Husqvarna FR335 Workshop Manual Download Page 57 | Manualshive

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7

Crankshaft and crankcase

502 50 18-01

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. This puts special demands on the bearings that must withstand quick
changes in load. Moreover, the bearing’s roller retainer must also cope with high temperatures and friction. It
is therefore extremely important when servicing to check the roller retainer for cracks, wear and discoloura-
tion caused by overheating.

The crankshaft is journalled in the crankcase on heavy-duty ball bearings. In addition to the journalling
point for the crankshaft, the crankcase acts as a scavenging pump for the fuel/air mixture when this is
“sucked” from the carburettor and is forced into the cylinder’s combustion chamber. The crankcase must
be perfectly sealed so as not to aff ect this pump function. There cannot be any leakage from the crankshaft,
between the crankcase halves or between the crankcase and the cylinder.

Always replace the sealing rings and gaskets when servicing the crankcase.

Dismantling

Dismantle all components so that only
the crankcase and crankshaft remain.

Dismantling

Dismantle all components so that only
the crankcase and crankshaft remain.

See the respective sections for detailed
information if necessary.

Dismantle the 4 screws holding the
crankcase halves together.

Separate the crankcase halves.

Separate the crankcase halves (a spe-
cial tool is not required).

The crankshaft has a snug fi t in the
crankshaft bearing.

NOTE!

Note the guide sleeves between
the crankcase halves so they are
not lost!

Lift out the crankshaft.

Remove the crankcase gasket.

Lift out the crankshaft out of the clutch
side’s crankcase half (a special tool is
not required).

Remove the crankcase gasket.

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Summary of Contents for FR335

Page 1: ...67 German Workshop manual English R135 R333 RJ333 RJ535 RJX335 RX335 RX535 RXT535 FR335 FR336 FRD336 LS335 LS535 LX335 ...

Page 2: ...______________________________3 2 Electrical system _________________________________9 3 Fuel system ___________________________________ 17 4 Centrifugal clutch ______________________________ 36 5 Angle gear____________________________________ 41 6 Cylinder and piston_____________________________ 45 7 Crankshaft and crankcase________________________ 55 8 Tools _____________________________________...

Page 3: ... Some of the work described in this workshop manual re quires special tools In each section where this is necessary there is a picture of the tool and an order number We recommend the use of special tools in order to avoid ex pensive damage to parts in question and personal injury and to provide an efficient repair procedure Contact faces and gaskets Ensure all surfaces are clean and free from gas...

Page 4: ...ts Dismantling _______________________________________ 4 Assembly__________________________________________ 5 Assembling the starter with a start assistance spring ______ 5 Replacing the drive dogs _____________________________ 7 ...

Page 5: ...efully swing down the protective plate so far that the starter can be lifted out The cylinder cover does not need to be loosened or detached NOTE Ensure the bushings that guide the starter towards the fuel tank are not lost The starter equipped with a start assistance spring is dismantled in the same way as described above However to remove the screw in the centre of the starter pulley requires a ...

Page 6: ...ter cord can be fitted without the need of dismantling the starter Assemble a new starter cord Assemble a new starter cord Slide it into the slot on the starter pulley as shown in the picture Make sure that the knot at the end of the cord is as small as possible and that it is pressed in the starter pulley Assembling the starter with a start assistance spring Clean the component parts and assem bl...

Page 7: ...semble the starter pulley Place the start assistance spring A in position Position the cover disc B over the start assistance spring and make sure that the spring pin enters the disc correctly Place the spacer C and washer D in position in the hub on the cover disc B Tighten the screw E in the centre of the starter pulley Position the start assistance spring in position in the starter pulley and a...

Page 8: ...lock wise 6 turns For starters with a start assistance spring the starter pulley must be turned anti clockwise 5 turns Check the spring tension With the star ter cord fully extended it should still be possible to turn the starter pulley further at least a half turn Remove the circlip and replace any da maged drive dogs or springs if neces sary Remove the circlip holdings the drive dog Lift out the...

Page 9: ...8 1 Starter ...

Page 10: ...9 2 Electrical system 2 Electrical system Contents Checking the ignition spark______________________ 10 Dismantling __________________________________ 12 Assembly_____________________________________ 14 ...

Page 11: ...crankcase 336 Give a sharp pull on the starter handle A spark should be seen between the electrodes If no spark is seen test with test spark plug no 502 71 13 01 If a spark then occurs the spark plug is faulty Try a new spark plug Checking the ignition spark Clean the electrodes and check the electrode gap Checking the ignition spark Remove the spark plug and clean it from soot deposits with the h...

