Starter General recommendations The workshop used to carry out repairs must be equipped with Fire risk safety devices in accordance with local directives. Handle fuel with respect as it is extremely infl ammable. No one may carry out repairs without fi rst having read and understood the contents of this Workshop Manual.
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Starter Dismantling Dismantling Remove the 8 screws and lift off the starter The starter, the cylinder cover and the cover from the engine body. over the muffl er is one unit. Remove all the 8 screws. 502 71 27-02 Offl oad the spring tension. Offl...
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Starter Assembly Assembly Clean the component parts and assemble in Clean component parts before assembling. the reverse order as set out for dismantling. Replace the return spring/starter pulley and starter cord, if necessary. NOTE! The return spring and starter pulley are supplied pre-assembled and are fi...
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Starter Tension the return spring. Tension the return spring. Check the spring tension. Pull the starter cord out completely and slow the starter pulley with your thumb. Fit the starter on the engine body. Lift the cord into the notch on the starter pulley.
Electrical system Electrical system Contents Checking the ignition spark ______________________ 8 Dismantling __________________________________ 10 Assembly ___________________________________ 12...
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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...
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Electrical system It there is still no spark even now, then When no spark is obtained, dismantle the separate the short-circuit cables. short-circuit cable from the ignition switch. If the plug now sparks, the fault is either Still no spark? in the ignition switch or the short-circuit Check that the short-circuit cable is not cable.
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Electrical system Still no spark? Still no spark? Check other cables and connections for Check other cables and connections. poor contacts (dirt, corrosion, cable brea- kage and damaged insulation). Make sure that the cables are correctly drawn and lie in the cable grooves. Do not forget to check the cables in the throttle too.
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Electrical system Separate the short-circuit cables. Separate both short-circuit cables. Remove the screws (A) and slide the Remove both screws (A), one on each throttle forwards. side of the throttle handle. Push the throttle forward onto the shaft. Loosen the screws and remove the shaft Loosen the screws and remove the shaft from the engine.
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Electrical system Dismantle the centrifugal clutch. Remove the two screws holding the cen- trifugal clutch. Lift off the clutch and both support wash- ers. 502 71 27-02 Fit the piston stop no. 502 54 15-01 and Fit piston stop no. 502 54 15-01 in the remove the nut holding the fl...
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Electrical system Assemble the ignition module and adjust Assemble the ignition module. the air gap to 0.3 mm. Adjust the air gap. It should be 0.3 mm between the permanent magnets in the fl ywheel and the ignition module. Assemble other parts in the reverse order as set out for dismantling.
Fuel system In addition to the fuel tank and carburettor, the fuel system consists of the air fi lter, fuel fi lter and tank ven- ting. All these components interact so that the engine receives the optimal mixture of fuel and air to make it as effi...
Fuel system Check that the slot in the non-return valve Remove the fi lter housing (A) from the (B) is not damaged. bracket (D) on the carburettor cover using fl at nose pliers. Clean the foamed plastic fi lter (C). Remove the fi...
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Fuel system The carburettor’s design The carburettor’s design The carburettor can be divided into three The carburettor can be divided into three different functional units: the metering different functional units: the metering unit, the blending unit, and the pump unit. unit, the blending unit, and the pump unit.
Fuel system Dismantling the Dismantling the carburettor carburettor The metering unit The metering unit Remove the 4 screws (A) and lift off the Remove the 4 screws (A) and pull apart cover (B) and the pump bellows (C). the various parts for inspection and pos- sible replacement.
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Fuel system Check the needle valve for damage on the Check the needle valve and the lever arm for damage or wear. tip and in the lever arm groove. Replace damaged components with new Check the lever arm for damage to the groove for the needle valve and wear on ones.
Fuel system The blending unit The blending unit Remove the main jet. Press out the main jet (A) with a suitable punch. Remember how far it is pressed into the carburettor housing. Remove the valves and dampers. If these Check valves and dampers for wear. components are worn, idling is disrupted.
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Fuel system Fit the carburettor needles. Fit the carburettor needles and adjust them to the basic setting: Screw them in so that they just reach the H = 1.0 turn bottom of the needle seat. Then screw them out according to the L = 1.5 turns basic setting: H = 1.0 turn...
Fuel system Assembly Assembly Connect the fuel hoses to the carburettor 1. Connect the fuel hoses to the carburet- and screw it on to the distance piece. tor. Do not forget the top screw! 2 Hold the carburettor against the air fi...
