Table of Contents
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S4810-0006
R
Workshop Manual
STRATO CHARGED ENGINE
GZ25N
Applicable Model Name:
1. Brushcutters BCZ2500S/BCZ2500SU
2. Long Reach Trimmer LRTZ2500
3. Short Reach Trimmer SRTZ2500
4. Pole Saw PSZ2500
5. Reciprocator SGCZ2500S
6. Sweeper RMSZ2500
7. Hand Held Edger HEZ2500S
8. Split Boom Trimmer : EXZ2500S
July 2000
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Table of Contents
Summary of Contents for RedMax GZ25N
- Page 1 S4810-0006 Workshop Manual STRATO CHARGED ENGINE GZ25N Applicable Model Name: 1. Brushcutters BCZ2500S/BCZ2500SU 2. Long Reach Trimmer LRTZ2500 3. Short Reach Trimmer SRTZ2500 4. Pole Saw PSZ2500 5. Reciprocator SGCZ2500S 6. Sweeper RMSZ2500 7. Hand Held Edger HEZ2500S 8. Split Boom Trimmer : EXZ2500S...
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Page 2: Table Of Contents
CONTENTS BRUSHCUTTERS BCZ2500S/BCZ2500SU 1. OUTLINE OF STRATO-CHARGED ENGINE ......... 2 Special Features ..........................2 Principle of Operation ......................... 3 Construction (Developed Drawing) ..................... 4 2. SPECIFICATIONS AND TECHNICAL DATA ........5 3. OUTLINE DRAWING ..............6 4. MAINTENANCE SPECIFICATIONS ..........7 Engine Block ............................ -
Page 3: Outline Of Strato-Charged Engine
1. OUTLINE OF STRATO-CHARGED ENGINE STRATO CHARGED ENGINE GZ25N 1-1 Special Features Unlike the conventional 2-stroke engine scavenging system, the Strato-charged Engine scavenges burnt gas by the stratified lead air scavenging method. By creating a stratified air layer between burnt gas and the air-fuel mixture, this system significantly reduces exhaust of unburned air-fuel mixture. -
Page 4: Principle Of Operation
1. OUTLINE OF STRATO-CHARGED ENGINE STRATO CHARGED ENGINE GZ25N 1-2 Principle of Operation Major difference of the Strato-charged Engine to the conventional 2-stroke engine is that as illustrated on the following drawing, there are lead air intake tubes which are connected to the scavenging port via reed valves. -
Page 5: Construction (Developed Drawing)
1. OUTLINE OF STRATO-CHARGED ENGINE STRATO CHARGED ENGINE GZ25N 1-3 Construction (Developed Drawing) Parts in the frames are exclusively designed for the Strato-charged Engine. • Reciprocator SGCZ2500S Spark Plug Reed Valve Cylinder Lead Air Intake Tube Carburetor Reed Valve Insulator Lead Air Intake Tube •... -
Page 6: Specifications And Technical Data
Effective Compression Ratio Fuel Mixture of 87 octane or above unleaded Use JASO FC gasoline and RedMax 2-cycle engine oil or ISO EDG (ratio 50 :1) or quality oil for air cooled grade 2-cycle 2-cycle engines (ratio 32:1). engine oil. -
Page 7: Outline Drawing
3. OUTLINE DRAWING STRATO CHARGED ENGINE GZ25N Engine Cover Carburetor Muffler Air Cleane Fuel Cap Fuel Tank Tank Guard 122 ( 4.80 ) 223 ( 8.78 ) Plug Cap Fan Cover Recoil Starter Fan Cover 7.85 168 ( 6.61 ) ( 0.31 ) -
Page 8: Maintenance Specifications
4. MAINTENANCE SPECIFICATIONS STRATO CHARGED ENGINE GZ25N 4-1 Engine Block Measuring Limit Standard Remarks Maintenance Item Instrument Cylinder Compression Compression 8.7(124) 5.5(78) kg/cm (psi) Gauge Bore Peel off of plating or Cylinder ø34(1.339) mm(in.) expose of base met Gauge Piston Piston dia. -
Page 9: Carburetor
4. MAINTENANCE SPECIFICATIONS STRATO CHARGED ENGINE GZ25N 4-2 Carburetor Measuring Limit Standards Remarks Maintenance Item instrument Carburetor WYA-1B ±0.16 (±0.006) Metering Lever set. mm.(in.) 1.5 (0.059) Vanier ±0.5 (±7.1) Inlet valve opening pressure. kg/cm (p.s.i) 1.5 (21.3) Leak Tester ±0.5 (±7.1) Inlet valve reseating pressure. -
Page 10: Special Tools
5. SPECIAL TOOLS STRATO CHARGED ENGINE GZ25N Part name Part No. External appearance Usage Puller Assy 2890-96100 To remove rotor. To hold crankshaft when disassembling / Piston Stopper 4810-96220 assembling clutch and rotor. To remove / install piston Rod Assy 1101-96220 pin. -
Page 11: Service Guide
