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Husqvarna 343R, 345RX, 343F, 345FX, 345FXT Workshop Manual

Husqvarna 343R, 345RX, 343F, 345FX, 345FXT Workshop Manual

Husqvarna brush cutter workshop manual
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Workshop manual
343R 345RX
343F 345FX 345FXT


Table of Contents

Summary of Contents for Husqvarna 343R, 345RX, 343F, 345FX, 345FXT

  • Page 1 Workshop manual 343R 345RX 343F 345FX 345FXT English...
  • Page 2: Table Of Contents

    Workshop Manual Brushcutter, Trimmer Model 343R, 345RX, 343F, 345FX, 345FXT Contents General recommendations ___________________ 2 1. Starter __________________________________ 3 2. Electrical system _________________________ 7 3. Fuel system _____________________________ 15 4. Centrifugal clutch ________________________ 31 5. Angle gear ______________________________ 37 6. Cylinder and piston ______________________ 41 7.
  • Page 3: General Recommendations

    General recommendations Remember: Never start the engine without the clutch and clutch drum mounted. Do not grasp hot elements such as the muffler or the clutch before they have cooled sufficiently to avoid burn injuries. Avoid getting petrol on you skin or in your mouth. Use protective cream on your hands.
  • Page 4: Starter

    Starter Contents Dismantling _________________________________ 4 Assembly __________________________________ 5 Replacing the drive dogs ______________________ 6...
  • Page 5 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. Starter Dismantling Remove the starter from the engine. 502 50 18-01 Loosen the spring tension. Remove the bolt in the centre of the starter pulley and remove the starter pulley.
  • Page 6 Starter Remove the spring cassette. WARNING! Wear protective glasses. The return spring can fly out and cause personal injury if improperly handled. Assembly Clean requisite parts and assemble in the reverse order as set out for disman- tling. NOTE! Be careful when opening the packaging with the return spring so that the spring does not fly out.
  • Page 7 Starter Tighten the return spring. Check the spring tension. Mount the starter onto the engine. Replacing the drive dogs See chapter 2 Ignition system. Tighten the return spring. Lift up the starter cord when the return spring is completely loose and the cord pulled out completely.
  • Page 8: Electrical System

    Electrical system Contents Checking the ignition spark ____________________ 8 Replacing the spark plug cover ________________ 10 Dismantling ________________________________ 11 Drive dogs _________________________________ 12 Assembly _________________________________ 12 Heated handles _____________________________ 12...
  • Page 9: Checking The Ignition Spark

    The engine is equipped with an electronic ignition system completely without moving parts. Conse- quently, 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 10 Electrical system If no spark occurs, disconnect the stop switch. Replace the switch if necessary The stop switch can be easily detached with a screwdriver. Still no spark? Check the ignition cable’s connection to the spark plug cover. Still no spark? Check other cables and connections.
  • Page 11: Replacing The Spark Plug Cover

    Electrical system Still no spark? Check the air gap. 502 51 34-02 Adjust the air gap. Replacing the spark plug cover 1. Insert the ignition cable through the spark plug cover. 2. Make a hole in the ignition cable for the ignition coil.
  • Page 12: Dismantling

    Electrical system Dismantling Remove the starter, cylinder cover, and spark plug. Attach piston stop no. 502 54 15-01. 502 54 15-01 Remove the nut holding the flywheel. Remove the flywheel. 502 51 94-01 Remove the ignition module and the generator. 502 50 18-01 Dismantling Remove the starter, cylinder cover, and...
  • Page 13: Drive Dogs

    Electrical system Drive dogs Remove the bolts. Remove the hooks and the springs to replace them. Mind the washer (A) so as not to lose it. Replace damaged parts. Assemble in the reverse order. 502 50 18-01 Assembly Check the key groove in the crankshaft and key in the flywheel.
  • Page 14 Electrical system Separate the contacts (A-A) and (B-B). Then extend the cables (A) and (B) with approx. 90 cm long steel wires attached to the contacts. Remove the bolt and pull off the left grip from the handle. Pull one cable at a time from the handle.
  • Page 15 Electrical system...
  • Page 16: Fuel System

