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Operator’s Manual. The assembly of other equipment or accessories or spare parts not approved by Husqvarna can result in the failure to meet these safety demands and that the person carrying out assembly bears responsibility for this.
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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 5 bolts and lift off the starter. Remove the 5 bolts and lift off the starter.
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Starter Assembly Assembly Fit the return spring in the starter housing. If the return spring has, despite all the precautions, fl own out or if you intend to fi t a new spring proceed as follows: 1. The lies tensioned with a sturdy steel wire in shrink wrap.
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Starter Tighten the return spring. Tighten the return spring. Check the spring tension. Pull out the starter cord completely and slow the starter pulley with your thumb. Lift the starter cord up out of the cut-out on starter pulley. Then turn the starter pulley anti-clock- wise 5 revolutions.
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Electrical system Electrical system Contents Checking the ignition spark _______________________ 8 Dismantling __________________________________ 10 Assembly_____________________________________ 11...
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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 cult to see while troubleshooting.
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Electrical system If there is still no spark the fault may be If there is still no spark, disconnect the either in the stop switch or in the short- short-circuit cable. circuit cable. If the plug now sparks, the fault is either in Replace any faulty parts.
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Electrical system Still no spark? Still no spark? Check other cables and connections. Check other cables and connections for poor contacts (dirt, corrosion, cable brea- kage and damaged insulation). See chapter 3 “Throttle”. TIP! Use an Ohmmeter in order to easily check if cable breakage has occurred, due to pinching, for example.
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Electrical system Dismantle the centrifugal clutch. Position the piston stop 522 43 18-01 in the spark plug hole so that it is on top of the piston top in the combustion room. Remove both screws (E) that hold the centrifugal clutch. Lift off the clutch.
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Electrical system Assemble the ignition module. Fit the ignition module on the cylinder. Adjust the air gap. NOTE! Do not forget the spacer sleeves between the cylinder and the ignition module. Adjust the air gap between the ignition module and the permanent magnets on 502 50 19-01 the fl ywheel to 0.3 mm and tighten the screws.
Make sure that the air fi lter is free of cleaning agent before it is impregnated with air fi lter oil. TIP! Use Husqvarna’s cleaning agent Active Cleaning no. 505 69 85-70. 505 69 85-70 Impregnate the fi lter with air fi lter oil.
Fuel system Tank venting Tank venting Check that the tank venting valve works Tank venting takes place through the fuel correctly. cap and needs to be functional for the engine to work. • Empty the fuel tank. • Remove the air fi lter cover. •...
Fuel system Carburettor Carburettor Dismantling Dismantling 1. Remove the carburettor cover and the Remove the carburettor cover and the air air fi lter. fi lter then blow clean around the carburet- 2. Close the choke valve and blow off any dirt around the carburettor. Dismantle the throttle cable and fuel hoses.
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Fuel system Remove the 4 screws. Dismantle the control diaphragm. These are long and hold together the complete carburettor. Now lift off the fuel pump’s bellows (A), valve housing (B) and control diaphragm. Dismantle the high-speed screw. Dismantle the high-speed screw. Before dismantling, note how many turns it is open.
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Fuel system Dismantle the lever arm and needle valve Loosen the screw and lift off the lever, to check for wear and replacement if axle, needle valve and spring. necessary. Exercise care so that the spring does not fl y out. Check the lever arm and needle valve for Check the wear to the lever arm partly wear.
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Fuel system Assembling the carburettor Assembling the carburettor Walbro WYK Clean and inspect all parts. Clean and inspect all parts. Worn or damaged parts are replaced with Worn or damaged parts are replaced with new ones. new ones. Pay attention to the following when the Pay attention to the following when the carburettor is assembled in the reverse carburettor is assembled in the reverse...
Fuel system Assembly Assembly Check that the sealing ring is seated cor- Check that the sealing ring is seated rectly. correctly on the carburettor before this is fi tted on the engine. The wide edge on the ring should be near- est to the carburettor housing.
Fuel system Throttle handle Dismantling If the throttle is to be removed from the handle, only screw (A) needs to be re- moved. If the two halves of the throttle are to be separated, all screws must be removed. NOTE! When lifting off the handle half, be careful that the spring (B) does not get lost.
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Fuel system Assembly 1. Hook the throttle cable (F) into the throt- tle control. 2. Insert the return spring (G) in the hole in the throttle control. 3. Position the throttle control with spring over the bearing pin and tension the spring.