6. SERVICE GUIDE STRATO CHARGED ENGINE GZ25N 6-1 GENERAL PRECAUTIONS Before beginning repair work Precautions before disassembly Assembly precautions Note: Note:... -
Page 12: Removing Of Clunch Shoe
6. SERVICE GUIDE STRATO CHARGED ENGINE GZ25N 6-2 Removing of Clunch Shoe 6-3 Mounting of Clutch Shoe Caution: Care for orientation of the wave washers and clutch shoe. 6-4 Removing of Rotor... -
Page 13: Removing Recoil Pulley
6. SERVICE GUIDE STRATO CHARGED ENGINE GZ25N 6-5 Removing Recoil Pulley Note: Pulley screw is right turn screw. 6-6 Assembling of lgnition Coil 6-7 Installing of Spark Plug Important: Fixing the spark plug using other tools than the custom plug wrench may apply over torque and end... -
Page 14: Laying Of Switch Cable
6. SERVICE GUIDE STRATO CHARGED ENGINE GZ25N 6-8 Laying of Switch Cable 6-9 Fitting of Plug Cap Caution: Check that the plug cap is not deteriorated, stiffened, nor has cracks. Also check that there is no play after fitting the cap. -
Page 15: Installing Of Piston
6. SERVICE GUIDE STRATO CHARGED ENGINE GZ25N 6-11 Installing of Piston 6-12 Assembling of Piston Pin Circlip Caution: Deformed circlip may come off during engine operation and damage the engine. 6-13 Direction of Setting Cylinder Gasket Caution: An oppositely set gasket will touch with the insulator, and makes a gap between the muffler. -
Page 16: Positioning Of Lead Air Intake Tube
6. SERVICE GUIDE STRATO CHARGED ENGINE GZ25N 6-14 Positioning of Lead Air Intake Tube Caution: Oppositely assembled tubes will cause a sealing failure. Before assembling the tubes, check for deterioration or cracks and change with new ones if necessary. 6-15 Assembling of Cylinder Plate... -
Page 17: Mounting Of Reed Valve
6. SERVICE GUIDE STRATO CHARGED ENGINE GZ25N 6-17 Mounting of Reed Valve Important: Check the gap between the valve case and the reed valve. Replace with new valve if the gap is larger than 0.2mm (0.008in.), or the valve is distorted. -
Page 18: Assembling Cluch Drum
6. SERVICE GUIDE STRATO CHARGED ENGINE GZ25N 2) Removing Clutch Drum Hammer Drum Remover Clutch Drum 6-19 Assembling Cluch Drum 1) Assembling Snap Ring Tap the stopper by hand and engage the snap ring into the drum groove. Snap Ring... -
Page 19: Carburetor
7. CARBURETOR STRATO CHARGED ENGINE GZ25N STRATO CHARGED ENGINE GZ25N 7-1 Construction The Strato-charged Engine is applied with a custom designed carburetor employing diaphragm rotary valves and 2 venturies, one for the lead air and the other for the air-fuel mixture. -
Page 20: Specifications
7. CARBURETOR STRATO CHARGED ENGINE GZ25N 7-3 Specifications Item Unit Specifications Product Name Engine Type GZ25N Carburetor Type Name WYA-1B Part Number 4810-81001 Carburetor Specification Main Jet #38.5 1.5 ±0.16 (0.059 ±0.006) Metering Lever Height mm (in.) Venturi Bore mm (in.) MIX 9.0 (0.354) AIR 8.0 (0.315) -
Page 21: Composition And Inspection
7. CARBURETOR STRATO CHARGED ENGINE GZ25N 7-4 Composition and Inspection a) Adjusting Idle Speed Screw Bracket Adjustment Washer Screw Adjustment Screw Throttle Valve Carburetor Body O-ring Main Jet( 38.5) Pump Diaphragm Screen Body b) Judgement of the main check valve... -
Page 22: Trouble Shooting
8. TROUBLE SHOOTING STRATO CHARGED ENGINE GZ25N 8-1 Engine does not start Description Cause Countermeasure No spark in the spark plug Spark Plug 1.Wet spark plug electrodes Make them dry 2.Carbon deposited on the electrodes Cleaning 3.Insulation failure by insulator damage Exchange 4.Inproper spark gap... -
Page 23: Engine Cannot Be Stopped
8. TROUBLE SHOOTING STRATO CHARGED ENGINE GZ25N 8-3 Engine cannot be stopped Description Cause Countermeasure Overheating 1.Lean fuel Adjust carburetor 2.Cylinder fin clogged with dusts Cleaning 3.Inproper fuel Change with proper fuel 4.Carbon deposited inside of combustion Cleaning chamber 5.Spark plug electrode red hot... - Page 24 STRATO CHARGED ENGINE GZ25N...
- Page 25 KOMATSU ZENOAH AMERICA INC. 4344 Shackleford Road, Suite 500 Norcross, Georgia, 30093...