Zenoah EBZ7500 Instruction manual

Workshop Manual
[2017]
EBZ7500/ 8500

This workshop manual describes the main maintenance items and procedures for the
Husqvarna Zenoah engine blower EBZ7500/ 8500. This manual is classified into three
categories.
Special tools for maintenance
Notice of teardown and reassembly
Inspection and adjustment of the carburetor
As reference information, the technical data, the maintenance standard and the
troubleshooting are listed, too.
After each item is thoroughly understood, apply the understanding to the actual maintenance
tasks. Frequently asked questions are also included in this manual. However, many cases
need rich maintenance experience and informed judgment. Please refer to this manual for
maintenance support.
“WARNING”
1. The contents of this manual are based on specifications as of 2017.
The contents may be modified due to performance improvement or some other
reason without notice.
2. Use Zenoah brand-name parts when replacing a part during maintenance, etc.
The manufacturer does not bear any responsibility if trouble occurs owing to
use of parts other than those endorsed by our brand.
3. Read this manual thoroughly before beginning the maintenance work,
understand it, apply the content to the actual maintenance tasks and guide the
customer if directions are needed.

Contents
-１-
1. Features of Engine Blower
1-1 Fan and Volute Case······························· 2
1-2 Pipes ··················································· 3
1-3 Air Cleaner············································ 4
1-4 Measures Against Static Electricity············· 4
2. Strato-charged Engine
2-1 Outline ················································· 5
2-2 Operating Principle ································· 6
3. Constructions - Exploded View············ 7
4. Technical Data
4-1 Blower ················································· 8
4-2 External Dimensions ······························· 9
4-3 Pipe and Nozzles ··································10
5. Special Tools
5-1 Description···········································11
5-2 How to Use ··········································12
6. Notice of Teardown
6-1 Guard Net Removal ·······························21
6-2 Lower Damper Removal ·························21
6-3 Crankcase and Crankshaft Disassembly·····22
6-4 Oil Seal and Rearing Removal··················23
7. Notice of Reassembly
7-1 Engine Short Block Assembly···················24
7-2 Handling of the bolt with a thread lock········28
7-3 Muffler Installation ·································29
7-4 Rotor Installation ···································29
7-5 Ignition Coil Installation···························30
7-6 Coupling Installation·······························31
7-7 Carburetor Installation ····························31
7-8 Fan Installation ·····································32
7-9 Recoil Starter Installation ························32
7-10 Engine Cover Installation·······················33
7-11 Intake Hose Installation ·························33
7-12 Frame Installation ································34
7-13 Fuel Pipes Installation···························35
7-14 Switch Cords and Cable Installation·········36
7-15 Elbow Installation·································36
7-16 Recoil Starter Assembly ························37
7-17 LHD-Throttle Lever Set Assembly············40
7-17 RHD-Throttle Lever Set Assembly ···········42
8. Carburetor
8-1 Technical Data······································ 44
8-2 Description·········································· 45
8-3 Inspection ··········································· 46
8-4 Adjustment·········································· 50
9. Maintenance Standards/ Tightening
Torques
9-1 Standards and Service Ability Limit ··········· 53
9-2 Tightening Torque ································· 54
10. Troubleshooting
10-1 Engine does not star···························· 55
10-2 Engine stop during operation ················· 56
10-3 Engine cannot be stopped····················· 56
10-4 Lack of output power or unstable
revolution·········································· 57
10-5 The amount of the wind is weak·············· 57
10-6 Others ·············································· 58

-２-
1. Fe atu r es of E ngi n e Bl ower
1-1 Fan and Volute Case
Air is sucked from the whole circumference of the full cover type guard net and from the side structure of the
newly designed blow molding frame to send a lot of air to the fan. The fan uses a half-closed fan, optimizing
the air flow with the new flat volute case, realizing the very best of the air volume and wind velocity.
Intake from the side of the frame.
Guard Net
New type Flat Volute Case
Half-closed Fan
The notches are formed in the shroud (wing covering) and
height of fins is increased while maintaining rigidity in
order to increase wind volume and decrease the weight.
Blow molded
new frame

