Partner K 650/700 Active, K 950/1250 Active Workshop Manual
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Workshop Manual
Petrol power cutters
Contents
General recommendations .................................................. 2
1. Starter unit ......................................................................... 3
2. Ignition system ............................................................... 11
3. Fuel system ..................................................................... 19
4. Centrifugal clutch ........................................................... 41
5. Cylinder and piston ........................................................ 47
6. Crankshaft and crankcase ............................................. 59
7. Cutting equipment .......................................................... 77
8. Tools................................................................................. 85
9. Technical data ................................................................. 93
This manual covers models:
K 650/700 Active
K 950/1250 Active
©
Copyright Partner Industrial Products, Sweden
1
General recommendations
Keep this in mind:
Do not start the engine unless the clutch and clutch drum
!
are fitted.
!
Do not touch hot parts, e.g. silencer and clutch, before they
have cooled sufficiently to avoid burn injuries.
!
Avoid getting petrol or oil on the skin or in the mouth. Use
protective cream on the hands. This reduces the risk of
infection and makes it easier to wash off dirt. Prolonged
exposure to engine oil can be hazardous to health.
!
Never start the engine indoors. The exhaust fumes are
toxic!.
Wipe up spilled oil immediately from the floor to avoid
!
slipping.
!
Do not use tools which are worn or have a poor fit, e.g. nuts
and screws.
+Always work on a clean work bench.
+Always work in a logical way to make sure that all parts are
correctly fitted and that screws and nuts are tightened.
+Use special tools where so recommended in order to do the
work correctly.
Fire hazard
Handle petrol with respect since it is highly inflammable.
Do not smoke, and make sure that there are no naked 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.
Use an anti-spill fuel can.
Special tools
Some work procedures in this Workshop Manual require the
use of special tools. In each section where this is appropriate
the tool and order number are illustrated.
We recommend the use of special tools partly to avoid personal
injury and partly to eliminate expensive damage to the
components in question.
Sealing surfaces and gaskets
Make sure that all sealing surfaces are clean and free from the
residue of old gaskets. Use a tool which will not damage the
sealing surface when cleaning it. Scratches and irregularities
are removed with a fine, float cut file.
Sealing rings
Always replace a sealing ring which has been dismantled. The
sensitive sealing lip can easily be damaged and result in poor
sealing capacity. The surface which the seal seals must also be
completely undamaged. Lubricate the sealing lip with grease
before it is fitted and make sure that it is not damaged, e.g. by
the shoulder and splines on a shaft. Use tape or a conical
sleeve as protection. It is important that the sealing ring is
correctly turned for it to function as intended.
Toxic fumes
Read the instructions carefully when using cleaning liquids.
Make sure that there is adequate ventilation when handling petrol
and other viscous liquids.
The engine exhaust fumes are toxic. Test run the engine outdoors.
!
WA RN I NG
The engine exhaust from this product
contains chemicals known to the State
of California to cause cancer, birth
defects or other reproductive harm.
2
Starter unit
1.
1
Contents
Dismantling of the starter unit ..............................................4
Replacing the starter cord without dismantling the pulley ... 5
Dismantling ...........................................................................7
Assembly .............................................................................. 8
3
1
Starter unit
!
WARNING!
When working on the starter unit wear protective glasses to avoid eye injuries in the
event that the return spring flies out.
Dismantling of the
starter unit
Mod. 650, 700
Dismantle the air filter cover, intermediate
wall and cylinder cover.
A
Dismantle the starter unit from the engine
body.
Dismantling of the
starter unit
Mod. 650, 700
Untighten the screws for the air filter
cover.
Lift off the cover and intermediate wall.
Release the screw (A) and lift off the
cylinder cover.
Untighten all the screws and lift off the
starter unit.
Release the spring tension.
4
Release the spring tension.
Pull out the starter rope approx. 30 cm
(12 in).
Hold the pulley with your thumb and place
the cord in one of the recesses in the
pulley.
Starter unit
1
Allow the pulley to slowly rotate backwards.
Remove the starter handle.
Mod. 950, 1250
Remove the screws which hold the starter unit, and lift off the starter unit.
The next stage in the dismantling work
follows mod. 650/700.
