This service manual contains detaileddescriptions of all servicing procedureson model 044 chain saws and can thusbe used as a basis for professionaloverhauls and repairs to all versions ofthis machine.
We recommend that you make use ofthe exploded views in the illustratedparts lists while carrying out repair work.Most of the illustrations show the in-stalled positions of the individual com-ponents and assemblies.
Whenever possible you should refer tothe latest edition of the parts list for thepart numbers of any spares you mayrequire. Microfilmed parts list are alwaysmore up to date than printed lists.
In the event of faults it is quite possiblethat a particular condition may haveseveral causes. It is, therefore, advis-able to consult the "troubleshootingcharts" for all assemblies and systemswhen tracing faults. You will find thesetroubleshooting charts immediately afterthe specifications.
Engineering changes which have beenintroduced since publication of thisservice manual are announced in"Technical Information Bulletins".Such bulletins should be treated assupplements to the service manual.
This service manual and all technicalinformation bulletins describing engi-neering changes are intended exclu-sively for the use of STIHL servicingdealers and staff within the STIHL serv-ice organization and must not bepassed on to third parties.
Servicing and repairs are made consid-erably easier if the chain saw ismounted on assembly stand 5910 8903100 or 5910 850 3100. The saw canbe quickly secured to the stand bymeans of the two bar mounting studsand nuts.
While on the assembly stand the sawcan be swivelled to any required posi-tion to suit the ongoing repair. This notonly has the advantage of keeping thecomponent in the best position for therepair but also leaves both hands freefor the work and thus helps save time.
The "STIHL Special Tools" manualillustrates and lists the part numbers ofall available model-related servicingtools as well as general-purpose toolsfor all machines.
8.1 Removing and Installing 628.2 Throttle Trigger/
Interlock Lever 63
1. Specifications 3
1.1 Engine 31.2 Fuel System 31.3 Ignition System 41.4 Cutting Attachment 51.5 Weights 51.6 Tightening Torques 61.7 Special Accessories 71.7.1 For User 71.7.2 For Service Shop 7
Electrode gap:Spark plug thread:Length of thread:Heat range:
0.8 I (27 fl.oz)min. 90 RONRegular brand-name gasolineand brandname two-strokeengine oil50:1 with STIHL 50:1two-stroke engine oil;40:1 with STIHL 40:1two-stroke engine oil;25:1 with other brandedtwo-stroke, air-cooledengine oilsPrefilter and bisectionalbox filterSpecial accessory:Heavy-duty (HD) air filter
Transistorized (breakerless)magneto ignition with trigger unitintegrated in ignition module0.15-0.3 mm (0.006-0.012 in)2.0-3.0 mm (0.08-0.12 in)B.T.D.C. at 8,000 rpm24.5-29.5° B.T.D.C.at 8,000 rpmCoil winding resistancesPrimary: Secondary:0.7...1.0 Ω 7.7...10.3 kΩBosch WSR 6 For NGK BPMR 7 A0.5 mm (0.020 in)M14 x 1.259.5 mm (0.37 in)200
1.3 Ignition System
STIHL 044 5
1.4 Cutting Attachment Guide bars:
Bar tail:Bar lengths:
Oilomatic chain:
Chain sprockets:
Chain speed:
Chain lubrication:
Oil delivery rate:
Oil tank capacity:
STIHL Rollomatic guide barswith sprocket noseSTIHL Duromatic guide barswith stellite-stipped noseBoth types with corrosion-resistant finish and inductionhardened rails3003Rollomatic: 37, 40, 45 and 50 cm(14, 16, 18 and 20 in)Rollomatic S: 40, 45, 50, 63and 75 cm(16, 18, 20, 25 and 30 in)Duromatic: 40, 45, 50, 63and 75 cm(16, 18, 20, 25 and 30 in)3/8" (9.32 mm) Rapid-Microand Rapid-Super3/8" (9.32 mm) Topic-Microand Topic-Super7-tooth, 3/8" rim sprocket7-tooth, 3/8" spur sprocketOptions:8-tooth, 3/8" rim and spursprockets20.7 m/s (68 ft/sec) at 9,500 rpm(with 7-tooth, 3/8" sprocket)Fully automatic speed-controlledreciprocating oil pump; no oilfeed at idle speed. Additionalmanual oil flow control (withEconomic mark)Adjustable 8 - 18 cm³/min(0.3 - 0.6 fl.oz/min) at 10,000 rpm0.33 I (0.7 US pt)
1.5 Weights 044 C
6.2 kg(13.6 Ib)
7.6 kg(16.7 lb)
044 W
6.1 kg(13.4 Ib)
7.5 kg(16.5 Ib)
044
5.9 kg(13.0 lb)
7.3 kg(16.1 lb)
Dry powerhead without barand chain:
Dry powerhead with 37 cm(15 in) bar and chain:
STIHL 044 6
Remarks
1)
1)1)2)3)
4)4)
2)1)
1)
1)
(Ibf.ft)
(8.5)(8.5)
(8.1)
(6.3)(8.1)(6.6)
(24.3)(2.6)(3.0)
(37.0)(18.5)
(4.0)(4.0)(5.9)(5.9)
(0.7)(3.7)
(4.4)
(4.4)(1.5)
(2.2)(2.6)(2.2)(2.2)(3.0)
(3.0)(2.2)
(17.0)
TorqueNm
11.511.5
11.0
8.511.0
9.0
33.03.54.0
50.025.0
5.55.58.08.0
1.05.0
6.0
6.02.0
3.03.53.03.04.0
4.03.0
23.0
For component
CrankcaseCylinderMuffler lower casingto cylinderMuffler upper casing(top)Muffler (bottom)Ignition moduleCrankshaft (ign. end)(flywheel)CarburetorShroudCarrier (clutch)Spark plugBuffer, topBuffer, bottomFront handle, topFront handle, bottomHandle molding (rearhandle)Buffer plateChain catcher to spikedbumperSpiked bumper tocrankcase (top)Generator (heating)Cover of chaintensionerOil pumpCover of chain brakeBrake bandFan housingHand guard (left) to fanhousingInner side plateBar mounting
1) Screw must be secured with adhesive 0786 111 1109 (Loctite 270)2) Screw must be secured with adhesive 0786 111 1101 (Loctite 242)3) A washer must be fitted under the screw head4) Screw must be secured with adhesive 0786 111 1117 (Loctite 648)
Note: Screws secured with adhesive are easier to release if the adhesive is heated first with a hot air blower (hairdryer). Exercise caution on polymer components.
Remove intake air preheatingcomponents; close rotaryshutter
STIHL 044 10
2.3 Ignition System
Warning: Exercise extreme caution while carrying out maintenance and repair work on the ignition system. The high voltageswhich occur can cause serious or fatal accidents!
Ignition system in order.Look for fault in fuel system andcarburetor.
yes
Replace ignition module. Does enginenow run after positive spark test?
Fit new flywheel.Is spark test positive?
Use ohmmeter to check ignition leadfor break. If break is detected, replaceignition lead. Does spark test nowproduce sparkover?
