Workshop Manual Brushcutter, Trimmer Model 555FX, 555FXT, 555RXT, 555FRM 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.
General recommendations Remember: Special tools Never start the engine without the clutch and clutch drum Certain tasks in this handbook require the use of special tools. mounted. In sections where this is applicable, an image of the tool with an ordering number is provided. Do not grasp hot elements such as the mufﬂ...
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 ﬂ y out. Dismantling Dismantling Remove the 4 bolts and lift off the Remove the starter from the engine. starter.
Starter Remove the spring cassette. Remove the two bolts holding the spring cassette and remove the cassette for replacement if necessary. WARNING! Wear protective glasses. The return spring can ﬂ y out and cause personal injury if improperly handled. Assembly Assembly Clean requisite parts and assemble Clean all components before assembly:...
Starter Tighten the return spring. Tighten the return spring. Check the spring tension. Lift up the starter cord when the return spring is completely loose and the cord Check that the reinforcement sleeves in pulled out completely. the starter cover’s securing holes are in position.
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 difﬁ...
Electrical system If no spark occurs even now, remove the short-circuit cable from the stop switch. Remove the screw A and lift off the cover B to make the stop switch accessible. If the plug now sparks, the fault is either in the stop switch or the short-circuit cable.
Electrical system Still no spark? Still no spark? Check the air gap. Dismantle the starter, air guide plate and the guard over the mufﬂ er. Check the air gap between the ﬂ ywheel magnet and the ignition module. The gap should be 0.3 mm. Use a 502 51 34-02 feeler gauge.
Electrical system Dismantling Dismantling Dismantle the starter, air guide plate, Dismantle the starter, air guide plate, cylinder cover, mufﬂ er guard and the cylinder cover, mufﬂ er guard and the spark plug. spark plug. Attach piston stop no. 502 54 15-01. Fit piston stop no.
Electrical system Drive dogs Drive dogs Remove the bolts. The drive dogs can be easily replaced if they are damaged. Remove the hooks and the springs to replace them. Remove the bolts, the hooks and the springs. Mind the washer (A) so as not to lose it. Mind the washer (A) so as not to lose it.
Electrical system Separate the contacts (A-A) and (B-B). Separate the contacts (A-A) and (B-B). Then extend the cables (A) and (B) with Then extend the cables (A) and (B) with approx. 90 cm long steel wires attached approx. 90 cm long steel wires attached to the contacts.
Fuel system In addition to the fuel tank and carburettor, the fuel system consists of the air ﬁ lter, fuel ﬁ lter and tank venting. All these components interact so that the engine receives the optimal mixture of fuel and air to make it as efﬁ cient as possible.
Fuel system The fuel cap can be taken apart for cleaning. Use a screwdriver and pry off the housing (A) that contains a rubber membrane (B) and a ﬁ lter (C). Knock the housing against a table top and the cap (D) that covers the memrane will come off.
Fuel system Carburettor Carburettor Dismantling Dismantling Remove the cylinder cover, air ﬁ lter Remove the cylinder cover, air ﬁ lter cowling, air ﬁ lter and air ﬁ lter holder. cowling, air ﬁ lter and air ﬁ lter holder. Remove both screws (A) and the nuts (B) and lift off the air ﬁ...
Fuel system 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 metering unit, the blending unit, and the metering unit, the blending unit, and the pump unit.
Fuel system Dismantling the carburettor Dismantling the carburettor Remove the control diaphragm and Remove the 4 screws (A) holding the check for damage. control diaphragm cover and lift off the cover. Replace if required. Carefully remove the control diaphragm (B) and gasket (C). Check the diaphragm for holes and wear on the pin (D).
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.
Fuel system Dismantle the main jet (A) and the plug Press out the main jet (A) with a suitable (B). punch. Remove the plug (B). Carefully drill a small hole (Ø 2 mm) in the plug and pry it up with a pointed object.
Fuel system • Mount the valves and dampers. Tip! Any numbers on the valves should be able to be read from the outside. Replace the fuel screen (A) if damaged or if it cannot be cleaned. Place the pump diaphragm (B) closest to the carburettor housing.
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.
Fuel system 3. Connect the fuel hose (C) coming Connect the fuel hose (C) and other from the fuel tank. parts in the reverse order to dismantling. 4. Slide the carburettor in fully against the distance piece and connect the throttle cable.
Fuel system Fine adjustment Fine adjustment of the carburettor should be carried out after the engine has been “run-in”. • The air ﬁ lter should be clean and the cylinder cover ﬁ tted when all adjustments are made. First adjust the L-needle, then the H-needle and ﬁ nally the idling speed’s T-screw. Idling speed = 2,800 rpm.