Page 12: ...move a segment of cable if required to get sufficient contact at the connec tion coil Use pliers no 502 50 06 01 to make a hole in the ignition lead When a part of the ignition lead has been cut off it helps to use the pliers no 502 50 06 01 to make a hole in the igni tion lead to fit the contact coil NOTE It is important that the tip of the contact coil hits the centre of the ignition lead to pre...

Page 13: ... Use a 502 51 34 02 feeler gauge See Dismantling below Still no spark Check other cables and connections Still no spark Check other cables and connections for poor contacts dirt corrosion cable breakage 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 See chapter 3 Throttle TIP Use an Ohmmeter in...

Page 14: ...emoving the screw F and prying off the flat pin con nector G Option B Lift out the ignition lead and short circuit cables from their guides Remove the 3 screws E and swing the engine body to one side so the clutch becomes accessible Option A Loosen the screw and slide the cable holder B forwards Remove the screws and slide the cover D forwards Option A Loosen the screw A and slide the ca ble holde...

Page 15: ...Gently knock the puller screw with a hammer if the flywheel sits tightly on the crankshaft Assembly Check that the cast key in the flywheel and key way in the crankshaft are unda maged Fit the flywheel and centrifugal clutch Do not forget the washers A Note the slots on the washer lie closest to the flywheel Align with the equivalent pins on the flywheel Dismantle the ignition module and the centr...

Page 16: ...and the ignition module Tighten the screws and do not forget the ring cable lug under the outer screw Assemble other parts in the reverse order as set out for dismantling NOTE Do not forget the rubber bushings between the fuel tank and the crankcase clutch cover and the fuel tank and starter Assemble the ignition module and ad just the air gap to 0 3 mm ...

Page 17: ...16 2 Electrical system ...

Page 18: ...19 Fuel filter_______________________________________ 19 Fuel pump______________________________________ 20 Carburettor_____________________________________ 20 Throttle ________________________________________ 29 Start throttle speed ______________________________ 31 Carburettor settings______________________________ 32 Fuel system ...

Page 19: ...function and repair methods are essentially the same Air filter Remove the air filter cover and lift off the air filter The filter is manufactured of foamed plastic and should be cleaned in tepid soapy water A damaged filter should be replaced with a new filter WARNING Do not clean not the filter with petrol Hazardous NOTE Do not blow the filter clean with compressed air It can be damaged Ensure t...

Page 20: ...t the edges of the slit are not damaged Replace diaphragm if necessary Model 336 The fuel cap can be taken apart for cleaning Use a screwdriver and prise off the housing A Remove the nipple B using a small flat nosed pliers Blow the bleeding opening in the hous ing A clean with compressed air Blow clean both sintered filters C with compressed air Assemble the fuel cap in reverse order as set out f...

Page 21: ...carbu rettor compartment using compressed air 2 Remove the three screws holding the carburettor and the air filter housing NOTE Do not lose the washer under the head of the upper screw 3 Lift off the carburettor and the air filter housing from the cylinder and discon nect the throttle cable the fuel hose from the carburettor and pull up the fuel hose which joins the tank and the fuel pump from the...

Page 22: ...the carburettor s function The blending unit Fuel and air are mixed here The blending unit In this section of the carburettor fuel and air are mixed in the proper proportions The choke and throttle valves are pla ced here In the middle of the venturi narrowest part of the throughput the main jet D is found The pump unit Pumps fuel from the tank to the carbu rettor The pump unit This is where the p...

Page 23: ...t B Check the diaphragm for holes and wear on the pin C Replace the diaphragm if required Pressure test the metering unit Connect pressure tester 531 03 06 23 to the fuel hose nipple Lower the carburettor in a vessel with petrol in order to discover any leaks more easily Test the pressure at 50 kPa No leakage is permitted In the event of leakage remove the needle valve In the event of leakage remo...

Page 24: ...and in the lever arm groove Check the lever arm for damage to the groove for the needle valve and wear on the mounting points towards the control diaphragm 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 Remove the bolt holding the cover over the pump diaphragm Lift off the cover A the gasket ...

Page 25: ... the same time NOTE Do not lose the ball and spring in the carburettor housing where the choke shaft is stored Note how valves and recoil springs are fitted Dismantle the main jet A and the plug B Press out the main jet A with a suitable punch Remove the plug B Carefully drill a small hole Ø 2 mm in the plug and pry it up with a pointed object ...

