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Husqvarna 357XPG E-tech, Workshop Manual, Page: 37 / 48

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Husqvarna 357XPG E-tech Workshop Manual Download Page 37

36

 – English

Carburettor – adjustment

For instructions on adjusting the EPA carburettor
see appendix A.

Adjusting the carburettor involves adjusting the
engine to the local conditions e.g. climate, altitude,
fuel and type of two-stroke oil.

The carburettor is equipped with three adjustment
options.

L = Low speed jet
H = High speed jet
T = Idling adjustment screw

Fine adjustment

Once the chainsaw is “run in” the carburettor
should be readjusted. First adjust the L jet screw,
then the idling screw T and finally the H jet screw.

The recommended engine speeds are as follows:

Model

Max revs

Idle revs

357XP/G

14 000 rpm

2 700 rpm

359/G

13 500 rpm

2 700 rpm

Repair instructions

NOTE!

If the chain turns at idling speed, the T
screw should be turned anti-clockwise
until the chain stops.

WARNING!
The guide bar, chain and clutch
cover must be fitted before the
saw is started, otherwise the
clutch may fly off and cause injury.

The L and H jets adjust the fuel flow to match the
airflow that the throttle valve opening allows.
Turning them clockwise makes the fuel/air mixture
weaker (less fuel in relation to the amount of air)
and turning them anti-clockwise makes the fuel/air
mixture richer. A weak mixture increases the
engine speed and a rich mixture decreases the
engine speed.

The T screw controls the throttle position when
idling. Turning the T screw clockwise gives faster
idling; turning it anti-clockwise lowers idling speed.

Basic requirements

• Before making any adjustments the air filter

should be clean and the cylinder cover should
be in place. If the carburettor is adjusted with a
dirty air filter, the mixture will be too weak next
time the air filter is cleaned. This can cause
serious engine damage.

• Carefully screw in the L and H jets fully, then

back them off 1 turn. The carburettor now has
the settings H = 1 and L = 1.

• Start the chainsaw and allow it to warm up for 10

minutes.

• Place the saw on a flat surface so that the guide

bar is pointing away from you and the guide bar
and chain are not touching the surface.

Low speed jet L

• Find the highest idling speed by slowly screwing

the L screw in and then out again.

• When the highest speed has been found, screw

out the L screw 1/8 - 1/4 turn.

Basic settings and running in

During testing at the factory the carburettor is
adjusted to the basic factory settings.
The factory settings are H = 1 turn and L = 1 turn.

To ensure that engine components receive
adequate lubrication (running in) the carburet-
tor should be set to a somewhat richer fuel
mixture for the chainsaw’s first 3-4 running
hours. This is done by adjusting the maximum
speed to 6-700 rpm less than the recommended
maximum speed.

If it is not possible to check the maximum speed
with a tachometer then the H jet should not be set
to a weaker mixture than the basic factory setting.

The recommended maximum speed must not
be exceeded.

Summary of Contents for 357XPG E-tech

Page 1: ...Workshop manual 101 91 17 26 357XP 359 ...

Page 2: ...5 Choke control 16 Throttle trigger 17 Hand grip heater 18 Starter assembly 20 Starter cord 21 Recoil spring 21 Ignition module testing 22 Ignition module and flywheel 22 Generator 23 Centrifugal clutch 25 Oil pump 27 Carburettor 29 Carburettor pressure testing 32 Carburettor adjustment 36 Fuel tank 37 Fuel filter 38 Fuel hose 38 Piston and cylinder 40 Decompression valve pressure testing 41 Cylin...

Page 3: ...aning and inspection instructions in each section Working from the back of the manual follow all the instructions under the headings Refitting Reassembly in reverse order Each of the sections covering removal dismantling and refitting reassembly include the relevant lubrication instructions and bolt torques for each stage of repair Construction and function This chapter gives a simple description ...

Page 4: ...cause breathing difficulties Highly flammable When using compressed air the air jet should never be pointed at the body Air can be forced into the bloodstream and cause fatal injury Wear ear protection when testing saws After testing a saw do not touch the silencer until it has cooled down The silencer gets very hot and you may burn yourself Wear protective gloves when working on the silencer The ...

Page 5: ...4 English Special tools 4 5 8 11 10 1 2 3 6 9 7 12 ...

