Zenoah EBZ7500 Workshop Manual
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Zenoah EBZ7500 Workshop Manual

Engine blower
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EBZ7500/ 8500
Workshop Manual
[2017]

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  • Page 1 EBZ7500/ 8500 Workshop Manual [2017]...
  • Page 2 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.

  • Page 3: Table Of Contents

    Contents 1. Features of Engine Blower 8. Carburetor 1-1 Fan and Volute Case ······························· 2 8-1 Technical Data······································ 44 1-2 Pipes ··················································· 3 8-2 Description ·········································· 45 1-3 Air Cleaner ············································ 4 8-3 Inspection ··········································· 46 1-4 Measures Against Static Electricity ············· 4 8-4 Adjustment ··········································...

  • Page 4: Features Of Engine Blower

    1 . Fe at u r e s o f E n g i n e B l ow e r 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.

  • Page 5: Pipes

    The maximum air volume in this class is acquired. Outlet inner diameter φ84mm EBZ7500/ 8500 The new spiral type flexible hose has no sharp on its surface contrary to the conventional flexible hose. It Conventional flexible hose is hard to split and has excellent durability.

  • Page 6: Air Cleaner

    1 . Fe at u r e s o f E n g i n e B l ow e r 1-3 Air Cleaner EBZ7500/ 8500 It is equipped with a large capacity cleaner with Air Cleaner Cover double structure of pre-filter and paper filter. The...

  • Page 7: Strato-Charged 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.

  • Page 8: Operating Principle

    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. Lead Air Air-fuel Mixture 2.

  • Page 9: Constructions - Exploded View

    3. Constructions - Exploded View 7-15 Elbow Installation (see page 36) 7-7 Carburetor Installation (see page 31) 7-3 Muffler Installation (see page 29) 7-8 Fan Installation (see page 32) 8 Carburetor (see page 44) 7-10 Engine Cover Installation (see page 33) 7-5 Ignition Coil Installation (see page 30) 7-6 Coupling Installation (see page 31)

  • Page 10: Technical Data

    － ← Engine lubrication Fuel-oil mixture ← － Engine lubrication Oil Two-stroke engine oil － ← Mixing Ratio Zenoah FC 40:1/ Zenoah FD 50:1 ← － Type Diaphragm type rotary throttle valve Carburetor － Models Walbro WYA-236A Walbro WYA-237A ←...

  • Page 11: External Dimensions

    4 . T e c h n i c a l D a t a 4-2 External Dimensions Unit：mm Models EBZ7500 1198 EBZ8500 1198 Illustration shown is EBZ7500. ☆: Reference. -９-...

  • Page 12: Pipe And Nozzles

    Grip Assembly Swivel Joint Appearance Inner diam. Inner diam. Length Length Outer diam. Outer diam. Applicable Inner diam. EBZ7500 φ 99.5 φ 99.5 φ 97.4 φ 99 φ 103 EBZ8500 Part No. 576 56 49-01 576 56 50-01 576 57 64-01...

  • Page 13: Special Tools

    5. Special Tools 5-1 Description Tool Name Tool Number Appearance Usage Size: T20/ T25/ T27 2850-96410 Torx Wrench Bolt and screw loosen/ tighten Size: M10 H502502301 Socket Key Damper nut loosen/ tighten Rotor and coupling removal (see pages 13 577 40 97-01 Puller Assy.
  • Page 14 5. Special Tools 5-1 Description Tool Name Tool Number Appearance Usage Pressure H531030623 Engine seal check (see page 19) Vacuum Gauge Set in the hole of the spark plug, and Pressure Tester H503844001 connect the pressure gauge Attachment (see page 19). φ10 Outlet Cover Closure of exhaust port and inlet port...