Page 26: ...ted NOTE Do not lose the ball and spring in the carburettor housing where the choke shaft is stored Always replace the valves and dampers at the same time Assembling the carburettor Blow all channels in the carburettor compartment clean Mount a new plug Use a suitable punch to get a com pletely tight seal Press in a new main jet Assembling the carburettor Blow the carburettor housing clean Fit a n...

Page 27: ...ed correctly and that they close completely and tightly in the closed position Use Loctite on the valve screws Attach the various parts of the measuring unit in the reverse order as set out for dismantling The lever arm should lie flush with the carburettor housing Attach the various parts of the measuring unit in the reverse order as set out for dismantling The lever arm should lie flush with the...

Page 28: ...ated and that the slot in the plug aligns with the ball B in the carburettor housing Check that the carburettor is sealed No leakage is permitted at 50 kPa Connect pressure tester 531 03 06 23 to the fuel intake on the carburettor Pump up the pressure to 50 kPa Lower the carburettor in a vessel with petrol in order to discover any leaks more easily No leakage is permitted Attach the control diaphr...

Page 29: ...earing sleeve B Also make sure that the sealing ring C is not damaged Check the rubber connection on the distance piece heat shield for leakage Remove the screws B holding the heat guard Check that the rubber connection A on the distance piece heat shield does not show signs of cracking or in any other way leaks Replace the connection if this is the case Remove the screws B holding the heat guard ...

Page 30: ... the lever arm on the carburettor first Then press it down into the groove in the lever arm by the choke con trol Connect the fuel hose 1 to the carburettor 5 Insert the remaining fuel hose into the tank 6 Place the carburettor gasket in posi tion and tighten the carburettor with the two screws 7 Tighten the upper screw on the air filter cowling in the heat guard Do not forget the washer under the...

Page 31: ... note how it is placed Remove the lock for unintentional th rottle activation 6 If the front vibration damper 7 is to be replaced the shaft must be split See below Split the shaft Separate both halves of the throttle Slide the front vibration damper 7 off of the shaft Assemble in the reverse order as set out for dismantling Loosen the screw A and pull away the front part of the two piece shaft Sep...

Page 32: ...el wire is wrapped around the handle and bolt F in order to hold the throttle cable and short circuit cables in place Start throttle speed The start throttle speed can be adjusted using screw G Proceed as follows 1 Start the engine and let it idle 2 Press down the start throttle lock C 3 When the start throttle speed is too low below 4000 rpm screw the ad juster screw G clockwise until the cutting...

Page 33: ...ther with the shaft and angle gear under all circumstances Otherwise there is a risk of the clutch becoming loose resulting in serious personal injury Basic setting The carburettor is set to its basic setting when test run at the factory The basic set ting is richer than the optimal setting fast idle speed is 600 800 rpm under the re commended max speed and should be kept during the engine s first...

Page 34: ...lockwise until it stops rotat ing 2 Turn the H needle at full throttle to the position where the engine starts running as a 4 stroke 3 Stop the engine Second adjustment 1 Start the engine still warm 2 Turn the L needle anticlockwise so that the speed drops by 500 rpm 3 Stop the engine 4 Turn the H needle a 3 4 turn clockwise half a turn for models 135 and 336 5 Then adjust the idling speed to 2 90...

Page 35: ...34 3 Fuel system ...

Page 36: ... Centrifugal clutch Dismantling____________________ 36 Centrifugal clutch Assembly ______________________ 37 Clutch drum and drive axle Dismantling ____________ 37 Clutch drum and drive axle Assembly ______________ 39 Centrifugal clutch ...

Page 37: ...ismantle the protective cover under the engine Remove the 3 screws E and swing the engine body to one side so the centrifu gal clutch becomes accessible Dismantling opt B Remove the protective plate under the engine body 3 or 4 screws Lift out the ignition lead and short circuit cables from their guides Remove the 3 screws E and swing the engine body to one side so the clutch becomes accessible Ce...

Page 38: ...gs which in addition to wear can also show signs of cracking Assembly Connect the clutch shoes together with the spring NOTE Both clutch shoes should be replaced even if only one of them is showing signs of heavy wear This is to avoid engine vibration caused by imbalance in the clutch Bolt the clutch on the flywheel Do not forget the washers A Note the slots on the washer lie closest to the flywhe...