-３-
1. Fe atu r es of E ngi n e Bl ower
1-2 Pipes
BZ7500
The tip of the pipe end is cut obliquely so that the
wind flows slightly downward. By letting the wind flow
downward, holding of the pipe feels lightly. It
promotes easy operation.
EBZ8500
By increasing the diameter of the aperture of the
pipe end, the wind loss at the pipe outlet is reduced.
The maximum air volume in this class is acquired.
EBZ7500/ 8500
The new spiral type flexible hose has no sharp on its
surface contrary to the conventional flexible hose. It
is hard to split and has excellent durability.
In addition, wind resistance is reduced compared
with conventional uneven path.
Wind direction
3 to 5 degrees
downward
Indication of the
orientation of
installation
NOTE:
If the pipe end is set upside down, it gives
you a powerful feeling to blow the object far,
but you will need power to hold the grip.
Cut it obliquely.
Outlet inner
diameter
φ84mm
φ76mm Flare
Conventional flexible hose
New type spiral flexible hose

-４-
1. Fe atu r es of E ngi n e Bl ower
1-3 Air Cleaner
EBZ7500/ 8500
It is equipped with a large capacity cleaner with
double structure of pre-filter and paper filter. The
high cleaning efficiency realizes longer time to
clogging even at sites where there are many dust.
EBZ8500
The fresh air intake system is used. Because the
clean air in the volute case is taken in directly through
the dedicated passage, it is powerful and the
maintenance interval can be lengthened.
1-4 Measures Against Static Electricity
A conductive throttle lever discharges static
electricity through the hands of the operator.
Throttle Lever
Air Cleaner Cover
Paper Filter
Pre-filter
Air Cleaner Body
Fresh Air Intake Passage
Air Cleaner Case
Volute Case

-５-
2. Strato-charged Engine
2-1 Outline
■Efforts to the exhaust gas regulations
Husqvarna Zenoah has developed its own "Strato-charged
Engine" as a two-stroke engine compliant with exhaust gas
regulations since 1999, and it has been in compliance with the
regulations of each country starting from the US.
The Strato-charged engine realizes clean exhaust while taking
advantage of two-stroke engine.
■Structure
Normally, approximately 30% of unburned gas is discharged in a two-stroke engine, because air-fuel
mixture pushes out the combustion gas. However, Husqvarna Zenoah's Strato-charged engine adopts
"air-guided stratified scavenging system" which introduces leading air to the scavenging port separately
from the air-fuel mixture. The leading air pushes out the combustion gas in order to prevent blowing out
of unburned gas resulting in reduction of the concentration of hydrocarbons in the exhaust gas.
■Features
Because it does not use any special equipment, it is lightweight with a simple structure.
Excellent cooling performance promotes stable output performance even in continuous operation in
summer.
It realizes low fuel consumption of 40% or less. (In comparison with our previous model)
混合気
Lead Air Venturi
Air-fuel Mixture Venturi
Carburetor
Scavenging Port
Piston Groove
Lead Air Intake Port
Air-fuel Mixture
Intake Port

-６-
2. Strato-charged Engine
2-2 Operating Principle
1. As the piston proceeds through the upstroke
of the intake cycle, the crankcase vacuum
sucks the lead air in through the scavenging
port via the groove on the piston skirt.
2. As the piston begins its downstroke after top
dead center, a scavenging port starts to open
and lead air in the scavenging port moves into
the cylinder earlier than the air-fuel mixture.
3. As the piston begins its upstroke after bottom
dead center, burnt gas in the cylinder is pushed
out through the exhaust port by lead air.
Therefore, almost no air-fuel mixture is emitted.
Piston
Exhaust Port
Burnt Gas
Air-fuel Mixture
Lead Air
Air-fuel Mixture
Lead Air