Does flywheel appear to bein good condition?
Fit new spark plug.Is air gap correct?
Correct the air gap (0.15 - 0.3 mm).Is spark test positive?
Insert screwdriver in place of spark plug in spark plugterminal and hold about 4 mm (1/8") away fromground. Sparkover?
Replace faulty ignition lead of short circuit wire.Repair contact spring or switch shaft.
Faulty insulation on ignitionlead or short circuit wire?Is connector sleeve touchingshort circuit contact?
Clean spark plug and reset electrodegap. Does spark test produce powerfulspark?
Press terminal firmly onto sparkplug and fit spring if necessary.
Spark plug terminal firmly seated on spark plug?
Remove spark plug.Is it in good condition?
no
no
nono
no
yesno
no
yes
yes
no
no
no
no
yes
yes
STIHL 044 11
Condition
Starter rope broken
Rewind spring broken
Starter rope can be pulled outalmost without resistance(crankshaft does not turn)
Starter rope is difficult to pulland rewinds very slowly
Cause
Rope pulled out too vigorouslyas far as stop or over edge - i.e.not vertically
Normal wear
Spring overtensioned - noreserve when rope isfully extended
Heavily soiled or corroded
Guide pegs on pawls or pawlsthemselves are worn
Spring clip fatigued
Starter mechanism is very dirty(dusty conditions)
Lubricating oil on rewind springbecomes viscous at very lowoutside temperatures (spring wind-ings stick together)
Remedy
Fit new starter rope
Fit new starter rope
Fit new rewind spring
Fit new rewind spring
Fit new pawls
Fit new spring clip
Thoroughly clean completestarter mechanism
Apply a few drops of kerosine(paraffin) to spring, thenpull rope carefully severaltimes until normal action isrestored
2.4 Rewind Starter
STIHL 044 12
2.5 Chain Lubrication
Cause
Oil tank empty
0-ring on oil line in crankcaseseat faulty or oil line damaged
Oil inlet hole in guidebar is blocked
Intake hose or pickup body(strainer) clogged orintake hose ruptured
Valve in oil tank blocked
Teeth on pump piston and/orworm worn
0-ring on oil line in crankcaseseat faulty or oil line damaged
Cylinder bore in pump housingworn
Control screw and/or controledge on pump piston worn
Cylinder bore in pump housingworn
Remedy
Fill up with oil
Remove oil pump, fit new 0-ringand reinstall oil pump or fitnew oil pump
Clean oil inlet hole
Wash intake hose and pickupbody (strainer) in whitespirit and blow out withcompressed air; replace ifnecessary
Clean or replace valve
Fit new pump piston and/or newWorm
Remove oil pump, fit new 0-ringand reinstall oil pump or fitnew oil pump
Fit new pump housing
Fit new control screw and/ornew pump piston
Fit new pump housing
Condition
Chain receives no oil
Machine losing chain oil
Oil pump delivers toolittle oil
Important: In the event of trouble with the chain lubrication system, always investigate the other possible sources of faultsbefore disassembling the oil pump.
STIHL 044 13
2.6 Fuel System
Condition
Carburetor floods; engine stalls
Poor acceleration
Engine will not idle,idle speed too high
Cause
Inlet needle not sealing.Foreign matter in valveseat or cone damaged.
Inlet control lever stickingon spindleHelical spring not locatedon nipple of inlet controlleverPerforated disc ondiaphragm is deformedand presses constantlyagainst inlet controlleverInlet control lever is too high(relative to design position)
Idle jet "too lean"
Main jet "too lean"
Inlet control lever is too low(relative to design position)
Inlet needle sticking to valve seat
Connecting bore toatmosphere blockedDiaphragm gasket leakingMetering diaphragmdamaged or shrunk
Throttle valve openedtoo far by idle speedadjusting screw
Remedy
Remove and clean or replaceinlet needle, clean fueltank, pickup body and fuelline if necessaryFree off inlet control lever
Remove inlet control leverand refit correctly
Fit new metering diaphragm
Set inlet control leverflush with top of meteringchamber face
Back off low speed adjustingscrew slightly (see carburetoradjustment)
Back off high speed adjustingscrew slightly (see carburetoradjustment)
Set inlet control leverflush with top of meteringchamber face
Remove inlet needle, cleanand refit
Clean bore
Fit new diaphragm gasketFit new metering diaphragm
Reset idle speed adjustingscrew correctly
STIHL 044 14
Remedy
Clean jet bores and blow outwith compressed air
Screw in low speed adjustingscrew slightly(see carburetor adjustment)
Set idle speed adjusting screwcorrectly
Clean or renew valve jet
Clean air filter
Clean tank vent or replace ifnecessary
Seal or renew connections andfuel line
Fit new pump diaphragm
Clean bores and channels
Clean pickup body, fit new filter
Clean fuel strainers
Cause
Idle jet bores or channelsblocked
Idle jet "too rich"
Setting of idle speed adjustingscrew incorrect - throttle shuttercompletely closed
Bottom:Assembly sequence of chain drive1 = Spur sprocket (with clutch drum)2 = Needle cage3 = Washer4 = E-clip5 = Clutch drum (for rim sprocket)6 = Rim sprocket
- Remove the E-clip from the clutchdrum or chain sprocket.
- Pull off the rim sprocket with clutchdrum or the spur spocket.
- Take the needle cage out of theclutch drum or chain sprocket.
Reassemble in the reverse sequence.Note: Clean stub of crankshaft. Re-place the needle cage or wash it inclean white spirit and lubricate withSTIHL multipurpose grease, see 12.2.Rotate the clutch drum or spursprocket, apply slight pressure at thesame time, until the oil pump drivespring engages the slot on the outsidediameter of the drum.
STIHL 044 16
3.2 Clutch
Top:Master Control in cold start positionchoke shutter closed
Bottom:Twist lock on carburetor box cover
Top:Outer half of air filter
Bottom:1 = Spark plug terminal2 = Spark plug
Top:Locking strip 0000 893 5901
Bottom:Locking strip in position
- Push the locking strip into the sparkplug hole so that "TOP" or "OBEN" isfacing upward.
Important! To avoid the risk of pistondamage, use only the specified lockingstrip.
- Pull outer air filter element off thefilter base.
- Pull terminal off the spark plug andthen unscrew the spark plug.
Troubleshooting chart - see 2.1.
To remove and disassemble theclutch:
- Close the choke - hold down throttletrigger interlock and move MasterControl to lowest position.
- Release twist lock and lift awaycarburetor box cover.
STIHL 044 17
- Use assembly hook to remove allthe clutch springs.
- Pull the clutch shoes off the carrier.
- Pull the retainers off the clutchshoes.
- Clean all parts and stub of crank-shaft in white spirit. Replace anydamaged or worn parts.
To reassemble and install the clutch:
- Push the retainers onto the clutchshoes.
- Fit the clutch shoes over the arms ofthe clutch carrier so that the seriesnumber, e.g. 1128, is on the sameside as the carrier's hexagon.
