Husqvarna 120 Workshop Manual
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Husqvarna 120 Workshop Manual

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Workshop Manual
120
125
English

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Summary of Contents for Husqvarna 120

  • Page 1 Workshop Manual English...
  • Page 3 Service data ............14 Safety equipment ..........18 Repair instructions ..........26 Troubleshooting ........... 51 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 Index Carburettor 34 Muffler 19 Adjustment 42 Assembling the muffler 20 Assembly 38 Cleaning and inspection 19 Cleaning and inspection 38 Dismantling the muffler 19 Design 34 Dismantling 36 Function 35 Oil pump and screen 31 Pressure testing 40 Assembling the oil pump and screen 32 Cleaning and inspection 31 Centrifugal clutch 30...
  • Page 5 Index English -...
  • Page 6 Introduction and safety instructions 2 Introduction and safety regulations 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 saw .......................9 2.11 Symbols in the Workshop Manual ..................9 - English...
  • Page 7 Workshop Manual. Usage is made apparent in each section. Some sections include an introductory Descrip- tion of the actual unit in order to increase the basic Always use Husqvarna’s original: understanding. • Spare parts 2.7 Numbering •...
  • Page 8 Introduction and safety instructions 2.8 General Instructions 2.9 Special Instructions The workshop where the chain saw is to be re- The fuel used in the chain saw has the following paired must be equipped with safety equipment in hazardous properties: accordance with local regulations.
  • Page 9 Introduction and safety instructions 2.10 Symbols on the chain saw 2.11 Symbols in the Workshop Manual The symbols below are embedded on the chain saw. This symbol warns of personal injury Choke Lever when the instructions are not followed. Wear protective gloves. Wear protective goggle.
  • Page 10 Displacement Cylinder diamete Stroke length Max. output/speed cm3/cubic inch Ø mm/Ø inch mm/inch kW/hp/rpm 120 model: 35 / 1.38 37.9 / 1.49 31 / 1.22 1.44 / 1.96 / 9 000 125 model: 40 / 1.57 40.5 / 1.59 31 / 1.22 1.52 / 2.07 / 9 000...
  • Page 11 Technical data Engage speed Spark plug Type of oil pump 120 model: 4100 (+/- 250) TORCH CMR7H Automatic 125 model: 4100 (+/- 250) TORCH CMR7H Automatic Volume fuel tank Capacity oil pump Volume oil tank Weight without bar and Litre/US. pint at 9,000 rpm Litre/US.
  • Page 12 Service tools 4 Service tools - English...
  • Page 13 Service tools Pos. Description Used for Order No. Air gap tool, ignition Setting ignition module 502 51 34-02 Piston stop Locking the crank shaft 575 29 36-01 Wrench Clutch out or in 513 63 60-01 Mandrel Dismantling the flywheel 502 51 94-01 Rod assy Piston pin out or in 521 53 35-01...
  • Page 14 Service data 5 Service data 2-3 N.m 8-14 N.m 2x 4-6 N.m 2x 2-3.5 N.m 2x 5-6.5 N.m 2x 19-23.7 N.m 12 m.m 22-23.7 N.m 1-1.5 N.m 2x 1-1.5 N.m 2x The numbers by bolted components represent the tightening torque in Nm. Lubricate with two-stroke oil.
  • Page 15 Service data 5-8 N.m 4x 11-14 N.m 16 mm 7.5-9 N.m 2x 8 mm 3-4 N.m 6x 3-4 N.m x2 3-4 N.m x2 1-2 N.m English -...
  • Page 16 2-4 N.m 2-4 N.m 2x 3.5-5 N.m 2x 1.5-3 N.m 5x 1.5-3 N.m 4x - English...
  • Page 17 3-4 N.m 8 mm 11.8-14.7 N.m 2-3 N.m 13 mm 2-3 N.m 2x 3-5 N.m 5-6.5 N.m 4x 1.5-3 N.m 3x English -...