Fuel system Setting the L jet Setting the H jet 1. Fit the trimmer head T45 and use 2.7 mm plain cord. The 1. Fit the trimmer head T45 and use 2.7 mm plain cord. The cord length should be as standard, i.e. reach the knife on the cord length should be as standard, i.e.
Fuel system 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 groove.
Fuel system Dismantle the throttle handle (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 disassembled now, and replaced if necessary.
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. When the friction against the drum is sufﬁ...
Centrifugal clutch Dismantle the clutch from the Replace the spark plug with piston stop crankshaft. no. 502 54 15-01. Unscrew the clutch from the crankshaft. 502 54 15-01 Fix the clutch in a vice and remove the Remove the 3 bolts and separate the 3 bolts.
Centrifugal clutch Assembly Assembly Temporarily place the clutch shoes on Temporarily place the clutch shoes on the clutch hub and loosely tighten the the clutch hub and loosely tighten the screws. screws. Pry out the shoes and hook one spring Pry out the shoes and hook one spring to each shoe from underneath.
Centrifugal clutch Dismantle the clutch drum using tool Slide the tool (E) into the clutch cover. 501 35 47-01. Assembling the plate (B). The locking pin on the plate must be guided through the hole in the clutch cover and into the hole (F) on the tool.
Centrifugal clutch Assembly Assembly Assemble the bearing in the clutch 1. Heat the clutch housing to approx. housing. 110 °C using a hot air gun. 2. Insert the bearing into position in the clutch housing and ﬁ t the circlip (G). Assemble the clutch drum and the 3.
Angle gear The angle gear has two purposes: The ﬁ rst is to gear down the engine’s high speed to better suit the lower speed a saw blade or trimmer requires to work efﬁ ciently. Second, the angle gear contributes to the saw operator’s working stance so that it is comfortable and at the same time efﬁ...
Angle gear Remove the lubricant top-up plug. Remove the lubricant top-up plug and warm the entire gearbox using a hot air Warm the gearbox and knock it against gun to about 150°C. a wooden block so that the input axle falls out.
Angle gear Shaft Shaft The shaft contains a drive axle guide The shaft contains a long plastic guide that is easily replaced. to prevent vibrations in the drive axle. Centre the axle control in the shaft when The guide is easily removed for a new one is ﬁ...
Cylinder and piston 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.
Cylinder and piston Remove the circlips from the gudgeon Using long-nose pliers remove the pin. gudgeon pin circlips. Keep your thumb over the circlip to prevent it from ﬂ ying out. Dismantle the piston. Push the gudgeon pin from the piston using punch 502 52 42-01.
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.
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%).
Cylinder and piston 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.
Cylinder and piston 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 side. caused by a broken roller retainer.
Cylinder and piston Action: Cause: Fit a ﬁ ner grade ﬁ lter. • Faulty air ﬁ lter. Small dust particles pass through the ﬁ lter. • The ﬁ lter is worn out due to too Check the ﬁ lter carefully for holes and damage after cleaning.
Cylinder and piston Service tips Action: Defect: In severe cases – replace the cylinder. Broken cooling ﬁ ns, damaged threads or sheared bolts by the exhaust port. Repair the threads using Heli-Coil. Polish the damaged area using a ﬁ ne grade emery cloth so Seizure marks in the cylinder bore (especially by the that the coating of aluminium disappears.
Crankshaft and crankcase Contents Dismantling ________________________________ 52 Inspecting the crankshaft ______________________ 54 Assembly _________________________________ 55...
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.
Crankshaft and crankcase Separate the crankcase halves. Fit tool 501 32 78-01 to the clutch side of the crankcase as illustrated. Use two screws to secure the puller plate in the holes for the clutch cover. Tighten the puller screw using a 14 mm socket spanner and counterhold using an adjustable spanner or 22 mm open- ended spanner.
Crankshaft and crankcase Inspecting the Inspecting the crankshaft crankshaft Inspect the large end of the connecting The crankshaft cannot be reconditioned rod. 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.
Crankshaft and crankcase Ensure that there is no play on the Ensure that there is no play on the coppers around the crank disks. coppers around the crank disks. Assembly Assembly Mount the bearings in the crankcase Heat the crankcase halves to approx. halves.
Crankshaft and crankcase Fit the sealing rings. Lubricate the axle spindles with engine oil and press the sealing rings until level with the crankcase using a suitable punch or tool 502 50 30-19. The metal covers of the sealing rings should face outwards! Assemble the remaining parts in the following order:...
Tools Contents Starter __________________________________ 58 Electrical system __________________________ 58 Fuel system ______________________________ 58 Centrifugal clutch __________________________ 58 Angle gear _______________________________ 59 Cylinder and piston ________________________ 59 Crankshaft and crankcase ___________________ 59 Workshop equipment _______________________ 59...