Husqvarna 250PS Instruction manual

Workshop manual
250 PS
Nummer XX
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2
Technical specification
Engine
Hydraulic transmission
Ignition system
Fuel/Oil system
Weight
Cutting attachment
Cylinder volume
Cylinder diameter
Stroke
Idle speed
Max. recommended speed
Hydraulic motor capacity
Hydraulic pump capacity
Working pressure, high pressure hose
Pulse pressure, high pressure hose
Pressure in return hose
Flow
Manufacturer/type of ignition system
Spark plug
Electrode gap
Shaft length
Weight
Bar length
Pitch
Thickness of drive links
Engine unit without cutting attachment
Manufacturer/type of carburettor
Fuel tank capacity litre
Hydraulic oil tank capacity
Method of chain lubrication
2-3-4-5-6
2,2-2,4-2,9-3,5-4,0
6/16
3/8
1,3
7,0
Walbro/HDA 86
0,9
1,3
Automatic
Electrolux, ET
Champion RCJ7Y
0,5
1,4
1,2
6-9
9
0,2-0,8
2-13
49
44
32
2 500
11 000
cm3/rev
cm3/rev
MPa
MPa
Mpa
l/min
mm
liter
liter
m
kg
inch/cm
inch
mm
cm3
mm
mm
rpm
rpm
kg
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3
Husqvarna 250 PS
Chapter Page
1. Service data 4
2. Starter unit 12
3. Fuel system 14
4. Throttle lock 24
5. Ignition system 25
6. Clutch 28
7. Cylinder and piston 30
8. Crankcase and crankshaft 33
9. Hydraulics 38
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4
1. Service data
Leak testing
Crankcase, cylinder
Remove the silencer, air filter and carburettor assembly.
Use the carburettor bolts and spacers 502 50 45-01 to
attach cover plate 502 50 72-01 to the inlet side of the
cylinder. Attach cover plate 502 50 71-01 to the exhaust
side of the cylinder. Use pressure tester 502 50 38-01.
Pressure: 0.08 MPa (0.8 kp/cm2)
Max. leakage: 0.02 MPa in 30 sec. (0.2 kp/cm2 in 30
sec.)
Leak testing
Carburettor
Remove the carburettor from the pruning saw. Connect
the hose of the pressure tester to the fuel hose nipple on
the carburettor.
Pressure: 0.03 MPa (0.3 kp/cm2, 4.3 psi)
Leakage: no leakage is permitted.
Tools: 502 50 38-01 Pressure tester
Remember...
...never start the pruning saw if the hydraulic oil
tank or hoses/shaft are not fitted. If the hydraulic
oil tank is not fitted the clutch may come loose and
cause injury. If the hoses or shaft are not fitted the
engine cannot be revved up and the hydraulic
pump and clutch may be damaged.
...the pressure relief valve in the hydraulic motor
must open if there is a blockage in the return hose.
If it opens without reason then it must be replaced.
(See page 45.)
...you must be able to turn the pulley on the starter
unit at least a further 1 1/2 turns when the starter
cord is fully extended.
...do not use the pruning saw until it has been
properly adjusted or repaired.
...the pruning saw is fitted with an electronic
ignition system. This produces a powerful spark
with a short burn time. If the performance of the
pruning saw is poor, if the saw is difficult to start,
or if it idles unevenly, first check the spark plug
before taking any other action.
...the pruning saw consists of an engine unit and
a hydraulic unit. It is often easier to handle the
pruning saw when the hydraulic oil tank has been
separated from the engine unit. (See page 38.)
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5
1
!Fuel
WARNING! The pruning saw is equipped with a
two-stroke engine and should always be run on a
mixture of petrol and two-stroke oil. To ensure the
correct mixture always measure out the amount of
oil that is needed accurately. If you mix small
amounts of fuel small errors in the amount of oil
will have a large effect on the mixture ratio. Always
ensure good ventilation when mixing fuel.
Petrol
Use good quality unleaded or leaded fuel.
The minimum recommended octane is 90. If the fuel is
less than 90 octane it may cause knocking. This will lead
to a higher engine temperature and may result in severe
engine damage.
Two-stroke oil
For best results use Husqvarna two-stroke oil, which is
specially developed for pruning saws.
Mixture ratio: 1:50 (2%).
If Husqvarna two-stroke oil is not available you may use
another high quality two-stroke oil made for air-cooled
engines.
Mixture ratio: 1:33 (3%) - 1:25 (4%).
Never use outboard oil, i.e. oil intended for water cooled
outboard engines.
Never use oil designed for four-stroke engines.
Mixing
Always mix petrol and oil in a clean container designed
for petrol.
Start by pouring half the petrol into the container. Then
add all the oil. Shake the fuel mixture well. Now add the
remaining petrol. Shake the fuel mixture thoroughly.
