Husqvarna 455 Rancher Instruction manual

Workshop manual
English
455 Rancher

English Ð 1
Workshop manual
Husqvarna 455 Rancher
Contents
Introduction ........................................................... 2
S a f et y re g ulations ................................................ 3
Ge n era l ins truct i o ns ........................................... 3
Spec i a l ins truct i o ns ............................................ 3
S pecial tools ......................................................... 4
T echnical data ...................................................... 6
Car b urettor ............................................................ 8
C ar b urettor ........................................................ 8
C ar b urettor - pre ss ure te s t ing .......................... 1 3
C ar b urettor - a dj u s t m e n t .................................. 1 4
T rou b leshootin g ................................................. 1 6
Repair instructions ............................................. 1 8
C h a in b ra k e ...................................................... 1 8
S il e n cer ............................................................ 2 0
C h a in catc h er ................................................... 2 0
Stop s w i tc h ....................................................... 21
Stop s w i tc h Ð re sis ta n ce m ea s ure m e n t ............ 21
C h o k e co n tro l ................................................... 22
T h rott l e tr igg er .................................................. 2 3
Starter a ss e mb l y .............................................. 2 4
Starter cor d ....................................................... 2 4
R eco il s pr ing ..................................................... 2 5
I gni t i o n m o d u l e Ð te s t ing .................................. 2 6
I gni t i o n m o d u l e a n d ß yw h ee l ............................ 2 6
C e n tr i f u g a l c l utc h .............................................. 2 8
O il pu m p ........................................................... 2 9
A i r in ta k e s y s te m ............................................. 3 1
F ue l Þ l ter ........................................................... 3 2
F ue l h o s e .......................................................... 3 2
F ue l ta n k ........................................................... 33
P is to n a n d c y lin d er ........................................... 33
D eco m pre ssi o n v a l v e Ð pre ss ure te s t ing ......... 3 4
C y lin d er Ð pre ss ure te s t ing ............................... 3 6
C ra n k sh a f t co m p l ete ........................................ 3 6
C ra n k sh a f t b ear ings ......................................... 3 7
T h rea d ins ert .................................................... 3 8
Gu i d e b ar b o l t s ................................................. 3 8

2 Ð English
Arrangement of the manual
This workshop manual can be used in two different
ways.
¥ To repair a speciÞ c sub-assembly on a chainsaw.
¥ To dismantle and reassemble a complete chain-
saw.
R e p a i r i ng a sp e ciÞ c s u b- a ss em b l y
I f a speciÞ c sub-assembly on the chainsaw needs
to be repaired :
1 . L ook up the page referring to the rele v ant sub-
assembly.
2. F ollow the instructions under the headings :
¥ R emo v al /D ismantling
¥ C leaning and inspection
¥ R eÞ tting /R eassembly
D is mantl i ng an d rea ss em b l i ng the ent i re c ha i n s a w
I f the entire chainsaw is to be dismantled , follow
the instructions under the heading Ò R emo v al /D is-
mantling Ó .
W ork through the manual and follow the instruc-
tions gi v en in each section under the heading
Ò R emo v al /D ismantling Ó .
Then follow all the Ò C leaning and inspection Ó
instructions in each section.
W orking from the back of the manual , follow all the
instructions under the headings Ò R eÞ tting /R eas-
sembly Ó in re v erse order.
Each of the sections co v ering remo v al / dismant-
ling and reÞ tting / reassembly include the rele v ant
lubrication instructions and bolt tor q ues for each
stage of repair.
C on s tru c t i on an d fun c t i on
This chapter gi v es a simple description of the
chainsaw carburettor and its v arious parts.
I ntro d u c t i on
T rou b le s hoot i ng
These pages describe the most common faults that
affect a chainsaw. They are di v ided into four dif-
ferent groups with the most likely faults described
Þ rst.
R e p a i r i n s tru c t i on s
The section that describes how to repair the chain-
saw consists of detailed , step-by-step instructions.
I t e x plains in detail the special tools , lubricants
and bolt tor q ues that are needed when working on
each component.
T h is w or k s ho p manual c o v er s the follo w i ng
c ha i n s a w mo d el s : 455

