RedMax HTZ750 Instruction manual

Workshop manual
HTZ750
English
1110 - 001 -

Contents
1 Introduction
1.1 Document description............................................ 3
1.2 Target group...........................................................3
1.3 Revisions................................................................3
1.4 Safety..................................................................... 3
1.5 Servicing tools........................................................3
2 Safety
2.1 Safety definitions....................................................4
2.2 General safety instructions.....................................4
2.3 Symbols on the product......................................... 4
3 Prepare and do servicing on the product
3.1 Maintenance schedule........................................... 5
4 Servicing data
4.1 Servicing data ....................................................... 6
5 Servicing tools
5.1 Servicing tools......................................................10
6 Function overview
6.1 Type plate and product serial number..................12
7 Repair instructions
7.1 Product overview for repair instructions............... 13
7.2 To clean and examine the product parts..............13
7.3 Starter.................................................................. 14
7.4 Muffler.................................................................. 17
7.5 Air filter................................................................. 17
7.6 Flywheel............................................................... 18
7.7 Ignition system..................................................... 20
7.8 Carburetor............................................................ 26
7.9 Handle and throttle trigger....................................30
7.10 Clutch, clutch drum and gearbox....................... 31
7.11 Cutting equipment.............................................. 33
7.12 Cylinder and piston............................................ 33
7.13 Crankshaft and crankcase................................. 39
7.14 Fuel tank............................................................ 45
8 Troubleshooting
8.1 Troubleshooting................................................... 48
9 Technical data
9.1 Technical data......................................................51
21110 - 001 -

1 Introduction
1.1 Document description
This manual gives a full description of how to do
maintenance and repair on the product. It also gives
safety instructions that the personnel must obey.
1.2 Target group
This manual is for personnel with a general knowledge
of how to do repair and do servicing. All personnel that
do repair or do servicing on the product must read and
understand the manual.
1.3 Revisions
Changes to the product can cause changes to the
maintenance work and spare parts. Separate
information is sent out for each change.
Read the manual together with all received information
about changes to maintenance and spare parts for the
product.
1.4 Safety
WARNING: All personnel that repair or do
servicing on the product must read and
understand the safety instructions in this
workshop manual.
1.5 Servicing tools
The manual gives information about necessary servicing
tools. Always use original tools from Redmax.
1110 - 001 - Introduction - 3

2 Safety
2.1 Safety definitions
Warnings, cautions and notes are used to point out
specially important parts of the manual.
WARNING: Used if there is a risk of injury or
death for the operator or bystanders if the
instructions in the manual are not obeyed.
CAUTION: Used if there is a risk of damage to
the product, other materials or the adjacent area
if the instructions in the manual are not obeyed.
Note: Used to give more information that is necessary in
a given situation.
2.2 General safety instructions
WARNING: Read the warning instructions that
follow before you use the product.
The service center that repairs the product must have
safety devices that obey local regulations. Warnings and
cautions are used to point out specially important parts
of the workshop manual.
2.3 Symbols on the product
WARNING! This product is dangerous.
Injury or death can occur to the operator
or bystanders if the product is not used
carefully and correctly. To prevent injury
to the operator or bystanders, read and
obey all safety instructions in the
operator's manual.
Read the operator's manual carefully and
make sure that you understand the
instructions before use.
Use approved hearing protection and
approved eye protection.
Use approved protective gloves.
Use heavy-duty slip-resistant boots.
Noise emission to the environment refer to
the European Community's Directive. The
emission of the product is specified in the
Technical data chapter and on the label.
The product agrees with the applicable
EC directives.
yyyywwxxxx The rating plate shows serial number.
yyyy is the production year and ww is
the production week.
Note: Other symbols/decals on the product refer to
certification requirements for some markets.
4 - Safety 1110 - 001 -

3 Prepare and do servicing on the product
3.1 Maintenance schedule
Maintenance Before
operation After 40 h After 100 h
Clean the external surface. After each operation.
Clean the muffler, exhaust pipe and engine from leaves, dirt and unwanted lubri-
cant. After each operation.
Make sure that the cutting attachment does not move at idle speed. X
Do a check of the stop switch. X
Examine the cutting attachment and the cutting attachment guard for damages
and cracks. Replace if it is damaged. X
Examine the hand guard for damages and cracks. Replace if it is damaged. X
Do a check of the throttle trigger lockout and the throttle trigger. X
Examine the engine, the fuel tank and the fuel lines for leaks. X
Tighten nuts and screws. X
Examine the fuel filter for contamination and the fuel hose for cracks and other
defects. Replace if necessary. X
Examine the starter and the starter rope for damages. X
Clean the air filter. Replace if it is necessary. X
Examine the vibration damping units for damages and cracks. X
Examine the spark plug, refer to To examine the spark plug on page 20 . X
Clean the cooling system. X
Clean the external surface of the carburetor and the area around it. X
Clean or replace the spark arrester mesh. X
Clean the inner surface of the fuel tank. X
Examine the spark plug. X
Make sure that the gear housing is filled with grease. X
1110 - 001 - Prepare and do servicing on the product - 5

