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Husqvarna 250PS, Workshop Manual, Page: 30 / 47

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Husqvarna 250PS Workshop Manual Download Page 30

30

7. Cylinder and piston

Removal

Remove the cylinder cover. Remove the air filter,
carburettor assembly, silencer cover, silencer and spark
plug.

Undo the cylinder bolts in diagonal sequence and lift off
the cylinder. Clean any carbon deposits from the cylin-
der.

Cover the crankcase opening with a rag and clean any
carbon  deposits from the top of the piston.
Remove the locking rings and push the gudgeon pin out
of the needle bearing.

Assembly

NOTE! Replace old gaskets. Lubricate the gudgeon pin
needle bearing with a few drops of oil.
Make sure the arrow on top of the piston points towards
the exhaust side.

Push in the gudgeon pin and fit the locking rings using
pliers.

For Husqvarna Parts Call 606-678-9623 or 606-561-4983

www.mymowerparts.com

Summary of Contents for 250PS

Page 1: ...Workshop manual 250 PS Nummer XX For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 2: ...tem Spark plug Electrode gap Shaft length Weight Bar length Pitch Thickness of drive links Engine unit without cutting attachment Manufacturer type of carburettor Fuel tank capacity litre Hydraulic oil tank capacity Method of chain lubrication 2 3 4 5 6 2 2 2 4 2 9 3 5 4 0 6 16 3 8 1 3 7 0 Walbro HDA 86 0 9 1 3 Automatic Electrolux ET Champion RCJ7Y 0 5 1 4 1 2 6 9 9 0 2 0 8 2 13 49 44 32 2 500 11...

Page 3: ...e data 4 2 Starter unit 12 3 Fuel system 14 4 Throttle lock 24 5 Ignition system 25 6 Clutch 28 7 Cylinder and piston 30 8 Crankcase and crankshaft 33 9 Hydraulics 38 For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 4: ...e injury If the hoses or shaft are not fitted the engine cannot be revved up and the hydraulic pump and clutch may be damaged the pressure relief valve in the hydraulic motor must open if there is a blockage in the return hose If it opens without reason then it must be replaced See page 45 you must be able to turn the pulley on the starter unit at least a further 1 1 2 turns when the starter cord ...

Page 5: ...ke oil made for air cooled engines Mixture ratio 1 33 3 1 25 4 Never use outboard oil i e oil intended for water cooled outboard engines Never use oil designed for four stroke engines Mixing Always mix petrol and oil in a clean container designed for petrol Start by pouring half the petrol into the container Then add all the oil Shake the fuel mixture well Now add the remaining petrol Shake the fu...

Page 6: ...assy 502 52 13 01 502 52 14 01 Allen key with square socket 502 51 61 01 Tool for removing crankcase and crankshaft 502 50 46 01 Spacer 502 50 66 02 U key 502 50 71 01 Cover plate exhaust 502 50 72 01 Cover plate inlet 502 52 16 01 Locking tool for clutch drum 502 51 49 01 Key 502 51 54 01 Bolts for key 4 mm 6 mm For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 7: ...gnition cable 502 50 16 01 502 50 18 01 502 50 19 01 502 50 57 01 502 50 64 01 Allen key 8 mm 10 mm 502 50 22 01 502 50 23 01 Socket spanner 502 50 37 01 Vacuum tester 502 50 70 01 Assembly kit for cylinder assy 502 50 83 01 Hook for tank 502 70 09 01 Pressure tester bulb 502 71 13 01 Test plug 502 71 14 01 Tachometer 6 mm 4 mm 3 mm 3 6 5 mm 0 5 mm 0 3 mm 0 5 mm For Husqvarna Parts Call 606 678 96...

