Husqvarna K 750 Instruction manual

HUSQVARNA CONSTRUCTION PRODUCTS
Workshop manual
K 750

1
1. LITERATURE 2
2. SPECIAL FUNCTIONAL COMPONENTS 3
3. COMPONENTS – ORIENTATION 4
4. DISMANTLING INTO BASIC MODULES 5
5. STARTER 9
6. IGNITION SYSTEM 12
7. FLYWHEEL 15
8. AIR FILTER 17
9. FUEL SYSTEM 18
10. CARBURETTOR 21
11. DECOMPRESSION VALVE 28
12. CYLINDER/PISTON 29
13. CRANKCASE 35
14. CLUTCH 40
15. CUTTING HEAD 44
16. FRICTION RETARDER 49
17. HANDLE 51
18. TOOLS 52
CONTENTS Page
HUSQVARNA
K 750
502 53 08-26

2
LITERATURE1
Workshop Manual
The Workshop Manual includes virtually
all workshop procedures that can come into
question on the K750. Some very simple and
self-evident repairs have been omitted.
Outline
An introductory section with the title
“Dismantling into Basic Modules” shows how
the machine is dismantled into large component
units, for example, the starter, cutting arm, air
filter, etc.
The manual goes on to describes in detail
through the different chapter how work on the
basic modules should be carried out.
This arrangement means that as a mechanic,
at least until you have learnt the basic composi-
tion of the machine, you need to start with the
chapter “Dismantling into Basic Modules” to
then move on to the chapter covering the speci-
fic service work.
Layout – pictures and text
Besides the pictures and illustrations there is
generally two columns of text. The left-hand text
column is a concise and is suitable for experienced
mechanics, the right-hand column gives a more
detailed description and is targeted at mechanics
with less experience of repair work on the power
cutter.
Contents
The manual is divided into numbered chapters
together with chapter headings that are stated in
bold at the top of each page.
The list of contents also has page references to
the start of each chapter.
Spare parts
Spare parts K750
The folder includes all the spare parts for
Husqvarna K750.
The folder contains complete exploded views
of the entire machine where each component's
placement, spare part number and appearance
can be easily identified.
HUSQVARNA CONSTRUCTION PRODUCTS
Workshop manual
K 750
“Dismantling into Basic Modules”
“Cutting head” (Example)
502 53 08-26

SPECIAL FUNCTIONAL COMPONENTS
3
New technical solutions
Husqvarna K750 is the first model in a new
generation of power cutters with a number of
new technical solutions:
New engine technology – Dual
Charge
The cylinder, piston and carburettor are
radically changed.
Apart from the inlet from the carburettor
with fuel-air mixture there are two ducts for
the inlet of clean air, the top duct in the pic-
ture. By leading the fuel-air mixture and the
clean air in separate flushing channels into
the cylinder, the proportions of the air-fuel
mixture and clean air can be controlled so
that these vary in different phases of the
engine's work cycle.
Cleaner exhaust fumes and improved
performance
The amount of uncombusted hydrocarbons
(HC) is reduced by the Dual Charge techno-
logy to about a third compared with a tradi-
tional design (K700). The emission values are
now well below levels in the regulations from
EPAII.
The output is higher over the entire speed
range and the torque in the lower speed range
is now significantly higher.
Lower vibration levels
The air filter system and the carburettor are
mounted in the dampened handle unit,
which means lower vibration on the handle
through the greater mass (weight) in the
handle unit.
The carburettor placement in the dampened
section results in stable carburettor function
and less wear on the moving parts in the car-
burettor.
New muffler
The volume of the muffler has now been
doubled and both the sound pressure and
sound power have been halved, all in compa-
rison with K700
Poly-V belt
This type of belt has improved strength and
is more resilient against stretching than
previous V-belts, which results in longer inter-
vals between adjustments.
Friction Retarder
A new front belt pulley is being introduced in
2007 with a braking mechanism that takes
effect at low speeds.
Torx – T27
Torx screws, with the dimensions T27, are
used virtually throughout to simplify the ser-
vice work.
Note that screws with both a flat and fluted
undersides are used.
2
Torx T27

COMPONENTS – ORIENTATION3
4
Components
1. Cutting blade
2. Blade guard
3. Adjustable handle for the blade guard
4. Front handle
5. Air filter cover
6. Cylinder cover
7. Starter handle
8. Starter
9. Combination spanner
10. Belt adjustment screw
11. Lock screws for belt adjustment
12. Cutting arm/rear belt guard
13. Fuel tank
14. Throttle control
15. Rear handle
16. Throttle trigger lock
17. Water valve with tool attachment
18. Water connector
19. Choke Lever
20. Sight glass for fuel
21. Start throttle lock
22. Stop switch
5
4
1
23
6
78
9
10
11
13 1214
17
18
19
15
16
22
21
20

Basic modules
This chapter shows how the machine is
built up of basic modules, for example,
the starter, carburettor, air filter system,
etc.
The purpose is to illustrate how you
can easily and effectively dismantle and
assemble the machine in its basic modules.
Service work on a component level, for
example, replacing the starter cord, is
described in detail in respective chapters.
Cutting arm
1. Loosen the screws on the cutting head.
2. Slacken off the belt tension using the
adjuster screw. Dismantle the screws on
the cutting head.
3. Dismantle the front belt cover by
sliding it forwards.
4. Loosen the hoses by the water valve.
Lift off the belt from the pulley and
remove the cutting head.
5. Loosen the two screws on the rear belt
guard.
(Tightening torque when assembling
6.6–8.1 lbf·ft/9–11 Nm.)
6. Remove the guard.
DISMANTLING INTO BASIC MODULES 4
5
Starter
1. Loosen the 4 screws on the guard.
2. Dismantle the starter.
12
12
34
56

