Workshop manual 340 345 346XP 350 351 353 English
Workshop manual Husqvarna 340/345/346XP/350/351/353 Contents Introduction ........................................................... 2 Safety regulations ................................................. 3 General instructions ........................................... 3 Special instructions ............................................ 3 Special tools .......................................................... 4 Technical data .......................................................
Introduction Arrangement of the manual Troubleshooting This workshop manual can be used in two different ways. These pages describe the most common faults that affect a chainsaw. They are divided into four different groups with the most likely faults described first. • To repair a specific sub-assembly on a chainsaw. • To dismantle and reassemble a complete chainsaw. Repairing a specific sub-assembly If a specific sub-assembly on the chainsaw needs to be repaired: 1.
Safety regulations General instructions Special instructions This workshop manual gives detailed instructions on how to troubleshoot, repair and test a chainsaw. This section also describes the various safety precautions that should be taken when carrying out repairs. The fuel that is used in a chainsaw poses the following hazards: The workshop manual has been written for personnel who are assumed to have general experience of repairing and servicing chainsaws. • May cause breathing difficulties.
Special tools 2 1 4 3 6 5 8 7 10 13 4 – English 9 11 14 12
Special tools 15 16 17 19 18 20 b 20 c Item Description Used for Order no.
Technical data 340: 345: 346XP/G: 350: 350 EPA: 351/G: 353/G: Cylinder bore Ø mm/Ø inches Stroke mm/inches Max power/speed kW/hp/rpm 40,8 / 2,44 45,0 / 2,75 45,0 / 2,75 49,4 / 3,01 51,7 / 3,15 49,4 / 3,01 51,7 / 3,15 40 / 1,57" 42 / 1,65" 42 / 1,65" 44 / 1,73" 45 / 1,77" 44 / 1,73" 45 / 1,77" 32 / 1,28" 32 / 1,28" 32 / 1,28" 32 / 1,28" 32 / 1,28" 32 / 1,28" 32 / 1,28" 2,0 / 2,7 / 9 000 2,2 / 3,0 / 9 000 2,5 / 3,4 / 9 600 2,3 / 3,1 / 9 000 2,3 / 3,1 / 9 000 2,3 / 3,1 / 9 000 2,4 / 3,3 / 9 000 Spark
Technical data rpm 340: 345: 346XP/G: 350: 350 EPA: 351/G: 353/G: Idling speed rpm Engagement speed rpm Max.
Construction and function Carburettor The carburettor consists of three sub-systems: The carburettor works in different ways depending on the setting: • Cold start mode • Idling mode • Part throttle mode • Full throttle mode • The metering unit (A) which contains the jets and the fuel control mechanism. This measures out the right amount of fuel to suit the speed of the saw and the power demand. • The mixing unit (B) consists of the choke, diffuser jets and throttle valve.
Construction and function In part throttle mode the throttle valve (F) is partially open. Fuel is supplied through the diffuser jets (E). In full throttle mode both valves are open and fuel is supplied through all the diffuser jets (E).
Troubleshooting The various faults that can affect a chainsaw 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. Idling (low rpm) (cont.
Troubleshooting High rpm Acceleration and retardation Will not run at Adjust H screw full throttle Blocked air filter Blocked fuel tank vent Blocked fuel filter Fuel line blocked Loose or damaged fuel hose Impulse channel leaking Impulse channel blocked Loose cover on carburettor pump side Faulty pump diaphragm Leaking air intake hose (rubber) Loose carburettor mounting bolts Needle valve set too low Metering system damaged Metering system incorrectly assembled Leaking control diaphragm/cover plate Needle
Repair instructions Chain brake – dismantling 3 1 Disengage the brake by pushing the kickback guard backwards. Unscrew the guide bar bolts and remove the clutch cover, chain and guide bar. 2 Grip the clutch cover carefully in a vice. Release the brake spring by using the kickback guard from the saw as a tool. Engage it with the brake mechanism and turn anticlockwise to activate the brake. WARNING! Make sure the spring does not fly out and cause injury. Wear eye protection.