English Ð 3
General 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 workshop manual has been written for person-
nel who are assumed to have general experience
of repairing and servicing chainsaws.
Workshops where chainsaws are repaired must be
e uipped with safety e uipment that meets local
regulations.
No-one should carry out repairs on a chainsaw
until they have read and understood the contents
of this workshop manual.
Chainsaws are type-approved to meet the relevant
safety legislation, but this only applies when the
saw is Þ tted with the cutting e uipment speciÞ ed
in the userÕs manual. The Þ tting of any other
e uipment, or of accessories or parts that are not
approved by Jonsered, could mean that the saw
no longer meets these safety re uirements 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.
Sp ecial instructions
The fuel that is used in a chainsaw poses the fol-
lowing ha z ards :
¥ The fuel and its fumes are toxic.
¥ M ay cause irritation to skin or eyes.
¥ M ay cause breathing difÞ culties.
¥ H ighly ß ammable.
When using compressed air the air j et should
never be pointed at the body. A ir can be forced into
the bloodstream and cause fatal in j ury.
Wear ear protection when testing saws.
A fter 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 Þ tted before the saw is started. If
not, the clutch may come loose and cause in j ury.
P oor chain lubrication can result in failure of the
chain, which could cause serious or fatal in j ury.
Take care to ensure that the spring inside the
starter assembly does not ß y out and cause in j ury.
Wear eye protection. If the spring is under
compression when the pulley is removed it could
ß y out and cause in j ury.
B efore removing the tensioning spring from the
chain brake, ensure that the brake is in the on
position, otherwise the spring may ß y out and
cause in j ury.
A fter completing the repair the chain brake must be
tested, see Ò Chain brake Ð reassembly \ O perating
test Ó .
A lways consider the Þ re risk. A chainsaw can
produce sparks that could start a Þ re.
Inspect the chain catcher and replace it if it is
damaged.
WARNIN G !
Th e w arnin g te x t w arns o f t h e ris k
o f p ersonal in j ur y i f t h e instruc -
tions are not f ollo w e d.
NOTE!
Th e w arnin g te x t w arns o f t h e ris k o f
m aterial d a m a g e i f t h e instructions are
not f ollo w e d.
S a f et y re g ulations

4 Ð English
10
Special tools
45
8
123
6
7
9

English Ð 5
Item Description Used for Order no.
1 Clutch tool Centrifugal clutch 502 52 22-01
2 Piston stop ocking the crankshaft 504 91 06-05
3 Fuel Þ lter hook Withdrawing the fuel Þ lter 502 50 83-01
4 Allen key For M5 bolts 502 50 18-01
5 Pressure tester Pressure testing cylinder 502 84 40-02
6 Feeler gauge Adjusting ignition module 502 51 34-02
7 Assembly Þ xture Assembling chain saw 502 51 02-01
8 Pressure gauge Pressurisation during testing 531 03 06-23
9 Test spark plug Checking the ignition module 502 71 13-01
10 Rev counter Adjusting carburettor 502 71 14-01
11 Assembly pliers Fitting spark plug guard 502 50 06-01
12a Cover plate, exhaust Sealing the exhaust port 502 54 11-02
12b Cover plates, inlet Sealing the intake manifold 502 52 48-01
13 Assembly tool Assembling spring, chain brake 502 50 67-01
14 Puller Pulling bearing of crankshaft 504 90 90-01
15a Sleeve Fitting crankshaft 502 50 30-18
15b Shaft extension Flywheel side 502 50 30-18
15c Shaft extension Cluch side 502 50 30-18
16 Punch Dismantling the ß ywheel 502 51 94-01
Special tools
11 12a
13 14
12b
15a
15c
15b
16