-７-
3. Constructions - Exploded View
7-9 Recoil Starter Installation (see page 32)
7-16 Recoil Starter Assembly (see page 37)
7-10 Engine Cover Installation (see page 33)
7-5 Ignition Coil Installation (see page 30)
7-4 Rotor Installation (see page 29)
7-14 Switch Cords and Cable Installation
(see page 36)
7-3 Muffler Installation (see page 29)
7-13 Fuel Pipe Installation
(see page 35)
6-1 Guard Net Removal (see page 21)
7-12 Frame Installation (see page 34)
7-17 LHD-Throttle Lever Set
Assembly (see page 40)
7-8 Fan Installation (see page 32)
7-15 Elbow Installation (see page 36)
7-11 Intake Hose Installation
(see page 33)
6-2 Lower Damper Removal
(see page 21)
7-6 Coupling Installation
(see page 31)
7-7 Carburetor Installation (see page 31)
8 Carburetor (see page 44)
6-3 Crankcase and Crankshaft Disassembly (see page 22)
6-5 Oil seal and Bearing Removal (see page 23)
7-1 Engine Short Block Assembly (see page 24)
7-17 RHD-Throttle Lever Set
Assembly (see page 42)

-８-
4. T e c h n i c a l D a t a
4-1 Blowers
Item
Unit
Specifications
Remarks
Category
－
Back-pack Engine Blower
Engine Types
－
GZ66N5
GZ76N3
Blower Models
－
EBZ7500
EBZ8500
Cycle
－
Two-stroke
←
Number of Cylinders
－
1
←
Valve Type
－
Piston valve
←
Cylinder Bore
mm
47.5
51
Stroke
mm
37
←
Displacement
cm3
65.6
75.6
Fuel
－
Lubricating blended gasoline
←
Engine lubrication
－
Fuel-oil mixture
←
Engine lubrication Oil
－
Two-stroke engine oil
←
Mixing Ratio
－
Zenoah FC 40:1/ Zenoah FD 50:1
←
Carburetor
Type
－
Diaphragm type rotary throttle valve
←
Models
－
Walbro WYA-236A
Walbro WYA-237A
Starting Method
－
Recoil starter
←
Ignition System
－
Digital controlled (CDI) with
automatic timing advance
←
Digital control misfire for
excessive speed maximum
speed: 8,500 rpm
Ignition Timing BTDC
°/rpm
30.5/ 7,000
←
Spark Plug
Type
－
NGK CMR7H
←
Noise-proof
Gap
mm
0.6 to 0.7
←
Stopping
Method
Type
－
Primary coil short-circuiting
←
Switch
－
Push type
←
Cooling System
－
Forced air cooling
←
Air Cleaner Element Type
－
Primary: Dry puff
Secondary: Dry paper
←
Two stage filters
Output Axle Rotation
Direction
－
Counterclockwise
←
View from output axle
Dimensions
Length
mm
354※
357※
※Throttlearmvertical state
Width
mm
536※
535※
※Throttlearmvertical state
Height
mm
499
540
Body dry weight
with standard pipes
kg
10.6 (9.6)
11.2 (10.2)
( ): Elbow included,
without blower pipes
Fuel Tank Capacity
L
2.1
2.3
Idling Speed
rpm
2,000
←
Idlingspeedstability：±200
Operating Speed
rpm
7,250
←
Wide open throttle stability：
±100
Pipe Nozzle Diameter
mm
72
84
Average air volume at
aimed blowing point
m３/ m
21.8
25.7
ANSI
Maximum air speed at
aimed blowing point
m/s
105.6
92.2
ANSI
Maximum Output
kW/rpm
(PS/rpm)
2.8/ 7,200
(3.8/ 7,200)
3.3/ 7,250
(4.49/ 7,250)
Fuel Consumption
L/h
1.85
2.07
Under actual blower state
Ambient noise at 15 m
from the blower
dB(A)
77
←
ANSI B.175.2-2000
Noise at operator
dB(A)
103.4
103.2
Reference
Sound Power Level
dB(A)
110
←
ISO11094 (EBZ7500/8500)

-９-
4. T e c h n i c a l D a t a
4-2 External Dimensions
Unit：mm
Models
A
B
BB
C
D
EBZ7500
354
536
479
499
1198
EBZ8500
357
535
497
540
1198
Illustration shown is EBZ7500.
☆: Reference.