Allow the pulley to slowly rotate backwards.
NOTE!
Brake the rotation with the thumb.
Untie the knot on the starter rope and
remove the starter handle.
Tips!
The knot may be difficult to untie. It is
easier if it first is tapped with a hammer
while placed on a hard surface.
Mod. 950, 1250
Remove the screws which hold the starter unit, and lift off the starter unit.
NOTE!
The air filter and cylinder covers do not
need to be dismantled.
The next stage in the dismantling work
follows mod. 650/700.
K650/700
K950
Replacing the starter
cord without dismantling the pulley
Mod. 650, 700, 950, 1250
Remove any remaining rope from the
pulley and check that the return spring
recoils.
Insert the new starter rope through the
hole in the pulley.
K1250
Replacing the starter
cord without dismantling the pulley
Mod. 650, 700, 950, 1250
Remove any remaining rope from the
pulley.
Check that the return spring and its
attachment in the pulley has not been
damaged by turning the pulley clockwise.
Enter the new starter rope through the
hole in the pulley as shown in the illustration.
Anchor the rope round the hub on the
pulley as shown in the illustration.
Pull the rope tight and make sure that the
free end is as short as possible.
Cord lengths
Models 650, 700, 950: 1150 mm.
Models 1250: 1250 mm.
These lengths apply to Ø 4 mm cord.
5
1
Starter unit
Anchor the starter rope in the starter
handle with a double knot.
Te ns i on the retur n spring.
Check that the spring tension is completely
released, and lift the starter cord up into
the cut-out in the pulley.
Insert the rope through the rope guide in
the starter housing and anchor it in the
starter handle with a double knot.
Te ns i on the retur n spring.
1. Check that spring tension is competely
released.
2. Lift the starter cord up into the cut-out
in the pulley.
Max
Wind the pulley 7 turns
Pull the cord out completely and check
that the pulley can be turned at least a
further half turn.
clockwise.
3. Wind the pulley 7 turns
Be careful and brake the pulley with
your thumb.
4. Pull the cord out completely and check
that the pulley can be turned at least
a further half turn.
clockwise.
+1/2
6
Starter unit
1
Dismantling
Mod. 650, 700, 950
Remove the screw in the centre of the
pulley and lift off the pulley.
Dismantle the spring cassette.
WARNING!
!
The return spring in the spring cassette is pre-tensioned and can if not
handled carefully during dismantling/fitting fly out and cause personal injury.
Dismantling
Mod. 650, 700, 950
Remove the screw in the centre of the
pulley.
Lift off the pulley.
Remove the screws and lift off the spring
cassette.
WARNING!
!
The return spring in the spring cassette is pre-tensioned and can if not
handled carefully during dismantling/fitting fly out and cause personal injury.
Mod. 1250
Remove the screw in the centre of the
pulley and lift off the pulley.
Make sure that the return spring is
completely released, and dismantle the
pulley.
WARNING!
!
The return spring is
starter unit cover.
Observe care during dismantling/assembly, the spring can fly out and cause
personal injury.
not
placed in a separate cassette but i s p la ced directly in the
Mod. 1250
Remove the screw in the centre of the
pulley and lift off the pulley.
Make sure that the return spring is
completely released.
Remove the screw and washer in the
centre of the pulley.
Carefully lift off the pulley.
7
1
Starter unit
Assembly
Mod. 650, 700, 950
Clean the starter unit components and fit
the spring cassette.
Anchor the cord in the pulley.
Push the pulley on the shaft stem.
Assembly
Mod. 650, 700, 950
Clean the different starter unit parts.
Lubricate the return spring with oil and
place the spring cassette in the starter
unit housing.
Make sure that the spring end is not
clenched.
Tighten the screws.
Anchor the cord round the pulley hub as
shown in the illustration.
Push the cord down on the shaft journal in
the starter unit housing.
Make sure that the return spring grips in
the pulley.
Lubricate the starter housing stem and
pulley with a few drops of oil.
Fit the other parts in the pulley hub.
NOTE!
Turn the metal sleeve (B) correctly.
B
C
Anchor the starter cord in the starter
handle with a double knot.