  • Page 15: How To Use

    5. Special Tools 5-2 How to use Item Procedures 1. Remove the recoil starter, the engine Rotor Recoil Rope cover, the intake hose and the spark plug. Removal 2. Turn the rotor to the clockwise (CW) 90 degrees from the TDC. NOTE: The piston TDC is the position where the "S"...
  • Page 16 5. Special Tools 5-2 How to use Item Procedures 1. Remove the recoil starter, the engine Coupling cover, the intake hose, the fan, the volute Recoil Rope case and the spark plug. Removal 2. Turn the rotor to the counterclockwise (CCW) 90 degrees from the TDC.
  • Page 17 5. Special Tools 5-2 How to use Procedures Item 1. Apply thread lock to the mounting bolts. Set the spacers, the ignition coil and the Ignition Coil Mounting Bolts terminal, and temporarily tighten the M4x 22L (T27) Installation Rotor mounting bolts。 (Adjusting air gap) Thread Lock: Three Bond #1342/1342H...
  • Page 18 5. Special Tools 5-2 How to use Item Procedures 1. Remove the cylinder from the engine short Piston Pin block. Rod Assy. Piston Removal/ 2. Remove the snap ring on the fan side of Installation the piston and remove the piston pin from Piston Pin the piston.
  • Page 19 5. Special Tools 5-2 How to use Item Procedures In the case of the crankshaft reuse, the fit between the crankshaft and the crankcase-F Crankshaft Press of Plate side of the bearing may be slightly tight. Crankshaft 1. Insert the crankshaft until halfway into the -F: Fan side crankcase-F.
  • Page 20 5. Special Tools 5-2 How to use Item Procedures -8） 1. Insert the oil seal to the crankcase-F until Oil Seal it stops with your fingers. Push with a finger. Press of Fan side Oil Seal NOTE:  When inserting the oil seal, do not damage the lip of it at the edge of the crankshaft.
  • Page 21 5. Special Tools 5-2 How to use Item Procedures -10) 1. Remove the muffler and the gasket. Engine Seal Pressure Tester Attachment 2. Temporarily install the muffler and insert Check Muffler the outlet cover plate (special tool) diagonally between the muffler and the Gasket exhaust port of the cylinder.
  • Page 22 5. Special Tools 5-2 How to use Item Procedures -10) 6. Connect the pressure vacuum gauge Engine Seal (special tool) to the pressure tester attachment of the cylinder. Check Pressure Vacuum Gauge 7. Adjust the "Pressure Mode" press to 80 kPa. After 30 seconds, if the seal stays at 60 kPa, the sealing should be fine Pressure...

  • Page 23: Notice Of Teardown

    6. Notice of Teardown 6-1 Guard Net Removal The guard net is mounted by four clips. The removal procedure is shown below. Guard Net 1. Loosen the resin screw of the clip and remove it completely. NOTE: When loosening the resin screw, securely fit Frame the Phillips screwdriver into the (+) of the screw head.

  • Page 24: Crankcase And Crankshaft Disassembly

    6. Notice of Teardown 6-3 Crankcase and Crankshaft Disassembly 1. Remove the mounting bolts, twist the flat-tip screwdriver at the two notches of the crankcase, Crankcase-S then separate the crankcase-S and the Notch crankcase-F. If necessary, gently tap with a plastic hammer to the crankcase-F.

  • Page 25: Oil Seal And Rearing Removal

    6. Notice of Teardown 6-3 Crankcase and Crankshaft Disassembly 3. Use the press to remove the crankshaft from the crankcase-F. Press Crankcase-F NOTE: Do not remove the crankshaft by tapping with Crankshaft an iron hammer because it may cause the rotation of the crankshaft will be off-balance or the thread may be damaged.