Then pour the fuel into the fuel tank of the pruning saw.
Never mix more fuel than you need for around 2 months
work. If you do not intend to use the pruning saw for a
long period the fuel tank should be drained and cleaned.
The table on the left shows the various mixture ratios.
5
10
15
20
2%(1:50)
0,10
0,20
0,30
0,40
3%(1:33)
0,15
0,30
0,45
0,60
4%(1:25)
0,20
0,40
0,60
0,80
Gasolin
Benzin
Essence
Gasolina
Lit.
Oil • Öl
Huile •Aceite
Lit.
1
2 1/2
5
2%(1:50)
2 1/2
6 1/2
12 7/8
3%(1:33)
3 3/4
9 3/4
19 1/4
4%(1:25)
5 1/8
12 7/8
25 3/4
US
gallon US
fl. oz.
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6
1
Tools
502 42 45-01
Test hose
502 42 50-01
Tool for pressure
relief valve
502 50 26-01
Puller
502 50 30-12
Crankshaft fitting tool
502 50 33-01
Piston plug
502 50 38-01
Pressure tester assy.502 52 13-01
502 52 14-01
Allen key with square
socket
502 51 61-01
Tool for removing
crankcase and
crankshaft
502 50 46-01
Spacer
502 50 66-02
U key
502 50 71-01
Cover plate,
exhaust
502 50 72-01
Cover plate, inlet
502 52 16-01
Locking tool for
clutch drum
502 51 49-01
Key
502 51 54-01
Bolts for key
4 mm
6 mm
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7
1
Tools 3 mm
4 mm
5 mm
502 50 86-01
502 50 87-01
502 50 88-01
Allen screwdriver
with ball
502 50 91-02
Touch-up paint,
orange
502 51 91-01
Feeler gauge
502 51 34-02
Feeler gauge
502 50 79-01
Mandrel for sealing
ring
502 50 06-01
Pliers, ignition cable
502 50 16-01
502 50 18-01
502 50 19-01
502 50 57-01
502 50 64-01
Allen key
8 mm
10 mm 502 50 22-01 502 50 23-01
Socket spanner
502 50 37-01
Vacuum tester
502 50 70-01
Assembly kit for
cylinder assy.
502 50 83-01
Hook for tank
502 70 09-01
Pressure tester bulb
502 71 13-01
Test plug
502 71 14-01
Tachometer
6 mm
4 mm
3 mm
3/6"
5 mm
0,5 mm
0,3 mm
0,5 mm
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8
Cylinder cover Silencer
Air filter, carburettor
Fuel tank
Bolt torques
1
38 Nm
39 Nm
40 Nm
29 Nm
42 Nm
28 Nm
27 Nm
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9
Cylinder, piston
Starter unit
Crankcase,
crankshaft
Flywheel, ignition module
Bolt torques 1
37 Nm
25 Nm
26 Nm 36 Nm
35 Nm
33 Nm
34 Nm
32 Nm
32 Nm
41 Nm
23 Nm
24 Nm
22 Nm
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10
Hydraulic oil tank
Bolt torques
1
10 Nm
53 Nm
48 Nm
58 Nm
59 Nm
54 Nm
57 Nm
31 Nm
50 Nm
49 Nm
47 Nm
56 Nm
55 Nm
30 Nm
51 Nm
52 Nm
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11
Bar
Sele
Throttle handle
Shaft, hydraulic hose
1
Bolt torques
4 Nm
5 Nm
2 Nm 7 Nm
3 Nm
8 Nm
21 Nm
19 Nm
17 Nm 18 Nm
20 Nm
12 Nm
15 Nm
16 Nm
45 Nm
44 Nm
46 Nm
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12
2. Starter unit
Release the spring by lifting up the cord and letting the
pulley rotate clockwise. Undo the bolt at the centre of the
pulley and the screws that hold the spring cassette.
Assembly
Replace the spring cassette in the starter casing.
Removal
Undo the four fuel tank clamps and move the fuel tank
out of the way. Undo the cylinder cover.
Unscrew the bolts that hold the starter unit against the
crankcase and lift off the starter unit.
Carefully lift out the pulley and spring cassette. Clean
them. Replace the cord and/or spring (with cassette) if
necessary. Lubricate the return spring with light oil.
!WARNING! If handled carelessly the return spring
may spring out and cause injury. Always take care
when you replace the starter cord or spring.
Wear safety goggles!
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13
2
Thread in a new cord and attach it to the pulley.
Wind about 4 turns of the cord around the pulley,
anticlockwise. Fit the pulley above the spring cassette so
that the end of the return spring engages in the pulley.
Fit the bolt through the centre of the pulley.
Thread the starter cord through the hole in the starter
casing, then through the starter handle. Tie a good knot
in the end of the cord.