Top:Clutch
Bottom:Assembly hook 5910 890 2800
Top:Removing a clutch spring
Bottom:Component parts of clutch
Top:Fitting retainer on clutch shoe
Bottom:Pushing clutch shoe onto carrier
- Remove the clutch drum or chainsprocket, see 3.1.
- Unscrew clutch from stub of crank-shaft.
Caution! Clutch has left-hand thread.Unscrew it clockwise.
- Remove oil pump cover washer fromstub of crankshaft.
STIHL 044 18
3.3 Chain Brake
3.3.1 Disassembly
- Remove the clutch drum with rimsprocket (or spur sprocket) - see 3.1.
- Remove mounting screw from innerside plate and lift side plate away.
- Remove mounting screws fromcovers and take out the two covers.
- Slip the cover washer, its raisedcenter must face outward, over thestub of the crankshaft.
- Screw clutch onto crankshaft andtighten down to a torque of 50 Nm(37 Ibf.ft).
- Install clutch drum with rim sprocket(or spur sprocket) - see 3.1.
- Remove locking strip from cylinder.Install spark plug and tighten downto a torque of 25 Nm (18.5 Ibf.ft).
- Fit outer half of air filter.
- Clamp the clutch, e.g. one clutchshoe, in a vise.
- Attach one end of each spring tothe clutch shoes by hand.
- Use the assembly hook to attachthe other ends of the springs andpress them firmly into the clutchshoes with one finger.
Top:Clutch clamped in vise
Bottom:Attaching clutch springs
Top:Cover washer
Bottom:Tightening the clutch
Top:Inner side plate mounting screw
Bottom:Mounting screws of covers
STIHL 044 19
- Carefully pry the brake spring off thebearing pin.
- Take out the brake band mountingscrew.
- Pry the brake band out of its seat inthe crankcase.
- Remove the brake band from theanchor lugs in the crankcase and thebell crank.
- Take out the hand guard mountingscrew.
- Remove E-clip from bell crank pivotpin.
Top:Detaching brake spring
Bottom:Brake band mounting screw
Top:Prying brake band out of recess
Bottom:Removing brake band
Top:Hand guard mounting screw
Bottom:E-clip on bell crank
STIHL 044 20
3.3.2 Assembly
- Position bearing boss of hand guardagainst the pivot pin and fit the otherside of the hand guard over the fanhousing.
- Press the cam lever downward andpush the hand guard and bell crankonto the pivot pins.
- Secure bell crank with E-clip.
- Fit hand guard mounting screw atfan housing side and tighten to atorque of 4 Nm (3.0 Ibf.ft).
- Slip cam lever over the pivot pin andsecure it with the E-clip.
- Attach spring to pivot pin and camlever.
- Insert bell crank in the side of thehand guard so that the short end ofthe lever points upward.
- Carefully pry the hand guard andbell crank off their pivot pins and liftaway.
- Remove the E-clip from the camlever pivot pin.
- Remove the spring.
Inspect condition of all parts. Replaceany damaged or worn parts.
Top:Pivot pins for hand guard and bell crank
Bottom:Detaching spring
Top:1 = Spring2 = Cam lever3 = E-clip
Bottom:Bell crank inserted in hand guard
Top:Pressing cam lever downward
Bottom:Correct installed position of hand guard
STIHL 044 21
Top:Position of protective tube on brake spring
Top: a = 20 mm (3/4") Top:Attaching brake band to bell crank b = 32 mm (1 1/4") Assembly tool 1117 890 0900
Bottom: Bottom: Bottom:Fitting brake band Brake spring attached to bell crank Attaching brake spring to bearing pin
- Attach brake band to bell crank.
- Position the brake band in thecrankcase so that it is behind theretaining lugs and then push it intoits seat in the crankcase.
- Fit the mounting screw and tightenit to 3 Nm (2.2 Ibf.ft).
- Check that protective tube is cor-rectly positioned on the brakespring.
- Attach the brake spring to the bellcrank.
- Use the assembly tool to attach thebrake spring to the bearing pin.
- Fit cover over the brake band.
- Fit the inner side plate.
- Install the clutch drum with rimsprocket (or spur sprocket) - see3.1.
STIHL 044 22
3.4 Chain Tensioner
Top:Inner side plate mounting screw
Bottom:1 = Thrust pad2 = Tensioner slide
Top:1 = Retainer2 = Mounting screw
Bottom:1 = Spur gear2 = Cover plate
Top:Removing tensioner slide with adjustingscrew and thrust pad
Bottom:0-ring in spur gear
- Remove chain sprocket cover.
- Remove mounting screw from innerside plate and lift side plate away.
- Use a screwdriver to turn spur gearclockwise until tensioner slide is atthe extreme right against the thrustpad.
- Pull out the retainer.
- Remove the cover plate mountingscrew.
- Pull the cover plate off the spur gear.
- Pull out the spur gear.
- Take out the tensioner slide withadjusting screw and thrust pad.
- Inspect the teeth on the spur gearand adjusting screw. Replace bothparts if recessary.
Reverse the above sequence to installthe chain tensioner.
Note: Coat teeth of adjusting screwand spur gear with grease, see 12.2,.before refitting.Check that 0-ring is fitted in spur gear.
STIHL 044 23
4.2 Catalytic Converter
4.2.1 Construction andFunction
The catalytic converter is integrated inthe upper casing of the muffler andhelps reduce the amount of noxiouselements in the exhaust gas by meansof a chemical reaction (afterburning).
A metal carrier catalyzer is installed inthe STIHL 044. The advantage of thistype of construction is that there is noloss of engine power compared tomachines without a catalyzer. Further-more, this catalyzer is temperatureresistant up to approx. 1,300 °C(2375 °F). Very thin corrugated stain-less steel foil inside the catalyzer isrolled in an "S" shape to produce ahoneycomb structure which is enclosedin a round steel jacket.
The honeycomb cells are coated withthe noble metal platinum which acts asthe catalyst. A chemical reaction takesplace when hot exhaust gas flowsthrough the catalyzer. Approximately80% of the hydrocarbons (HC) and upto 20% of the carbon monoxide (CO)are transformed into water (H2O) andnonpoisonous carbon dioxide (CO2).
4. ENGINE
4.1 Removing and RefittingExhaust Muffler (alsowith Catalytic Converter)
Lower casing with catalytic converter (cutopen in this view)
- Clean the spark arrestor screen or fita new one.
Reassemble in the reverse sequence.
Note: Fit a new exhaust gasket. Coatthreads of screws with Loctite, see12.2. Tighten screws of lower casingto 11.5 Nm (8.5 Ibf.ft). Tighten the twotop screws of upper casing to 9 Nm(6.6 Ibf.ft) and the two bottom screwsto 11.5 Nm (8.5 Ibf.ft).
Troubleshooting chart - see 2.2.
- Take out the upper casing mount-ing screws. If catalyzer is fitted,also remove the sleeve. Lift off theupper casing.
- Take out the lower casing mountingscrews. Remove the lower casingand exhaust gasket.
- Inspect the spark arrestor screen, iffitted. If necessary, bend back theretaining tabs and pull out thescreen.