  • Page 26: Notice Of Reassembly

    7. Notice of Reassembly 7-1 Engine Short Block Assembly 1) Lubricating and Degreasing  Apply two-stroke engine oil to the inner surface of the main bearings, needle bearing, between the crank weight and the connecting rod large end.  Apply two-stroke engine oil to the inner surface of the cylinder and the outer periphery of the piston excluding the piston head.
  • Page 27 7. Notice of Reassembly 7-1 Engine Short Block Assembly 2) Main Bearing and Oil Seal  Press the bearing using the bearing guide of Bearing Guide the special tool (see page 16). Bearing  Press the oil seal using the guide of the crankshaft installing tool (special tool) (see page 16).
  • Page 28 7. Notice of Reassembly 7-1 Engine Short Block Assembly 4) Crankcase Gasket Crankcase Gasket NOTE: Cut off. Be sure to use the new parts of the crankcase gasket. Crankcase  Cut off the crankcase gasket ends exceeding the cylinder mating surface. ...
  • Page 29 7. Notice of Reassembly 7-1 Engine Short Block Assembly 7) Cylinder Gasket When setting the cylinder gasket, make the arrow mark to the fan side. Arrow Mark Cylinder Gasket 8) Scavenging Port Cover Do not remove the scavenging port cover as much as possible.

  • Page 30: Handling Of The Bolt With A Thread Lock

    7-2 Handling of the bolt with a thread lock As for EBZ7500/ 8500, a thread lock is applied to the ignition coil, the recoil starter, the insulator mounting bolts, and the upper damper mounting screws. When handling the mounting bolts or screws, pay attention to the following items.

  • Page 31: Muffler Installation

    7. Notice of Reassembly 7-3 Muffler Installation  Check the muffler for deformation and cracks. If necessary, replace it with a new one. Gasket  Remove the carbon deposits that have Muffler accumulated in the muffler with a screwdriver. NOTE: Bolts (2) Do not burn the carbon deposits in the muffler M6x 30L (T27)

  • Page 32: Ignition Coil Installation

    7. Notice of Reassembly 7-5 Ignition Coil Installation 1. Apply thread lock to the mounting bolts. Set the spacers, the ignition coil and the terminal, and temporarily tighten the mounting Bolts (2) bolts. M4x 22L (T27) Terminal Thread Lock: Three Bond #1342/ 1342H or LOCTITE #242 or equivalent Ignition Coil Spacers...

  • Page 33: Coupling Installation

    7. Notice of Reassembly 7-6 Coupling Installation 1. Turn the rotor to the clockwise (CW) 90 degrees Coupling Parallel. from the TDC. Insert the recoil rope into the 。 cylinder from the plug hole to stop the movement of the piston (see page 13). 2.

  • Page 34: Fan Installation

    7. Notice of Reassembly 7-8 Fan Installation 1. Install the engine short block to the volute vase. Bolts (4) Engine Short Block Torque: 5.88～7.84N･m (60～80kgf･cm) M6x 50L (T27) Volute Case Align the holes of the coupling and the fan. Tighten the mounting bolts and attach the fan to the coupling.

  • Page 35: Engine Cover Installation

    7. Notice of Reassembly 7-10 Engine Cover Installation Fit the engine cover to the volute case, and fix it with the mounting screws. Screws (5) TP5x 25L (T27) Torque: 2.94～3.92N･m (30～40kgf･cm) NOTE: If the mounting screws are tightened tightly, threads of the volute case may be damaged. Engine Cover Muffler NOTE:...

  • Page 36: Frame Installation

    7. Notice of Reassembly 7-12 Frame Installation 1. Match the convex portions of the upper damper and the convex portions of the volute cover as shown. Set the washer for falling prevention and Upper Damper securely attach the upper damper to the volute cover.

  • Page 37: Fuel Pipes Installation

    7. Notice of Reassembly 7-13 Fuel Pipes Installation  When installing the fuel pipes, align the “○”mark of the pipe grommet and the “△” mark of the fuel “○” Mark tank. Pipe Grommet NOTE:  If it is not aligned to the “○” and “△” marks, the fuel pipe may be twisted and the fuel filter may not be in the proper position.

  • Page 38: Switch Cords And Cable Installation

    7. Notice of Reassembly 7-14 Switch Cords and Cable Installation Securely fix the switch cord and the throttle cable Screws (2) TP5x 14L (T27) with the clamps as shown. Torque: 1.96～2.94N･m (25～30kgf･cm) Clamp Clamp Throttle Cable Switch Cord 7-15 Elbow Installation ...