6 Ð English
Displacement Cylinder bore Stroke Max power/speed
cm
3/cubic inches ¯ mm/¯ inches mm/inches kW/hp/rpm
55: 55,5 / 3,38 7 / 1,85" 32 / 1,28" 2,5 / 3, / 9 000
Spark plug gap Ignition system Air gap Carburettor type
mm/inches mm/inches
55: 0,5 / 0,02" SEM CD 0,3 / 0,012" Walbro WTA 29
Effective cutting length Chain speed at Chain pitch Drive link
cm/inches max power Ð revs mm/inches mm/inches
m/s Ð rpm
55: 31-50 / 13"-20" 17,3 / 9 000 9,52 / 3/8 1,3 / 0,050" - 1,5 / 0,058"
8,25 / 0,325"
T echnical data

English Ð 7
Technical data
Idling speed Engagement speed Max. speed Spark plug
rpm rpm rpm
455: 2 700 3 00 13 500 NGK BPMR 7A
Champion RCJ 7Y
Fuel tank capacity Oil pump capacity at Oil tank capacity Automatic oil pump
Litres/US pints ,500 rpm, Litres/US pints
ml/min
455: 0,44 / 0,93 9 0,32 / 0,6 Yes
Weight without Weight with
bar and chain bar and chain
kg / lbs kg / lbs
455: 5, / 12, 6,2 / 13,6

8 Ð English
C arburettor
WARNING!
The fuel used in the chainsaw has
the following hazardous properties:
1. The ß uid and its fu es are poi-
sonous.
2. Can cause skin irritation.
3. Is highly inß a able.
Carburettor
Description
The drawings accompanying this description do
not correspond with the carburettor on the chain-
saw. They only show the principle for the design
and function.
Design
The carburettor is based on three sub-systems :
¥ The metering unit , A .
¥ The mi x ing v enturi , B .
¥ The pump unit , C .
The j ets and the fuel Õ s control functions are located
in the metering unit (A) . H ere the correct q uantity
of fuel is ad j usted for the actual speed and power
output.
A
B
C
The mi x ing v enturi (B) houses the cho k e , throttle
v al v e and diffuser j ets. H ere air is mi x ed with the
fuel to gi v e a fuel / air mi x ture that can be ignited by
the ignition spar k .
I n the pump unit (C), fuel is pumped from the fuel
tan k to the metering unit. O ne side of the pump di-
aphragm is connected to the cran k case and pulses
in time with the pressure changes in the cran k case.
The other side of the diaphragm pumps the fuel.

English Ð 9
Carburettor
Function
T he c arburettor o p erates d i ff erentl y in the f ollo w ing
m o d es :
¥ Col d start m o d e
¥ Id ling m o d e
¥ P art throttle m o d e
¥ F ull throttle m o d e
I n the c ol d start m o d e ( see Þ gure belo w) the c ho k e
v al v e (H) is f ull y c lose d. T his in c reases the v a c uu m
in the c
arburettor so that f uel is su ck e d m ore easil y
f ro m all the d i ff user j ets (D, E an d F). T he throttle
v al v e (I) is p artl y o p en . E x tra air inlet (J) is c lose d.
I
H
DF
E
J
I
D
J
I
J
DF
E
DF
E
I n the i d ling m o d e the throttle v al v e (I an d J) is
c lose d.
A ir is su ck e d in through an a p erture in the throttle
v al v e an d a s m all a m ount o f f uel is su pp lie d th -
rough the d i ff user j et (D).
I n the p art throttle m o d e the throttle v al v e (I) is
p artiall y o p en . F uel is su pp lie d through the d i ff user
j ets (D an d E ).
I n f ull throttle m o d e all v al v es are o p en an d f uel is
su pp lie d through all d i ff user j ets (D, E , F an d G).
E x tra air inlet (J) is also f ull y o p ene d.