-１０-
4. T e c h n i c a l D a t a
4-3 Pipes
Unit：mm
Part No.
576 56 47-01
576 56 51-01
576 56 48-01
Name
Flexible Hose
Grip Assembly
Swivel Joint
Appearance
Applicable
Inner diam.
d1
Inner diam.
d2
Length
L1
Inner diam. d3
Outer diam.
D4
Outer diam.
D5
Length
L2
EBZ7500
φ99.5
φ99.5
349
φ97.4
φ99
φ103
340
EBZ8500
Part No.
576 56 49-01
576 56 50-01
576 57 64-01
Name
Straight Pipe
Pipe End
Pipe End
Appearance
Air velocity type
Air volume type
Applicable
Inner diam.
d6
Outer diam.
D7
Length
L3
Inner diam.
d8
Inner diam.
d9
Length
L4
Inner diam.
d10
Inner diam.
d11
Length
L5
EBZ7500
φ103
φ103
380
φ103
φ72
350
―
―
―
EBZ8500
―
―
―
φ103
φ84
350

-１１-
5. Special Tools
5-1 Description
Tool Name
Tool Number
Appearance
Usage
Torx Wrench
2850-96410
Size: T20/ T25/ T27
Bolt and screw loosen/ tighten
Socket Key
H502502301
Size: M10
Damper nut loosen/ tighten
Puller Assy.
577 40 97-01
Rotor and coupling removal (see pages 13
and 14)
Gauge
0.3mm
516 88 03-01
(2750-96240)
Ignition coil setting (Air gap)
(see page 15)
Rod Assy.
516 18 29-01
(1101-96220)
Piston pin removal or installation
(see page 16)
Bearing Guide
577 40 98-01
Main bearing installation (see page 16)
Crankshaft
Installing Tool
①582 04 35-01
②582 04 36-01
③01582-01613
Press the crankshaft to the PTO side
crankcase.
Guide also used for press of the oil seals.
(see pages 16, 17 and 18)
①
②①Guide ②Bolt ③Nut
Crankcase
Support
577 41 01-01
When pressing the bearing, oil seal and
crankshaft, support the crankcase (see
pages 16 and 17).
①
②
③

-１２-
5. Special Tools
5-1 Description
Tool Name
Tool Number
Appearance
Usage
Pressure
Vacuum Gauge
H531030623
Engine seal check (see page 19)
Pressure Tester
Attachment
H503844001
Set in the hole of the spark plug, and
connect the pressure gauge
(see page 19).
Outlet Cover
Plate
H502541102
Closure of exhaust port and inlet port
(see page 19)
Compression
Gauge (φ14mm)
Adapter Size:
(φ10mm)
H531031686
583 84 98-01
Compression pressure check
(see page 18)
Piston Fitting Kit
H502507001
Piston installation (see pages 17 and 20)
Fuel Filter Hook
H502508301
Suspending the fuel filter
Fuel Filter
φ10
Adapter
φ10
Stopper
Do not use.
φ10