Check that the O-ring (C) is undamaged.
Lubricate it with a few drops of oil.
Tighten the centre screw and check that
the pulley can turn freely.
Enter the cord through the cord guide in
the starter unit and anchor it in the starter
handle with a double knot.
8
Starter unit
1
Te ns i on the retur n spring.
Check that the spring tension is completely
released, and lift the starter cord up into
the cut-out in the pulley.
Wind the pulley 7 turns
clockwise.
Te ns i on the retur n spring.
1. Check that spring tension is competely
released.
2. Lift the starter cord up into the cut-out
in the pulley.
3. Wind the pulley 7 turns
Be careful and brake the pulley with
your thumb.
clockwise.
Max
+1/2
Pull the cord out completely and check
that the pulley can be turned at least a
further half turn.
Mod. 1250
Press a new return spring down in the
starter unit cover.
Lubricate the spring with a few drops of
oil.
Anchor the cord in the pulley.
Push the pulley down onto the shaft journal.
4. Pull the cord out completely and check
that the pulley can be turned at least
a further half turn.
Mod. 1250
Press down a new return spring in the
starter unit cover.
NOTE!
Do not remove the lock round the spring,
but push down the spring all round by
using your thumbs.
Lubricate the spring with a few drops of
oil.
Anchor the starter cord round the hub of
the pulley as shown in the diagram.
Push the cord wheel down on the shaft
journal in the starter unit housing.
Make sure that the spring grips the cord
wheel.
Lubricate the bearing with a few drops of
oil.
9
1
Anchor the starter cord in the starter
handle with a double knot.
Fit the starter unit and other parts in the
reverse order to dismantling.
Enter the cord through the cord guide in
the starter unit and anchor it in the starter
handle with a double knot.
Fit the starter unit.
Pull out the starter cord a little. Place the
starter unit in position. Release the starter cord and check that the pawls engage
the pulley.
Tighten the screws.
10
Ignition system
2.
2
Contents
The principle of the ignition system ............................ 12
Checking the ignition spark ........................................ 13
Replacing the spark plug protection ........................... 15
Dismantling ................................................................. 15
Starter pawls ............................................................... 17
Assembly .................................................................... 17
11
2
Ignition system
The engine is fitted with an electronic ignition system consisting of flywheel, ignition coil and trigger
unit.
The ignition system has no moving parts. A defective
component cannot be repaired but must be replaced
with a new one.
The ignition spark in an electronic ignition system
has a very short burn time and may therefore be
experienced as weak, and sometimes be dif ficult to
see during trouble shooting.
2
+
Volts
0
1
A
N
S
N
2
3
B
A
C
S
1
DBC
The ignition module components are
completely enclosed to protect them from
moisture and dirt.
In the event of a failure in the ignition
module it must be replaced with a new
one.
E
3
G
E = Ignition point
F = Trigger unit
G = Stop switch
NOTE!
During all test running of the cutting saw the
clutch and clutch cover must be fitted before the
engine is started!
Principle of the ignition
system
The ignition system is completely enclosed and no after-adjustment of the
ignition point is possible or necessary.
The ignition module is built up of an iron
core (C). Round this lies the primary coil
(A) which consists of a small number of
turns of thick copper wire. Outside this
lies the secondary coil (B) which has a
F
very large number of turns of copper
wire.
The trigger unit (F) is fitted on the
secondary coil and has the purpose of
breaking the current (D) in the primary
winding at exactly the right time, i.e. just
before the piston reaches the top dead
centre.
When the permanent magnet (1) on the
flywheel passes the ignition module’s
iron core, an electric current is generated
in the primary coil (A). At the breaking
moment the current in the primary coil
rises from 5 volts to approx. 200 volts by
means of induction.
In the secondary coil (B) a high voltage
(approx. 20 000 volts) is simultaneously
transformed to the spark plug.
Models K650,K700, K950 and K1250
have a built-in overspeeding protection
in the electronic unit which limits the
unloaded speed of the engine to about
9 750 rpm.
The ignition module components are
completely enclosed to protect them from
moisture and dirt.
In the event of a failure in the ignition
module it must be replaced with a new
one.
