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Husqvarna 525BX Workshop Manual
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Husqvarna 525BX Workshop Manual

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Workshop Manual
525BX
English

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Summary of Contents for Husqvarna 525BX

  • Page 1 Workshop Manual 525BX English...
  • Page 3 Service data ............15 Safety equipment ..........18 Repair instructions ..........24 Troubleshooting ............. 63 Husqvarna AB has a policy of continuous product development and therefore reserves the right to modify the design and appearance of products without prior notice. English -...
  • Page 4 Index Piston, dismantling ..........45 Air filter, dismantling and assembling ....32 Piston, assembling ..........54 Carburetor ............33 Safety equipment P18 ........18 Carburetor, dismantling ........35 Service data ............15 Carburetor, assembling ........38 Special tools ............12 Carburetor, settings ..........
  • Page 5 Index English -...
  • Page 6 Introduction and safety instructions 2 Introduction and safety instructions Contents General ...........................7 Safety ..........................7 Target group ........................7 Modifications ........................7 Tools ..........................7 Structure .........................7 Numbering ........................7 General instructions ......................8 Special instructions ......................8 2.10 Symbols on the machine ....................9 2.11 Symbols in the Workshop Manual ..................9 - English...
  • Page 7 2.5 Tools Special tools are required for some stages. All service tools are listed in the Workshop Manual. Usage is made apparent in each section. Always use Husqvarna’s original: • Spare parts • Service tools • Accessories English -...
  • Page 8 Introduction and safety instructions 2.8 General Instructions 2.9 Special Instructions The workshop where the machine is to be repaired The fuel used in the machine has the following must be equipped with safety equipment in accord- hazardous properties: ance with local regulations. •...
  • Page 9 Introduction and safety instructions 2.10 Symbols on the machine 2.11 Symbols in the Workshop Manual The symbols below are embedded on the machine This symbol warns of personal injury Choke control when the instructions are not followed. Use protective gloves. Refuelling Use protective goggles.
  • Page 10 Technical data 3 Technical data Displacement Cylinder diameter Stroke length Max. output/speed cm3/cubic inch Ø mm/Ø inch mm/inch kW/rpm 525BX 25.4/1.55 34/1.34 28/1.10 0.85/7300 Electrode gap Ignition system Air gap Carburettor type mm/inch mm/inch 525BX 0.65/0.026 IKEDA UK-08977-501 0.3/0.012 Ruixing H226A...
  • Page 11 Technical data 3 Technical data Spark plug Volume fuel tank Litre/US. pint 525BX (3000 (+/- 200) idle) NGK BPMR8Y 0.45/0.95 Weight without fuel kg / lbs 525BX 4.3/9.5 English -...
  • Page 12 Engine special tools 4 Engine special tools Contents Special tools ........................13 - English...
  • Page 13 Engine special tools 4.1 Special tools Description Used for Order No. Torx wrench General disassembly / assembly tasks 578 28 90-01 Air gap tool (t 0.4 mm) Adjust the air gap when installing the 514 22 10-01 ignition module Stopper (14 mm use) Fix piston in place when installing/ 514 24 39-01 removing clutch, rotor and starter pulley.
  • Page 14 Engine special tools - English...
  • Page 15 Service data 5 Service data 2~2.5Nm To set the actuating torque of the lever within 0.6~0.82Nm 2~2.5Nm 2~2.5Nm 2 ~ 2.5Nm 1~1.5Nm 3~4.5Nm 3~5Nm 1.8~2.1Nm 2~2.5Nm (4-springs) Note! Lubricate with two-stroke oil. Some of the screws are captive screws Lubricate with Grease and will remian into the cover.
  • Page 16 Service data 6~5Nm 15~22Nm 5~7Nm 6~8Nm 2.5~3.5Nm 2.5~3.5Nm 7~9Nm 2~3Nm - English...
  • Page 17 Service data 14.7~17.6Nm 6~8Nm English -...

  • Page 18: Table Of Contents

    safety equipment 6 Safety equipment Content Dismantling the muffler ....................19 Assembling the muffler ....................19 Dismantling the throttle ....................20 Dismantling the stop switch ....................20 Resistance text - stop switch ..................20 Assembling the stop switch ....................21 Assembling the throttle ....................21 - English...

  • Page 19: Dismantling The Muffler

    Safety equipment 6.1 Dismantling the muffler Remove the cover of the muffler. Dismantle the two screws to the muffler. Also remove the gasket. 6.2 Assembling the muffler Check the muffler; if you find any deformation or cracks, replace the muffler. If the muffler is fitted with a spark arrestor mesh, put it in place first.