10 Ð English
Carburettor
C arburettor Ð removal
1
R e m o v e the cy lin d er c o v er an d air Þ lter . D is c on -
ne c t the lea d s f ro m the sto p s w it c h an d the f uel
hoses f ro m the c arburettor . P ull out an d li f t u p the
stri p (A), see Þ gure .
2
NOTE!
D o n ot u s e kn urle d p l i er s to disc o nn e c t or
re c o nn e c t t
h e f uel h o s e . This c oul d d ama g e
t h e h o s e a nd lea d to lea k a g e or f ra c ture .
L oosen the s c re w s ( 4 ) on the c arburettor . L i f t the
c arburettor out o f the c arburettor c o mp art m ent .
5
R e m o v e the c o v er (A) o v er the m etering unit an d
c are f ull y re m o v e the m etering d ia p hrag m ( B ) an d
gas k et . S ee Þ gure belo w.
6
R e m o v e the s c re w ( E ) an d ta k e out the nee d le
v al v e (D) w ith le v er ( C ), s p in d le an d s p ring . S ee
Þ gure belo w.
D is m antle the throttle a c tuator ro d b y p ulling out
an d li f ting u p C f ro m its seating . F irst re m o v e the
throttle a c tuator ro d f ro m the le v er an d then f ro m
the han d le .
3
4
A
C
B
B
L oosen the c arburettor Õ s rubber m ounting ( B ).
7
R e m o v e the c o v er ( J ) o v er the p u mp unit an d
c are f ull y re m o v e the gas k et ( I ) an d p u mp d ia p hrag m
( G ). S ee Þ gure belo w.
A
B
C
D
E

English Ð 11
WARNING!
Never direct the compressed air
jet towards the body. Air can pe-
netrate into the blood circulation,
which means mortal danger.
WARNING!
uel has the following hazardous
properties:
1. The ß uid and its fumes are poi-
sonous.
2. Can cause skin irritation.
3. Is highly inß ammable.
Cleaning and inspection
See Þ gures on previous page and check the fol-
lowing:
1
T hat gaskets , pu m p and control diaphrag m s are
unda m aged .
2
T hat there is no pla y on the throttle and choke valve
shafts .
3
T he needle valves and lever are not worn at C and D
in Þ gure on previous page .
4
T he fuel Þ lter is unda m aged .
5
T he tips of the high and low speed screws are not
da m aged .
8
U se a needle or the like to carefull y re m ove the
fuel Þ lter (F) . See Þ gure b elow .
9
R e m ove caps with the high and low speed screws .
See Þ gure b elow .
1 0
I f necessar y , re m ove the throttle and choke valves
and re m ove the spindles together with levers and
springs . See Þ gure b elow .
6
T he intake m anifold is unda m aged .
7
T he car b urettor has an e x tra air shutter connected
in parallel with the ordinar y throttle valve . T he
valve housing with a x le is secured in the car b uret-
tor using two screws .
C ar b urettor
C lean all units in clean petrol .
U se co m pressed air to dr y the petrol on the co m -
ponents . D irect the air through all channels in the
car b urettor housing and m ake sure that the y are
not b locked .
F
G
I
J

12 Ð English
A ssembly
Where no Þ gure is referred to, see Þ gure on the
previous page.
Maintain a high level of cleanliness when assem-
bling the carburettor. The slightest contamination
can result in running problems.
1
f the throttle and choke valves, together with
levers and springs were removed, they should be
reÞ tted. Lubricate the spindle bearings with light oil.
2
F it the high and low speed screws and springs.
N ote ! D o not fully tighten the screws. This will
damage the seats and needle tips.
3
F it the fuel Þ lter ( F ) by using the handle of a small
screwdriver. S ee Þ gure below.
4
F it the pump diaphragmas ( G and H ) , gasket ( )
and cover ( J ) on the pump unit. S ee Þ gure below.
F
G
I
J
C
D
E
7
F it the control diaphragm ( B ) with gasket and cover
( A ) on the metering unit. S ee Þ gure below.
A
B
5
F it the needle valve ( D ) with lever ( C ) , spindle and
spring and tighten the screw ( E ) . F it welch plug ( K ) .
S ee Þ gure below.
6
C heck with a ruler or the like that the lever is level
1. 6 5 mm below plane. S ee Þ gure below. f neces-
sary, the lever can be bent slightly.
C arburettor
8
F it the a x le on the air shutter ( L ) and connect the
throttle actuator rod ( N ) in parallel with the ordinary
throttle valve. The valve housing ( P ) is secured in
the carburettor using two screws.