12
F
A = Primary coil
B = Secondary coil
C = Iron core
F = Trigger unit
Ignition system
2
Checking ignition spark
Clean the electrodes and check the
electrode gap.
If the electrodes are worn down more
than 50% the plug should be replaced.
Checking ignition spark
Dismantle the plug and clean it from soot
by means of a wire brush.
Check the electrode gap. It should be 0.5
mm (.020 in).
Adjust the gap to the correct distance with
the side electrode.
If the electrodes are worn down more
than 50% the plug should be replaced.
If the gap is too wide this results in strain
on the ignition module and the risk of
short circuiting.
Check if there is a spark by pulling the
engine over with the starter.
Try with test plug No. 502 71 13-01 if
there is no spark.
502 71 13-01
Try with a new plug.
If there is no spark disconnect the stop
switch wire.
If necessary replace the switch.
Check if there is a spark by pulling the
engine over with the starter.
Ground the plug to the cylinder and briskly
pull the starter handle.
Make sure that the stop switch is in the
start position.
There should be a spark between the
electrodes.
If there is no spark try with test plug No.
502 71 13-01!
If there is a spark the fault lies in the plug.
Replace the plug.
Try with a new plug.
If there is still no spark remove the short
circuiting cable from either the ignition
module or the stop switch.
If there is now a spark the fault lies in the
stop switch.
Replace the switch.
13
2
Ignition system
Check the ignition cable’s connections.
A
B
Grease the cable ends before fitting.
Still no spark?
Check the plug connection.
Pull off the rubber protection at the plug
(A) and ignition module (B) and check
that the ignition cable is undamaged. If
necessary cut off a piece of the cable to
ensure good contact.
Grease the cable ends to simplify fitting
and to prevent moisture penetrating into
the connections.
0,3 – 0,5 mm
Check the other cables and connections. Still no spark?
Check the other cables and connections
for poor contact (dirt, corrosion, cable
break and damaged insulation).
Tips!
Use an Ohm meter to check if there is a
cable break, e.g. as a result of pinching.
Check the air gap. Still no spark?
Check the air gap between the flywheel
magnet and ignition module. The gap
should be 0.3 – 0.5 mm (0.012–0.020").
Use air gap measure 502 51 34-06.
14
502 51 34-06
Ignition system
2
Adjust the air gap.
502 51 34-06
Replacing spark plug
protection
1. Take the ignition cable through the
plug protection.
2. Fit the contact spiral on the ignition
cable.
Adjust where appropriate the air gap to
the correct distance.
• Release the screws holding the
ignition module.
• Position the feeler gauge on the
magnets of the flywheel and press the
ignition module against flywheel.
• Tighten the screws and check the air
gap again.
If there is still no spark then the ignition
system should be replaced.
Replacing spark plug
protection
1. Grease the ignition cable with a little
grease and take it through the plug
protection.
2. Cut off a piece of the ignition cable
(approx. 5 mm, 3/16") to obtain full
contact with the spark plug protection.
3. Fit the contact spiral on the ignition
cable and make sure that the wire is
folded along the cable.
4. Pull the contact spiral in the plug
protection.
NOTE!
It is important that the point on the contact
spiral meets the middle of the ignition
cable to prevent sparking.
Dismantling
Mod. 650, 700
Dismantle the cylinder cover, plug, starter unit, and air conductor.
Dismantle the ignition module and release the other cable connections.
K 950 K 1250
Dismantling
Mod. 650, 700
Dismantle the plug, cylinder cover, starter unit, and air conductor.
Dismantle the ignition module by removing the two screws.
Release the other cable connections and
lift off the ignition module.
Mod. 950, 1250
Dismantle the starter unit, air filter cover,
air filter and cylinder cover.
Remove the air conductor.
Note the position of the cables so that
they can be replaced in the same way.
15
2
Ignition system
Fit piston stop No. 502 54 15-01 in the
spark plug hole.
502 54 15-01
Mod. 650, 700, 950, 1250
Dismantle the starter pawls.
Insert piston stop No. 502 54 15-01 in the
sparking plug hole.
Make sure that the piston stop does not
come out through the exhaust port, it
must rest against the front of the cylinder
wall when the piston approaches Top
Dead Centre.
