Husqvarna 125C Workshop Manual

Brushcutter, trimmer
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Workshop manual
125C, 125L


Table of Contents

Summary of Contents for Husqvarna 125C

  • Page 1 Workshop manual 125C, 125L English...
  • Page 2: Table Of Contents

    1. Starter ___________________________________ 3 2. Electrical system ___________________________ 9 3. Fuel system ______________________________ 15 4. Centrifugal clutch _________________________ 27 5. Angle gear _______________________________ 33 6. Cylinder, piston, crankshaft, crankcase ________ 37 7. Tools ___________________________________ 47 © Copyright Husqvarna AB, Sweden 2006...
  • Page 3: General Recommendations

    Operator’s Manual. The assembly of other equipment or accessories or spare parts not approved by Husqvarna can result in the failure to meet these safety demands and that the person carrying out assembly bears responsibility for this.
  • Page 4: Starter

    Starter Starter Contents Dismantling ___________________________________ 4 Assembly ____________________________________ 5 Replacing the drive dogs ________________________ 6...
  • Page 5 Starter WARNING! Protective glasses should be worn when working on the starter to avoid injury to the eyes if, for some reason, the return spring should fly out. Dismantling Dismantling Remove the starter from the engine. Remove the 2 screws and lift off the starter.
  • Page 6 Starter Assembly Assembly Clean the component parts and Clean component parts before assemble in the reverse order as set out assembling. for dismantling. Replace the return spring/starter pulley and starter cord, if necessary. NOTE! As a spare part the return spring is supplied rolled up and secured by a plastic band.
  • Page 7 Starter Assemble the starter handle. Assemble the starter handle. Tie a double knot on the starter cord and fold under the free end. Pull the knot fully into the handle. Tension/check the return spring. Tension/check the return spring. Pull out the starter cord completely and slow the starter pulley with your thumb.
  • Page 8 Starter Replace the drive dogs by using a pair of flat nose pliers to push together the shanks (A) and at the same time push the dog out of the drive cup. Assemble in the reverse order as stated for dismantling and make sure that both ends of the drive dog’s return spring are positioned on the same side of the dog i.e.
  • Page 9 Starter...
  • Page 10: Electrical System

    Electrical system Electrical system Contents Checking the ignition spark _________________ 10 Dismantling ______________________________ 12 Assembly _______________________________ 14...
  • Page 11 Electrical system The engine is equipped with an electronic ignition system completely without moving parts. Consequently, a faulty component cannot be repaired, but must be replaced by a new component. The spark in an electronic ignition system has a very short burn time and can therefore be interpreted as weak and can be difficult to see while troubleshooting.
  • Page 12 Electrical system When no spark is obtained, dismantle When there is still no ignition spark, the short-circuit cable from the stop dismantle the short-circuit cable from switch. the stop switch. Still no spark? Remove the connector by prying it up out of the throttle with a knife.
  • Page 13 Electrical system Dismantling Dismantling Dismantle the following: the spark plug, Dismantle the spark plug, starter and starter, air filter cowling, air filter, air filter cowling. contact guard and the heat shield over Lift out the air filter. the muffler. Dismantle the contact guard over the Dismantle the carburettor cover.
  • Page 14 Electrical system Pull out the engine body from the clutch Pull out the engine body from the clutch cover. cover. The ignition system will now be easily accessible for further servicing. Check the air gap. Check the air gap between the ignition module and the flywheel’s magnet.
  • Page 15 Electrical system Now dismantle: Remove the screw in the centre of the crankshaft. The screw in the centre of the Lift off the needle bearing and the crankshaft, the needle bearing, spacer ring, clutch, the large support washer, spacer ring. spacer sleeve and the washer closest Use slip-joint pliers and unscrew the to the flywheel.
  • Page 16: Fuel System

    Fuel system Fuel system Contents Air filter ___________________________________ 16 Tank venting _______________________________ 16 Fuel filter __________________________________ 17 Fuel pump _________________________________ 17 Carburettor ________________________________ 17 Assembly _________________________________ Throttle ___________________________________ 23 Carburettor settings _________________________ 24...
  • Page 17: Air Filter