    Fuel system Contents Air filter ___________________________________ 16 Tank venting _______________________________ 17 Fuel filter __________________________________ 17 Fuel pump _________________________________ 18 Carburettor ________________________________ 18 Assembly _________________________________ 24 Carburettor settings _________________________ 25 Throttle ___________________________________ 27...
  • Page 17: Air Filter

    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: Tank Venting

    Fuel system Impregnate the filter with air filter oil. 531 00 60-76 Tank venting Check that the tank venting valve works correctly. Replace the fuel cap if the valve is faulty. 531 03 06-23 Fuel filter The fuel filter can be removed through the tank’s fill hole.
  • Page 19: Fuel Pump

    Fuel system Clean the filter externally if it is not too dirty. Replace the filter if required. Fuel pump The fuel pump facilitates cold starts. The pump cannot be repaired and must be replaced if it stops working. Note how the fuel hoses are connected to simplify assembly.
  • Page 20 Fuel system Remove the throttle cable and fuel hose from the carburettor. Remove the carburettor. The carburettor is made by Zama. Design, function and servicing corre- spond with the Walbro carburettor. Default carburettor settings: H = 1 revolution open L = 1 revolution open The carburettor needles are fitted with movement limiters (caps).
  • Page 21 Fuel system The pump unit Pumps fuel from the tank to the carbu- rettor. Dismantling the carburettor Remove the control diaphragm and check for damage. Replace if required. Pressure test the metering unit. 531 03 06-23 The pump unit This is where the pump diaphragm (E) that pumps fuel from the tank to the carburettor’s measuring unit is found.
  • Page 22 Fuel system In the event of leakage – remove the needle valve. Check the needle valve and the lever arm for damage or wear. Replace damaged components with new ones. Remove the pump diaphragm. Check the diaphragm for damage. Remove the fuel screen and clean it or attach a new one.
  • Page 23 Fuel system Dismantle the main jet (A) and the plug (B). Check valves and dampers for wear. Replace if required. Remove the movement limiters from the jet needles using flat nose pliers. Unscrew the jet needles. Do not lose the small washers (A)! Lift off the plastic and rubber guides.
  • Page 24 Fuel system Assembling the carburettor Blow the carburettor housing clean. Fit a new plug. Fit a new main jet. Assembling the carburettor • Blow all channels in the carburettor compartment clean • Mount a new plug. Use a suitable punch to get a completely tight seal.
  • Page 25: Assembly

    Fuel system Attach the various parts of the measur- ing unit in the reverse order as set out for dismantling. Check that the carburettor is sealed. No leakage is permitted at 50 kPa. 531 03 06-23 Attach the control diaphragm and cover.
  • Page 26: Carburettor Settings

    Fuel system Carburettor settings WARNING! When testing the engine in connection with carburettor adjustment, the clutch and clutch cover must be mounted together with the shaft and angle gear under all circumstances Otherwise there is a risk of the clutch becoming loose resulting in serious personal injury.
  • Page 27 When checking the speed on a trimmer no part of the cord should be extended. Use the 502 71 14-01 tachom- eter to check the speed. • Carefully screw in (clock- 502 71 14-01 wise) the L- and H-jets until they bottom.
  • Page 28: Throttle

    Carburettor adjustment 345RX/FX Adjusting the L-needle 1. Mount the Trimmy Fix (4 wires) and use 3.3 mm smooth cord. The cord length should be 160 mm measured from the end of the cord to the cord bushing on the trimmer head. 2.
  • Page 29 Fuel system Remove the bolt (A) and remove the throttle from the handle. Remove bolts (B) and (C). Separate the halves of the throttle. Check for wear on pins (A) and (B). Replace the throttle control (C) and lever arm (D) if necessary. Check that the cables are properly pressed into the cut-outs (E) and that the throttle cable (F) is in the right...
  • Page 30 Fuel system Disassemble the throttle control (A), the lock to prevent accidental throttle operation (B), the start throttle lock (C) and the throttle stop (D) in order to check if replacement is necessary. The stop switch can also be disassem- bled now, and replaced if necessary.
  • Page 32: Centrifugal Clutch

