Arrangement of the manual This workshop manual can be used in two different ways. • To repair a specific sub-assembly on a chainsaw. • To dismantle and reassemble a complete chainsaw. Repairing a specific sub-assembly If a specific sub-assembly on the chainsaw needs to be repaired: 1.
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. •...
Construction 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). English –...
The various faults that can affect a chainsaw are divided into four groups. In each group the likely symp- toms are given on the left and possible causes are listed on the right. The most likely faults are given first, and so on.
In addition to the faults described in the above table, trouble shooting can be carried out on specific components or sub-systems of the chainsaw. The various procedures are described in the relevant chapters, see the contents page, as follows: •...
Chain brake – dismantling Disengage the brake by pushing the kickback guard backwards. Unscrew the guide bar bolts and remove the clutch cover, chain and guide bar. Grip the clutch cover carefully in a vice. Release the brake spring by using the kickback guard from the saw as a tool.
• Hold the chainsaw over a firm surface. The height of the guide bar above the surface is given in the table above. • Let go of the front handle and let the chainsaw fall towards the surface. • When the guide bar hits the surface the chain brake must engage.
Stop switch – removal Remove the cylinder cover and air filter. Disconnect both leads from the stop plate and stop switch. Remove the stop plate by carefully sliding it over the lug on the front mounting. Carefully prise the carburettor assembly off the left- hand rubber mounting using a small screwdriver.
Stop switch – refitting Carefully press the new stop switch into place. Check that the switch’s upper mounting clips over the air filter holder. Refit the stop plate. Engage the stop plate in the front slot first then lift the rear edge onto the stop switch.
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 • throttle pushrod into the fuel tank and connect to throttle lever.
Hand grip heater on model 346XPG, 351G, 353G – removal No heating or heating only in front hand grip • Front hand grip – troubleshooting Remove the three bolts that secure the cover over the front hand grip. Disconnect the leads from the switch and generator and measure the resistance of the hand grip heater, which should be 3–4 ohm.
Unscrew the two bolts from the right side of the rear hand grip. Remove the throttle lock and throttle handle, see “Throttle trigger”. Pull out the heater element with the leads still connected. Troubleshooting carburettor heater (346XPG, 351G, 353G) Operation The carburettor temperature is controlled by an electronic thermostat to eliminate the risk of ice formation in the carburettor.
Heater element and rear hand grip – removal Remove the cylinder cover, hand grip cover, hand grip and right-hand stop. Then remove: • throttle lock, throttle trigger and recoil spring, see “Throttle trigger”. • fuel hose and throttle pushrod from the carburettor Unbolt the rear tank mounting from the crankcase, i.e.
Starter assembly – removal Undo the four bolts that fasten the starter assembly to the crankcase and lift off the starter assembly. Pull out about 30 cm of the cord and fasten it in the notch in the pulley rim. Release the tension in the return spring by letting the pulley wind backwards slowly.
Cleaning and inspection: • Clean and inspect all parts carefully. If there are any cracks or other defects replace the dam- aged parts with new ones. Lubricate the return spring with light oil. Tensioning the recoil spring Fasten the starter cord in the notch in the pulley rim and wind the pulley about 2 turns clockwise.
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.
Replacing the generator, model 346XP, 351, 353 Remove the cylinder cover. Disconnect the HT lead, remove the spark plug and fit piston 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.
Ignition module and flywheel – refitting Place the flywheel on the crankshaft. Turn the flywheel so that the key lines up with the keyway in the shaft. Fit the washer and nut on the shaft and tighten to a torque of 25-30 Nm. 0,3 mm To refit the ignition module proceed as follows: Turn the flywheel so that the magnets are in line...
Centrifugal clutch – removal 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. Disconnect the HT lead. Remove the spark plug and fit piston stop 502 54 15-01 in its place.
Unbolt the oil pump from the crankcase. Remove the oil hose and filter (A). Model 350: Push the housing up a little from the fuel tank and remove the filter (A) from underneath, see the diagram under “Oil pump – removal 340, 345”. English –...
Press in the pump piston (C) so that the adjuster screw (D) can be removed. Remove the pump piston. Oil pump – removal 340, 345 See ”Oil pump – removal, models 346XP, 350, 351, 353”, points 1-4. Remove the bolts on the anti-vibration elements on the same side.
NOTE! Check that the chain tensioner is in posi- tion. Fit the bolts on the anti-vibration elements. Note. Models 340 and 345 have another type of chain tensioner, which is adjusted from the side. See ”Oil pump – Refitting, models 346XP, 350, 351, 353”...
