0.65 bar)
before the tank venting valve opens.
• Lower the pressure in the fuel tank.
It must not drop below –5 kPa (0.05
bar) before the tank venting valve
opens.

17
3
Fuel pump, Fuel filter
The fuel pump facilitates cold starts.
The pump cannot be repaired and must
be replaced if it stops working.
Dismantle the fuel pump from the fuel
tank.
Fuel pump, Fuel filter
The fuel pump has the task of facilitating
the start of the engine when cold. The
pump fills the carburettor with fuel
before attempting to start the engine.
This also prevents vapour bubbles from
blocking the narrow fuel channels.
If the pump does not work it must be
replaced.
Remove the cover over the fuel pump.
Remove the fuel hose (A) from the
connection on the carburettor.
Clamp together the spring clip and pull
off the fuel hose (B) from the fuel pump.
Remove the screws (C) and lift off the
fuel pump with the suction hose and fuel
filter attached.
Replace any damaged parts.
Clean or replace the fuel filter.
Use a small screwdriver and pry the
fuel hose (D) off of the fuel pump (E) to
replace any damaged parts.
The fuel filter (F) must be replaced with
a new filter if it is dirty.
Fuel system
The fuel cap can be taken apart for
cleaning.
Use a screwdriver and pry off the
housing (A) that contains a rubber
membrane (B) and a filter (C).
Knock the housing against a table
top and the cap (D) that covers the
memrane will come off.
Use compressed air to clean the filter
(C) and the cintered filter (E) and
assemble the fuel cap in reverse order
to dismantling.
Ensure that the flat surface of the cap
(D) is facing the membrane.

18
3
A
B
505 38 13-08 502 50 18-01
Pry off the fuel hose and remove the
carburettor.
Pry off the fuel hose from the carburettor
with the help of a small screwdriver.
Remove the carburettor.
Remove the fuel hose. Remove the fuel hose (F) by clamping
together the clamp (G).
Carburettor
Dismantling
Remove the cylinder cover, air filter
cowling, air filter and air filter holder.
Carburettor
Dismantling
Remove the cylinder cover, air filter
cowling, air filter and air filter holder.
Remove both screws (A) and the nuts
(B) and lift off the air filter holder.
Fuel system
Dismantle the throttle cable. Unhook throttle cable’s ball (C) from the
lever on the carburettor.
The supply air shutter (D) does not need
to be dismantled.
Remember how the pressure rod (E) is
fitted.
NOTE!
Ensure that the
reinforcement sleeves in the
cylinder cover’s securing
holes are not lost.