Page 8: ...8 Cylinder cover Silencer Air filter carburettor Fuel tank Bolt torques 1 38 Nm 39 Nm 40 Nm 29 Nm 42 Nm 28 Nm 27 Nm For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 9: ...rter unit Crankcase crankshaft Flywheel ignition module Bolt torques 1 37 Nm 25 Nm 26 Nm 36 Nm 35 Nm 33 Nm 34 Nm 32 Nm 32 Nm 41 Nm 23 Nm 24 Nm 22 Nm For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 10: ...Hydraulic oil tank Bolt torques 1 10 Nm 53 Nm 48 Nm 58 Nm 59 Nm 54 Nm 57 Nm 31 Nm 50 Nm 49 Nm 47 Nm 56 Nm 55 Nm 30 Nm 51 Nm 52 Nm For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 11: ...ttle handle Shaft hydraulic hose 1 Bolt torques 4 Nm 5 Nm 2 Nm 7 Nm 3 Nm 8 Nm 21 Nm 19 Nm 17 Nm 18 Nm 20 Nm 12 Nm 15 Nm 16 Nm 45 Nm 44 Nm 46 Nm For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 12: ...ay Undo the cylinder cover Unscrew the bolts that hold the starter unit against the crankcase and lift off the starter unit Carefully lift out the pulley and spring cassette Clean them Replace the cord and or spring with cassette if necessary Lubricate the return spring with light oil WARNING If handled carelessly the return spring may spring out and cause injury Always take care when you replace ...

Page 13: ... end of the cord Run the cord through the cut out in the pulley and wind the spring up a couple of turns Make sure the pulley is free to rotate a further 1 1 2 turns when the cord is fully extended Refit the starter unit by first pulling out the starter cord and then placing the starter unit in position on the crankcase Now release the starter cord slowly so that the starter lugs engage on the pul...

Page 14: ... Replace the filter Pull the hose back to its original position Remove the cable Remove the filter cover and take out the filter Wash the filter in soapy water Soak in filter oil 503 47 73 01 then squeeze out the excess Always replace a damaged air filter Replacing the fuel hose Push the old hose into the tank Pull the hose and filter out through the filler hole of the tank Fit a new hose through ...

Page 15: ...in the venturi and includes the choke and throttle flap 3 Pump unit Here fuel is pumped from the tank to the metering unit Removal Remove the air filter throttle cable and fuel hose Unscrew the 2 bolts from the air filter mounting unscrew the carburettor bolts and remove the carburettor with air filter mounting and spacer Clean all components 1 2 3 For Husqvarna Parts Call 606 678 9623 or 606 561 ...

Page 16: ...rol Pressure test to 0 4 bar 40 kPa No leakage is permitted If there is a leak remove the needle valve Undo the screw and lift off the lever spindle needle valve and spring Examine the needle valve for wear Replace the needle if worn or damaged Examine the lever for wear Replace the lever if worn or damaged For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 17: ...he pump membrane Lift off the gasket and pump membrane Carefully remove the fuel mesh using a needle for example Unscrew the jet needles H long L short Clean all components For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 18: ...flaps and their spindles for wear If they are worn it will be difficult to set the idle speed Always replace the flap and spindle at the same time Make sure the flaps are fitted correctly Fit the various components of the metering unit in the reverse order to removal NOTE Make sure the lever springs are replaced the right way round Check that the lever is level with the top of the carburettor Adju...

Page 19: ...e H and L needles Check the angle of the fuel hose nipple if it was moved during servicing Check that the carburettor is airtight Pressure test to 0 4 bar 40 kPa No leakage is permitted Check that the automatic choke levers are not worn and that they engage in each other For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 20: ...the gaskets and spacer Insert the spacer through the baffle NOTE Make sure the gasket between the cylinder and spacer is correctly positioned Screw the carburettor bolts in alternately Do not tighten Tighten the bolts for the air filter holder Then tighten the carburettor bolts Check that the spacer is undamaged and that the pulse channel is not blocked For Husqvarna Parts Call 606 678 9623 or 606...

Page 21: ...they are turned clockwise the fuel air mixture is made richer more fuel The T screw controls the throttle setting at idle turning it anticlockwise reduces the idle speed WARNING Do not operate the pruning saw until it has been correctly adjusted or repaired When the carburettor is correctly adjusted the pruning saw should accelerate smoothly without hesitating and the engine will burble slightly a...

Page 22: ... procedure after turning the H needle a further 1 4 turn anticlockwise You have now run the pruning saw at H 1 H 1 1 4 and H 1 At full throttle the engine should sound different at each setting The H needle is correctly set when the engine burbles slightly If smoke comes from the silencer and the engine burbles too much then the mixture is too rich If the pruning saw screams then the setting is to...