  • Page 39: Recoil Starter Assembly

    7. Notice of Reassembly 7-16 Recoil Starter Assembly 1. Wind up the return spring while winding it inside Return Spring as shown. NOTE: Wind up the return spring so that the outer diameter becomes 65 mm or less. Wind up. 65 mm or less Set the return spring which has been wound to the recoil case.
  • Page 40 7. Notice of Reassembly 7-16 Recoil Starter Assembly 4. Wind the rope to the reel counterclockwise, and Wind up counterclockwise. hang the rope to the notch of the reel. Reel However do not wind up all the rope, leave about 35 to 40cm from the notch of the reel.
  • Page 41 7. Notice of Reassembly 7-16 Recoil Starter Assembly Pass the rope through the knob and the cover Knob Rope and make a knot at the end of the rope. Cover Knot How to knot a rope： Hold this portion. Push the knot of the rope into the cover and insert the cover into the knob.

  • Page 42: Lhd-Throttle Lever Set Assembly

    7. Notice of Reassembly 7-17 LHD-Throttle Lever Set Assembly Cover the engine switch with the cap, pass the Engine Switch switch cords through the arm cover. Arm Cover Place the switch cord connectors on the L shape side of the throttle cable and pass them through Corrugate Tube the corrugate tube.
  • Page 43 7. Notice of Reassembly 7-17 LHD-Throttle Lever Set Assembly Set the throttle lever to the wide open throttle position. Connect the contact plate to the terminal of the switch cords (black) and set it in Switch Cords the throttle arm. Push the contact plate firmly into the guide of the throttle arm.

  • Page 44: Rhd-Throttle Lever Set Assembly

    7. Notice of Reassembly 7-18 RHD-Throttle Lever Set Assembly 1. Make an alignment line at 2.2 mm from the end Left Handle Half Control Lever of the shaft. Shaft 2.2mm Shaft Alignment Line 2. Set the control lever to the left handle half, and install the rubber spring and the washer while inserting the shaft.
  • Page 45 7. Notice of Reassembly 7-18 RHD-Throttle Lever Set Assembly 6. Set the control lever to the wide open throttle position. Hook the end of the spring to the contact plate (black cord side), set it on the Screw TPM3x 6L handle, and attach the retainer with the mounting screw.

  • Page 46: Carburetor

    8. Carburetor 8-1 Technical Data Items Specifications Blower Model EBZ7500 EBZ8500 Model WYA-236A WYA-237A Part Number 581 15 61-01 581 17 70-01 Limiter Cap ○ ○ L-needle ※ 14 - 1/2 (Low Speed Mixture) Basic Adjustment Turns ※ ※ H-needle 1- 3/4±1/2...

  • Page 47: Description

    8. Carburetor 8-2 Description If the carburetor is malfunctioning, adjust the fuel and inspect the damage of the component parts. If engine speed is not stable and has bad acceleration, adjust the mixture needles according to the item “8-4 Adjustment”. L-needle Adjustment of the low and medium engine Limiter Cap...

  • Page 48: Inspection

    8. Carburetor 8-3 Inspection 1) Metering Diaphragm  Check the metering diaphragm for damage and Metering Diaphragm stiffness. If necessary, replace it with a new one.  Check that the convolution height of metering diaphragm does not become flat. When convolution height is flat, replace the metering Convolution Height diaphragm with a new one.
  • Page 49 8. Carburetor 8-3 Inspection 4) Metering Lever and Inlet Valve Metering Lever  Measure the metering lever height using a 1.5±0.16mm depth gauge or scale. Specified standard: 1.5±0.16mm  If the reading is out of the specified standard, repair the metering lever or replace it with a new one.
  • Page 50 8. Carburetor 8-3 Inspection 7) Main Check Valve  Make sure to check the main check valve in Plastic Pipe case fuel is not supplied though the priming tic when operated.  Press the vinyl pipe (inner diameter:φ 5mm) Main Check Valve against the main check valve and blow and suck with mouth.
  • Page 51 8. Carburetor 8-3 Inspection 9) Gaskets When assembling the new metering diaphragm and the new pump diaphragm, be sure to replace the gasket with new parts at the same time. New Gasket Pump Diaphragm New gasket Metering Diaphragm 10) Throttle Valve Throttle Valve Assy.