English Ð 13
Pressure testing
Pressure testing should be carried out with the car-
burettor fully assembled. Testing should always be
carried out after the carburettor has been repaired,
but it can also be carried out as trouble shooting
before dismantling the carburettor.
See Þ gure below and carry out the test as follows
Leakage at Fault with
Diffuser jets Needle valve
Leakage in impulse tube Pump diaphragm
Ventilation hole
on metering unit. Control diaphragm
A
L
A
A
P
A
N
9
Carry out a pressure test.
1
Unscrew the high and low speed screws one turn
from closed position.
2
Connect pressure tester to the carburettor Õ s fuel
intake.
3
Lower the carburettor into a beaker of water.
4
Pump up the pressure to 50 kPa (0 . 5 bar ) .
5
No leakage is permitted. I f a leakage occurs refer
to the table below.
Carburettor
Connect the leads to the stop switch.
C a r b urett o r Ð re Þ tting
NOTE!
Cl e a n l iness is v er y i mpo rt a nt wh en re a s -
se mbl ing t h e ca r b urett o r . T in y pa rti cl es of
d irt ca n ca use op er a ting p r obl e m s .
1
Tighten the carburettor screws ( 4 ) with a tor q ue
of 1-1. 5 Nm. Fit the fuel hoses ( 2 ) Fit the throttle
actuator rod and press down its lock. Secure the
cables on the stop switch and Þ t the air Þ lter and
cylinder cover.
3
A
Position the carburettor in the carburettor compart-
ment. Fit the carburettor in the rubber mountings.
2
B
B

14 Ð English
Basic adjustment for EPA II saws with capped
carburettors
Model 455 is equipped with a capped carburettor.
A slightly different adjustment procedure is neces-
sary when replacing the carburettor or needles.
C apped carburettor
T his means that this chain saw is equipped with
mo v ement limiters on the carburettor Õ s adjuster
screws. T hese limit the adjustment range to a
ma x imum of 1 /2 turn.
R ep l acement of the H- need l e or comp l ete
carburettor
1. C arefully screw the new H -needle to the bottom
and turn it anticloc k wise Ó A Ó turns.
455 A = 2 1 /2
2 . C hec k that :
T he H -cap is adjusted to its richest setting
( turned countercloc k wise to stop ) .
T he cap is not Þ x ed to the needle , it should
rotate independently.
Adjust the L -cap to a center position ( 1 / 4 turn
countercloc k wise = minimum , 1 / 4 turn cloc k wise =
ma x imum ) .
3 . S tart the engine. I f necessary , adjust the idling
speed with the T -screw until the chain stops.
4. Adjust the H -needle to gi v e a top speed of Ó B Ó
rpm. U se a tachometer.
455 B = 1 2 5 00
U se a narrow blade screwdri v er ( ref.no. 5 3 1 00 4 8 -
63) and insert it through the hole in the cap ( ma x .
blade width 2 mm / 0,08 inch ) .
C arburettor
After replacing the carburettor or high speed and / or
low speed needle on an E P A ( T he US En v ironme-
ntal P rotection Agency ) certi Þ ed product , a basic
adjustment must be carried out as described below
in order to meet the E P A-requirements. T his to
achie v e as low emissions as possible. T his instruc-
tion is made for E P A certi Þ ed products only.
O n E P A carburettors both the H - and L -needles
are Þ tted with caps to pre v ent the chain saw
operator from changing the adjustment abo v e E P A
standard. T he caps can be remo v ed to achie v e
richer or leaner adjustments. T o set the needles
correctly an adjustment slee v e is Þ tted from the
factory o v er the caps to loc k them in ma x imum
allowed settings.
W hen correctly set the caps must be Þ x ed on
the needles. T he adjustment slee v e then can be
remo v ed. O v er the caps on complete sparepart
carburettor , there is a plastic slee v e which is
intended to loc k the caps at the richest position
( anticloc k wise towards stop ) during the time that
the needles are adjusted. W hen the adjustment
is complete and the caps ha v e been Þ x ed on the
needles , the slee v e is no longer of any function
and can be remo v ed.
C onditions
¥ T he air Þ lter should be clean and the cylinder
co v er Þ tted when adjustments are made. Adjus-
ting the carburettor with a dirty air Þ lter will gi v e
a too lean fuel mi x ture the ne x t time the air Þ lter
is cleaned. T his can result in serious damage to
the engine.
¥ Mount , for this model , appro v ed bar and
chain combination ( see T echnical data in the
O perator ' s Manual ) .
455 1 6 "
¥ T he chain should not be tensioned more than
that it remains ~ 0, 2 inches to the bar.