Page 6: ...01 8 Fuel filter hook Withdrawing the fuel 502 50 83 01 9 Clamp stand Clamping the saw 502 51 02 01 10 Feeler gauge Adjusting ignition module 502 51 34 02 11 Clutch tool Centrifugal clutch 502 52 22 02 12 Cover plate Sealing during pressure testing 502 54 11 02 13 Piston stop Locking crankshaft 502 54 15 01 14 Stop plate Locating intake gaiter 502 54 17 01 15 Test plug Checking ignition module 502...

Page 7: ...em Air gap Carburettor type mm inches mm inches 357XP 0 5 0 02 FHP ET 0 3 0 012 Walbro HDA 174 EPA Walbro HDA 175 359 0 5 0 02 FHP ET 0 3 0 012 Walbro HDA 174 EPA Walbro HDA 175 Effective cutting length Chain speed at Chain pitch Drive link cm inches max power revs mm inches mm inches m s rpm 357XP 33 61 13 24 21 4 9 600 8 25 0 325 9 52 3 8 1 5 0 058 359 31 58 13 24 20 1 9 000 8 25 0 325 9 52 3 8 ...

Page 8: ... Fuel tank capacity Oil pump capacity at Oil tank capacity Automatic oil pump Litres US pints 8 500 rpm Litres US pints ml min 357XP 0 68 1 44 5 15 0 38 0 80 Yes 359 0 68 1 44 5 15 0 38 0 80 Yes GAS OIL Weight without bar and chain Weight with bar and chain Heated hand grips kg lbs kg lbs 357XP 5 5 12 1 6 3 13 9 357XPG 5 6 12 4 6 4 14 1 Yes 359 5 5 12 1 6 3 13 9 359G 5 6 12 4 6 4 14 1 Yes ...

Page 9: ...user jet E Construction and function Carburettor The carburettor consists of three sub systems The metering unit A which contains the jets and the fuel control mechanism This measures out the right amount of fuel to suit the speed of the saw and the power demand The mixing unit B consists of the choke diffuser jets and throttle valve This is where the air and fuel are mixed to create a flammable m...

Page 10: ...tion and function In part throttle mode the throttle valve F is par tially open Fuel is supplied through the diffuser jets E In full throttle mode both valves are open and fuel is supplied through all the diffuser jets E ...

Page 11: ...ed Blocked impulse channel Loose or faulty fuel pipe Hole in diaphragm Worn needle valve Needle valve assembly sticking Needle valve set too high Leak in metering system air or fuel Loose cover on carburettor pump side Worn needle valve Needle valve set too high Needle valve assembly sticking Difficulty starting Carburettor leaking fuel Flooding when engine not running Starting The various faults ...

Page 12: ...on valve Page 41 Pressure testing the cylinder Page 43 Adjust H screw Blocked air filter Blocked fuel tank vent Blocked fuel filter Fuel line blocked Loose or damaged fuel hose Impulse channel leaking Impulse channel blocked Loose cover on carburettor pump side Faulty pump diaphragm Leaking air intake hose rubber Loose carburettor mounting bolts Needle valve set too low Metering system damaged Met...

Page 13: ... brake spring 4 Place one hand over the brake spring and insert a small screwdriver between the rear end of the spring and the clutch cover Carefully prise the spring upwards to release it and slide it onto the screwdriver shaft Release the locking washer from the elbow joint and lift it off Cleaning and inspection Clean and inspect all parts carefully If there are any cracks or other defects repl...

Page 14: ...brake band and tighten to a torque of 1 1 5 Nm Locate the elbow joint and connected brake band in their recesses in the clutch cover Lubricate the recess for the spring with grease 2 Grip the clutch cover in a vice Compress the spring with special tool 502 50 67 01 and push it down with your thumb 3 Fit the cover over the chain brake spring tightening the screws to a torque of 1 1 5 Nm 4 Tension t...

Page 15: ...l parts carefully If there are any cracks or other defects replace the damaged parts with new ones The spark arrestor mesh is best cleaned with a wire brush If the mesh is damaged it must be replaced If the mesh is blocked the saw will overheat and this will cause damage to cylinder and piston Never use the saw with a silencer that is in poor condition Always use original parts Silencer refitting ...