Page 23: ...n e n t s L e v e r s e t t o o h i g h L e v e r w o r n L e a k a g e f r o m p u m p s e c t i o n F u e l m e s h b l o c k e d L e a k a g e f r o m s p a c e r g a s k e t F u e l f i l t e r b l o c k e d H o l e i n f u e l h o s e F u e l h o s e l o o s e o r d a m a g e d D i r t i n f u e l h o s e A d j u s t e r n e e d l e s b e n t o r b r o k e n N e e d l e s e a t s d a m a g e ...

Page 24: ... two halves of the handle and tighten the 6 screws Replacing the throttle cable Take the handle apart and disconnect the throttle cable Disconnect the throttle cable from the carburettor and pull it out through the sleeve Thread a new cable through the sleeve connect it to the carburettor and the handle Refit the throttle lock and spring Reassemble the halves of the handle and tighten the screws F...

Page 25: ... is still no spark check the spark plug cap cables and connections for poor contact dirt a break in the circuit or damaged insulation Using a feeler gauge 502 51 34 02 check that the air gap between the ignition module and the flywheel magnets is 0 3 mm Adjust if necessary Loosen the screws on the ignition module Position the feeler gauge and push the ignition module towards the flywheel Tighten t...

Page 26: ...e freely that they are not worn or damaged and that the return springs provide the required tension Replace if necessary Place the key in the slot in the crankshaft Line up the slot in the flywheel with the key Screw the piston plug into the cylinder Place the washer and nut on the flywheel Tighten the nut clockwise Bolt torque 24 29 Nm Remove the piston stop For Husqvarna Parts Call 606 678 9623 ...

Page 27: ...and tighten the screws Fit the air baffle Make sure the leads are routed correctly and cannot become trapped Fit the starter unit Fitting the spark plug cap Make a hole in the ignition lead using pliers 502 50 06 01 Push the ignition lead through the spark plug cap and fit the connector spring using the tongs Slide the cap back over the connector spring For Husqvarna Parts Call 606 678 9623 or 606...

Page 28: ...ed Otherwise the clutch may come loose and cause injury Removal Fit the piston plug in the spark plug hole Use the full thread length Unscrew the centre nut anticlockwise Remove the clutch The complete clutch assembly should be replaced to prevent imbalance For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 29: ...ssembly Fit the clutch in place and tighten the nut clockwise Fit the engine adapter with the hole on top and the slot at the bottom For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 30: ...rankcase opening with a rag and clean any carbon deposits from the top of the piston Remove the locking rings and push the gudgeon pin out of the needle bearing Assembly NOTE Replace old gaskets Lubricate the gudgeon pin needle bearing with a few drops of oil Make sure the arrow on top of the piston points towards the exhaust side Push in the gudgeon pin and fit the locking rings using pliers For ...

Page 31: ...e piston ring must not exceed 0 6 mm Defect Broken cooling fins damaged threads or broken bolt near exhaust port Signs of seizing in cylinder barrel especially near exhaust port Surface coating in cylinder barrel worn through especially near top of cylinder Piston shows signs of seizing Piston ring seized in slot Fit the cylinder with the aid of assembly kit 502 50 70 01 making sure that the openi...

Page 32: ...w then a silencer without spark arrester mesh should be used NOTE A blocked spark arrester mesh can cause overheating and result in damage to the cylinder Removal Remove the cylinder cover Unbolt the silencer cover Undo the two silencer bolts and remove the silencer Open up the silencer and clean it Refit in the reverse order to removal For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mym...

Page 33: ...l to fit the new sealing ring The sealing ring must be flush with the surface of the crankcase Replacing sealing rings Magnet side Remove the cylinder cover air filter starter unit and baffle Remove the flywheel See pages 25 26 Undo the 3 bolts that hold the housing onto the crankcase Prise off the sealing ring housing using a screwdriver or the like Press the new sealing ring into place with a su...

Page 34: ...ystem clutch cylinder assembly piston and cylinder base gasket Undo the seven crankcase bolts unscrewing them a short distance at a time Checking the crankshaft The crankshaft cannot be repaired and must be replaced if it is defective or damaged On some crankshafts there may be a slight blue discoloration around the crank pin This is entirely normal and is due to a heat treatment applied around th...