Run the cord through the cut-out in the pulley and wind
the spring up a couple of turns. Make sure the pulley is
free to rotate a further 1 1/2 turns when the cord is fully
extended.
Refit the starter unit by first pulling out the starter cord
and then placing the starter unit in position on the
crankcase. Now release the starter cord slowly so that
the starter lugs engage on the pulley. (Starter lugs, see
page 26.) Tighten the bolts that hold the starter unit.
Refit the cylinder cover and tank.
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14
3. Fuel system
Cleaning the air filter
The air filter has two components. Alow resistance pre-
filter and the air filter itself. Regularly clean any dust or
dirt from the air filter to prevent:
•Carburettor problems
•Starting problems
•Reduced performance
•Unnecessary wear to engine components
•Excessive fuel consumption
Replacing the fuel filter
Push the hose into the tank until only about 20 mm of the
hose projects from the tank. Insert a 3 mm diameter
steel cable into the hose. Pull the filter out of the filler
hole using pliers.
NOTE! Make sure the hose does not fall into the tank.
Replace the filter. Pull the hose back to its original
position. Remove the cable.
Remove the filter cover and take out the filter. Wash the
filter in soapy water. Soak in filter oil 503 47 73-01 then
squeeze out the excess.Always replace a damaged air
filter.
Replacing the fuel hose
Push the old hose into the tank. Pull the hose and filter
out through the filler hole of the tank. Fit a new hose
through the tank opening. Push the hose in until only
about 20 mm projects from the tank. Insert a 3 mm
diameter cable into the hose and out through the filler
hole. Pull the end of the hose out of the filler hole using
pliers. Fit the filter and pull the hose back to its original
position. Remove the cable.
20 mm
Ø 3 mm
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15
3
Carburettor
The carburettor is of the membrane type. It is divided
into three units or main functions.
1. Metering unit
This includes the fuel jets and control mechanism.
2. Mixture unit
This is where fuel and air are mixed in the venturi and
includes the choke and throttle flap.
3. Pump unit
Here fuel is pumped from the tank to the metering unit.
Removal
Remove the air filter, throttle cable and fuel hose.
Unscrew the 2 bolts from the air filter mounting, unscrew
the carburettor bolts and remove the carburettor with air
filter mounting and spacer. Clean all components.
1
2
3
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16
3
Remove the membrane cover and carefully lift off the
control membrane.
Connect the pressure tester to the fuel hose nipple.
Lower the carburettor into a container filled with petrol.
Pressure test to 0.4 bar (40 kPa). No leakage is
permitted.
If there is a leak, remove the needle valve. Undo the
screw and lift off the lever, spindle, needle valve and
spring.
Examine the needle valve for wear. Replace the needle if
worn or damaged.
Examine the lever for wear. Replace the lever if worn or
damaged.
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17
3
Remove the screw and lift the cover off the pump
membrane
Lift off the gasket and pump membrane.
Carefully remove the fuel mesh using a needle, for
example.
Unscrew the jet needles. (H=long, L=short). Clean all
components.
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18
3If the carburettor is very dirty the chamber under the
blind plug must also be cleaned. Drill a small hole in the
centre of the blind plug and carefully prise it out. Clean
the carburettor housing and blow all channels clean
using compressed air.
Assembly
Fit a new blind plug. Use a suitable mandrel to drive in
the plug and give an airtight seal.
Inspect the throttle flaps and their spindles for wear. If
they are worn it will be difficult to set the idle speed.
Always replace the flap and spindle at the same time.
Make sure the flaps are fitted correctly.
Fit the various components of the metering unit in the
reverse order to removal.
NOTE! Make sure the lever springs are replaced the
right way round
Check that the lever is level with the top of the
carburettor. Adjust the lever if necessary.
If lever is too high = too much fuel.
If lever is too low = too little fuel.
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19
3
Fit the cover.
Fit the pump unit components. Replace the fuel mesh if it
is damaged. Fit a new pump membrane and new gasket
if necessary. Fit the H and L needles.
Check the angle of the fuel hose nipple if it was moved
during servicing. Check that the carburettor is airtight.
Pressure test to 0.4 bar (40 kPa.) No leakage is
permitted.
Check that the automatic choke levers are not worn and
that they engage in each other.
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20
3
Connect the fuel hose and throttle cable.
Fit the choke/start control and check its operation. Fit the
air filter and air filter cover.
Fit the filter holder and carburettor bolts (with insulating
sleeves) to the carburettor. Fit the gaskets and spacer.
Insert the spacer through the baffle.
NOTE! Make sure the gasket between the cylinder and
spacer is correctly positioned.
Screw the carburettor bolts in alternately. Do not tighten.
Tighten the bolts for the air filter holder. Then tighten the
carburettor bolts.
Check that the spacer is undamaged and that the pulse
channel is not blocked.
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