Repair instructions Chain brake – reassembly 4 1 Bolt the elbow joint to the brake band and tighten to a torque of 1–1.5 Nm. Locate the elbow joint and connected brake band in their recesses in the clutch cover. Lubricate the recess for the spring with grease. 2 WARNING! Make sure the spring does not fly out and cause injury. Wear eye protection. Tension the brake spring by using the kickback guard from the saw as a tool. Engage it with the brake mechanism and turn clockwise to release the brake.
Repair instructions Silencer – removal WARNING! Do not touch the silencer until it has cooled down, otherwise you may burn yourself. 1 Silencer – refitting 1 If the saw is equipped with a spark arrestor mesh this should be fitted first. 2 Refit • cooling plate • gasket • silencer, tighten bolts to a torque of 8–10 Nm. • silencer support • cylinder cover 3 Run the saw for at least 1 minute, then retighten the silencer bolts to 8–10 Nm.
Repair instructions Stop switch – removal Cleaning and inspection 1 Remove the cylinder cover and air filter. 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. 2 Stop switch – resistance measurement Clean the mating surfaces and check the resistance as follows: Disconnect both leads from the stop plate and stop switch. Remove the stop plate by carefully sliding it over the lug on the front mounting.
Repair instructions Stop switch – refitting Choke control – removal 1 1 Remove the cylinder cover, air filter and stop switch. Disconnect the fuel hose from the carburettor. NOTE! Do not use knurled pliers to disconnect or reconnect the fuel hose. This could damage the hose and lead to leakage or fracture. A 2 C Carefully press the new stop switch into place. Check that the switch’s upper mounting clips over the air filter holder.
Repair instructions Choke control – refitting Cleaning and inspection First reattach the choke control to the air filter, then press it onto the carburettor so that the clips engage. • 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. Then refit: • Lubricate the throttle lock with oil. • stop switch • Check that the spring is not broken and has not lost its tension.
Repair instructions Hand grip heater on model 346XPG, 351G, 353G – removal 2 Reconnect the lead and refit the hand grip cover and cylinder cover. No heating or heating only in front hand grip • Switch – troubleshooting • Front hand grip – troubleshooting 1 1 Carefully free the switch and frame from the front hand grip using a screwdriver. 2 Disconnect the leads from the switch and connect a multimeter to it. The meter should read over 1000 ohm when the switch is in the “0” position.
Repair instructions 6 Rear handle heater Measure the resistance between F and Z. It should be 1 ± 0.5 ohm. If not, replace the rear handle heater. Generator Measure the resistance between G and H. It should be between 0.3–1.3 ohm. If not, replace the generator. Carburettor heater Disconnect the lead at X and clean the connectors. Measure the resistance between X and G. The reading should be between 3–10 ohms. If not, disconnect the lead at Y and clean the connectors.
Repair instructions Heater element and rear hand grip – removal Hand grip heater on model 346XPG, 351G, 353G – refitting 1 Remove the cylinder cover, hand grip cover, hand grip and right-hand stop. 1 Feed the leads into the rear hand grip and insert the heater element in the hand grip. Screw in the two bolts through the right side of the hand grip to secure the heater. Then remove: • throttle lock, throttle trigger and recoil spring, see “Throttle trigger”.
Repair instructions Starter assembly – removal Replacing a broken or worn starter cord 1 1 Before replacing a worn starter cord the tension in the recoil spring must be released. Pull the starter cord out through the notch in the pulley rim and wind the pulley anti-clockwise to release the tension in the spring. Undo the four bolts that fasten the starter assembly to the crankcase and lift off the starter assembly. 2 Pull out about 30 cm of the cord and fasten it in the notch in the pulley rim.
Repair instructions Replacing a worn recoil spring WARNING! Make sure the recoil spring does not fly out and cause injury. Wear eye protection. 1 Remove the bolt from the centre of the pulley and lift off the pulley and spring. 2 Remove the broken recoil spring. Cleaning and inspection: • Clean and inspect all parts carefully. If there are any cracks or other defects replace the damaged parts with new ones. Lubricate the return spring with light oil.