Page 39: ...clip and press out the clutch drum Dismantle the circlip using circlip pliers Press out the clutch drum using a suita ble punch and hammer Dismantle the circlip and heat the clutch cover so the bearing can be dismantled Dismantle the circlip using circlip pliers Heat the clutch case to approx 120 C using a hot air gun Knock the edge of the cover against a wooden block so the ball bearing falls out...

Page 40: ...the drive axle Model 336 Loosen the turn handle A and both screws B Press down the locking spring C and seperate the shaft Pull out the drive axle D and remove the sleeve E with the help of a screw driver This makes the guide for the drive axle F accessible if it must be replaced The shaft contains a long guide for the drive axle Dismantling for possible replacement is done by first removing the p...

Page 41: ...40 4 Centrifugal clutch ...

Page 42: ...____________________________ 42 Dismantling ____________________________________ 42 Assembly_______________________________________ 43 Drive axle dismantling____________________________ 43 Drive axle assembly _____________________________ 44 Angle gear ...

Page 43: ...s comfortable and at the same time efficient In other words the power from the engine via the drive axle should be angled so that the cutting tool works parallel with the ground Remove the circlips holding the bearings on the input respective output shafts Heat the entire angle gear to approx 110 C and first dismantle the input axle and then the output axle 3 Remove the circlip D 4 Remove the larg...

Page 44: ... damaged or worn Fit the bearings on respective axles This is easier if the bearings are heated to approx 110 C using a hot air gun The bearings on the input axle are sealed on one side Turn the bearings so this side faces outwards Heat the gearbox to approx 110 C and first place the output axle in position and then the input axle Make sure the bearing bottoms in its seating Fit the circlips B and...

Page 45: ...pull out the guide B by pulling the drive axle Model 336 Loosen the turn handle A and both screws B Press down the locking spring C and seperate the shaft Pull out the drive axle D and remove the sleeve E with the help of a screw driver This makes the guide for the drive axle F accessible if it must be replaced Assembling Lubricate the drive axle with grease no 503 80 17 01 when assembling in the ...

Page 46: ...46 Cleaning inspection______________________________ 47 Analysis and actions______________________________ 47 Service tips _____________________________________ 52 Wear tolerances _________________________________ 52 Assembly_______________________________________ 53 Cylinder and piston ...

Page 47: ...oroughly cleaned before being dismantled from the crankcase Dismantling Dismantle the following components to make the cylinder accessible Starter cylinder cover muffler grille muffler with heat guard plate decompression valve and spark plug Dismantle the air filter carburettor and heat guard distance piece see chapter Fuel system Then loosen the 4 bolts holding the cylinder Carefully remove the c...

Page 48: ... actions required to prevent the same thing happening again 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 4 Wash all the components 5 Inspect the different components for damage and wear Check the pisto...

Page 49: ... piston Seizure scores along the entire piston skirt on the inlet and exhaust sides Medium to deep scores on the exhaust side The piston ring is stuck in the groove Black discoloration under the piston ring due to blow by Cause Wrong type of two stroke oil or pet rol Incorrect oil mixture in the petrol Incorrect carburettor setting Piston scoring caused by heavy carbon deposits Too heavy carbon de...

Page 50: ...oves on the piston s inlet side caused by a broken roller retainer Deep irregular grooves caused by a loose circlip Shown here on the piston s inlet side Piston ring guide pin vibrated loose A too high engine speed can cause the ends of the piston ring to hammer against the guide pin when the piston ring moves in its groove The intensive hammering can drive out the pin through the top of the pisto...

Page 51: ... ring sits firmly in the groove Piston material has been worn away The lower part of the piston skirt is thinner on the inlet side than on the exhaust side Foreign objects Everything other than clean air and pure fuel that enters the engine s inlet port cau ses 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 t...

Page 52: ...ter correctly Fit a new air filter The piston scored and worn from the piston ring down on the inlet side Cause Air filter damaged or missing Parts from the carburettor or intake system have come loose and ente red the engine Extensive damage to the lower part of the piston s inlet side Larger harder particles that enter the engine cause serious damage to the under side of the piston skirt Action ...

Page 53: ...at the coating of aluminium disappears With deep seizure score marks the piston and cylinder should be replaced Replace the cylinder and piston Carefully polish the damaged area using a fine file of fine grade emery cloth Before the piston is refitted the cylinder should be polished as above With deep score marks the piston and cylinder should be replaced Carefully loosen the piston rings and clea...