-１３-
5. Special Tools
5-2 How to use
Item
Procedures
-1)
Rotor
Removal
1. Remove the recoil starter, the engine
cover, the intake hose and the spark plug.
2. Turn the rotor to the clockwise (CW) 90
degrees from the TDC.
NOTE:
The piston TDC is the position where
the "S" mark of the rotor is aligned with
the center of the cylinder.
3. Insert the recoil rope into the cylinder from
the plug hole to stop the movement of the
piston.
4. Remove the mounting nut of the rotor.
NOTE:
Turn the rotor counterclockwise (CCW)
slowly, contact the piston head to the
recoil rope lightly and loosen the nut.
5. Set the puller (special tool) to the rotor.
NOTE:
When attaching the puller bolts, screw
in more than half of the threaded
portion to the rotor.
6. Tighten the center bolt of the puller and
remove the rotor from the crankshaft.
Recoil Rope
“S”Mark
Rotor
Puller Bolts
17 mm Hex
Puller
Rotor
Mounting Nut
(14 mm Hex)

-１４-
5. Special Tools
5-2 How to use
Item
Procedures
-2)
Coupling
Removal
1. Remove the recoil starter, the engine
cover, the intake hose, the fan, the volute
case and the spark plug.
2. Turn the rotor to the counterclockwise
(CCW) 90 degrees from the TDC. Insert
the recoil rope into the cylinder from the
plug hole to stop the movement of the
piston.
3. Remove themounting nut of the coupling.
NOTE:
Turn the coupling counterclockwise
(CCW) slowly, contact the piston head
to the recoil rope lightly and loosen the
nut.
4. Set the puller (special tool) to the coupling.
NOTE:
When attaching the puller bolts, screw
in more than half of the threaded
portion to the coupling.
5. Tighten the center bolt of the puller and
remove the coupling from the crankshaft.
Recoil Rope
Rotor
Coupling
“S”Mark
Mounting Nut
(14 mm Hex)
17 mm Hex
Coupling
Puller Bolts
Puller

-１５-
5. Special Tools
5-2 How to use
Item
Procedures
-3)
Ignition Coil
Installation
(Adjusting
air gap)
1. Apply thread lock to the mounting bolts.
Set the spacers, the ignition coil and the
terminal, and temporarily tighten the
mounting bolts。
Thread Lock: Three Bond #1342/1342H
or equivalent
2. Insert the gauge (special tool) between the
rotor magnet metal and ignition coil.
Tighten the mounting bolts while pushing
the ignition coil against the rotor.
Torque: 2.45～3.92N･m (25～40kgf･cm)
NOTE:
When contacting the iron core of the
ignition coil and part of the rotor
magnet metal, the engine may stop
suddenly. Secure the air gap (03.mm)
using the gauge.
[Resistance]
The resistance values shown above are the reference values for resistance tester
measurement. The resistance value within the normal range shows no internal leakage or
any other defect.
Ignition Checker (Tool No. 3699-90247) We supply the measurement
equipment (Ignition Checker) that can
measure spark energy while the
engine is running. When measuring
the spark energy, discharge gaps are
different depending on the connected
place of the alligator clip.
Refer to the ignition checker
manufacturer’s instruction details.
Rotor
Gauge
(0.3mm)
Ignition Coil
Spacer
0.3mm
0.3mm
プラグキャップ
Mounting Bolts
M4x 22L (T27)
Spacer
High-tension
Cord
Iron Core
Primary
Lead
Resistance (Reference)
Air Gap
Primaryside
(IronCore↔PrimaryTerminal)
SecondarySide
(IronCore↔SecondarySide)
90kΩ± 20％
2kΩ± 10％
0.3mm
Discharge
Window
If connected to the engine.
Discharge gaps: 6mm
If connected to the spark plug.
Discharge gaps: 4mm
Discharge Gap
Adjustment Knob
Plug Cap