  • Page 20: Dismantling The Throttle

    Safety equipment 6.3 Dismantling the throttle Assembly of the throttle is done in the reverse order as set out for dismantling. Unhook the throttle cable from the carburettor and disconnect the cables from the ignition module, see Dismantling the handle frame and vibration system from Volute.

  • Page 21: Assembling The Stop Switch

    Safety equipment 6.6 Assembling the stop switch Put all details in the both handle halves. Make sure that all cables is fitted in the handle and will not be clamped. Make sure the stop switch and cables, throttle trig- ger and cable are properly assembled. Carefully put the handle together.
  • Page 22 Safety equipment Check that the cable is installed in the circle terminal and the ferrite core correctly. The cable shall be installed trough the ferrite core and termi- nal attached on pin. Switch cord to be installed to the each grooves firmly.
  • Page 23 Safety equipment English -...
  • Page 24 Startapparat 7 Repair instructions Content Dismantling the starter housing..................25 Assembling the starter housing..................25 Replacing the starter ratchet on the flywheel ..............27 Checking the ignition spark ....................28 Dismantling the handle frame and vibration system from volute ........30 Adjust the air gap when installing the ignition module............30 Fuel system ........................32 Dismantling and assembling the Air filter ...............32 Tank venting ........................32...

  • Page 25: Repair Instructions

    Repair instructions 7 Repair instructions 7.1 Dismantling the starter housing Loosen the 4 screws and remove the engine cover (A). Then loosen 3 screws on the starter housing and remove it (B). WARNING! Wear protective glasses. The return spring lies tensioned in the starter and can fly out and cause personal injury with careless handling.
  • Page 26 Repair instructions Lubricate the spindle with a little grease and fit the starter pulley. Tighten the screw. Assemble a new starter cord. Slide it into the starter pulley’s slot as illustrated and then out through the cord guide in the starter housing. Make sure the knot on the end of the cord is as small as possible! NOTE!

  • Page 27: Replacing The Starter Ratchet On The Flywheel

    Repair instructions 7.3 Replacing the starter ratchet on the flywheel Remove the screw holdings the starter ratchet. Lift out the starter ratchet and spring for replace- ment. Assemble in the reverse order as set out for dismantling. Torque 3~4Nm English -...

  • Page 28: Checking The Ignition Spark

    Repair instructions 7.4 Checking the ignition spark Dismantle the engine cover after the starter is removed. Earth the spark plug on the cylinder and pull sharply on the start handle. A spark should be seen between the electrodes. If no spark is seen test with test spark plug no. 502 71 13-01.
  • Page 29 Repair instructions Fit the spark plug cap onto the ignition cable and make sure the ends of the wire is inserted into the centre of the spark plug cap for best contact. TIP! Lubricate the ignition cable using for instance silicon spray to make it easier to push the ignition coil in.

  • Page 30: Dismantling The Handle Frame And Vibration System From Volute

    Repair instructions 7.5 Dismantling the handle frame and vibration system from volute Remove the engine cover. Remove the air filter. See Dismantling and assembling the Air filter Disconnect the throttle cable from the lever arm (B) on the carburettor and from the guide in the air filter (A).

  • Page 31: Adjust The Air Gap When Installing The Ignition Module

    Repair instructions 7.6 Adjust the air gap when installing the ignition module Adjust the air gap as needed to the correct value. • Loosen the bolts. • Position the gauge to adjust the gap and press the ignition module against the flywheel. •...

  • Page 32: Fuel System

    Repair instructions 7.7 Fuel system In addition to the fuel tank and carburettor, the fuel system consists of the air filter, fuel filter and tank venting. All these components interact so that the engine receives the optimal mixture of fuel and air to make it as efficient as possible.

  • Page 33: Replacing The Fuel Filter

    Repair instructions 7.10 Replacing the fuel filter The fuel hose in the tank contains a fuel filter. It is accessible through the fill hole. Pull out the filter with your fingers or with help of tool 502 50 83-01. If the filter is not too dirty, its surface can be cleaned with a brush.

  • Page 34: Replacing The Fuel Tank And Fuel Lines

    7.12 Replacing the Fuel tank and Fuel lines Remove the engine cover. Remove the air filter. See Dismantling and assembling the Air filter. Assembly is done in the reverse order as set out for dismantling. Caution: When dismantling and assembling the fuel tank, be careful not to damage the fuel line tubes.