    Centrifugal clutch Contents Dismantling ________________________________ 30 Assembly _________________________________ 32 Clutch drum _______________________________ 32...
  • Page 33 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 out- wards towards the clutch drum at a certain engine speed. When the friction against the drum is sufficiently great it drives the drive shaft at the same speed as the engine.
  • Page 34 Centrifugal clutch Dismantle the clutch from the crank- shaft. 502 54 15-01 Remove the 3 bolts and separate the clutch. Twist apart the clutch. Clean and inspect the different parts with regard to wear or other damage. Replace the spark plug with piston stop no.
  • Page 35 Centrifugal clutch Assembly Temporarily place the clutch shoes on the driving disc and loosely tighten the bolts. Pry out the shoes and hook one spring to each shoe from underneath. Get in the clutch shoes as far as possible and hook the springs to the adjacent clutch shoe.
  • Page 36 Centrifugal clutch Change the bearings in the clutch housing if necessary. 505 38 17-09 Change the bearings in the clutch housing if necessary. Remove the circlip and push out the bearings with a suitable punch and hammer. Dismantling is easier if the clutch housing is heated to about 110°C.
  • Page 38: Angle Gear

    Angle gear Contents Dismantling ________________________________ 36 Assembly _________________________________ 37 Shaft _____________________________________ 38...
  • Page 39 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. Angle gear Second, the angle gear contributes to the saw opera- tor’s working stance so that it is comfortable and at the same time efficient.
  • Page 40 Angle gear Remove the lubricant top-up plug. Warm the gearbox and knock it against a wooden block so that the input axle falls out. Remove the output axle. 502 50 65-01 503 97 64-01 Remove the lubricant top-up plug and warm the entire gearbox using a hot air gun to about 150°C.
  • Page 41 Angle gear Shaft The shaft contains a drive axle guide that is easily replaced. It can be dismantled once the plastic sleeve (B) has been removed. Centre the axle control in the shaft when a new one is fitted. Fit a new O-ring to ensure a good seal. 503 80 17-01 Shaft The shaft contains a long plastic guide...
  • Page 42: Cylinder And Piston

    Cylinder and piston Contents Dismantling ________________________________ 42 Decompression valve ________________________ 43 Inlet manifold ______________________________ 44 Cleaning, inspection _________________________ 44 Assembly _________________________________ 44 Analysis and actions _________________________ 45 Service tips ________________________________ 49 Wear tolerances ____________________________ 50...
  • Page 43: Dismantling

    The cylinder and the piston are two of the compo- nents exposed to most strain in the engine. They must withstand, for example, high speeds, large tempera- ture swings and high pressure. Moreover, they must be resistant to wear. Despite these tough working conditions, major piston and cylinder failure is rela- tively uncommon.
  • Page 44: Decompression Valve

    Cylinder and piston Dismantle the piston. 502 52 42-01 Decompression valve Dismantle the decompression valve. Check that the non-return valve (A) is tight under a vacuum of – 50 kPa. Otherwise replace the valve. NOTE! Turn the valve the right way when fitting.
  • Page 45: Inlet Manifold

    Cylinder and piston Cleaning, inspection After dismantling, clean the individual components: 1. Scrape carbon deposits from the top of the piston. 2. Scrape carbon deposits from the cylinder’s combustion chamber. 3. Scrape carbon deposits from the cylinder’s exhaust port. NOTE! Scrape carefully with not too sharp a tool so as not to damage the soft aluminium parts.
  • Page 46: Analysis And Actions

    Small to medium size scores primarily in the middle of the exhaust port. Cylinder and piston Use a new gasket and fit the cylinder. Make sure that the inlet manifold is correctly connected to the sleeve coupling on the cylinder and that the impulse nipple sits right.
  • Page 47 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 48 Exhaust side damaged by a broken piston ring. The piston ring parts damage the top section and cause score marks. The guide pin for the piston ring has been pushed up through the top of piston. Piston ring guide pin vibrated loose A too high engine speed can cause the ends of the piston ring to hammer against...
  • Page 49 Small score marks and a matt, grey surface on the piston’s inlet side caused by fine dust particles. Inlet side. Particles of dust and dirt from carbon-like deposits on the top of the piston and in the piston ring groove. The piston ring sits firmly in the groove.
  • Page 50: Service Tips