English Ð 15
5. Let the engine run at ÓBÓ rpm ~ 1 minute, until
warm.
6. Close the H-needle to a top speed of ÓCÓ rpm.
55 C = 13 500
7. Check that the H-cap is still adjusted to its
richest setting (turned counterclockwise to stop).
Note! The H-needle must not rotate!
8. Gently knock the H-cap into position. Use a
5 mm/0,2 inch mandrel (for example the locking
pin for the bevel gear ref. no. 502 02 61-03).
This is a basic carburettor adjustment. Further
Þ ne adjustments, within the limits the caps allow,
may be necessary to achieve optimum perfor-
mance. See the Operator's Manual.
Replacement of the L-needle
1. Take off the cap from the L-needle using a pair
of cutting pliers and unscrew the needle.
2. Screw the new L-needle to the bottom and then
turn it counterclockwise ÓDÓ turns.
55 D = 1 1/2
3. Press a new L-cap on the L-needle to the Þ rst
stop, which means that the cap is not Þ xed to
the needle, it should rotate independently.
. Adjust the L-cap to the richest position (turned
counterclockwise to stop) without turning the
needle.
5. Let the engine run at ~ ÓEÓ app. 1 minute until
warm and then let it run on idle.
55 E = 12 500
6. Adjust the idle speed to ÓFÓ rpm.
55 F = 2700
7. Adjust the L-needle until the highest possible
idling speed is achieved and then turn the L-
needle 1/2 turn counterclockwise. Use a narrow
blade screwdriver (ref.no. 531 00 8-63) and
insert through the hole in the cap (max. blade
width 2 mm/0,08 inch). Note! I f the chain rotates,
turn the idling speed screw (T) counterclockwise
until the chain stops.
8. Check that the L-cap is still adjusted to its ri-
chest position (turned counterclockwise to stop).
Note! The L-needle must not rotate!
9 . Gently knock the L-cap into position. Use a
5 mm/0,2 inch mandrel (for example the locking
pin for the bevel gear ref.no. 502 02 61-03). This
is a basic carburettor adjustment. Further Þ ne
adjustments, within the limits the caps allow,
may be necessary to achieve optimum perfor-
mance. See the Operator's Manual.
Carburettor

16 Ð English
T roubleshooting
Worn needle valve
Leaking control diaphragm/cover
plate
Needle valve assembly sticking
Worn needle valve lever
Faulty diffuser jet
Fuel lter blocked
Fuel line blocked
Leaking air intake hose (rubber)
Loose carburettor mounting
bolts
Worn throttle valve pivot
Loose throttle valve screw
Worn throttle valve
Needle valve assembly sticking
Leak in metering system (air
or fuel)
Metering system centre knob
is worn
Hole in diaphragm
Leaking control diaphragm/cover
plate
Crankcase leaking
Fuel line blocked
Needle valve set too high
Needle valve assembly sticking
Leak in metering system (air
or fuel)
Leaking control diaphragm/cover
plate
Faulty diffuser jets
Crankcase leaking
Needle valve set too high
Needle valve assembly sticking
Metering system damaged
Worn needle valve
Leaking control diaphragm/cover
plate
Metering system incorrectly
assembled
Adjust L screw
Air lter blocked
Choke not working
Worn choke pivot
Worn choke valve
Fuel lter blocked
Fuel line blocked
Piston ring seized
Blocked impulse channel
Loose or faulty fuel pipe
Hole in diaphragm
Worn needle valve
Needle valve assembly sticking
Needle valve set too high
Leak in metering system (air
or fuel)
Loose cover on carburettor
pump side
Worn needle valve
Needle valve set too high
Needle valve assembly sticking
Dif culty starting
Carburettor
leaking fuel
Flooding when
engine not
running
S t a rting
T he various faults that can affect a chainsaw are divided into four groups . I n each group the likely
symptoms are given on the left and possible causes are listed on the right . T he most likely faults are
given rst , and so on .
Id ling ( lo w r pm)
I dles when L
screw closed
I dling uneven
L screw re q uires
constant adjust -
ment
T oo much fuel at
idling
Id ling ( lo w r pm) ( c ont . )
Adjust L screw
Leaking air intake hose (rubber)
Loose carburettor mounting
bolts
Loose or faulty fuel hose
Fuel lter blocked
Fuel line blocked
Fuel tank vent blocked
T hrottle valve pivot stiff
T hrottle pushrod sticking
Defective throttle return spring
Bent throttle stop
Faulty diffuser jet
Adjust L screw
Worn needle valve
Needle valve set too high
Worn needle valve lever
Leaking control diaphragm/cover
plate
Needle valve assembly sticking
Will not idle
I dling too rich