  • Page 35: Replacing The Fan

    7.13 Replacing the Fan Loosen 6 screws on volute cover (A) and 1 captive screw (B) on volute case. Remove the volute cover. Loosen the nut (C) using piston stopper (5142439-01) in clockwise direction. Remove the washer (D), fan (E) and washer (F). There are two washers, one on each side of the fan.

  • Page 36: Carburettor

    Repair instructions 7.14 Carburettor 1. Remove the air filter cover and blow the carbu- rettor compartment clean with compressed air. 2. Disconnect the throttle cable from the lever arm on the carburettor and from the guide in the filter housing. 3.

  • Page 37: Dismantling The Carburettor

    Repair instructions 7.15 Dismantling the carburettor Carefully remove the metering diaphragm (A) and gasket (B). Check the diaphragm for holes and wear on the pin (C). Replace the diaphragm if required. Connect pressure tester 531 03 06-23 to the fuel hose nipple.
  • Page 38 Repair instructions Check the needle valve for damage on the tip and in the lever arm groove. Check the lever arm for damage to the groove for the needle valve and wear on the mounting points towards the control diaphragm. Replace damaged components with new ones.
  • Page 39 Repair instructions Unscrew the jet needles. Make sure they are clean and not damaged on the tip of the needle. NOTE! Note how the jets are positioned. (For example, the H-needle is a little shorter than the L-needle). Press out the main nozzle (H) with a suitable punch.

  • Page 40: Assembling The Carburettor

    Repair instructions 7.16 Assembling the carburettor • Blow all channels in the carburettor compart- ment clean Groove • Mount a new plug (A). Use a suitable punch to get a completely tight seal (B). • Press in a new main nozzle(B). 45°...
  • Page 41 Repair instructions Attach the various parts of the measuring unit in the reverse order as set out for dismantling. The lever arm should lie flush with the carburettor housing. Too high setting = too much fuel. Too low setting = too little fuel. Connect pressure tester 531 03 06-23 to the fuel intake on the carburettor.

  • Page 42: Carburettor Settings

    Repair instructions 5. Connect the throttle cable on the carburettor with the help of flat nose pliers. Check that the cable sits correctly in the arm on the carburetor(C) and that it sits correctly in the filter cover(D). 6. Connect the fuel pipe from the tank. Assemble the remaining parts in the reverse order as set out for disman 7.17 Carburettor settings...
  • Page 43 L = 3 3/8 turns open to 3000 rpm. * New carburettors: • 525BX EMEA APAC (967 28 42-01): produced after serial no SN 20171703003 and from 20171702691 to 20171702890 • 525BX US/CA (967 28 42-02): produced after serial no SN 20172602897 •...

  • Page 44: Dismantling The Flywheel And Ignition Module

    Repair instructions 7.18 Dismantling the flywheel and ignition module Remove the engine cover, starter housing and spark plug. Screw the stopper (special tool A) into the plughole to fix the piston in place.Stopper 14 mm 514 24 39-01. Remove the two screws holding the ignition module and take away the earth cable.
  • Page 45 Repair instructions NOTE! Slowly turn the fly wheel anticlockwise, and after applying the stopper (special tool) lightly to the piston head, loosen the nut. The piston head can be dama- ged if too much force is applied when loosening the nut. Take out the flywheel nut (A).

  • Page 46: Assembling The Flywheel And Ignition Module

    Repair instructions 7.19 Assembling the flywheel and ignition module When setting the key on the crankshaft, make sure the end face of the key is parallel with the crankshaft. Fix the piston in place with the stopper (special tool) and tighten the rotor nut. Torque 10~15 Nm Fig 10 Flywheel...

  • Page 47: Dismantling The Cylinder And Piston

    Repair instructions 7.20 Dismantling the cylinder and pis- The cylinder and the piston are two of the components exposed to most strain in the engine. They must withstand, for example, high speeds, large temperature swings and high pressure. Moreover, they must be resistant to wear.
  • Page 48 Repair instructions Pull the cylinder straight up without turning it. There is a risk that a piston ring may break. Remove the piston pin circlips. Use small needle nose pliers and remove the piston pin circlips. TIP! Keep your thumb over the circlip to prevent it from flying out.