    Extensive damage to the lower part of the piston’s inlet side. Service tips Defect: Broken cooling fins, damaged threads or sheared bolts by the exhaust port. Seizure marks in the cylinder bore (especially by the exhaust port). Surface coating in the cylinder bore worn out (primarily at the top of the cylinder).
  • Page 51: Wear Tolerances

    Wear tolerances Cylinder bore When the surface coating is Max. 1.0 mm with the piston worn and aluminium appears. ring inserted in the lower part of the cylinder. Cylinder and piston Piston ring gap Piston ring groove Max. 1.6 mm. Clean the groove before checking the measure- ment.
  • Page 52: Crankshaft And Crankcase

    Crankshaft and crankcase Contents Dismantling ________________________________ 52 Inspecting the crankshaft _____________________ 54 Assembly _________________________________ 55 Leakage testing the crankcase _________________ 56...
  • Page 53: Dismantling

    Crankshaft and crankcase 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. In addition the connecting rod is exposed to large acceleration and retardation forces as it moves between the top and bottom dead centres.
  • Page 54 Crankshaft and crankcase Separate the crankcase halves. 502 52 39-01 Push out the crankshaft from the crankcase half. Remove the bearing and sealing rings from the crankcase halves. 505 38 17-09 Fit tool 502 52 39-01 to the clutch side of the crankcase as illustrated.
  • Page 55: Inspecting The Crankshaft

    Crankshaft and crankcase Inspecting the crankshaft Inspect the large end of the connecting rod. Inspect the small end of the connecting rod. Check the crank bearing. Inspect the crankshaft bearing and sealing rings. Inspecting the crankshaft The crankshaft cannot be reconditioned but must be replaced if it is worn or damaged.
  • Page 56: Assembly

    Crankshaft and crankcase Check that the there is no play in the fill-out plates around the crank disks (applies to models F Assembly Mount the bearings in the crankcase halves. First fit the crankshaft in the clutch-side crankcase half. 502 50 30-19 Fit a new gasket to the clutch-side crankcase half.
  • Page 57: Leakage Testing The Crankcase

    Crankshaft and crankcase Fit the sealing rings. 505 38 17-09 Assemble the remaining parts in the following order: 1. Cable guide and heat guard on the carburettor side of the crankcase. 2. Protective grating on the underside of the crankcase. 3.
  • Page 58 Bubbles clearly mark the position of the leakage. Husqvarna E-Tech In 1996 Husqvarna presented a new, improved two-stroke engine as a part of the company’s efforts to produce engines that emit smaller amounts of hazardous substances.
  • Page 60: Tools

    Tools Contents Starter __________________________________ 60 Electrical system __________________________ 60 Fuel system _____________________________ 60 Centrifugal clutch _________________________ 60 Angle gear ______________________________ 61 Cylinder and piston ________________________ 61 Crankshaft and crankcase __________________ 61 Workshop equipment ______________________ 61...
  • Page 61 502 50 18-01 502 51 91-01 502 71 13-01 502 51 34-02 502 50 06-01 502 54 15-01 502 51 94-01 502 50 18-01 List of tools 531 00 60-76 502 50 83-01 501 60 02-03 502 50 18-01 505 38 13-08 531 00 48-63 502 21 58-01 531 03 03-98...
  • Page 62 502 50 65-01 502 52 42-01 503 97 64-01 502 50 70-01 503 80 17-01 502 50 18-01 List of tools 502 52 39-01 502 51 03-01 505 38 17-09 531 03 06-23 502 50 30-19 502 71 14-01 502 54 11-02 505 69 85-70 503 84 40-01 503 55 22-01...
  • Page 63 114 01 98-26 2003W24...

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