STIHL 044 24
A catalyzer is a component whichinitiates chemical reactions withoutbeing consumed in the process.
The platinum coating of the honey-comb cells is sensitive to lead, i.e.lead collects on platinum. This inhibitsthe chemical reaction. If several tank-fuls of leaded fuel are used, the cata-lyzer's function can be reduced bymore than 50%. For this reason onlyunleaded gasoline may be used inchain saws with catalytic converters.
In order to avoid damage to the en-gine, the catalyzer must be replaced ifcracks are found in the honeycombstructure or if the catalyzer's steeljacket is damaged in any way.
The special construction of the mufflerbrings the exhaust gas temperaturedown to about the same as that of astandard muffler. Exhaust gas leavingthe injector nozzle in the upper casingflows into the jet tube located at theside of the lower casing. Owing to thehigh gas flow speed a relatively largevolume of fresh air is sucked in andused for cooling at this point. Thetemperature of the gas leaving the jettube (sideways above the chainsprocket cover) is reduced to approx.350 °C (660 °F) in this way.
Never attempt to modify either the jettube or the injector nozzle. In theevent of damage to the jet tube, re-place the lower casing. If the injectornozzle is damaged, fit a new uppercasing. Damage to either of theseparts can cause an increase in thetemperature of the exhaust gas leav-ing the jet tube.
Always check and, if necessary, repairthe fuel system, carburetor, air filter andignition system before looking for faultson the engine.- Troubleshooting chart - see 2.2.- Remove the carburetor - see 11.2.- Remove the lower casing - see 4.1.- Pull terminal off the spark plug and
then unscrew the spark plug.- Remove shroud mounting screws and
Bottom:Shroud mounting screws (thirdscrew hidden in this view)
STIHL 044 25
4.4 Cylinder and Piston
4.4.1 Removal
For preparations see 4.3.
- Unscrew the cylinder base screws.
- Pull the cylinder off the piston and,at the same time, push the manifoldthrough the tank housing opening.
Caution! Do not use pointed orsharp-edged tools for this job.
- Remove the cylinder gasket.
- Release the hose clamp on themanifold. Pull the manifold off theintake port.
- Inspect the cylinder and replace it ifnecessary.
Note: If a new cylinder has to be in-stalled, always fit the matching piston.Replacement cylihders are only sup-plied complete with piston for thisreason.
Top:1 = Washer2 = Sleeve
Bottom:Correct position of ignition lead
Top:Throughholes to cylinder base screws
Bottom:Removing cylinder and pushing manifoldout of tank housing
Top:Removing cylinder gasket
Bottom:1 = Hose clamp2 = Manifold
- Pull the washer off the studs andremove the sleeve from the mani-fold.
Reassemble in the reverse sequence.
Note: When refitting the shroud, makesure the ignition lead is properly lo-cated in the shroud recess (see illus-tration).
STIHL 044 26
4.4.2 Installation
Top:Removing snap ring
Bottom:Assembly drift 1110 893 4700
Top:Pushing out piston pin
Bottom:Piston rings
Top:Needle cage in small end
Bottom:1 = Arrow on piston head2 = Snap ring
- Thoroughly clean the gasket seatingsurface on the cylinder. Lubricate theneedle cage with oil and fit it in thesmall end.
- Fit snap ring in the forward facingpiston boss (arrow on piston headpointing to the right).
Note: Fit the snap ring with specialinstalling tool 5910 890 2210.
- Now use the assembly drift to pushthe piston pin out of the piston. If thepiston pin is stuck, tap the end ofthe drift lightly with a hammer ifnecessary. Important: Hold thepiston steady during this process toensure that no jolts are transmittedto the connecting rod. Remove thepiston and take the needle cage outof the connecting rod.
- Inspect piston rings and replace ifnecessary - see 4.5.
Important! Before removing the pis-ton, decide whether or not the crank-shaft has to be removed as well. Toremove the flywheel, see 5.1.7, blockthe crankshaft by sliding the woodenassembly block between the pistonand crankcase.
- Use a scriber or similar tool to easethe hookless snap rings out of thegrooves in the piston bosses.
STIHL 044 27
- Apply the installing tool to the pistonboss (flat face on shank must pointtoward piston head), hold the pistonsteady, center the tool shank exactlyand press home until the snap ringslips into the groove.
Note: The snap ring must be fitted sothat the ring gap is on the piston'svertical axis (it must point either up ordown).
- Push the slotted diameter of thesleeve over the magnet and snapring so that the inner pin slides onthe flat face of the tool's shank.
- Stand the installing tool, sleevedownward, on a flat surface (woodenboard) and press vertically down-wards until the sleeve butts againstthe tool's shoulder.
- Remove the sleeve and slip it ontothe other end of the shank.
Note: Pin must point toward flat faceof tool's shank.
Top:1 = Installing tool 5910 890 22102 = Sleeve
Bottom:1 = Snap ring (hookless)2 = Magnet
Top:1 = Flat on end of shank2 = Pin
Bottom:Pushing installing tool into sleeveas far as stop
Top:Slipping sleeve onto other endof shank
Bottom:Inserting snap ring in piston boss
- Use the installing tool as follows:
- Remove the sleeve from the tool.
- Attach the hookless snap ring to themagnet so that the snap ring gap ison the flat side of the tool's shank(see illustration).
STIHL 044 28
- Lubricate the piston and piston ringswith oil and place the piston on thewooden assembly block.
- Position the piston rings so that theradii at the ring gap meet at the fix-ing pin in the piston groove when therings are compressed.
- Heat the piston on an electric heat-ing plate to approx. 60 °C (140 °F)and slip it over the connecting rod sothat the arrow on the piston headpoints toward the muffler.
- Use the assembly drift to push thepiston pin into the piston and needlebearing (the piston pin slides homeeasily when the piston is hot).
Top:Arrow on piston head points toward muffler
Bottom:Installing the piston pin
Top:Inserting snap ring with installingtool 5910 890 2210
Bottom:Wooden assembly block 1108 893 4800
Top:Piston resting on wooden assembly block
Bottom: Upper piston ring correctly posi-tioned
- Use the installing tool 590 890 2210to fit the snap ring in the piston boss.
- Fit the cylinder gasket.
STIHL 044 29
- Push the manifold onto the intakeport so that its integrally molded tablines up with the rib on the cylinder(see illustration).
- Slide the hose clamp onto the mani-fold. The screw head must point tothe right.
- Tighten the hose clamp so that itsends point to the right at an angle of45° ± 10° (looking at intake port).Continue tightening the screw untilthe gap between the two ends of thehose clamp is 5.5 ± 0.5 mm(7/32" ± 1/64").
- Use the clamping strap to compressthe piston rings around the piston(check again to see that they are cor-rectly positioned).
- Lubricate the inside of the cylinderwith oil and line it up so that it is po-sitioned exactly as it will be in theinstalled conditon (see illustration). Ifthis point is not observed, the pistonrings may break.
- Now slide the cylinder over the pis-ton - the clamping strap is pusheddownward as the piston rings slipinto the cylinder.