Fuel system Place the catch for involuntary throttling Place the catch for involuntary throttling and the throttle in position and make sure and the throttle in position and make sure the recoil spring is tensioned and pressed the recoil spring is tensioned and pressed against the pin in the throttle handle as against the pin in the throttle handle as shown in the illustration.
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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 recommen- ded max. speed) and should be kept during the engine’s fi rst working hours. Thereafter the carburettor should be fi...
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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.
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Centrifugal clutch Replacing the clutch Replacing the clutch drum drum Pull both short-circuit cables apart and Pull the short-circuit cables apart and disconnect the throttle cable from the disconnect the throttle cable from the carburettor. carburettor. Remove both screws (A), one on each Remove the screws (A) and slide the side of the throttle handle.
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Bevel 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. Secondly, the angle gear contributes towards the operator’s working stance so that it is comfortable and at the same time effi...
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Bevel gear Assembly Assembly Assemble the new bevel gear in the Assemble the new bevel gear in the re- reverse order as set out for disman- verse order as set out for dismantling. tling and check that the gear is fi lled Remove the plug (F) and check that the with grease.
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 Dismantle the piston. Push the gudgeon pin from the piston using punch 502 52 42-01. If the pin is too tight, carefully warm the piston. NOTE! Make sure the spacer washers on each side of the needle bearing are not misplaced.
For the best results we recommend McCulloch two-stroke oil or ready-mixed fuel that is specially developed for air-cooled two-stroke engines. Mixing ratio: 1:50 (2%). If McCulloch two-stroke oil is not available another good quality two-stroke oil can be used. Mixing ratio: 1:33 (3%) or 1:25 (4%).
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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.
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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.
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Cylinder and piston Cause: Action: • Faulty air fi lter. Small dust particles Fit a fi ner grade fi lter. pass through the fi lter. Check the fi lter carefully for holes and • The fi lter is worn out due to too damage after cleaning.
Cylinder and piston Larger, harder particles that enter the engine cause serious damage to the underside of the piston skirt. Cause: Action: • Air fi lter damaged or missing. Fit a new air fi lter. Regular service and inspection. • Parts from the carburettor or intake system have come loose and entered the engine.
Cylinder and piston Wear tolerances Piston ring gap Piston ring groove Piston ring play Cylinder bore When the surface coating is Max. 1.0 mm with the piston ring Max. 1.6 mm. Clean the Max. 0.15 mm. Clean the worn and aluminium appears. inserted in the lower part of the groove before checking the groove before checking the...
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Cylinder and piston Check the carburettor’s distance piece/ heat shield (A) for cracks. Make sure the impulse channel (B) is open and that the gasket (C) is not damaged. Screw the distance piece to the cylinder and tighten the screws crosswise and diagonally.
Crankshaft and crankcase Crankshaft and crankcase Contents Dismantling ________________________________ 46 Inspecting the crankshaft ______________________ 47 Assembly _________________________________ 48...
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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 bet- ween the top and bottom dead centres.
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Crankshaft and crankcase Dismantle the ball-bearings from the Dismantle the ball-bearings from the crankcase halves. crankcase halves. Heat the crankcase halves to 110°C using a hot air gun. Knock the crankcase half against a Knock the crankcase half against a wooden block so that the ball-bearing wooden block so that the ball-bearing falls out.
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Crankshaft and crankcase Inspect the small end of the connecting Inspect the small end of the connecting rod. rod. If seizure marks or discolouration are found in the bearing track the crankshaft must be replaced. Check the crank bearing. Check the crank bearing. The connecting rod shall not have any radial play (up and down).
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Crankshaft and crankcase Fit the crankshaft in the clutch side’s Fit the crankshaft in the clutch side’s crankcase half. crankcase half. Lubricate the stub axle with a few drops of oil and carefully slide in the crankshaft in the ball-bearing so that the sealing ring is not damaged by the shoulder on the stub axle.
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Crankshaft and crankcase Full engine assembly sequence 1. Crankshaft with attached piston in the crankcase. 2. Flywheel on the crankshaft. 3. Drive cup on the crankshaft. 4. Centrifugal clutch on the fl ywheel. 5. Cylinder. 6. Ignition module, air gap adjustment. 502 51 34-02 7.