  • Page 18: Table Of Contents

    Safety equipment 6 Safety equipment Contents Dismantling the chain brake ...................19 Assembling the chain brake ....................20 Dismantling the muffler ....................22 Assembling the muffler ....................23 Replacing the chain catcher ...................23 Dismantling the stop switch ....................23 Assembling the stop switch ....................23 Resistance test - stop function ..................24 Dismantling the throttle lockout, throttle control and spring ..........24 6.10 Assembling the throttle lockout, throttle control and spring ..........25...

  • Page 19: Safety Equipment

    Safety equipment 6 Safety equipment 6.1 Dismantling the chain brake WARNING! Exercise care to ensure the spring does not fly out and cause personal injury. Wear protective goggles. Loosen the bar nuts and remove the clutch cover, Fig 1 guide bar and saw chain. See figure 1. Use a heat gun to loosen the thread lock on the mounting screw.

  • Page 20: Assembling The Chain Brake

    Loosen the screws and remove carefully the covers over the brake spring. See figure 3. Fig 3 Hold one hand over the brake spring and press in a small screwdriver into the spring. Carefully bend upwards until the spring is released and slides onto the screwdriver, see figure 4.
  • Page 21 Compress the spring with a wide screwdriver (or special tool 513 63 70-01) and press it down with your thumb, see figure 7. WARNING! Exercise care to ensure the spring does not fly out and cause personal injury. Wear protective goggles. Fig 7 Fit the two covers using 2 - 3 Nm tightening torque, see figure 8.

  • Page 22: Dismantling The Muffler

    Safety equipment NOTE! After repairing, the chain brake must be in- spected in line with the instructions below. Functional inspection: Do not turn on the engine when carrying out this inspection. Guide bar length Height 12”-18” 45 cm/18" • Hold the chain saw over a stable surface. The distance between the guide bar and the sur- face is shown in the table above.

  • Page 23: Assembling The Muffler

    Safety equipment 6.4 Assembling the muffler Assemble the muffler according to the instructions given in chapter 6.3 in reversed order. Tighten the nuts (B) with a tightening torque of 7.5 - 9 Nm. Warm up the chain saw for at least one minute and retighten the screws on the muffler to 7.5 - 9 Nm.

  • Page 24: Dismantling The Throttle Lockout, Throttle Control And Spring

    Safety equipment 6.8 Resistance test - stop switch Dismantle the stop switch as outlined in “6.6 Dis- mantling the stop switch”. Clean the contact areas. Test the resistance by connecting a multimeter to the stop switch. See figure 16. The resistance should be as follows: ”0”...

  • Page 25: Assembling The Throttle Lockout, Throttle Control And Spring

    Safety equipment Cleaning and inspection • Carefully clean and check all parts. See figure 19. Parts must be replaced if cracked or show signs of other defects. Always use original spare parts. • Check that the spring is intact and retains all its tension.
  • Page 26 Repair Instructions 7 Repair instructions Contents Dismantling the starter ....................27 Replacing a broken or worn starter cord ................28 Tensioning the return spring ...................27 Starter assembly ......................29 Dismantling the ignition module and flywheel ..............30 Assembling the ignition module and flywheel ..............29 Dismantling the centrifugal clutch ...................30 Assembling the centrifugal clutch ...................31 Dismantling the oil pump and screen ................31...

  • Page 27: Dismantling The Starter

    Repair Instructions 7 Repair instructions 7.1 Dismantling the starter WARNING! If the spring tension is activated on the starter pulley, the spring can fly out and cause personal injury. Wear protective glasses. Loosen the three screws, which hold the starter to the crankcase, and remove the starter.

  • Page 28: Replacing A Broken Or Worn Starter Cord

    Repair instructions Make sure the starter pulley is not tensioned. Loosen the screw in the centre of the pulley and remove the sprocket. See figure 4. Cleaning and inspection Clean the parts and check: • The starter cord. • That the starter pawls on the flywheel are intact, i.e.