  • Page 49: Cleaning And Inspection

    Repair instructions 7.21 Cleaning and inspection After dismantling, clean the individual components: Scrape carbon deposits from the top of the piston. Scrape carbon deposits from the cylinder’s combustion chamber. Scrape carbon deposits from the cylinder’s exhaust port. NOTE! Scrape carefully off soot deposits using a not too sharp tool so as not to damage the soft aluminium parts.
  • Page 50 Mixing ratio: 1:50 (2%). If Husqvarna two-stroke oil is not available another good quality two-stroke oil can be used. Mixing ratio: 1:33 (3%) or 1:25 (4%). - English...
  • Page 51 Repair instructions Piston scoring caused by heavy carbon deposits Too heavy carbon depositing can cause damage similar to that caused by insufficient lubrication. However, the piston skirt has a darker colour caused by the hot combustion gases that are blown past the piston. This type of piston damage starts at the exhaust port where carbon deposits can become loose and get trapped between the piston and the cylinder...
  • Page 52 Repair instructions Piston ring guide pin vibrated loose A too high engine speed can cause the ends of the piston ring to hammer against the guide pin when the piston ring moves in its groove. The intensive hammering can drive out the pin through the top of the piston causing serious damage also to the cylinder.
  • Page 53 Repair instructions Foreign objects Everything other than clean air and pure fuel that enters the engine’s inlet port causes some type of abnormal wear or damage to the cylinder and piston. This type of increased wear shows on the piston’s inlet side starting at the lower edge of the piston skirt.
  • Page 54 Repair instructions Larger, harder particles that enter the engine cause serious damage to the underside of the piston skirt. Cause: Action: Air filter damaged or Fit a new air filter. missing. Parts from the carbu- Regular service and rettor or intake system inspection.
  • Page 55 Repair instructions Wear tolerances Cylinder bore When the surface coating is worn and aluminium appears Piston ring gap Max. 0.5 mm with the piston ring inserted in the lower part of the cylinder. Piston ring groove Max. 1,1 mm. Clean the groove before checking the measurement.

  • Page 56: Assembling The Piston And Cylinder

    Repair instructions 7.23 Assembling the piston and cylinder Clean the crankcase Lubricate the piston pin’s needle bearing with a few drops of engine oil. Direct the arrow on the top of the piston towards the exhaust port. Press in the piston pin and fit the Snap Ring circlips.

  • Page 57: Dismantling Crankshaft And Crankcase

    Repair instructions 7.24 Dismantling crankshaft and crank- case The task of the crankshaft is to transform the reciprocating motion of the piston to rotation. This requires a stable design withstanding immense pressure and rotational and bending strain, as well as high rotational speed.
  • Page 58 Repair instructions Inspecting the crankshaft The crankshaft cannot be reconditioned but must be replaced if it is worn or damaged. Inspect the large end of the connecting rod. If seizure marks, discolouration on the sides or damaged needle holders are found the crankshaft must be replaced.

  • Page 59: Assembling The Crankshaft And Crankcase

    Repair instructions 7.25 Assembling the crankshaft and crankcase Check the crankshaft as set out in the section ”Inspecting the crankshaft”. Insert the crankshaft into each crankcase halves. To ensure: -not to push the bearings inner when installing new bearing and installing the crankshaft -not to damage the lip of the oil seals with the crankshaft.

  • Page 60: Leakage Testing The Crankcase

    Repair instructions 7.26 Leakage testing the crankcase Remove the cylinder cover, spark plug and guard over the muffler Loosen the screws holding the carburettor suf- ficiently so that the sealing plate no. 502 54 11-02 (A) can be slid down between the carburettor and insulator.
  • Page 61 Repair instructions English -...
  • Page 62 Troubleshooting 8 Troubleshooting Contents Engine does not start ....................63 Engine stops working during operation .................64 Engine has difficulties to stop ..................64 Insufficient output or unstable rotation ................65 The amount of the wind is weak ..................65 - English...

  • Page 63: Troubleshooting

    Troubleshooting 8 Troubleshooting 8.1 Engine does not start Remove the spark plug from the cylinder, and holding the cylinder, pull the starter housing and check whether any sparks appear between the spark plug electrodes. Symptom/Category Cause Action There are no sparks at the spark plug 1.

  • Page 64: Engine Stops Working During Operation

    Troubleshooting 8.2 Engine stops working during operation Symptom/Category Cause Action There are no sparks at the spark plug 1. The switch has been touched, stopping Restart the engine 2. The switch is OFF and not return ON Replace automatically 3. The plug cap has come off Fit it back on fully Engine suddenly 4.

  • Page 65: Insufficient Output Or Unstable Rotation

    Troubleshooting 8.4 Insufficient output or unstable rotation Symptom/Category Cause Action 1. Air has entered through the fuel pipe joint, Insert it securely etc. 2. Air has entered the fuel pipe due to a Replace crack or pin hole 3. Air has entered through the insulator and Replace or tighten the gasket carburetor installation part Compression is...
  • Page 66 Troubleshooting - English...
  • Page 68 2017W53...

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