4 Servicing data
4.1 Servicing data
T27
5 - 8 Nm
14 mm
6 - 8 Nm
T27
7 - 9 Nm
T27
3 - 4 Nm
T27
2 - 3 Nm
T27
1.5 - 2.5 Nm
T25
2 - 3 Nm
T27
3 - 4 Nm
T27
7 - 10 Nm
T27
1.6 - 3.0 Nm
T27
3 - 4 Nm
6 - Servicing data 1110 - 001 -

T27
6 - 8 Nm
T27
6 - 9 Nm
10 - 15 Nm
8 mm
6 - 9 Nm
T27
4 - 6 Nm
T27
3 - 5 Nm
1110 - 001 - Servicing data - 7

T27
1.5 - 2.5 Nm
T27
4.5 - 5.5 Nm
T27
6 - 8 Nm
T27
6 - 8 Nm
16 mm
10 - 12 Nm
T27
4 - 6 Nm
T27
8 - 10 Nm
T27
3 - 4 Nm
T27
3 - 4 Nm
13 mm
14 - 16 Nm
T27
2.5 - 3 Nm
10 - 12 Nm
T27
3 - 4 Nm
8 - Servicing data 1110 - 001 -

T27
6 - 9 Nm
T27
3 - 5 Nm
T27
3 - 5 Nm
8 mm
6 - 9 Nm
8 mm
6 - 9 Nm
522HS75S
1110 - 001 - Servicing data - 9

5 Servicing tools
5.1 Servicing tools
10
8
3
11 129
124
5 6 7
13 14 15
10 - Servicing tools 1110 - 001 -

Item Description Use for Article number
1 Piston stop To lock the crankshaft 521 54 83-01
2 Hook for fuel filter To remove the fuel filter 502 50 83-01
3 T-handle Torx For Torx screws 502 71 31-01
4 Piston assembly kit To assemble the piston 502 50 70-01
5 Air gap tool To measure the distance between the
flywheel and the ignition module
502 51 34-02
6 Carburetor tool To adjust the carburetor settings 597 10 85-01
7 Sleeve for crankshaft Protection for the sealing ring 577 90 21-01
8 Flywheel removal tool To remove the flywheel 577 90 66-01
9 Test spark plug To do a check of the ignition module 502 71 13-01
10 Ignition tester Spark strength check 501 97 64-01
11 Pressure gauge Pressure test 531 03 06-23
12 Assembly pliers To assemble spark plug caps 502 50 06-01
13 Gear drive removal tool To remove the drive gear 597 10 95-01
14 Clutch removal tool Centrifugal clutch 502 54 16-03
15 Ball bearing removal tool Removal tool for the ball bearing 505 38 17-09
1110 - 001 - Servicing tools - 11

6 Function overview
6.1 Type plate and product serial number
RedMax HTZ750
s/n 20XX XXXXXXX
XXX XX XX-XX
Husqvarna AB
Huskvarna, Sweden
12 - Function overview 1110 - 001 -

7 Repair instructions
7.1 Product overview for repair instructions
1
10
9
6
2
12
3
4
8
7
5
11
13
1. Starter unit
2. Muffler
3. Spark plug
4. Flywheel
5. Ignition module
6. Air filter
7. Fuel tank
8. Carburetor
9. Handle
10. Gearbox
11. Cutting attachment
12. Cylinder and piston
13. Crankcase and crankshaft
7.2 To clean and examine the product parts
• Clean and examine all parts fully. You find more
instructions in the chapter for each part if special
tools or procedures are necessary.
• Replace damaged or defective parts.
• Always use original spare parts.
1110 - 001 - Repair instructions - 13

7.3 Starter
7.3.1 To disassemble the starter unit
1. Remove the 4 screws and remove the starter unit.
2. Pull out the rope approximately 30 cm /12 in and put
it into the notch in the pulley. Slow the starter pulley
with your thumb.
3. Let the pulley rotate slowly rearward to release the
tension of the recoil spring.
4. Remove the bolt (A) and washer. Carefully remove
the starter pulley (B) together with the recoil spring
(C).
WARNING: The recoil spring can eject and
cause injury. Use eye protection.
A
B
C
D
E
5. Use pointed pliers to pull out the ends of the starter
rope (D) from the handle (E). Loosen the knot, if it is
possible. If not, cut the rope.
6. Use pointed pliers to pull out the ends of the starter
rope from starter pulley (B).
7.3.2 To clean and examine the starter unit
• Clean all components.
• Examine the starter rope. Replace the starter rope if
it is damaged.
• Examine the starter pulley. Replace damaged parts.
14 - Repair instructions 1110 - 001 -