Page 16: ...ance by connecting a multimeter to the ignition coil NOTE The switch must be in the on position to give the correct reading The resistance must not be higher than 0 2 ohm when the switch is in the on position Stop switch resistance measurement Remove the cylinder cover and starter assembly Clean the mating surfaces and check the resist ance as follows Cleaning and inspection Clean and inspect all ...

Page 17: ...e lever forwards B while pressing the throttle pushrod backwards C and lifting it off the lever Withdraw the throttle pushrod from the tank and lift it upwards without pulling it through the rubber inlet manifold Carefully release the carbu rettor assembly from the right hand rubber mount ing and lift it upwards 3 NOTE Do not use knurled pliers to disconnect or reconnect the fuel hose This could d...

Page 18: ...e throttle trigger by first pressing it towards the clutch side of the saw until it clicks then towards the flywheel side until it clicks again Remove it from the tank and lift out the return spring Choke control refitting First reattach the choke control to the air filter then press it onto the carburettor so that the clips engage Then refit stop switch carburettor into its rubber mountings throt...

Page 19: ...ert the rear edge of the throttle trigger into the tank Then push clip the front edge into the two clips on the tank with the aid of a combination tool for example Drive in the steel pin from the clutch side Use a 2 5 mm 0 1 diameter drift 3 Then press down the return spring while pressing the throttle lock forwards upwards into the retaining clip in the fuel tank until you hear a click Release th...

Page 20: ...ring see Throttle lock throttle trigger and return spring removal fuel hose and throttle pushrod to the carburettor check that the hose is not trapped between the tank and crankcase measurement 43 mm 1 69 inches hand grip cover air filter and cylinder cover Generator troubleshooting 1 Remove the cylinder cover and cover from the front hand grip Disconnect the black lead from the generator and conn...

Page 21: ... lift off the pulley Bolt the vibration damping springs that hold the tank unit back in place and refit the cover over the front hand grip Tighten to a torque of 4 5 Nm 3 Run the red lead to the front hand grip and connect it 4 Refit the throttle trigger and throttle lock and check that they work correctly see Throttle lock throttle trigger and return spring removal 5 Hand grip heater on model 357...

Page 22: ...h oil That the pawls on the flywheel are undamaged i e that they spring back towards the centre and move freely Lubricate the return spring with light oil Fit a new cord through the hole in the pulley and tie a knot to secure it Feed the other end of the cord through the hole in the starter housing and through the starter handle then tie a double knot in the end Wind about 3 turns of the starter c...

Page 23: ...ng 1 Ignition module testing If there is a fault in the ignition system the ignition module must be tested before the ignition system is removed Test the ignition module as follows Connect a test spark plug 502 71 13 01 to the ignition lead and clip the test spark plug onto the cylinder Turn the engine over using the starter cord If the test spark plug produces a spark the ignition module is OK Re...

Page 24: ...n stop 502 54 15 01 in its place Take off the starter assembly release the leads from the cable guide and remove it Remove the cover from the hand grip 2 Loosen the flywheel nut using a suitable socket and unscrew it until it is flush with the end of the shaft Position puller 504 90 90 02 over the magnets and counterweight on the flywheel Tighten 2 3 turns and tap the head of the puller with a met...

Page 25: ... and hand grip Bolt the generator in position tightening the bolts to a torque of 5 Nm Clip the lead to the tank NOTE The lead connector must be positioned to the right of the clip Connect the lead to the con nector on the hand grip and refit the cover 2 Refit fuel tank with both stops and rear vibration damping spring fuel hose to carburettor hose length between tank and crankcase 43 mm 1 69 inch...

Page 26: ...o a torque of 2 5 3 5 Nm cylinder cover Centrifugal clutch removal 1 Disconnect the HT lead Remove the spark plug and fit piston stop 502 54 15 01 in its place Remove the cylinder cover Disengage the chain brake by pushing the kickback guard backwards Undo the guide bar bolts and remove the clutch cover chain and guide bar 2 ...

Page 27: ... it to a torque of 15 Nm then connect the HT lead Then refit cylinder cover guide bar chain clutch cover Repair instructions Carefully prise out the clutch springs with a screw driver Inspection and cleaning Clean and inspect all parts carefully If there are any cracks or other defects replace the dam aged parts with new ones Always use original parts Check the thickness of the clutch shoes by usi...