-１６-
5. Special Tools
5-2 How to use
Item
Procedures
-4)
Piston Pin
Removal/
Installation
1. Remove the cylinder from the engine short
block.
2. Remove the snap ring on the fan side of
the piston and remove the piston pin from
the piston.
NOTE:
The piston pin can be removed without
using a tool usually. If it is difficult to
remove, use the rod assy. (special tool)
to push out from the piston.
-5）
Press of
Bearing
Illustration
shows the MAG
side. PTO side
similar.
-S: Starter side
1. Set the support (special tool) outside of
the crankcase-S as shown.
2. Tap the bearing with a plastic hammer
lightly and fit it into the crankcase
horizontally.
3. Insert the bearing guide (special tool) to
the bearing and press the bearing into the
crankcase using a press.
-6）
Press of
Starter side
Oil Seal
1. Set the support (special tool) inside of the
crankcase-S as shown.
2. Press the guide (special tool) against the
oil seal and press the oil seal into the
crankcase-S with a press.
Guide
(①of Crankshaft
installing tool)
Oil Seal
Bearing
Support
Rod Assy.
Piston
Piston Pin
Snap Ring
Bearing Guide
Crankcase-S
Crankcase-S
Support

-１７-
5. Special Tools
5-2 How to use
Item
Procedures
-7)
Press of
Crankshaft
-F: Fan side
-S: Starter side
In the case of the crankshaft reuse, the fit
between the crankshaft and the crankcase-F
side of the bearing may be slightly tight.
1. Insert the crankshaft until halfway into the
crankcase-F.
2. Insert the guide of the crankshaft installing
tool (special tool) into the crankshaft, and
contact the tip of it to the inner race of the
bearing. Screw the bolt to the crankshaft
and fix it with the nut as shown.
3. Fix the connecting rod with the plate of
piston fitting kit (special tool) so that the
crankshaft does not turn.
4. Fix the bolt and insert the crankshaft into
the bearing while screwing the nut.
NOTE:
After press, rotate the crankshaft to
check the operation of the bearing.
If the movement of the bearing is
heavy, tap the bolt head with a plastic
hammer to release the pressure on the
bearing.
5. Set the support (special tool) outside of
the crankcase-S as shown.
6. Set the crankcase gasket and temporarily
install the mounting bolts.
7. Set the guide of the crankshaft installing
tool (special tool) on the crankcase-F and
press the crankshaft into the crankcase-S
with a press.
NOTE:
When inserting the crankshaft, do not
damage the lip of the oil seal on the
crankcase-S side at the edge of the
shaft.
Crankshaft
Plate
Guide
Nut
Tighten.
Bolt
Fix.
Crankcase-F
Guide
Bolt
Crankshaft
Bearing
Nut
Crankcase-F
Crankcase
Gasket
Support
Crankcase-S
Crankcase-F
Press
Guide
(①of Crankshaft
installing tool)

-１８-
5. Special Tools
5-2 How to use
Item
Procedures
-8）
Press of Fan
side Oil Seal
1. Insert the oil seal to the crankcase-F until
it stops with your fingers.
NOTE:
When inserting the oil seal, do not
damage the lip of it at the edge of the
crankshaft.
Insert the oil seal horizontally so as
not to be tilt.
Because there is a groove preventing
coming off on the outside of the oil
seal, its insertion is not easy.
2. Place the guide (special tool) against the
oil seal and tap it with a hammer to press
the oil seal into the crankcase-F.
NOTE:
After press, rotate the crankshaft to
check the operation of the bearing.
-9)
Compression
Pressure
Check
1. Warm-up the engine for at least 5 minutes.
NOTE:
After warm-up, the engine and the
muffler will become hot. Be careful
not to burn yourself.
2. Remove the attachment of the
compression gauge (special tool) and
attach the adapter (φ10mm).
3. Remove the spark plug and set the
compression gauge (special tool) to the
cylinder.
4. Pull the recoil knob quickly and strongly
about 5 times.
More than 8.4 kg/cm2 (872kPa) is fine.
“This value is only an estimate.”
NOTE:
Engine parts is not thermal expansion
in the warm-up the shortage, or
immediately after replacement with
the new part, cannot be to correctly
measure the compression pressure.
Compression
Gauge
(φ14mm)
Adapter (φ10mm)
Oil Seal
Push with a finger.
Crankcase-F
Attachment
Do not use.
Guide
(①of Crankshaft
installing tool)