Repair instructions Ignition module – testing 2 If there is a fault in the ignition system the ignition module must be tested before the ignition system is removed. If replacing the ignition module, disconnect its leads and unscrew it. The ignition module can be left in place if you are simply removing the flywheel. 3 Test the ignition module as follows: • Connect a test spark plug 502 71 13-01 to the ignition lead and clip the test spark plug onto the cylinder.
Repair instructions Replacing the generator, model 346XP, 351, 353 1 Remove the cylinder cover. Disconnect the HT lead, remove the spark plug and fit piston stop 502 54 1501 in its place. Take off the starter assembly, release the leads from the cable guide and remove it. Remove the cover from the hand grip. 2 4 Remove the fuel hose and throttle pushrod from the carburettor. Unbolt the rear tank mounting from the crankcase, i.e. the rear vibration damping spring, and both stops.
Repair instructions Ignition module and flywheel – refitting 3 1 Place the flywheel on the crankshaft. Turn the flywheel so that the key lines up with the keyway in the shaft. Fit the washer and nut on the shaft and tighten to a torque of 25-30 Nm. Then refit: • cable guide and press the leads into position • HT lead • starter assembly, tighten to a torque of 2.5–3.
Repair instructions Centrifugal clutch – removal Inspection and cleaning 1 Remove the cylinder cover. Disengage the chain brake by pushing the kickback guard backwards. Undo the guide bar bolts and remove the clutch cover, chain and guide bar. • 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.
Repair instructions 2 3 D C B A Fit the clutch onto the crankshaft and tighten anticlockwise as far as it will go. Then tighten to a torque of at least 20 Nm using tool 502 54 16-01 and a suitable socket or combination spanner. 3 Remove the piston stop. Fit the spark plug, tightening it to a torque of 15 Nm, then connect the HT lead. Unbolt and remove the clutch drum (A), RIM chain sprocket (B) if fitted, needle bearing (C) and pump drive wheel (D).
Repair instructions 6 Remove the pin (B) from the adjuster screw, using a small drift to press it out. Oil pump –refitting 346XP, 350, 351, 353 1 C 7 Press in the pump piston (C) so that the adjuster screw (D) can be removed. Remove the pump piston. A Oil pump – removal 340, 345 D 1-4 See ”Oil pump – removal, models 346XP, 350, 351, 353”, points 1-4. Remove the bolts on the anti-vibration elements on the same side. 5 B Lubricate the pump piston (C) with chain oil and fit the pump piston and washers.
Repair instructions Oil pump –refitting 340, 345 5 1 Lubricate the piston pump (C) with chain oil and fit the pump piston. 2 Fit the pump. A round pin secures its position. Fit the chain guard plate, tightening the bolts to a torque of 2–3 Nm. Model 350: Fit the bolts on the anti-vibration elements on the same side. 6 D C B A Push the crankcase up a little from the fuel tank and screw on the filter (A) from underneath. Lubricate the needle bearing with grease.
Repair instructions Adjustable oil pump – adjustment 346XP, 350, 351, 353 2 A Use a screwdriver or adjustable spanner to turn the adjuster screw on the pump. Turning the screw clockwise decreases the oil flow and turning it anticlockwise increases the oil flow. 2 3 1 + – Recommended setting: 13–15" bar Min. setting 15–18" bar Midway setting 18–20" bar Max.
Repair instructions On saws with a carburettor heater 346XPG, 351G, 353G Heating element Carburettor – dismantling Remove the bracket’s two bolts above the carburettor. Disconnect the cable connections to the carburettor heater and remove the heating element. O O Z Z 5 N N G G 5 F The item numbers in the diagram refer to the steps below (1–7). 3 F 3 KV X KV X 1 Remove the cover from the metering unit and carefully remove the metering diaphragm and gasket.
Repair instructions Cleaning and inspection Clean all the carburettor components in petrol. Use an airline to dry off the petrol from all components. Blow through all the channels in the carburettor body and check that they are not blocked. Check that: • The gasket, pump diaphragm and metering diaphragm are undamaged. • There is no play in the throttle and choke valves. • The needle valve and its lever arm are not worn. • The fuel filter is undamaged.