  • Page 29: Tensioning The Return Spring

    Repair Instructions 7.3 Tensioning the return spring Lift the starter cord into the notch on the starter pulley and turn the pulley about 3 turns clockwise. Check that the pulley can be turned at least a fur- ther 1/2 turn when the starter cord is pulled all the way out.

  • Page 30: Dismantling The Ignition Module And Flywheel

    Repair Instructions 7.5 Dismantling the ignition module and flywheel Remove the cylinder cover. Remove the starter. Snap off the ignition cable from the air guide plate and remove the air guide plate. See figure 9. Fig 9 Knock out a few of the pins in the tool if it does not match up with the flywheel.

  • Page 31: Assembling The Ignition Module And Flywheel

    Repair Instructions 7.6 Assembling the ignition module and flywheel Place the ignition module in position and fit the screws. See figure 13. Do not tighten the screws. Fig 13 Fit the flywheel onto the crankshaft pin. Turn the flywheel until the key fits into the key slot on the shaft.

  • Page 32: Dismantling The Centrifugal Clutch

    Repair Instructions 7.7 Dismantling the centrifugal clutch Remove the cylinder cover. Release the brake by moving the front hand guard backwards. Loosen the bar nuts and remove the clutch cover, saw chain and guide bar. See figure 16. Fig 16 Remove the spark plug hat and the spark plug.

  • Page 33: Assembling The Centrifugal Clutch

    Repair Instructions 7.8 Assembling the centrifugal clutch Use special tool 513 63 65-01 and assemble the clutch according to figure 20. Screw the clutch (counterclockwise) until it stops. Then tighten the clutch using tool 513 63 60-01 and a suitable socket wrench or combination span- ner.

  • Page 34: Assembling The Oil Pump And Screen

    Repair Instructions 7.10 Assembling the oil pump and screen Replace the oil pump, connect oil hoses to the pump and put the pump back in place, tighten the screws. Fit the pump drive wheel and apply thread lock to the screws. Tightening torque 3 - 4 Nm. See figure 22B.

  • Page 35: Assembling The Intake System

    Repair Instructions 7.12 Assembling the intake system Assemble the intake system according to the in- structions given in chapter 7.14 in reversed order. NOTE! It is very important that the intake system is sealed. Otherwise the engine may seize up. English -...

  • Page 36: Carburettor

    Repair Instructions 7.13 Carburettor WARNING! The fuel used in the chain saw has the following hazardous properties: 1. The fluid and its vapour are poisonous. 2. Can cause skin irritation. 3. Is highly inflammable. Description The images for this description do not correspond to the carburettor on the chain saw.
  • Page 37 Repair Instructions Function The carburettor functions differently in the following modes: Cold start mode In cold start mode the choke valve D is completely shut. This increases the vacuum in the carburettor and fuel is easier to suck from all the diffuser jets E, F and G.
  • Page 38 Repair Instructions Dismantling the carburettor Remove the cylinder cover and the air filter. Loosen the threes screws outlined in figure 33. Remove the air filter system. Fig 33 Remove the choke and throttle wire. See figure 34. Detach the fuel hose. Lift the carburettor up and detach the hose under the carburettor.
  • Page 39 Repair Instructions Remove screw (D) and needle valve (E) with lever arm (F), shaft (G) and spring (H). See figure 36. Fig 36 Remove screw (I) and remove gasket (J) and dia- phragm (K). See figure 37. Use a needle or similar device and carefully pull up the fuel screen (L).
  • Page 40 Repair Instructions If necessary, dismantle throttle valve (M) and the High (N) and Low (O) jet screws valve. Remove the shafts with lever arms and springs. See figure 38. Cleaning and inspection Clean all units in clean petrol. Use compressed air to dry the petrol on the com- ponents.
  • Page 41 Repair Instructions Assemble needle valve (E) with lever arm (F), shaft (G) and spring (H), and tighten screw (D). See figure 40. Fig 40 Check using a ruler or the like that the lever is in le- vel with the assembly plane on the cover. If neces- sary, the lever arm can be bent, see figure 41.
  • Page 42 Repair Instructions Pressure testing the carburettor Pressure testing should be carried out with the car- burettor fully assembled. Testing should always be carried out after the carburettor has been repaired, but a test can also be made for troubleshooting before dismantling. Option 1 Carry out the check as follows: Connect pressure tester to the carburettor fuel inlet.
  • Page 43 Repair Instructions Adjustment Basic factory setting 120: 967 06 79-01/967 06 79-02 WARNING! The guide bar, saw chain and H needle 2 + 3/4 turns clutch cover must be fitted before L needle 2 turns the chain saw is started, other-...
  • Page 44 Repair Instructions Basic adjustment for chain saws with ignition system and carburettors without limiters To ensure that the engine components receive adequate lubrication (running in) the carburettor should be set to a somewhat richer fuel mixture for the chain saw's first 3-4 running hours. This is done by adjusting the maximum speed to 600-700 rpm less than the recommended maximum speed.