Page 28: ...uide bar Disconnect the HT lead Remove the spark plug and fit piston stop 502 54 15 01 in its place Unbolt the clutch using tool 502 52 22 02 and a suitable socket or combi nation spanner Turn the nut clockwise to remove it 3 Unbolt and remove the clutch drum A chain sprocket B needle bearing C and pump drive wheel D Unbolt the oil pump from the crankcase 6 Remove the chain guide plate 5 4 Remove ...

Page 29: ...with new ones Always use original parts Lubricate all moving parts with grease Lubricate the pump piston C with grease and fit the pump piston and washers 2 Press down the pump piston C Fit the adjuster screw and spring so that the pin B can be pressed into position 3 Reconnect the oil hose and filter A Repair instructions Oil pump refitting 1 4 Refit the oil pump tightening the bolts to a torque ...

Page 30: ...Turning the screw clockwise decreases the oil flow and turning it anti clockwise increases the oil flow Recommended setting 13 15 bar Min setting 15 18 bar Midway setting 18 20 bar Max setting 1 2 3 Carburettor removal 1 Remove the cylinder cover and air filter Disconnect the leads from the stop switch 2 Disconnect the throttle pushrod from the carburet tor by first carefully prising up the spring...

Page 31: ...he fuel filter 5 Remove the high low and idling jet screws HDA 159A high and low jet screws are protected by plastic caps which can be prised off with a screw driver Only on EPA see appendix A 6 Remove the plug by first drilling a hole in it and then prising it out with a screwdriver or the like 7 If necessary remove the throttle and choke valves and remove the spindles together with the lever arm...

Page 32: ...ms The item numbers in the diagram refer to the steps below 1 8 Fit the needle valve with lever arm spindle and spring and tighten the screw Use a rule to check that the lever arm is level with the cover face If necessary the lever arm can be bent slightly 7 Fit the metering diaphragm with its gasket and refit the cover to the metering unit 8 Carry out pressure testing 1 If the throttle and choke ...

Page 33: ...leakage occurs refer to the table below Leakage Fault lies in Diffuser jets Needle valve In impulse tube Pump diaphragm Ventilation hole above metering unit Control diaphragm Fit stop plate 502 54 17 01 between the carburet tor flange and the insulating plate Carburettor refitting NOTE Cleanliness is very important when reas sembling the carburettor Tiny particles of dirt can cause operating probl...

Page 34: ...wdriver Remove stop plate 502 54 17 01 5 Connect the fuel hose to the carburettor Refit the throttle pushrod at the same time as the rubber inlet manifold press in the throttle pushrod so that it engages in the carburettor and fit the spring Connect the leads to the stop switch 7 Then refit cooling plate gasket silencer tighten bolts to a torque of 12 14 Nm silencer support tighten bolts to a torq...

Page 35: ... cylinder so that the intake system insulating plate is free of the crankcase 5 Free the insulating plate from the cylinder by releasing the clamp using pliers Remove the complete air intake system 6 Remove support ring carburettor flange from the inlet manifold insulating plate Cleaning and inspection Clean and inspect all parts carefully If there are any cracks or other defects replace the damag...

Page 36: ... and cylinder refitting silencer support tighten bolts to a torque of 8 10 Nm bark rest tighten bolts to a torque of 8 10 Nm air filter HT lead cylinder cover 6 After the test run retighten the silencer bolts to a torque of 8 10 Nm Refit the carburettor Screw in the carburettor bolts directly from behind without lifting the carburettor assembly tightening to a torque of 1 1 5 Nm It is important to...

Page 37: ...g Turning the T screw clockwise gives faster idling turning it anti clockwise lowers idling speed Basic requirements Before making any adjustments the air filter should be clean and the cylinder cover should be in place If the carburettor is adjusted with a dirty air filter the mixture will be too weak next time the air filter is cleaned This can cause serious engine damage Carefully screw in the ...

Page 38: ...h Screw in the H screw to the setting that sounds right NOTE For optimum adjustment a tachometer should be used The recommended maximum speed should not be exceeded Carburettor correct adjustment When the carburettor is correctly adjusted the saw should accelerate without hesitation and the engine will burble a little at full throttle without any load The chain must not turn when idling If the L s...