English Ð 17
Troubleshooting
A cceleration and retardation
D oes not
acc eler a te
Engine st a lls
w hen throttle
rele a se d
Ov er ri c h
acc eler a tion
Adj ust L s c re w
Adj ust H s c re w
B lo ck e d a ir Þ lter
B lo ck e d f uel t a n k v ent
B lo ck e d f uel Þ lter
F uel line blo ck e d
L oose or dama ge d f uel hose
Imp ulse c h a nnel blo ck e d
L oose c o v
er on ca rburettor p u mp
si d e
Fa ult y p u mp d i ap hr a g m
L e ak ing a ir int ak e hose ( rubber )
L oose ca rburettor m ounting bolts
N ee d le va l v e set too lo w
M etering s y ste m in c orre c tl y
a sse m ble d
N ee d le va l v e a sse m bl y sti ck ing
Fa ult y d i ff user j ets
B lo ck e d silen c er
Adj ust L s c re w
Adj ust H s c re w
Fa ult y p u mp d i ap hr a g m
N ee d le va l v e set too high
N ee d le va l v e a sse m bl y sti ck ing
Fa ult y d i ff user j ets
Adj ust L s c re w
Adj ust H s c re w
B lo ck e d a ir Þ lter
Fa ult y p u mp d i ap hr a g m
Fa ult y d i ff user j ets
T ro ub le sh ootin g m et h od s
I n add ition to the fa ults d es c ribe d in the a bo v e t a -
ble , trouble shooting ca n be ca rrie d out on s p e c i Þ c
c o mp onents or sub - s y ste m s o f the c h a ins aw . The
va rious p ro c e d ures a re d es c ribe d in the rele va nt
c h ap ters , see the c ontents pa ge , a s f ollo w s :
¥ C he ck ing the o p er a tion o f the c h a in br ak e
¥ M e a suring the resist a n c e o f the sto p p l a te
¥ P ressure testing the ca rburettor
¥ P ressure testing the d e c o mp ression va l v e
¥ P ressure testing the cy lin d er
Adj ust H s c re w
B lo ck e d a ir Þ lter
B lo ck e d f uel t a n k v ent
B lo ck e d f uel Þ lter
F uel line blo ck e d
L oose or dama ge d f uel hose
Imp ulse c h a nnel le ak ing
Imp ulse c h a nnel blo ck e d
L oose c o v er on ca rburettor p u mp
si d e
Fa ult y p u mp d i ap hr a g m
L e ak ing a ir int ak e hose ( rubber )
L oose ca rburettor m ounting bolts
N ee d le va l v e set too lo w
M etering s y ste m dama ge d
M etering s y ste m in c orre c tl y
a sse m ble d
L e ak ing c ontrol d i ap hr a g m / c o v er
p l a te
N ee d le va l v e a sse m bl y sti ck ing
B lo ck e d silen c er
Adj ust H s c re w
B lo ck e d f uel t a n k v ent
B lo ck e d f uel Þ lter
Imp ulse c h a nnel le ak ing
Imp ulse c h a nnel blo ck e d
L oose c o v er on ca rburettor p u mp
si d e
Fa ult y p u mp d i ap hr a g m
B lo ck e d a ir Þ lter
N ee d le va l v e a sse m bl y sti ck ing
L e ak in m etering s y ste m (a ir or
f uel )
M etering s y ste m in c orre c tl y
a sse m ble d
L oose d i ap hr a g m ri v et
H ole in d i ap hr a g m
L e ak ing c ontrol d i ap hr a g m / c o v er
p l a te
B lo ck e d f uel t a n k v ent
B lo ck e d f uel Þ lter
F uel line blo ck e d
L oose or dama ge d f uel hose
Imp ulse c h a nnel le ak ing
Imp ulse c h a nnel blo ck e d
L oose c o v er on ca rburettor p u mp
si d e
Fa ult y
p u mp d i ap hr a g m
L e ak ing a ir int ak e hose ( rubber )
L oose ca rburettor m ounting bolts
N ee d le va l v e set too lo w
L e ak in m etering s y ste m (a ir or f uel )
M etering unit in c orre c tl y a sse m ble d
L oose d i ap hr a g m ri v et
H ole in d i ap hr a g m
L e ak ing c ontrol d i ap hr a g m / c
o v er
p l a te
W ill not run a t
f ull throttle
L o w p o w er
W ill not Ò f our -
stro k e Ó
H i gh r p m