  • Page 52: Adjustment

    Do not tighten the L-needle more than the Basic Adjustment Turns. Tightening too much may damage the needle spring and L-needle. Models Basic Adjustment Turns WYA-236A (EBZ7500) 14- 1/2 WYA-237A (EBZ8500) ④ Turn the H-needle clockwise (CW) until very H-needle gently seated.
  • Page 53 ② Adjust the engine speed at Peak Idling rpm with the idle adjustment screw. Models Peak Idling (rpm) 2,700±200 WYA-236A (EBZ7500) 2,700±100 WYA-237A (EBZ8500) ② ③ ③ Set the engine speed at 2,000±200 rpm by L-needle turning the L-needle counterclockwise (CCW).
  • Page 54 Accelerate engine to wide open throttle, adjust the engine speed at Maximum Speed rpm by turning the H-needle clockwise (CW). Models aximum Speed (rpm) 7,100±200 WYA-236A (EBZ7500) H-needle 7,250±50 WYA-237A (EBZ8500) NOTE:  If the engine speed is too high, acceleration failure and output will decrease.

  • Page 55: Maintenance Standards/ Tightening Torques

    9. Maintenance Standards/ Tightening Torques 9-1 Standards and Service Ability Limit EBZ7500 EBZ8500 ※1 Maintenance Item Unit Procedure Measuring Standard Limit Standard Limit Cylinder/ Piston kgf/cm² ring Compression pressure （kPa） Replace. Cylinder Expose of base φ 47.5 ※2 φ 51 ※2...

  • Page 56: Tightening Torque

    9. Maintenance Standards/ Tightening Torques 9-2 Tightening Torques Thread size Tightening Torque Tightening Item (mm) N・m (kgｆ・cm) Spark Plug M10S×1.0 9～12 (90～130) Upper: M6×30L 8～12 (80～120) Muffler Lower: M6×16L M4×8L 2～3 (20～30) Diffuser Cylinder M5×22L 6～9 (60～90) M5×8L 3～4 (30～40) Cylinder Plate Crankcase M5×30L...

  • Page 57: Troubleshooting

    10. Troubleshooting 10-1 Engine does not start Remove the spark plug from the cylinder. Put the spark plug on the outside of the cylinder. Pull the recoil starter knob, and check whether sparks occur in the spark gap or not. Trouble Probable Cause Countermeasure...

  • Page 58: Engine Stop During Operation

    10. Troubleshooting 10-2 Engine stop during operation Trouble Probable Cause Countermeasure 1. Switch is OFF ON the switch. 2. Plug cap disconnect Connect properly. 3. Switch cord or high tension cord sheath Replace. worn out Suddenly stopped. 4. Air gap is not proper Adjust to 0.3mm 5.

  • Page 59: Lack Of Output Power Or Unstable

    10. Troubleshooting 10-4 Lack of output power or unstable revolution Trouble Probable Cause Countermeasure 1. Air is entering at fuel pipe joints, Secure connections. 2. Air is entering at crack or pinhole of fuel Replace. pipe. 3. Air is entering at insulator and carburetor Replace gasket and retighten.

  • Page 60: Others

    10. Troubleshooting 10-6 Others Trouble Probable Cause Countermeasure Wash with hot water containing neutral Pre-filter detergent and dry. Poor fuel Clogging of the pre-filter and consumption the paper filter Paper filter Clean with air blow or replace. -５８-...

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