Top:Correct position of manifold
Bottom:Correct position of hose clampa = 45°±10°b = 5.5 ± 0.5 mm (7/32" ± 1/64")
Top:Clamping strap 0000 893 2600
Bottom:Compressing piston ringswith the clamping strap Fitting aligned cylinder over the piston
STIHL 044 30
4.5 Piston Rings
Top:Pressing the manifold downward
Bottom:Pulling manifold through intakeopening in tank housing
Top:Spline screwdriver bit 0812 542 2104
Bottom:Tightening the cylinder base screws
Top:Piston ring grooves
Bottom:Fitting piston ring
- Remove the piston - see 4.4.1.
- Remove rings from piston.
- Use a piece of an old piston ring toscrape the grooves clean.
- Install the new piston rings in thegrooves so that the radii face up-ward.
- Install the piston - see 4.4.2.
- Remove the clamping strap andwooden assembly block and care-fully line up the cylinder and gasket.Fit the cylinder base screws andtighten them down to a torque loadof 10.5 Nm (7.7 Ibf.ft).
Assembly is now a reversal of thedisassembly sequence. Always fit newgaskets as a matter of routine.
- Fit the manifold in the tank housingintake opening as follows: Wind apiece of string (about 15 cm / 6"long) around the back of the man-ifold flange, then press the manifolddownward and pass the ends of thestring through the intake opening.
- Pull the ends of the string outward.The manifold flange is thus pulledthrough the tank housing intakeopening without damaging themanifold.
STIHL 044 31
- Pull the short circuit wire and groundwire out of the grommet in the hous-ing.
- Remove the E-clip from the bellcrank pivot pin.
- Carefully ease the hand guard andbell crank off the pivot pins and liftaway.
4.6 Crankcase
4.6.1 Removing the Crankshaft
Top:Fan housing mounting screws
Bottom:Releasing flywheel nut
Top:Removing flywheel with puller1110 890 4500
Bottom:1 = Mounting screws2 = Short circuit wire
Top:Removing short circuit and ground wires
Bottom:1 = Hand guard2 = Bell crank3 = E-clip
- Drain the chain oil tank.
Remove the exhaust muffler -see 4.1.
- Remove the oil pump - see 10.4.- Take out the fan housing mounting
screws and lift away the fan hous-ing.
- Remove the fan housing - see11.8.1.
- Remove the cylinder - see 4.4.1.- Unscrew the flywheel mounting nut
from the crankshaft.
- Pull the flywheel off the crankshaft,see 5.1.7.
- Take the Woodruff key out of the slotin the crankshaft stub.
- Pull the short circuit wire off theconnector.
- Remove the mounting screws fromthe ignition module and lift away themodule.
STIHL 044 32
- Remove the piston - see 4.4.1.
- Hold the nut steady and remove thespiked bumper mounting screw. Liftaway the spiked bumper.
- Unscrew the five mounting screwswhich join the two halves of thecrankcase.
- Use a screwdriver to rotate spurgear clockwise until the tensionerslide butts against the thrust pad.
Note: Use service tools AS and ZS toremove the crankshaft. Follow theinstructions supplied with the tool.
- Back off the spindle by turning itclockwise until the tool's drilled platelocates flat against the crankcase.
- With the crankcase horizontal (cyl-inder flange upward), rotate servicetool until the number 12 on platepoints downward.
- Secure the service tool to thecrankcase with the three M5 x 72mounting screws. Insert the screwsin the holes marked "12" andtighten them down against thedrilled plate.
- Turn spindle counterclockwise untilit locates against the crankshaft.
- Use a 19 mm wrench to continueturning the spindle and thus pushthe crankshaft out of its bearingseat at the ignition side.
- Turn the spindle clockwise until thecrankshaft is pressed out of the ballbearing. The two halves of thecrankcase separate during thisprocess.
- Fit service tool ZS against theoutside of the crankcase (ignitionside).
- Use a suitable tool, e.g. 5 mm(3/16") drift, to drive the dowel pin(at chain tensioner side) out of thetwo halves of the crankcase.
- Back off spindle of service tool ASall the way.
- Slip service tool AS over the twocollar studs, fit the hexagon nuts(for sprocket cover) and tightenthem down by hand.
Top:Driving out dowel pin
Bottom:Service tool AS mounted in position
Top:Pressing crankshaft out of bearingseat at clutch side
Bottom:Service tool ZS mounted in position
Pressing crankshaft out of bearingseat at ignition side
STIHL 044 34
- The crankshaft, connecting rod andneedle bearing form an inseparableunit. This means that the crankshaftmust always be replaced as a com-plete unit in the event of damage toany one of these parts. When fittinga replacement crankshaft alwaysinstall new oil seals and ball bear-ings.
- Remove the gasket from the crank-case sealing face.
- Pry the oil seal out of its seat at theignition side.
- Use arbor to press the ball bearingout of its seat at the ignition side.
- Pry the oil seal out of the ball bear-ing at the clutch side.
- Use arbor to press the ball bearingout of the clutch side of the crank-case.
- Inspect the two halves of the crank-case for cracks and replace if neces-sary.
Note: The crankcase must be replacedas a complete unit even if only one halfis damaged.
All other parts which are still service-able can then be transferred to thenew crankcase after the new bearingshave been fitted, i.e. the crankcasehas to be heated for this purpose.
- Remove the annular buffer mountingscrews and take out the buffer.
1 = Crankshaft2 = Connecting rod
Top:Pressing out ball bearing witharbor 1120 893 7200
Bottom:Prying out oil seal
Top:Pressing out ball bearing witharbor 1118 893 7200
Bottom:Annular buffer mounting screws
STIHL 044 35
- Pull the oil pick-up hose out of thebore in the crankcase.
- Remove the complete chain tensioner - see 3.4.
- If necessary, unscrew the collarstuds. To do this, push the stud pul-ler over the collar stud as far as itwill go and use a 15 mm wrench tounscrew the stud counterclockwise.
- Pry the annular buffer out of theother side of the crankcase.
- Pry the two annular buffers out ofthe clutch side of the crankcase.
Top:Prying out annular buffer (ignition side)
Bottom:Prying out annular buffer (clutch side)
Top:Prying out stop buffer
Bottom:1 = Spring2 = Lever3 = E-clip
Top:Removing oil pick-up hose
Bottom:Unscrewing collar stud with studpuller 5910 893 0506
- Pry the stop buffer out of its seat andremove it from the crankcase.
- Detach and remove the spring.
- Remove the E-clip from the lever'spivot pin and pull the lever off the pin.
STIHL 044 36
4.6.2 Installing the Crankshaft
If the original crankcase is used again,remove the gasket residue and cleanthe mating surfaces - they must becleaned very thoroughly to ensure aperfect seal.
Note: If you install a new crankcase,stamp the machine number on thecrankcase with 2.5 mm (0.1") figurestamps.
- Check that dowel pin is in position orfit it in the new crankcase.
- Pull the plastic plug out of the oilpump and take the 0-ring out of thegroove in the delivery line.