18 Ð English
3
WARNING!
Make sure the spring does not ß y
out and cause injury. Wear eye
protection.
Repair instructions
Chain brake Ð dismant ing
1
Disengage the brake by pushing the kickback
guard backwards. Unscrew the guide bar bolts and
remove the clutch cover, chain and guide bar.
2
Grip the clutch cover care ully in a vice. Release
the brake spring by using the kickback guard rom
the saw as a tool. Engage it with the brake mecha-
nism and turn anticlockwise to activate the brake.
Place one hand over the spring and insert a small
screwdriver between the bottom end o the spring
and the clutch cover. Care ully prise the spring
upwards so that it slides onto the screwdriver sha t.
C eaning and inspection
¥ Clean and inspect all parts care ully. I there are
any cracks or other de ects replace the damaged
parts with new ones. A lways use original parts.
¥ M easure the thickness o the chain brake band.
I t must be no less than 0 . 6 mm at any point.
¥ L ubricate the elbow j oint with grease.
Remove the screws and care ully remove the cover
rom the chain brake spring.
4

English Ð 19
Repair instructions
NOTE!
After completing the repair the chain
brake must be tested as described below.
Operating test:
T he engine m ust not b e running d uring the test .
G ui d e b ar length H eight
38 c m/ 1 5" 50 c m/20"
¥ H ol d the chainsa w o v er a Þ r m sur f ace . T he
height o f the gui d e b ar a b o v e the sur f ace is
gi v en in the ta b le a b o v e .
¥ L et go o f the f ront han d le an d let the chainsa w
f all to w ar d s the sur f ace .
¥
W hen the gui d e b ar hits the sur f ace the chain
b ra k e m ust engage .
Chain brake Ð reassembly
B olt the el b o w j oint to the b ra k e b an d an d tighten
to a tor q ue o f 1Ð1 .5 Nm.
L ocate the el b o w j oint an d connecte d b ra k e b an d
in their recesses in the clutch co v er . L u b ricate the
recess f or the spring w ith grease .
2
G rip the clutch co v er in a v ice . C o m press the
spring w ith special tool 502 50 67- 0 1 an d push it
d o w n w ith y our thu mb.
3
F it the co v er o
v er the chain b ra k e spring , tighte -
ning the scre w s to a tor q ue o f 1Ð1 .5 Nm.
T ension the b ra k e spring b y using the k ic kb ac k
guar d f ro m the sa w as a tool . Engage it w ith the
b ra k e m echanis m an d turn cloc kw ise to release
the b ra k e .
5
T urn the chain tensioner anticloc kw ise as f ar as it
w ill go .
Re Þ t :
¥ gui d e b ar
¥ chain
¥ clutch co v er
W A R N I N G !
M ake sure the spring does not ß y
out and cause in j ury. W ear eye
protection.
4