    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 18: Fuel Filter

    Fuel system Fuel filter Fuel filter The fuel filter can be removed through The fuel hose in the tank contains a fuel the tank’s fill hole. filter. It is accessible through the fill hole. Pull out the filter with your fingers Clean the filter externally if it is not too or with help of tool 502 50 83-01.
  • Page 19 Fuel system Dismantle the carburettor’s distance Remove the insulation placed above piece. the carburettor’s distance piece. Remove the screws (A). Lift off the distance piece (B) and insulation (C). 502 71 27-01 The carburettor’s design The carburettor’s design The carburettor can be divided into The carburettor can be divided into three different functional units: the three different functional units: the...
  • Page 20 Fuel system Dismantling the carburettor Dismantling the carburettor Remove the control diaphragm and Carefully remove the control diaphragm check for damage. (A) and gasket (B). Replace if required. Check the diaphragm for holes and wear on the pin (C). Replace the diaphragm if required. Pressure test the metering unit.
  • Page 21 Fuel system Check the needle valve and the lever Check the needle valve for damage on arm for damage or wear. the tip and in the lever arm groove. Replace damaged components with Check the lever arm for damage to the new ones.
  • Page 22 Fuel system Dismantle the main jet. Press out the main jet with the help of a hammer and suitable punch. Assembling the carburettor Assembling the carburettor Blow the carburettor housing clean. • Blow all channels in the carburettor compartment clean. Fit a new main jet.
  • Page 23: Assembly

    Fuel system Check that the carburettor is sealed. Connect pressure tester 531 03 06-23 to the fuel intake on the carburettor. No leakage is permitted at 50 kPa. Pump up the pressure to 50 kPa. Lower the carburettor in a vessel with petrol in order to discover any leaks more easily.
  • Page 24: Throttle

    Fuel system Fit the carburettor. Slide the fuel hoses on the carburettor nipples. Connect the throttle cable. Slide the carburettor into position on the distance piece. Fit the carburettor cover. Slide the choke to the closed position. Fit the air filter. Position the carburettor cover and tighten both nuts (A).
  • Page 25: Carburettor Settings

    Fuel system Assemble the throttle in the reverse order as set out for dismantling. Pay attention to the following: 1. Check that the short-circuit cables and the throttle cable (E) are inserted in the cable channel. 2. Make sure that the metal sleeve’s collar (F) on the throttle cable is seated in its slot.
  • Page 26 Fuel system Basic setting The carburettor is set to its basic setting when test run at the factory. The basic setting is “richer” than the optimal setting (fast idle speed is 600–800 rpm under the recommended max. speed) and should be kept during the engine’s first working hours.
  • Page 27 Fuel system...
  • Page 28: Centrifugal Clutch

    Centrifugal clutch Centrifugal clutch Contents Dismantling ________________________________ 28 Assembly _________________________________ 31 Replacing the clutch drum’s support bearings _____ 31 Replacing the drive axle ______________________ 32...
  • Page 29: Dismantling

    Centrifugal clutch The centrifugal clutch has the task of transferring the power from the engine to the cutting equipment’s drive axle. As the name implies, it works according to a centrifugal principle. This means the clutch’s friction shoes are thrown outwards towards the clutch drum at a certain engine speed.
  • Page 30 Centrifugal clutch Dismantle the carburettor’s distance Lift off the insulation positioned above piece. the carburettor’s distance piece. Split the connector (A). Remove the screws (B). Lift off the distance piece (C) and the insulation (D). Pull out the engine body from the clutch Pull out the engine body from the clutch cover.
  • Page 31 Centrifugal clutch Now dismantle: Remove the screw in the centre of the crankshaft. The screw in the centre of the crankshaft, the needle bearing, spacer Lift off the needle bearing and the ring, clutch, the large support washer, spacer ring. spacer sleeve and the washer closest Use slip-joint pliers and unscrew the to the flywheel.
  • Page 32: Assembly

    Centrifugal clutch Assembly Assembly Hold the clutch in a vice as illustrated Position the spring in one of the clutch and pry the clutch shoe into position. shoes so that the connection point is in the middle of the spoke on the clutch hub.
  • Page 33: Replacing The Drive Axle

    Centrifugal clutch Replacing the drive axle Replacing the drive axle Pull out the drive axle from the shaft Pull out the drive axle from the shaft with the help of a pair of flat nose pliers with the help of a pair of flat nose pliers for inspection and possible for inspection and possible replacement.
  • Page 34: Angle Gear