Fuel system Trouble Shooting Guide Symptom Starting Low speed Acceleration/ Deceleration Probable causes Stop screw for the throttle not working Fuel tank/hose Fuel fi lter blocked The fuel hose blocked Air in fuel ducts Incorrect/poor fuel Pump diaphragm Vacuum pulse leakage Vacuum pulse duct blocked Loose screw(s) on the pump cover Faulty pump diaphragm...
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Centrifugal clutch Centrifugal clutch Contents Centrifugal clutch, dismantling ___________________ 26 Centrifugal clutch, assembling ___________________ 27 Clutch drum, drive axle and AV element ____________ 27...
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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 Twist apart the clutch. Twist apart the clutch and inspect the spring and lining with regard to wear and Inspect and replace damaged or worn damage. parts. The thickness of the lining must be at least 1.0 mm at the most worn point. NOTE! Both clutch shoes should be replaced even if only one of them is...
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Centrifugal clutch Dismantle the AV element. Dismantle the AV element from the clutch housing. Clamp the element with your fi ngers. Use a blunt object, for example a mandrel. Insert the mandrels alternately in the holes in the clutch cover and push the AV ele- ment out.
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Centrifugal clutch Check the inside diameter of the clutch Check the clutch drum for wear. drum. If it exceeds 54,5 mm it should be The diameter must not exceed 54,5 mm. If replaced. this is the case replace the clutch drum. Assemble the diff erent components in the reverse order as set out for dismantling.
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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. Secondly, the angle gear contributes towards the operator’s working stance so that it is comfor- table and at the same time effi cient.
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Angle gear Dismantle the bearings from the output Dismantle the bearings from the output and input axles. and input axles with the help of a small bearing puller. TIP! Hold the bearing puller in a vice so that it gains a better grip around the bearing. Clean all components and inspect them for wear and damage.
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Angle gear Input shaft The input shaft should be fi tted after the output shaft has been fi tted. 1. Fit the ball bearings on the axle. Place the outer ball bearing with the sealed side facing outwards. Do not forget the circlip holding the ball bearings in place.
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Cylinder and piston Cylinder and piston Contents Dismantling ____________________________________ 38 Cleaning, inspection ______________________________ 39 Analysis and actions ______________________________ 39 Service tips _____________________________________ 44 Wear tolerances _________________________________ 44 Assembly_______________________________________ 45...
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 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.
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Blocked spark arrestor mesh in the Clean or replace the spark arrestor mesh. muffl er. 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.
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Cylinder and piston Piston damage caused by a too high engine speed. Typical damage from too high engine speed is ruptured piston ring/piston rings, broken circlip on the gudgeon pin, faulty bearings or that the guide pin for the piston ring has become loose.
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Cylinder and piston Foreign objects Everything other than clean air and pure fuel that enters the engine’s inlet port causes some type of abnormal wear or damage to the cylinder and piston. This type of increased wear shows on the piston’s inlet side starting at the lower edge of the piston skirt.
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Cylinder and piston Larger, softer particles that penetrate into the engine cause damage to the piston skirt under the piston ring as the illustration shows. Action: Cause: Fit the air fi lter correctly. • Air fi lter incorrectly fi tted. Fit a new air fi lter.
Cylinder and piston Service tips Action: Defect: In severe cases – replace the cylinder. Broken cooling fi ns, damaged threads or sheared bolts by Repair the threads using Heli-Coil. the exhaust port. Polish the damaged area using a fi ne grade emery cloth so Seizure marks in the cylinder bore (especially by the ex- that the coating of aluminium disappears.
Cylinder and piston Assembly Assembly Lubricate the gudgeon pin’s needle bea- Lubricate the gudgeon pin’s needle bea- ring with a few drops of engine oil. ring with a few drops of engine oil. Direct the arrow on the top of the piston towards the exhaust port.
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Crankshaft and crankcase Crankshaft and crankcase Contents Dismantling ____________________________________ 48 Inspecting the crankshaft _________________________ 49 Assembly ______________________________________ 50...
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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 between 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 120°C using a hot air gun. Knock the crankcase half against a woo- Knock the crankcase half against a woo- den 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 crankcase half on Fit the crankshaft in the crankcase half on the fl ywheel side. Lubricate the stub axle the fl ywheel side. with a few drops of oil and carefully slide the crankshaft into the bearing.