Mod. 650, 700, 950, 1250
Dismantle the starter pawls by releasing
the screws. Make sure the small washer
which lies next to the flywheel is not lost.
Remove the flywheel nut. Remove the flywheel nut by means of a
suitable box spanner.
Pull off the flywheel. Remove the flywheel by means of fly-
wheel puller 502 51 49-02, which is
screwed tight in the holes for the pawls.
NOTE!
Centre the flywheel puller over the shaft
centre. Select suitable screws and tighten
the withdrawing tool.
16
502 51 49-02
Ignition system
2
Tips!
Ta p t he flywheel puller screw sharply with
a hammer if the flywheel sits tight.
Starter pawls
Mod. 650, 700, 950, 1250
Check the starter pawls for wear and
damage.
Replace damaged parts.
The pawls are mounted on the flywheel
with a contact screw.
Pay attention to the spacer washer (A)
during dismantling and assembly.
Tips!
The flywheel may sit very tightly on the
shaft. To simplify dismantling - tap the
flywheel pullers screw sharply a few
times. Hold the engine in the air with the
handle on the flywheel puller.
Starter pawls
Mod.650, 700, 950, 1250
Check the starter pawls for wear and
damage.
Replace damaged parts.
The pawls are mounted on the flywheel
with contact screw and spacer washer
(A).
It is important not to forget the washer
during assembly.
Check that the pawls move freely.
A
Assembly
Check that the keyway and key in the
crankshaft are undamaged. (Mod. 650,
700, 1250)
Check that the keyway and the cast key
(mod. 950) in the flywheel are undamaged.
Fit the flywheel.
Assembly
Check that the keyway and key in the
crankshaft are undamaged. (Mod. 650,
700, 1250)
Fit where appropriate a new key and
make sure that it is positioned correctly in
the keyway.
Check that the keyway and the cast key
(mod. 950) in the flywheel are undamaged.
Fit the flywheel and check that the key
and keyway are correctly positioned
before the flywheel nut is tightened.
Tighten the nut with tightening torque 25–
35 Nm.
17
2
Ignition system
0,3 – 0,5 mm
Fit the ignition module.
Adjust the air gap (0.3 –0.5 mm/0.012–
0.020").
Fit the other cables.
Fit the other parts in the reverse order to
dismantling.
502 51 34-06
Fit the ignition module.
Adjust the air gap to the correct size (0.3
–0.5 mm/0.012–0.020").
See also page 14–15.
Fit the other cables and make sure that
they are correctly positioned in the cable
grooves etc. so that they cannot be
damaged.
Fit the other parts in the reverse order to
dismantling.
18
Fuel system
3.
Contents
Air filter ......................................................................... 20
Centrifugal cleaning (Active) ....................................... 21
Fuel filter ...................................................................... 22
Carburettor, dismantling/assembly .............................. 23
Carburettor design ....................................................... 25
Jets .............................................................................. 25
Speed limiter ................................................................ 26
Compensation device for blocked air filter .................. 26
Disassembly of the carburettor ................................... 27
Assembly of the carburettor ........................................ 30
Carburettor setting ....................................................... 32
Ta nk air v en t . .. . .. ... . .. .... . .. .... . .. .... . .. .... . .. .... . .. .... . .. .... . .. ... 34
Throttle control ............................................................. 35
Trouble shooting .......................................................... 40
19
3
Fuel system
In addition to the fuel tank and carburettor, the fuel
system also includes the air filter, fuel filter and
tank vent.
All these components interact to ensure that the
engine will have the optimum mixture of fuel and
air to make it as efficient as possible. Very small
deviations in the carburettor setting, or fouling of
Air filter
Mod. 650, 700, 950, 1250
Release the screws and lift off the air filter
cover with the main filter, intermediate
wall and protective filter.
the air filter, have a great effect on the running and
efficiency of the engine.
There are different makes of carburettors on our
different models, but the function and repair
techniques are basically the same.
! WARNING!
Do not clean the air filter in petrol. Health
hazard!
Air filter
Mod. 650, 700, 950, 1250
Release the two screws which hold the
air filter cover (mod. 1250 three screws).