DISMANTLING INTO BASIC MODULES
4
6
Air filter
1. Loosen the three screws on the air
filter cover and remove the cover.
2. Lift off the filter base.
3. Carefully lift up the paper filter so
that the dust does not fall down onto the
service filter.
Cylinder cover
1. Loosen the four screws on the cylinder
cover.
Press together the rubber seal's collar
so that the cylinder cover can be lifted
off.
2. NOTE! When reassembling the rubber
seal must be drawn up through the cover
and the collar then adjusted to fit
correctly against the cover.
Carburettor
1. The carburettor unit is attached to the
cylinder by a single screw. Loosen the
screw.
2. Lift up the carburettor unit. Loosen
the fuel hose (arrow) from the carburet-
tor.
Tip: Tape the throttle control in the
full throttle position to improve access
to the throttle rod's attachment on the
throttle control.
3. Pull the throttle rod out of the con-
trol.
4. The entire carburettor unit can now be
lifted out.
12
3
2!
34
1
12

DISMANTLING INTO BASIC MODULES 4
7
Assembly
5. Hook the throttle rod into the valve
arm as illustrated. Lift the carburettor
unit into position and fit the fuel hose.
Press down the throttle rod into throttle
control with the help of a pair of pliers.
6. Align the carburettor's choke arm in
the blue choke control.
7. Fit the carburettor unit. Align the lug
on the flange with the cut-out on the
cylinder. Tighten the screw at the top.
Carburettor compartment
1. Tank venting
This is dismantled by angling the unit
backwards and then pulling it out the
tank.
2. Stop switch
This is secured by a screw in the carburet-
tor compartment.
3. Controls
The controls in the rear handle become
accessible for service once the carburettor
unit has been dismantled.
Air duct
First dismantle the starter.
1. Lower air duct
Note, to facilitate reassembly, how the
cable to the stop switch is fitted in the
air duct. Lift the cable out of its
mounting.
2. Upper air duct
Loosen the ignition lead by the spark
plug and lift the cable out of its
mounting in the cover.
3. The engine's earth point
The engine's earth point to the stop
button is located here
5
1
3
2
6
7!
21
3

DISMANTLING INTO BASIC MODULES4
8
3. Dismantle the three screws on the air
duct cover.
4. Lift off the air duct cover.
Muffler
Dismantle the cutting head and the
starter.
1. Dismantle the four screws on the
muffler.
2. Dismantle the muffler.
Fit the gaskets correctly!
3. The insulated fibre gasket should lie
closest to the muffler.
4. Fit the heat shield.
5. The aluminium gasket should lie
against the cylinder.
The screws should be tightened to a tor-
que of 8.0–9.5 lbf·ft/11–13 Nm.
Vibration dampening
Some service work can be aided by split-
ting the machine by the vibration dampe-
ning element.
Dismantle the air filter unit, cylinder
cover and upper the air duct cover.
Dismantle the screw holding the carbu-
rettor. Dismantle the starter and the air
duct cover. Loosen the cable lug by the
ignition module and unscrew the cable
to the earth point. Pull off the water
hose by the valve.
The engine unit is attached to the
handle unit at three points with the vib-
ration dampening element in the form of
springs. Dismantle the screws located by:
1. The lower section on the flywheel side.
2. The base on the clutch side.
3. The handle loop next to the water
valve.
To gain access to the spring's inner
screw, Torx T27, the tool diameter must
be max. 5 mm. The combination spanner
fits.
3
12
345
4
123

STARTER 5
9
1
1
23
2
12
Replacing the starter cord
Dismantle the starter.
Eliminate the spring force from
the return spring
1. Pull out the starter cord approximately
12 in./30 cm. Hold the starter pulley
with your thumb and place the cord in
the cut-out on the starter pulley.
Replacing the starter
cord
Dismantle the starter.
Eliminate the spring force
from the return spring
1. Pull out the starter cord
approximately 12 in./30 cm.
Hold the starter pulley and
place the cord in the cut-out on
the starter pulley.
2. Let the starter pulley rotate slowly and
wind up the cord on the metal sleeve.
3. Lift off the cord from the starter
pulley.
2. Let the starter pulley rotate
and wind up the cord on the
metal sleeve.
3. Lift off the cord from the
starter pulley.
Attach the new starter cord
The starter cord should be 45 in./
115 cm long and have a diameter of
.16 in./4 mm.
1. Insert one end of the cord from the
top through the hole in the starter pulley
and then out through the notch for the
cord. Pull out virtually the whole cord
length until sufficient cord remains to tie
a knot as illustrated.
2. Insert the other end through the cover
and on through the handle. Tie a double
knot as illustrated.
Loading the return spring
1. Fit the starter cord in the cut-out.
2. Wind the start cord 4 turns around the
hub and pull out the starter handle and
release so that the cord is wound into the
starter pulley. Repeat the procedure with
3 turns of cord around the hub.
Important check!
Check that the return spring does not act
as an end stop by extending the cord
fully. In this position it should be possible
to turn the starter pulley a least a further
half turn before the spring stops the
movement.