- Position the oil pump against thecrankcase. Fit and tighten down themounting screws.
Note: Before heating the crankcase,remove all rubber and plastic com-ponents, such as oil pick-up and de-livery hoses, grommets, annular buff-ers and levers (7.1, 10.2). Checkcondition of all parts and replace asnecessary.
- Heat area of bearing seat on clutchside of crankcase to approx. 120 °C(250 °F).
- Place ball bearing with wider outerrace in position so that its flat sidefaces upward and then press it inuntil it locates against the oil pump.
Note: The ball bearing can be fitted byhand if the crankcase is heated asspecified. However, this operationmust be carried out very quickly be-cause the bearing absorbs heat im-mediately and begins to expand.
Top:Crankcase in correct assemblysequence
Bottom:Dowel pin
Bottom:1 = 0-ring2 = Plastic plug
Top:Oil pump fitted in position
Bottom:Ball bearing in position (flat sidefacing upward)
STIHL 044 37
- Use a blunt tool to push the oil pick-up hose into the bore so that the tablocates in its seat at the bottom right(see illustration).
- Fit the lever over the pivot pin andsecure it with the E-clip.
- Attach the spring.
- Install the chain tensioner - see 3.4.
- Push the two annular buffers (ta-pered side first) into position untiltheir annular grooves engage theinner rib.
- Slip the oil pick-up hose through thecrankcase bore.
If no facilities for heating the crankcaseare available, use the press arbor toinstall the ball bearing.
- Remove the oil pump and refit theplastic plug and new 0-ring.
- After the crankcase has cooleddown, push the stop buffer into itsseat. Make sure the tabs locate be-hind the housing face.
Top:Pressing in ball bearing witharbor 1118 893 7200
Bottom:Fitting stop buffer
Top:Fitting annular buffer
Bottom:Fitting oil pick-up hose
Top:Correctly fitted oil pick-up hose
Bottom:1 = lever2 = Spring3 = Chain tensioner
STIHL 044 38
- Heat area of bearing seat on ignitionside of crankcase to approx. 120 °C(250 °F).
- Press ball bearing fully home as faras stop. The open side of the bear-ing must face downward.
Important! The ball bearing is closedat one side. The closed side must beon the inside of the crankcase toguarantee proper protection.
Note: The ball bearing can be fitted byhand if the crankcase is heated asspecified. However, this operationmust be carried out very quickly be-cause the bearing absorbs heat im-mediately and begins to expand. If no facilities for heating the crankcase
are available, use the press arbor toinstall the ball bearing.
- Push the annular buffer into thecrankcase bore, from the outside,until its annular groove engages theinner rib.
- Place the annular buffer in positionthe large bore must face outward. Fitthe mounting screws and tightenthem to 6.5 Nm (4.8 Ibf.ft).
- Extend the spindle of service tool ZSfully and then screw the threadedsleeve onto the spindle as far as itwill go.
Ball bearing in position
Top:Pressing in ball bearing witharbor 1118 893 7200
Bottom:Fitting annular buffer in ignition sideof crankcase
Top:Annular buffer mounting screws
Bottom:Threaded sleeve 5910 893 2420 fittedon spindle of service tool ZS
STIHL 044 39
- Coat bearing seat of crankshaftstub at ignition end with oil and po-sition it in the bearing from the in-side of the crankcase.
- Screw the threaded sleeve onto thecrankshaft stub.
- Hold the service tool and crankshaftsteady and rotate the spindle clock-wise until the service tool buttsagainst the crankcase.
- Pull the crankshaft into the bearingas far as it will go by turning thespindle clockwise.
Important! The connecting rod mustpoint toward the cylinder flange whilethe crankshaft is being installed.
- Remove the service tool: Releasethe spindle by turning it counter-clockwise and then unscrew theservice tool counterclockwise.
- Fit a new gasket on the clutch sideof the crankcase.
- Coat crankshaft stub at clutch endwith oil and slide crankshaft into ballbearing as far as it will go.
- To prevent the crankcase and gaskettwisting, fit M5x72 screws (from serv-ice tool ZS) in two crankcase holes.
Important! Screw the right-hand screwfully home to the end of the thread.
- Make sure that tensioner slide buttsagainst the thrust pad. If necessary,rotate the tensioner's spur gearclockwise until the tensioner slide isagainst the thrust pad.
- Screw the spindle fully into servicetool AS by turning it clockwise.
- Screw threaded sleeve onto the endof the spindle as far as it will go (left-hand thread).
- Slip the threaded sleeve over thecrankshaft stub.
- Hold the crankshaft steady andscrew the threaded sleeve onto thecrankshaft stub by turning the spin-dle counterclockwise.
- Let go of the crankshaft. Hold theservice tool steady and continueturning the spindle until the tool lo-cates against the bar mounting face.
- Fit the two sprocket cover mountingnuts on the collar studs and tightenthem down by hand.
Mounting service tool AS
Top:1 = Thrust pad2 = Tensioner slide
Bottom:Threaded sleeve 5910 893 2409fitted on spindle
Top:Locating crankshaft stub
Bottom:Two screws fitted to prevent rotation
STIHL 044 41
- Rotate the spindle counterclockwiseand thus pull the crankshaft into thebearing as far as stop.
- Remove the hexagon nuts, unscrewthe spindle clockwise and lift awaythe service tool.
- Take out the two M5x72 screws.- Use a 5 mm (3/16") drift to drive the
dowel pin into the two halves of thecrankcase - from the chain tensionerside.
- Insert the crankcase connectingscrews and tighten them down alter-nately in a diagonal pattern to 9 Nm(6.6 Ibf.ft).
Note: Trim away any excess gasketmaterial in the area of the cylindermounting face. If the crankshaft doesnot turn freely, it is sufficient to tap theend of the stub with a plastic mallet torelieve axial stresses.
- Coat sealing lips of the oil seals withlubricating grease - see 12.2.
- Push the oil seal over the ignitionend of the crankshaft (the open sideof the seal must face the crankcase)and use the installing tool to press ithome.
- Slip the oil pump spacer bush (largediameter first) over the clutch end ofthe crankshaft.
Top: Top:Top: Tightening crankcase connecting Pressing in oil seal at ignition sidePulling two halves of crankcase together screws
Bottom:Bottom: Bottom: Fitting spacer bush overDriving in dowel pin Installing tool 1128 890 3900 crankshaft stub
STIHL 044 42
4.7 Leakage Testing theCrankcase
- Slide the oil seal over the spacerbush (the open side of the seal mustface the crankcase) and use thepress sleeve to press it home.
- Remove the spacer bush.
Assembly of the remaining parts is areversal of the disassembly sequence.
Defective oil seals and gaskets orcracks in castings are the usual cau-ses of leaks. Such faults allow sup-plementary air to enter the engineand thus upset the fuel-air mixture.
This makes adjustment of the pre-scribed idle speed difficult, if not im-possible.
Moreover, the transition from idlespeed to part or full throttle is notsmooth.
The crankcase can be checked ac-curately for leaks with the carburetorand crankcase tester and the vacuumpump.