Lift off the cover with main filter, intermediate wall and protective filter.
Clean the protective filter by tapping it
against your hand.
Clean the main filter carefully in lukewarm
soapy water.
Soak it in air filter oil (Partner) and squeeze
out the excess before refitting.
The protective filter is made of paper and
therefore must not be cleaned in water or
any other liquid, and neither with compressed air.
Clean the filter by tapping it against your
hand.
Clean the main foam plastic filter in
lukewarm soapy water. Air dry the filter
and soak it in air filter oil and squeeze out
the excess before refitting.
If the filter is damaged it should be replaced
with a new one.
20
Fuel system
K650/700
3
When the filter and covers are fitted it is
very important to make sure that all the
seals are undamaged and correctly
positioned.
Seals which do not seal properly result in
less efficient centrifugal cleaning and rapid blockage of the air filter.
Increased wear on the piston and cylinder barrel as a result of inferior air cleaning
shortens the engine’s service-life.
Centrifugal cleaning (Active)
Mod. 650, 700
Considerably longer cleaning intervals for the air filter are achieved by using the
centrifugal force during the filtering of the intake air to the carburettor.
By means of using the centrifugal force the heavier impurities are thrown out towards
the periphery of the air spiral and on past the cylinder.
The air to the carburettor is taken up by the centrifugal cleaning nozzle and the finer
impurities are effectively captured in air filter.
For centrifugal cleaning to be as efficient as possible it is important that:
1. The centrifugal cleaning nozzle is clean from deposits.
2. The connection of the nozzle to the carburettor chamber is tight.
3. The nozzle attachments are not broken.
4. The fan spiral and air conductor are clean.
The centrifugal cleaning nozzle is accessible for cleaning or replacement after
dismantling the starter unit and air conductor.
21
3
Fuel system
Fuel filter
Mod. 650, 700
The fuel filter can be taken out through
the tank's filler hole.
502 50 83-01
Clean the filter externally if it is not too
severely fouled.
Replace the filter if necessary.
Fuel filter
Mod. 650, 700
On the fuel pipe in the tank there is a fuel
filter. This is accessible through the filler
hole. Pull out the filter with your fingers or
by means of tool 502 50 83-01.
Remove the tank cap completely.
If the filter is not too severly fouled it can
be cleaned externally by means of a brush.
Otherwise it must be replaced.
Check the fuel pipe for cracking and
leakage.
NOTE!
Make sure that the filter's connecting collar
is pressed as far as possible in the fuel
pipe.
A
Mod. 950, 1250
The easiest way to take the fuel filter out
through the fuel tank refill hole is with tool
502 50 83-01.
Mod. 950, 1250
The fuel filter is located on the hose in the
fuel tank. It is accessible through the refill
hole.
Remove the tank fuel cap completely.
Pull out the filter with tool 502 50 03-01.
Pull the metal ring (A) from the filter
connection and then pull the filter off the
hose to either clean it or replace it.
A
502 50 83-01
Fuel hose
All models
Remove the fuel filter and connect
pressure tester No. 501 56 27-01. Pump
up the pressure to about 100 kPa and
observe whether any bubbles are formed.
Fuel hose
All models
Remove the fuel filter and connect
pressure tester No. 501 56 27-01.
Pump up the pressure to about 100 kPa.
Leakage and cracks in the hose are easy
to detect if any bubbles are formed.
22
30
3
5
5
2
40
0
2
200
250
4
150
5
15
300
100
0
5
350
10
50
5
400
5
5
0
0
0
6
501 56 27-01
Fuel system
3
Carburettor
Dismantling, all models
Dismantle all covers and air filters so that
the carburettor becomes accessible.
Blow clean the carburettor chamber with
compressed air.
Mod. 650, 700
Remove the screw guide and lock washer which holds the throttle push rod at
the lever.
Carburettor
Dismantling, all models
Dismantle all covers and air filters so that
the carburettor becomes accessible.
Close the choke flap to prevent dirt penetrating into the engine.
Blow clean the carburettor chamber with
compressed air.
Mod. 650, 700
1. Remove the screw guide from the
carburettor’s adjusting screws.
2. Bend away the lock washer which
holds the throttle push rod at the lever
by means of a screwdriver.