Repair instructions Carburettor – pressure testing Carburettor – refitting Pressure testing should be carried out with the carburettor fully assembled. Testing should always be carried out after the carburettor has been repaired, but can also be performed for troubleshooting before dismantling. Carry out the test as follows: NOTE! Cleanliness is very important when reassembling the carburettor. Tiny particles of dirt can cause operating problems.
Repair instructions 2 5 Connect the leads to the stop switch. Fit the carburettor. Screw in the carburettor bolts directly from behind, without lifting the carburettor assembly. Tighten to a torque of 1–1.5 Nm. It is important to hold the carburettor flange while tightening the bolts to prevent the inlet manifold from moving. Carburettor heater 346XP, 351, 353 – Refitting Heating element 3 Push the rear carburettor mounting into its rubber bushing using a small screwdriver.
Repair instructions Air intake system – removal 4 The air intake system comprises: • inlet manifold • insulating plate with clip • carburettor flange • impulse hose • support ring 1 Remove: • cylinder cover Unscrew the four cylinder bolts. Lift up the cylinder so that the intake system insulating plate is free of the crankcase. • air filter • carburettor • HT lead • starter assembly (340, 345) • Fuel tank (340, 345) 2 On models 340 and 345 there are cylinder bolts on the underside.
Repair instructions Air intake system – refitting 4 1 A B Fit the inlet manifold (A) through the insulating plate in the carburettor flange cut-out (B), and check that the insulating plate’s impulse tube sits correctly in the inlet manifold. Fit the perforated brass support ring in the inlet manifold. 2 Refit the carburettor. Screw in the carburettor bolts directly from behind without lifting the carburettor assembly, tightening to a torque of 1–1.5 Nm.
Repair instructions Carburettor – adjustment For instructions on adjusting the EPA carburettor see appendix A. Adjusting the carburettor involves adjusting the engine to the local conditions e.g. climate, altitude, fuel and type of two-stroke oil. If it is not possible to check the maximum speed with a tachometer then the H jet should not be set to a weaker mixture than the basic factory setting. The recommended maximum speed must not be exceeded.
Repair instructions Fine adjustment of idling speed T Fuel tank – removal • The idling speed is adjusted using the screw marked T. WARNING! The fuel used in chainsaws is harmful if inhaled, may cause skin irritation and is highly flammable. • If adjustment is necessary, screw in the idling screw T until the chain starts to turn. Then screw it out until the chain stops moving.
Repair instructions 5 Cleaning and inspection Carefully check that: • there are no leaks from the fuel tank • there are no leaks from the tank filler cap • the fuel hose is undamaged and free from wear • the fuel filter is not clogged • the tank vent is not blocked or leaking • the vibration damping springs and stops are not damaged Replacing the fuel filter NOTE! Do not use knurled pliers to disconnect or reconnect the fuel hose. This could damage the hose and lead to leakage or fracture.
Repair instructions Tank vent – testing 3 1 Connect pressure gauge 502 50 38-01 to the fuel hose. Pump the pressure up to 50 kPa (0.5 bar). The pressure should drop to 20 kPa (0.2 bar) within 60 seconds. Fit the throttle pushrod in the tank and connect it to the carburettor. Refit the spring. C 2 Use gauge 502 50 37-01 to measure vacuum. Readings should be as follows: the vacuum should increase from 30 to 15 within 30 seconds. If readings are outside this range the vyon plugs must be replaced.
Repair instructions Piston and cylinder – removal 1 Remove: 4 Cover the opening in the crankcase. 5 • cylinder cover • carburettor (see “Carburettor – removal”) • silencer • spark plug • fuel tank (applies to 340, 345) 2 Remove the circlips from the ends of the gudgeon pin and press it out. Then lift off the piston. 6 Unbolt the vibration damping spring from the hand grip. 3 Remove the bearing from the little end of the connecting rod.