Bottom: Bottom:Pressing in oil seal at clutch side Vacuum pump 0000 850 3500
STIHL 044 43
4.7.1 Preparations
- Remove the shroud.
- Take out the muffler upper casingmounting screws and remove theupper casing.
- Slacken off the muffler lower casingmounting screws about half way.
- Slide the sealing plate between themuffler lower casing and the cylinderexhaust port. Retighten the mount-ing screws moderately.
Note: The sealing plate must com-pletely fill the space between the twomounting screws. Push the narrowend of the sealing plate home until itjust locates under the lower casing.
- Remove the carburetor - see 11.2.
- Set the piston to top dead center(T.D.C.). This can be checked throughthe inlet port.
- Fit the test flange in place of the car-buretor.
Important! When fitting the test flange,make sure the pin locates properly inthe impulse hose.
Bottom: Bottom: Bottom:Muffler lower casing mounting screws Sealing plate fitted in position Test flange fitted in position
STIHL 044 44
4.7.2 Pressure Test
- Connect tester's pressure hose tonipple on test flange.
- Make sure the spark plug is properlytightened down before starting thetest.
- Close the vent screw on the rubberbulb.
- Pump air into the crankcase until thegauge indicates a pressure of0.6 bar (8.7 psi). If this pressure re-mains constant for at least 20 sec-onds, the crankcase is airtight.However, if the indicated pressuredrops, the leak must be located andthe faulty part replaced.
Note: Coat the suspect area with oiland pressurize the crankcase again.If bubbles appear in the oiled area,replace the faulty part.
- Now carry out the vacuum test - see4.7.3.
- After finishing the test, open thevent screw and disconnect thehose.
- Remove the test flange and refit thecarburetor - see 11.2.
- Take out the muffler lower casingmounting screws.
- Remove the sealing plate from be-tween the lower casing and cylinder.
- Coat the lower casing mountingscrews with Loctite (see 12.2), refitthem and tighten to a torque of11.5 Nm (8.5 Ibf.ft).
- Refit the muffler upper casing.
Top:Tester's pressure hose fitted on testflange nipple
Bottom:Closing the vent screw Pressure-testing the crankcase
STIHL 044 45
4.7.3 Vacuum Test
Oil seals tend to fail when subjected toa vacuum, i.e. the sealing lip liftsaway from the crankshaft during thepiston's induction stroke becausethere is no internal counterpressure.
An additional test can be carried outwith the vacuum pump to detect thiskind of fault. The preparations for thistest are the same as for the pressuretest - see 4.7.2.
- Connect the vacuum pump's suctionhose to test flange nipple.
Pull out the pump piston until thegauge indicates a vacuum of 0.4 bar(5.8 psi).Note: When you release the pumppiston the non-return valve automat-ically seals the suction hose.If the vacuum reading remains con-stant, or rises to no more than 0.3 bar(4.25 psi) within 20 seconds, it can beassumed that the oil seals are in goodcondition.However, if the pressure continues torise (reduced vacuum in crankcase),the oil seals must be re placed, even if
no leaks were detected in the pressuretest.
- Remove the test flange and refit thecarburetor - see 11.2.
- Take out the muffler lower casingmounting screws.
- Remove the sealing plate from be-tween the lower casing and cylinder.
- Coat the lower casing mountingscrews with Loctite (see 12.2), refitthem and tighten to a torque of11.5 Nm (8.5 Ibf.ft).
- Refit the muffler upper casing.
Tester's suction hose fitted on testflange nipple Leakage test with vacuum pump
STIHL 044 46
Top:Top: Oil pump Top:Flywheel Removing oil seal at clutch side
Bottom:Bottom: Puller 0000 890 4400 with jaws Bottom:Woodruff key for flywheel location 0000 893 3706 (No. 3.1+ 4) Fitting spacer bush
4.8 Replacing theOil Seals
It is not necessary to disassemble thecomplete crankcase if only the oilseals have to be replaced.
- Remove the flywheel - see 5.1.7.
- Remove the Woodruff key for theflywheel.
- Remove the clutch - see 3.2.
- Remove the brake band - see 3.3.1.
- Remove the oil pump - see 10.4.
Clutch side:- Apply the puller (with jaws 3.1) and
withdraw the oil seal at the clutch side.
Note: When using the puller make surethat it does not damage the crankshaftsurface, especially in the area of the oilseals.
- Slip the oil pump spacer bush without0-ring (large diameterfirst) over thecrankshaft.
STIHL 044 47
- Coat the sealing lip of the oil sealwith lubricating grease - see 12.2.
- Push the oil seal over the spacerbush. Open side of oil seal mustface the crankcase.
- Remove the spacer bush and presshome the oil seal with the presssleeve.
Ignition side:- Fit No. 6 jaws to the puller.
- Apply the puller and withdraw the oilseal at the ignition side.
Note: When using the puller makesure that it does not damage thecrankshaft surface, especially in thearea of the oil seals.
- Coat the sealing lip of the oil sealwith lubricating grease - see 12.2.
- Push the oil seal over the crankshaftstub (the open side of the oil sealmust face the crankcase) and pressit home with the installing tool.
- Fit the flywheel - see 5.1.7.- Fit the oil pump - see 10.4.- Fit the brake band - see 3.3.2.- Fit the clutch - see 3.2.
Bottom: Bottom: Bottom:Pressing in oil seal at clutch side Removing oil seal at ignition side Pressing in oil seal at ignition side
STIHL 044 48
5. IGNITION SYSTEM
Warning! Exercise extreme cautionwhen carrying out maintenance andrepair work on the ignition system. Thehigh voltages which occur can causeserious or even fatal accidents!
5.1 Repairing ComponentParts
5.1.1 Spark Plug
Top:Checking electrode gap withfeeler gauge
Bottom:Resetting electrode gap with Boschspark plug gauge
1 = Flywheel2 = Ignition module
Troubleshooting on the ignition sys-tem should always begin at the sparkplug.
In the event of starting difficulties, lowengine power, misfiring, etc., unscrewthe spark plug and check that it is theapproved type. Only the spark plugslisted in the specifications may be used.Other makes of spark plug are unsuit-able because they have long-reachelectrodes.
Sooted or carbonized spark plug:
- Use brass wire brush to clean thespark plug and then blow it clear withcompressed air.
Note: Never use a steel wire brush forthis job.
Spark plug is smeared with oil:
- Wash the insulator nose with a greasesolvent and blow it clear with com-pressed air.
Electrode gap:
Electrode gap becomes wider as aresult of normal erosion.
The STIHL 044 is equipped with a tran-sistor-controlled electronic (breakerless)magneto ignition system which requiresno outside power source (battery ordynamo).
The system consists basically of anignition module and flywheel and iseasily accessible.
Note: A special flywheel is installed inmodels with heated handles (with ringmagnet for the generator).
- Check the gap at regular intervals witha feeler gauge. It should be 0.5 mm(0.02").
- Bend the ground electrode as neces-sary.
Important! Always fit a new spark plugif the electrodes are badly pitted.