NOTE!
EPA-models have fixed jets and consequently do not have screwdriver guides.
Remove the fuel hose.
Release the carburettor screws and lift
off the carburettor together with the choke
control, air filter connection, and middle
piece.
502 50 18-01
Carburettor
4
2
Mod. 950
Blow clean the carburettor area with
compressed air before the carburettor is
removed.
1
3. Remove the fuel hose from the carburettor.
4. Unscrew the carburettor screws. Insert
hex key 502 50 18-01 through the
hole in the stop control when the left
screw is to be unscrewed.
5. Lift off the carburettor together with
the choke control, air filter connection
and middle piece.
For service procedures see ”Disassembly
of carburettor”.
Carburettor
Mod. 950
Dismantle all covers and air filter. Blow
clean the carburettor area with
compressed air.
Dismantle the following:
1. Impulse hose
2. Fuel hose
3. Choke lever
4. Throttle lever (from throttle control)
3
23
3
Fuel system
Dismantle the screw (A) and then the two
carburettor screws.
Lift off the carburettor.
A
502 50 18-01
Mod. 1250
Press off the rubber support from the
carburettor intake.
Remove the screw (A) and then the two
carburettor screws.
Insert key 502 50 18-01 through the hole
in the crankcase and tank part.
Lift off the carburettor together with the air
filter connection and throttle lever.
Fit in the reverse order to dismantling.
Mod. 1250
Press off the rubber support from the
carburettor intake with a screwdriver.
NOTE!
Do not pull off the support from the
crankcase since it is difficult to refit without
separating the crankcase and tank part.
Dismantle the fuel hose.
Unscrew the carburettor screws, remove
4
2
3
2
1
the choke lever and hook off the throttle
wire.
Fit in reverse order to dismantling.
Assembly
Mod. 650, 700
Fit the carburettor in the reverse order to
dismantling.
1. Dismantle the fuel hose.
2. Unscrew the carburettor screws.
3. Remove the choke lever from the
lever on the carburettor.
4. Hook off the throttle wire
Lift off the carburettor together with the
intake neck.
Fit in the reverse order to dismantling.
Assembly
Mod. 650, 700
Fit the carburettor to the cylinder in the
reverse order to dismantling.
Use new seals.
Place the air filter connection (with
screws), choke control and middle piece
on the carburettor.
Hold the complete carburettor unit against
the cylinder. Press down the choke control
in its guide and tighten the screws. Check
that the seal closest to the cylinder is
correctly positioned! Connect the throttle
push rod and fit the screw guide over the
carburettor’s adjusting screws.
24
Fuel system
3
Carburettor design
D
F
C
The carburettor can be divided into three
different functional units: the metering
section, mixing section, and pumping
section.
Metering section
The nozzles and control function for the
fuel are placed here.
The mixing section
The fuel and air are mixed here.
Carburettor design
The carburettor can be divided into three
different functional units: the metering
section, mixing section, and pumping
section.
Metering section
The nozzles and control function for the
fuel are placed here.
The needle valve (C) and metering diaphragm (D) are vital parts for the functioning of the carburettor.
The mixing section
The fuel and air are mixed to the correct
proportions in this part of the carburettor.
The choke (E) and throttle valves (F) are
placed here.
The main jet nozzle is located in the
middle of the venturi (the narrowest point
on the inlet).
E
Pumping section
This pumps fuel from the tank to the
carburettor.
H
G
Pumping section
The pump diaphragm (G) which pumps
fuel from the tank to the carburettor’s
metering unit is located here.
The membrane is activated by pressure
variations in the engine crankcase via an
impulse channel (H).
If the channel is blocked, e.g. by grease
or an incorrectly turned gasket, the pump
will not function and the engine will not
start.
Jets
A A
EPA-models have fixed carburettor jets, which means that the fuel/air mixture can not
be adjusted manually.
The right-hand carburettor in the illustration has fixed jets (A).
The nozzles can be cleaned and possibly changed once the sealing plugs have been
removed.
25
3
Fuel system
Speed limiter
Mod. 650, 700
A speed limiter is fitted on the side of the carburettor housing.