Page 35: ... end of the piston rod Replace the crankshaft if there are signs of seizing or discoloration on the bearing surface Assembly Clean all components before assembly Fit the casing bearings onto the crankshaft NOTE It is important that the bearings are drawn tight up against the crankshaft Heat the drive side of the crankcase and pull in the crankshaft using fitting tool 502 50 30 12 For Husqvarna Par...

Page 36: ...de sealing ring using the sleeve on the fitting tool no 502 50 30 12 The sealing ring must be flush with the crankcase surface The crankcase bolts are of different length and should be fitted as follows 1 5 l 30 mm 6 7 l 60 mm Tighten all the bolts starting with the ones closest to the crankshaft Always fit a new greased O ring Smear the 3 housing bolts with Loctite Then tighten For Husqvarna Part...

Page 37: ...on system Smear the bolts with Loctite Fit the starter unit Fit the clutch and engine adapter Fit the carburettor fuel hose short circuit lead choke control and air filter Fit the cylinder cover hydraulic oil tank and shaft or test hose before testing For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 38: ...ble based or synthetic hydraulic oil of an equivalent grade NOTE The flame point of the oil must exceed 160 C The oil should also be non conductive Fill with hydraulic oil so that the level is between the min and max marks on the dipstick If the hydraulic tank is new and unused it should be completely filled so that there is enough oil to fill the hoses Top up with hydraulic oil after the machine ...

Page 39: ... the rubber sleeve is undamaged and makes a good seal If not replace the rubber sleeve Disconnect the quick coupling at the top and pull the hydraulic hose out of the tank wall Disconnect the quick coupling at the bottom 17 socket and remove the diffuser from the tank Now remove the hydraulic pump and support ring For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

Page 40: ... support ring against the rubber sleeve on the inside of the tank and bolt the tank adapter in place Make sure the locating studs on the adapter are correctly positioned Lower the hydraulic pump into the tank the hydraulic hose must be attached Push the pump out through the opening against the tank adapter and tighten the four bolts For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymower...

Page 41: ... diffuser Detach the hydraulic pump and lift it out Disconnect the hydraulic hose Unscrew the 6 bolts in the cover and lift the cover off Remove the O ring cog and pump cogs Check that the pump cams are free from gouges If not both pump cogs and the cover must be replaced Make sure the pump cogs are not cracked or otherwise damaged For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerp...

Page 42: ...ly tap the pump shaft in Place the key in the pump shaft Fit the cog pump cogs and O ring then bolt on the cover Fit the pump in the tank Bar and shaft Removal Remove the cover from the chain drive cog Loosen the tensioning bolts and remove the chain tensioner bar and chain Do not lose the O ring that sits under the chain tensioner For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerp...

Page 43: ...e motor and the 4 bolts that hold the bar plate to the ball joint mounting Disconnect the hoses from the motor return hose jubilee clip pressure hose hose coupling Slide off the rubber sheath that holds the two hoses together If necessary dismantle the ball joint by first removing the jubilee clip then prising off the ball joint mounting For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www my...

Page 44: ... in the ball joint Pull the hoses through the second tube and third tube if fitted Replace the protective guards if necessary Assembly Slide the protective guards onto the hose Feed the hose through the larger shaft s and fit the shaft clips Feed both hoses through the smaller shaft positioning the pressure hose slightly in front of the pressure hose For Husqvarna Parts Call 606 678 9623 or 606 56...

Page 45: ...ma king sure it sits correctly in the groove in the bar The cutting edge on the chain links must face forward on top of the bar Tighten the bolts Place the bar as far back as it will go on the bar plate Fit the gasket chain tensioner and bar bolts tighten with your fingers Bolt the bar plate onto the ball joint mounting fit the motor to the bar plate and screw on the chain drive cog Fit the rubber...

Page 46: ...a repair hose coupling This hose coupling can be found in the list of spare parts square P Remove the bar and detach the motor see page 43 Disconnect the pressure hose and pull it out a short distance Cut the hose square and fit the new hose coupling Start by screwing the left hand threaded outer component of the hose coupling onto the hose as far as it will go Thread can be lubricated with engine...

Page 47: ...48 Jenny Florman 1994 Husqvarna AB 1994 For Husqvarna Parts Call 606 678 9623 or 606 561 4983 www mymowerparts com ...

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