Page 54: ...ds the exhaust port Press in the gudgeon pin and fit the circlips NOTE Place a rag in the crankcase opening to prevent the circlip from falling into the crankcase in case it should fly out Check that the circlips are correctly fitted into the grooves by turning the clips with flat nosed pliers Check that the pulse channel A in the cylinder is open Assemble the cylinder with the help of assembly se...

Page 55: ... 2 Attach the seal intake with 2 screws B 3 Attach the sealing plugs C to the distance piece heat shield 4 Attach the grommet with 2 screws D 5 Attach the pressure testing tool E 6 Connect pressure tester to the pressure testing tool 7 Test the pressure at 60 kPa In the event of leakage Lokate the lea kage with leakage spray Replace broken parts ...

Page 56: ...aft and crankcase 7 7 Contents Dismantling ____________________________________ 56 Inspecting the crankshaft _________________________ 58 Assembly ______________________________________ 59 Crankshaft and crankcase ...

Page 57: ...or the fuel air mixture when this is sucked from the carburettor and is forced into the cylinder s combustion chamber The crankcase must be perfectly sealed so as not to affect this pump function There cannot be any leakage from the crankshaft between the crankcase halves or between the crankcase and the cylinder Always replace the sealing rings and gaskets when servicing the crankcase Dismantling...

Page 58: ...rankcase halves to 110 C using a hot air gun Dismantle the sealing rings from the crankcase halves Dismantle the sealing rings from the crankcase halves Use a suitable punch or sleeve and knock out the sealing rings with the help of a hammer Do this while the crank case half is still warm if possible Now clean the crankcase halves and crankshaft Knock the crankcase half against a wooden block so t...

Page 59: ...ng rod If seizure marks discolouration on the sides or damaged needle holders are found the crankshaft must be repla ced Inspect the small end of the connecting rod Inspect the small end of the connecting 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 ...

Page 60: ...f Fit the crankshaft in the clutch side s 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 Place the guide rail in position in the flush channel Place the 2 guide sleeves in the crank case half Place a new crankcase gasket in posi tion Fit the flywheel si...

Page 61: ...lywheel on the crankshaft 3 Drive cup on the crankshaft 4 Centrifugal clutch on the flywheel 5 Cylinder 6 Ignition module air gap adjustment 7 Carburettor distancer heat shield against the cylinder Lubricate the connections with oil Tighten the two lower screws 8 Muffler with gasket 9 Carburettor complete with air filter holder and fitted pressure rods con nected fuel hoses and attached fuel tank ...

Page 62: ..._________________62 Fuel system___________________________________62 Centrifugal clutch______________________________62 Angle gear ___________________________________63 Cylinder and piston ____________________________63 Crankshaft and crankcase _______________________63 Workshop equipment __________________________63 ...

Page 63: ... 06 01 531 00 60 76 502 50 83 01 502 50 18 01 505 69 85 70 502 51 49 01 531 00 48 63 504 62 29 01 531 03 06 23 502 50 18 01 502 51 49 01 502 50 18 01 502 71 14 01 502 50 18 01 503 80 17 01 502 50 64 01 Electrical system Centrifugal clutch Starter Fuel system Fuel system ...

Page 64: ...02 50 18 01 505 69 85 70 502 52 42 01 503 80 17 01 502 50 70 01 502 50 18 01 502 50 70 01 544 13 05 01 544 13 08 01 544 13 09 01 544 13 10 01 544 34 87 01 505 38 13 08 Angle gear Cylinder and piston Crankshaft and crankcase Workshop equipment Workshop equipment 590 67 18 01 ...

Page 65: ...64 8 List of tools ...

Page 66: ..._______________________66 Ignition system________________________________66 Carburettor___________________________________66 Clutch _______________________________________66 Driving ______________________________________66 Dimensions___________________________________66 ...

Page 67: ...35 2 0 535 2 0 336 Basic setting L needle turns 0 75 135 1 0 333 335 1 0 335 1 0 335 1 0 1 0 333 1 0 535 1 0 535 0 75 336 Idle speed rpm 2900 2900 2900 2900 2900 Air filter type Foamed Foamed Foamed Foamed Foamed plastic plastic plastic plastic plastic Throttle control type Forefinger Forefinger Forefinger Forefinger Forefinger throttle throttle throttle throttle throttle Clutch 2 shoe clutch Diam...

Page 68: ...504 54 34 26 2018W35 ...

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