The speed limiter is fixed with Loctite and should not be released during servicing of
the carburettor.
When the engine speed is less than 9,200 rpm the ball seals the extra fuel channel (A).
The pressure of the spring presses the ball against the seat with a precise proven
A
pressure.
9600 r/min
When the engine speed exceeds the speed limit (9,600 ± 400 rpm) the spring-loaded
ball opens the extra fuel channel (A). The engine thereby receives extra fuel, begins to
putter and stops overspeeding.
Compensation insert for blocked air filter
The carburettor has been fitted with a compensation insert to prevent the engine
receiving an increasing amount of fuel as the air filter becomes blocked. This transfers
the underpressure in the carburettor’s inlet to the top of the metering diaphragm, as
opposed to the atmospheric pressure in a standard carburettor. The pressure difference
between the top and bottom of the diaphragm therefore remains constant and does not
increase as the air filter becomes blocked. The fuel supply to the carburettor’s main jet
nozzle is therefore always maintained at the correct level.
Check that the small O-ring (A) is in place
when the air filter union is installed.
A
It is important for correct function of the
compensation device that the O-ring is
neither damaged or missing.
26
Fuel system
Combinations of carburettors, induction pipe, seals, screwdriver guides
K650 Active, K700 Active
Carburettor Induct. pipe Seal Insert, seal Screwdriver guide
HS175E 503 28 03-20 506 21 41-01 506 22 65-01 Black
Not compensated Black
K650 Active II, K700 Active II
Carburettor Induct. pipe Seal Insert, seal Screwdriver guide
HS175F 503 28 04-03 506 21 41-01 506 25 34-01 506 25 33-01 Blue
Compensated, blue insert Black Moulded Blue
HS175G 503 28 04-04 506 21 41-01 506 25 34-01 506 25 33-01 Blue
Compensated,blue insert Black Moulded Blue
Small needle valve
HS175G 503 28 04-08 506 26 72-01 506 26 85-01 –
Comp., green insert, EPA Blue Moulded
HS175L 503 28 04-15 506 31 16-01 506 26 85-01 –
Comp., yellow insert, EPA Yellow Moulded
To we r m odel
HS175L, 503 28 04-16 506 31 16-01 506 26 85-01 Grey
Comp., grey insert, EPA Grey Moulded
To we r m odel
Rubber foam, bonded to cyl. housing
3
There are different sizes and versions of carburettors on the different models, but in
terms of servicing they are all treated in the same way.
Dismantling of the
carburettor
Remove the screw driver guide and cover
for the metering diaphragm.
Check the diaphragm for damage.
Replace if necessary.
Dismantling of the
carburettor
Remove the screw driver guide over the
adjusting screws.
Remove the 4 screws for the metering
diaphragm cover.
Lift off the compensation insert and the
diaphragm.
Check the diaphragm for holes and wear.
Replace the diaphragm if necessary.
Pressure test the metering system.
Connect pressure tester 501 56 27-01 to
the fuel pipe nipple.
Submerge the carburettor in a basin with
petrol to simplify inspection for leaks.
Pressure test with 0.5 bar.
No leakage is permissible.
30
3
5
5
2
4
0
0
2
200
250
4
150
5
15
300
100
0
5
350
10
50
5
400
5
5
0
0
0
6
501 56 27-01
27
3
Fuel system
In the event of leakage - dismantle the
needle valve.
Check the needle valve and lever for
wear.
Replace damaged parts with new ones.
In the event of leakage dismantle the
needle valve.
Release the screw and lift off the lever,
shaft, needle valve and spring.
Check the needle valve for damage at the
point and the groove for the lever.
Check the lever for wear in the grooves
for the needle valve and the diaphragm.
Replace damaged parts with new ones.
If the new needle valve also leaks the
fault may be that the seat for the valve is
damaged.
Remove the pump diaphragm.
Check the diaphragm for damage.
Remove the fuel strainer.
Remove the screws which hold the cover
over the pump diaphragm.
Lift off the cover, gasket and diaphragm.
Check the diaphragm for damage on the
valve tongues. Hold it up to a lamp to
inspect for holes in the material.
Carefully remove the fuel strainer, e.g. by
using a needle.
28
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