Page 39: ...nd crankcase The correct hose length between the tank and crankcase is 43 mm 1 69 inches The correct hose length be tween the crankcase and carburettor is 53 mm 2 09 inches 2 Remove the fuel hose from the fuel tank using tool 502 50 83 01 Trim off 5 mm 0 20 inches from the mitred end of the hose Fit the fuel filter and reinsert the hose in the tank NOTE Do not use knurled pliers to disconnect or r...

Page 40: ...r Refit the spring 4 Bolt the front vibration damping spring into posi tion followed by both stops and the remaining two vibration damping springs Tighten to a torque of 2 3 Nm Check that both vibration damping springs and the stops are correctly seated on the crankcase Incorrect fitting may result in higher vibration levels Connect pressure gauge 502 50 38 01 to the fuel hose Pump the pressure up...

Page 41: ...ully 4 Cover the opening in the crankcase If replacing the cylinder Unscrew the decompression valve Remove the air intake system see Air intake system removal Remove the bearing from the little end of the connecting rod 7 Piston and cylinder removal 1 Remove cylinder cover carburettor see Carburettor removal silencer spark plug 2 Unbolt the vibration damping spring from the hand grip 3 5 ...

Page 42: ...alve tightening to a torque of 12 14 Nm Lubricate the little end bearing with two stroke oil and insert it in the connecting rod 2 Cleaning and inspection Clean all the components scraping off all traces of old gasket and carbon from the following places Piston crown Top of the cylinder bore Cylinder exhaust port Decompression valve channel Cylinder base and or crankcase Check the following The su...

Page 43: ... lock the clamp over the manifold 5 Lubricate the piston ring and piston with two stroke oil Fit a new cylinder base gasket Compress the piston ring with tool 502 50 70 01 and lower the cylinder over it carefully 4 7 Fit the cylinder bolts tightening them in diagonal pairs to a torque of 8 10 Nm 8 Pressure test the cylinder 9 Refit spark plug tighten to a torque of 15 Nm carburettor see Carburetto...

Page 44: ... than 60 kPa 0 6 bar Remove the cover plates from the silencer and carburettor tighten the bolts to the specified torque Remove the pressure test nipple 503 84 40 02 and refit the spark plug WARNING After pressure testing the cylin der check that the inlet manifold is seated correctly otherwise the saw may be damaged Cylinder pressure testing Crankcase and crankshaft dismantling 1 Remove the follo...

Page 45: ...new bearings must be shrunk fit into the crankcase using a hot air gun Cleaning and inspection Clean and inspect all parts carefully Sealing ring replacement Remove the sealing ring from the crankcase using a small screwdriver WARNING Take care not to burn yourself when the crankcase is hot Wear protective gloves NOTE Take care to avoid damaging the crank case To fit the sealing ring use the sleev...

Page 46: ... clutch side of the crankcase in a vice Pull the crankshaft into its bearing using assembly tools 502 50 30 16 3 Check that the guide pins are in place Fit a new gasket to the mating surface of the clutch side of the crankcase Fit and tighten the six crankcase bolts to a torque of 8 10 Nm Check that the crankshaft rotates freely 357 only Fit the cups on the crankshaft NOTE It is important that the...

Page 47: ...nd crankcase 7 Check that the square shoulder of the bolt is correctly seated in the recess in the crankcase 8 Refill with chain oil Repair instructions NOTE If a new crankshaft has been fitted the saw must be run in for 3 4 hours with the carburettor adjusted to the factory settings Refit the following parts bark rest 8 10 Nm oil pump 3 4 Nm see Oil pump refitting chain tensioner centrifugal clut...

Page 48: ... 2 mm 0 08 inch 5 Let the engine run at 13 000 rpm 1 minute until warm 6 Adjust the H needle to a top speed of B rpm Model 357XP B 14 500 Model 359 B 13 000 7 Check that the H cap is still adjusted to its richest setting Turned counterclockwise to stop NOTE The H needle must not rotate 8 Gently knock the H cap into position Use a 5 mm 0 2 inch mandrel for ex the locking pin for the bevel gear ref ...

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