Repair instructions 8 When replacing the cylinder 340, 345: Unscrew the decompression valve. (345) Remove the intake system, see “Air intake system – removal”. Model 350 is fitted with a spacer, which is secured using four bolts from the underside. The spacer does not however need to be removed when removing the cylinder. • Measure piston ring wear. This should not exceed 1 mm. Use the piston to push down the piston ring. • The needle roller bearing is undamaged. • The inlet manifold is undamaged.
Repair instructions Piston and cylinder – refitting 346XP, 350, 351, 353 4 1 Press the insulating plate 503 86 62-01 onto the cylinder. Check that the impulse tube connected to the insulating plate is seated correctly in the inlet manifold and lock the clamp over the manifold. Lubricate the little end bearing with two-stroke oil and insert it in the connecting rod. 2 5 Lubricate the piston ring and piston with two-stroke oil. 6 Fit the piston with the arrow pointing towards the exhaust port.
Repair instructions Piston and cylinder – refitting 340, 345 Cylinder – pressure testing 1-5 See Piston and cylinder 346XP, 350, 351, 353 – Refitting points 1-5. 6 Apply silicone adhesive/sealing compound (037062) to the crankcase’s contact surfaces with the cylinder. Carefully slide the cylinder down over the piston towards the big end bearing. Note! Work is facilitated if the crankshaft complete with bearing and piston is released from the crankcase and the piston is pushed into the cylinder.
Repair instructions Crankcase and crankshaft – dismantling 346XP, 351, 353 3 1 Remove the following: • guide bar and chain • clutch cover • cylinder cover • starter assembly* • ignition system* • generator* • centrifugal clutch* • oil pump* • bark rest • chain tensioner Split the crankcase with the aid of tool 502 51 6101 (A) and stop plate 502 54 18-01 (B), working from the flywheel side of the saw.
Repair instructions Crankshaft complete - dismantling 340, 345, 350 1 Remove the following: Crankshaft bearings – replacement 346XP, 351, 353 If the crankshaft bearings are to be replaced, tap them out gently using drift 502 70 84-01. • chain and bar • clutch cover • cylinder cover • starter assembly* • ignition system* • generator • centrifugal clutch* • throttle pushrod The new bearings must be shrunk-fit into the crankcase using a hot air gun.
Repair instructions Cleaning and inspection Clean and inspect all parts carefully. Crankcase and crankshaft – reassembly 346XP, 351, 353 1 Sealing ring – replacement Remove the sealing ring from the crankcase using a small screwdriver. NOTE! Take care to avoid damaging the crankcase. To fit the sealing ring use the sleeve that is supplied with 502 50 30-16. The end with the half moon is used for the sealing ring on the clutch side, which must be fitted flush with the surface of the crankcase.
Repair instructions 4 Crankshaft complete 340, 345, 350 – reassembly Fit and tighten the six crankcase bolts to a torque of 8–10 Nm. Check that the crankshaft rotates freely. 5 Refit the following parts: 1 Fit the crankshaft complete in the crankcase. • chain tensioner 350: Fit and tighten the four bolts holding the spacer from underneath and fit the crankshaft complete in the crankcase.
Repair instructions Repairing damaged threads Guide bar bolts – replacement A repair kit, 503 27 33-01, is available for repairing damaged threads. 1 Drain the oil tank. First drill out the hole using: 6.1 mm drill bit for magnesium crankcase 2 Knock through the old guide bar bolt so that it falls into the oil tank. Then screw in the thread insert using a suitable bolt and spanner. 3 Remove the bolt from the oil tank. 4 Thread insert A damaged thread can be repaired using a thread insert.
Repair instructions Appendix A Basic adjustment for EPA II carburetors 5. Let the engine run at ”B” rpm ~ 1 minute, until warm. After replacing the carburetor or high speed and/or low speed needle on an EPA (The US Environmental Protection Agency) certified product a basic adjustment must be carried out as described below in order to meet the EPA-requirements. This to achieve as low emissions as possible. This instruction is made for USA & Canada only.
114 01 47-26 English – 51 2003W12