• Make sure that the pawls on the flywheel are not
damaged. Make sure that the pawl springs on the
flywheel are attached correctly and move freely.
• Lubricate the pawls on the flywheel.
• Lubricate the recoil spring.
7.3.3 To assemble the starter unit
1. Attach a new starter rope to the starter pulley. Make
sure that the knot is as small as possible and that it
goes into the notch in the pulley.
2. Put the starter pulley in a vise. The new spring is in
full tension with a solid plastic strap (F). Put the
recoil spring in the starter pulley, directly above the
groove (G) in the starter pulley.
F
G
3. Hold the recoil spring with 2 fingers. Push the recoil
spring down into the starter pulley with a
screwdriver. The plastic strap comes off as you push
the recoil spring down.
4. Lubricate the recoil spring and the stub axle of the
starter pulley with Redmax grease.
5. Put the starter rope through the opening (H) in the
starter housing. Put the starter pulley in position. Put
the free end of the recoil spring into the notch (I) on
the hub of the starter housing. Push the starter
pulley down into the starter housing.
I
H
1110 - 001 - Repair instructions - 15

6. Put the starter rope handle on the starter rope.
7. Pull the starter rope up into the notch in the starter
pulley. Turn the starter pulley to wind the starter
rope on the starter pulley. Continue to wind the
starter pulley until the starter pulley stops. Hold the
starter pulley with your thumb.
8. Pull the starter rope to make it straight, remove your
thumb and let the starter rope wind up.
9. Attach the starter unit to the crankcase.
16 - Repair instructions 1110 - 001 -

7.4 Muffler
7.4.1 To disassemble the muffler
1. Remove the 2 screws and remove the muffler cover.
2. Remove the 2 screws and remove the muffler.
3. Remove the gasket behind the heat shield.
4. Remove the screw and remove the spark arrester.
7.4.2 To clean and examine the muffler
1. Clean all components. Clean the contact surfaces of
the gasket, the heat deflector and the cylinder.
2. Examine the spark arrester for damage.
3. Examine the muffler and the muffler holder for
damage.
4. Examine the gasket for damage.
5. Replace all damaged parts.
7.4.3 To assemble the muffler
1. Assemble the muffler in the opposite sequence of To
disassemble the muffler on page 17 .
7.5 Air filter
7.5.1 To disassemble the air filter
1. Pull the clips (A) to the side to release the air filter
cover (B). The air filter cover is connected to the air
filter holder by a rod (C).
A
B
C
D
E
2. Remove the air filter (D) and the foam filter (E).
7.5.2 To clean and examine the air filter
1. Put on protective gloves.
2. Spray the foam filter (E) with air-filter oil.
3. Put the air filter in a plastic bag.
4. Rub the plastic bag to supply the oil equally across
the air filter.
5. Push the unwanted oil out of the air filter while in the
plastic bag.
7.5.3 To assemble the air filter
1. Assemble in the opposite sequence of To
disassemble the air filter on page 17 .
1110 - 001 - Repair instructions - 17

7.6 Flywheel
7.6.1 To disassemble the flywheel
1. Clean around the spark plug.
2. Remove the spark plug cap and the spark plug.
3. Put a piston stop in the spark plug hole.
CAUTION: Make sure that the piston stop
does not go into the exhaust port. There is a
risk of engine damage.
4. Remove the starter unit.
5. Remove the nut that holds the flywheel.
6. Attach the flywheel removal tool to the crankshaft,
refer to Servicing tools on page 10 . Keep a distance
of approximately 2 mm between the flywheel
removal tool and the flywheel.
7. Hit the flywheel removal tool lightly with a hammer
while you lift the flywheel with your other hand.
18 - Repair instructions 1110 - 001 -

8. Remove the locking washers (A) with a screwdriver.
This causes deformation of the 2 washers. Discard
the 2 washers.
A
B
C
9. Remove the starter pawls (C) and the recoil springs
(B).
7.6.2 To clean and examine the flywheel
• Examine the flywheel for cracks and damages.
7.6.3 To assemble the flywheel
1. Make sure that the key in the flywheel and keyway in
the crankshaft are not damaged.
2. Attach the recoil springs (B) and the starter pawls
(C) on the flywheel.
A
B
C
Note: Make sure that the recoil springs is attached to
the flywheel, as the illustration shows.
3. Attach new locking washers (A).
CAUTION: Always use new locking
washers.
1110 - 001 - Repair instructions - 19

4. Install the flywheel and attach the nut. Remove the
piston stop.
5. Put the air gap tool between the flywheel and the
ignition module. Refer to Servicing tools on page 10
for the correct distance.
a) If it is necessary, loosen the screws to adjust the
distance between the flywheel and the ignition
module.
b) Tighten the screws to the correct torque.
6. Install the starter unit.
7. Install the spark plug and the spark plug cap.
7.7 Ignition system
7.7.1 Introduction
The engine has an electronic ignition system fully
without moving parts. A defective component cannot be
repaired, but must be replaced by a new component.
If the engine does not fire, the ignition module can be
damaged. Before you replace the ignition module, do
the tests that follow.
7.7.2 To examine the spark plug
CAUTION: Always use the recommended spark
plug type. Incorrect spark plug type can cause
damage to the product.
• Examine the spark plug if the engine is low on
power, is not easy to start or does not operate
correctly at idle speed.
• To decrease the risk of unwanted material on the
spark plug electrodes, obey these instructions:
a) Make sure that the idle speed is correctly
adjusted.
b) Make sure that the fuel mixture is correct.
c) Make sure that the air filter is clean.
20 - Repair instructions 1110 - 001 -