    Angle gear Angle gear Contents Dismantling ________________________________ 34 Assembly _________________________________ 35...
  • Page 35 Angle gear The angle gear has two purposes: The first is to gear down the engine’s high speed to better suit the lower speed a saw blade or trimmer requires to work efficiently. Secondly, the angle gear contributes towards the operator’s working stance so that it is comfortable and at the same time efficient.
  • Page 36 Angle gear Dismantle the bearings from the output Dismantle the bearings from the output and input axles. and input axles with the help of a small bearing puller. TIP! Hold the bearing puller in a vice so that it gains a better grip around the bearing.
  • Page 37 Angle gear...
  • Page 38: Cylinder, Piston, Crankshaft, Crankcase

    Cylinder, piston, crankshaft, crankcase Cylinder, piston, crankshaft, crankcase Contents Dismantling ________________________________ 38 Cleaning, inspection _________________________ 39 Analysis and actions _________________________ 40 Service tips ________________________________ 44 Wear tolerances ____________________________ 44 Assembly _________________________________ 45...
  • Page 39: Dismantling

    Cylinder, piston, crankshaft, crankcase 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. Despite these tough working conditions, major piston and cylinder failure is relatively uncommon.
  • Page 40: Cleaning, Inspection

    Cylinder, piston, crankshaft, crankcase Dismantle the piston. Press the gudgeon pin out of the piston with the help of a punch. If the pin is too tight, carefully warm the piston. Cleaning, inspection After dismantling, clean the individual components: 1. Scrape carbon deposits from the top of the piston. 2.
  • Page 41: Analysis And Actions

    For the best results we recommend Husqvarna two-stroke oil or ready-mixed fuel that is specially developed for air-cooled two-stroke engines. 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%).
  • Page 42 Cylinder, piston, crankshaft, crankcase Piston scoring caused by heavy carbon deposits Too heavy carbon depositing can cause damage similar to that caused by insuffi- cient 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 wall.
  • Page 43 Cylinder, piston, crankshaft, crankcase The guide pin for the piston ring has been Deep, irregular grooves caused by a loose Irregular grooves on the piston’s inlet side pushed up through the top of piston. circlip. Shown here on the piston’s inlet caused by a broken roller retainer.
  • Page 44 Cylinder, piston, crankshaft, crankcase Cause: Action: Fit a finer grade filter. • Faulty air filter. Small dust particles pass through the filter. • The filter is worn out due to too Check the filter carefully for holes and damage after cleaning. Replace the much cleaning, whereby small holes have appeared in the material.
  • Page 45: Service Tips

    Cylinder, piston, crankshaft, crankcase Service tips Defect: Action: Broken cooling fins, damaged threads or sheared bolts by In severe cases – replace the cylinder. the exhaust port. Repair the threads using Heli-Coil. Seizure marks in the cylinder bore (especially by the Polish the damaged area using a fine grade emery cloth exhaust port).
  • Page 46: Assembly

    Cylinder, piston, crankshaft, crankcase Assembly Assembly Lubricate the gudgeon pin’s needle Lubricate the gudgeon pin’s needle bearing with a few drops of engine oil. bearing with a few drops of engine oil. Fit the piston so that the piston ring’s Check the play on the connecting rod.
  • Page 47 Cylinder, piston, crankshaft, crankcase Fit the pressure test nipple 503 84 40-01 in Fit the pressure test nipple 503 84 40-01 in the spark plug hole. the spark plug hole. Connect meter 531 03 06-23 and check Connect meter 531 03 06-23 to the for leakage.
  • Page 48: Tools

    List of tools Tools Contents Starter __________________________________ 48 Electrical system __________________________ 48 Fuel system _____________________________ 48 Centrifugal clutch _________________________ 48 Angle gear ______________________________ 49 Cylinder, piston, crankshaft, crankcase ________ 49 Workshop equipment ______________________ 49...
  • Page 49 List of tools 531 03 06-23 502 71 27-01 502 71 13-01 505 38 13-08 503 97 64-01 502 51 34-02 502 50 83-01 504 90 90-01 505 38 13-08 502 50 06-01 502 71 27-01 505 38 13-08 502 71 27-01 503 80 17-01 502 71 27-01 530 03 55-60...
  • Page 50 List of tools 502 51 03-01 502 71 27-01 503 26 70-01 531 03 06-23 502 54 11-02 502 71 14-01 502 50 48-01 505 69 85-70 531 03 06-23 503 84 40-01
  • Page 51 115 02 15-26 2006W17...

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