  • Page 45: Tank Unit

    Repair Instructions 7.14 Tank unit WARNING! The fuel used in the chain saw has the following hazardous properties: 1. The fluid and its vapour are poisonous. 2. Can cause skin irritation. 3. Is highly inflammable. Dismantling Drain the fuel from the tank. Remove the clutch cover, saw chain, guide bar, starter and the cylinder cover.

  • Page 46: Vibration Damping System

    Repair Instructions 7.15 Vibration damping system Dismantling Remove the spring dampers on both sides. See figures 51. Cleaning and inspection • Clean and inspect all parts carefully. If there are any cracks or other defects, replace the damaged parts with new ones. Always use original parts.

  • Page 47: Dismantling The Piston And Cylinder

    Repair Instructions Assembling 1. Fit the return and suction hose on the primer bulb. 2. Snap the primer bulb in place. 3. Fit the cylinder cover. 7.18 Replacing the fuel hose/return hose The fuel hose is moulded and can only be removed from outside of the fuel tank.
  • Page 48 Repair Instructions Remove the circlips and press out the gudgeon pin. Remove the piston. See figure 58. Remove the gudgeon pin bearing (the needle bea- ring) using a pliers. See figure 58. Replace with a new bearing. Fig 58 Cleaning and inspection of the cylinder Clean all components, scrape off all gasket re- mains and soot from the following areas: •...

  • Page 49: Assembling The Piston And Cylinder

    Repair Instructions 7.20 Assembling the piston and cylinder Oil the gudgeon pin bearing with two-stroke oil and insert the crank rod. Se figure 61. Attach the piston with the arrow facing the exhaust port. Slide in the gudgeon pin and fit the circlips. Note! Use new circlips.
  • Page 50 Repair Instructions 7.21 Leakage testing Remove the: • cylinder cover • spark plug Loosen the screws on the airbox and press the rub- ber wedge 502 54 11-02 between the adapter and carburettor. Tighten the screws. Attach the plug 503 84 40-03.
  • Page 51 Troubleshooting 8 Troubleshooting Contents Troubleshooting ......................52 Troubleshooting methods ....................53 - English...
  • Page 52 Troubleshooting 8.1 Troubleshooting The various faults that can affect a chain saw are divided into four groups. In each group the likely symptoms are given on the left and possible causes are listed on the right. The most likely faults are given first, and so on.
  • Page 53 Troubleshooting Acceleration och retardation High rpm Does not Adjust L screw Will not run at Adjust H screw accelerate Adjust H screw full throttle Blocked air filter Blocked air filter Blocked fuel tank vent Blocked fuel tank vent Blocked fuel filter Fuel line blocked Blocked fuel filter Fuel line blocked...
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