Adjustable oil pump – adjustment 346XP, 350, 351, 353 Use a screwdriver or adjustable spanner to turn the adjuster screw on the pump. Turning the screw clockwise decreases the oil flow and turning it anti- clockwise increases the oil flow. Recommended setting: 13–15"...
On saws with a carburettor heater 346XPG, 351G, 353G Remove the bracket’s two bolts above the carbu- rettor. Disconnect the cable connections to the carburettor heater and remove the heating ele- ment. When replacing the thermostat: Disconnect the cable from X and V. Trouble shooting, see page On saws with carburettor 346XPG, 351G, 353G Replacing the heating element: Lower the rear section of the tank by removing the bolt between...
Cleaning and inspection Clean all the carburettor components in petrol. Use an airline to dry off the petrol from all components. Blow through all the channels in the carburettor body and check that they are not blocked. Check that: • The gasket, pump diaphragm and metering diaphragm are undamaged.
Carburettor – pressure testing Pressure testing should be carried out with the carburettor fully assembled. Testing should always be carried out after the carburettor has been repaired, but can also be performed for trouble- shooting before dismantling. Carry out the test as follows: •...
Repair instructions Fit the carburettor. Screw in the carburettor bolts directly from behind, without lifting the carburettor assembly. Tighten to a torque of 1–1.5 Nm. It is important to hold the carburettor flange while tightening the bolts to prevent the inlet manifold from moving.
Unscrew the four cylinder bolts. Lift up the cylinder so that the intake system insulating plate is free of the crankcase. On models 340 and 345 there are cylinder bolts on the underside. Free the insulating plate from the cylinder by releasing the clamp using pliers.
Push down the rear carburettor mounting into the rubber bushings using a small screwdriver. Re- move tool 502 54 17-01. Refit: • cylinder, see special instructions • silencer support (does not apply to 340, 345, 350) • air filter • HT lead • cylinder cover •...
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.
Repair instructions Fine adjustment of idling speed T • The idling speed is adjusted using the screw marked T. • If adjustment is necessary, screw in the idling screw T until the chain starts to turn. Then screw it out until the chain stops moving. •...
Unscrew both stops and the three vibration damp- ing springs from the flywheel side and clutch side of the engine. Disconnect and remove the fuel hose from the crankcase. Cleaning and inspection Carefully check that: • there are no leaks from the fuel tank •...
Tank vent – testing Connect pressure gauge 502 50 38-01 to the fuel hose. Pump the pressure up to 50 kPa (0.5 bar). The pressure should drop to 20 kPa (0.2 bar) within 60 seconds. Use gauge 502 50 37-01 to measure vacuum. Readings should be as follows: the vacuum should increase from 30 to 15 within 30 seconds.
• cylinder cover • carburettor (see “Carburettor – removal”) • silencer • spark plug • fuel tank (applies to 340, 345) Unbolt the vibration damping spring from the hand grip. Undo the four cylinder bolts and lift the cylinder off carefully.
Repair instructions When replacing the cylinder 340, 345: Unscrew the decompression valve. (345) Remove the intake system, see “Air intake system – removal”. Model 350 is fitted with a spacer, which is secured using four bolts from the underside. The spacer does not however need to be removed when removing the cylinder.
Piston and cylinder – refitting 346XP, 350, 351, 353 Lubricate the little end bearing with two-stroke oil and insert it in the connecting rod. Fit the piston with the arrow pointing towards the exhaust port. Push in the gudgeon pin and fit the circlips.
Repair instructions Piston and cylinder – refitting 340, 345 See Piston and cylinder 346XP, 350, 351, 353 – Refitting points 1-5. Apply silicone adhesive/sealing compound (03- 7062) to the crankcase’s contact surfaces with the cylinder. Carefully slide the cylinder down over the piston towards the big end bearing.
3-4 hours with the carburettor adjusted to the factory set- tings. – English Crankshaft complete 340, 345, 350 – reassembly Fit the crankshaft complete in the crankcase. 350: Fit and tighten the four bolts holding the spacer from underneath and fit the crankshaft complete in the crankcase.
Repairing damaged threads A repair kit, 503 27 33-01, is available for repairing damaged threads. First drill out the hole using: 6.1 mm drill bit for magnesium crankcase Then screw in the thread insert using a suitable bolt and spanner. Thread insert A damaged thread can be repaired using a thread insert.
NOTE! Before making any adjustments the following must be done! • Mount, for this model, approved bar & chain combina- tion (See Technical data in the Operator’s manual). Model 340/345/350 16” 346XP/351 16” • The chain should not be tensioned more than that it remains ~0,2 inches to the bar.