STIHL 044 49
Checking the spark plug:
Accurate checking of the spark plug isonly possible with a special spark plugtester.
A provisional check can be carried outby fitting a clean spark plug in the sparkplug terminal and holding it againstground. There should be a powerfulsparkover at the electrodes when theengine is cranked by pulling the starterrope.
Warning! Do not touch any live parts -contact with high voltage can causeserious or fatal accidents!
Note: It is recommended that a newspark plug be fitted in all cases of doubt.
If there is no sparkover although thespark plug is in good condition, firstcheck the lead connections.
Note: Chafed insulation on the ignitionlead or short circuit wire will cause ashort-circuit to ground. In this case theengine with either not start or only runerratically.
To install the spark plug:
- Clean the spark plug seat and inspectthe sealing ring to make sure it is ingood condition.
- Fit the spark plug and tighten it downto a torque of 25 Nm (18.5 Ibf.ft).
STIHL 044 50
- Remove the air filter - see 11.1.
- Pull off the spark plug terminal andunscrew the spark plug.
- Unscrew the shroud mountingscrews and lift off the shroud.
- Pull the dust seal off the terminaland push it down the ignition lead.
- Use a suitable pair of pliers to grip theleg spring and pull it out of the sparkplug terminal.
- Coat the end of the ignition lead andinsulating tube with oil (about200 mm/8" long).
- Fit spark plug terminal over the ig-nition lead.
- Use a suitable pair of pliers to gripthe end of the ignition lead and pull itout of the spark plug terminal.
- Pinch the hook of the leg spring intothe center of the lead, about 15 mm(5/8") from the end of the lead.
- Pull the lead back into the terminalso that the leg spring locates prop-erly inside it (see illustration).
- Slip the dust seal over the spark plugterminal.
- Refit the shroud. Fit spark plug andtighten it down to a torque of 25 Nm(18.5 Ibf.ft).
- Push the terminal onto the sparkplug.
- Refit the air filter - see 11.1.
5.1.2 Spark Plug Terminal
Top:1 = Spark plug terminal Top:2 = Spark plug Pulling leg spring out of spark3 = Shroud plug terminal
Bottom: Bottom: Correct position of leg spring in sparkRemoving dust seal Attaching leg spring plug terminal
STIHL 044 51
5.1.3 Ignition Lead 5.1.4 Wiring Harness
- Remove the air filter - see 11.1.
- Pull off the spark plug terminal andunscrew the spark plug.
- Unscrew the shroud mounting screwsand lift off the shroud.
- Remove carburetor - see 11.2.
- Remove fan housing.
- Remove ignition module mountingscrews.
- Remove the spark plug terminal see5.1.2.
- Cut new ignition lead to length (seeparts list or cut to same length as oldlead).
Assembly is now a reversal of the dis-assembly sequence.
Note: The end of the ignition lead thatscrews into the module must be piercedwith a pointed tool (see illustration).
Top: Top:Pulling unscrewed ignition lead Top: Shroud mounting screws (thirdout of ignition module Spark plug terminal screw hidden in this view)
Bottom: Bottom: Bottom:Removing insulating tube Piercing center of ignition lead Ignition module mounting screws
- Remove the shroud - see 5.1.2.
- Remove ignition module - see5.1.6.2.
- Unscrew the lead from the contactpin and pull it out of the ignitionmodule.
STIHL 044 52
- Disconnect the short circuit wire fromthe ignition module.
- Pull the terminal pin out of thesocket.
- Pull the grommet out of the tankhousing and off the wires.
- Pull the wires to the rear and out ofthe tank housing.
- Remove the front grommet in thetank housing and pull the wires for-ward and out of the housing.
- Take out the handle molding fas-tening screw and carefully removethe molding.
- Pull the throttle trigger interlock leverout of its seat.
- Slide the insulating tube off the plugconnector of the wire from the gen-erator to the handle heating element.
- Separate the plug connector andremove the insulating tube.
Bottom: Bottom: Bottom:Grommet on wires Grommet in tank housing Removing insulating tube
STIHL 044 53
5.1.5 Stop Switch
- After fitting the wiring harness, posi-tion the grommets correctly in theirrespective tank housing openings.
Coat the threads of the module mount-ing screws with Loctite (see 12.2).Place the ignition module in position,insert the screws with washers (fitground wire under upper screw) but donot tighten down yet.
Important! A washer must be fittedunder each screw head.
Slide the setting gauge between thearms of the ignition module and theflywheel magnets.
Press the ignition module against theflywheel. Tighten down the mountingscrews to a torque of 9 Nm (6.6 Ibf.ft)and withdraw the setting gauge.
- Remove the switch shaft - see 8.1.- Rotate the switch housing until the
switch actuator is exposed.- Use suitable pliers to withdraw the
switch actuator and remove thespring.
- Ease the switch housing sidewaysand remove it carefully.
Installation is a reversal of the re movalsequence.
Note: The switch actuator must bepushed in until it snaps into position.
- Disconnect the short circuit andground wires from the contact springs.
- Remove the switch - see 9.2.
- Remove the wiring harness.
Installation is a reversal of the removalsequence.
Note: Make sure the generator wire isproperly located in the rear handle.
Withdrawing switch actuatorBottom:Correct position of wires in rear Tightening ignition module mounting Bottom:handle screws Removing switch housing from shaft
STIHL 044 54
5.1.6 Ignition Module 5.1.6.1 Ignition Timing 5.1.6.2 Removing and Installing
Ignition timing is fixed at 2.6 mm (0.10")B.T.D.C. at 8,000 rpm and cannot beadjusted. However, in view of the per-missible tolerances in the electroniccircuit, it may vary between 2.0 and3.0 mm (0.08" and 0.12") B.T.D.C. at8,000 rpm.
Since there is no mechanical wear inthese systems, ignition timing cannotget out of adjustment. However, aninternal fault in the circuit can alter theswitching point in such a way that aspark test will still show the system tobe in order although timing is outsidethe permissible tolerance. This willimpair engine starting and runningbehavior.The ignition module accommodates all
the components required to controlignition timing. There are only twoelectrical connections on the coil body,i.e.:
1. the high voltage output2. the connector tag for the short
circuit wire.
Accurate testing of the ignition moduleis only possible with sophisticated testequipment. For this reason it is onlynecessary to carry out a operationalcheck in the workshop. A new ignitionmodule must be installed if no ignitionspark is obtained (after checking thatwiring and stop switch are in goodcondition). - Remove fan housing - see 4.6.1.
- Disconnect short circuit wire from tagon ignition module and take it out ofthe retainer.
- Remove the ignition module mount-ing screws.
1 = High voltage output2 = Connector tag
Top:1 = Wire retainer2 = Short circuit wire
Bottom:Ignition module mounting screws
STIHL 044 55
5.1.7 Flywheel
- Unscrew the ignition lead from thecontact pin and pull it out of the igni-tion module.
- If necessary, remove the wire re-tainer from the module.
- Refit the ignition lead by screwing itinto the high voltage output.
- Coat the threads of the modulemounting screws with Loctite (see12.2). Place the ignition module inposition, insert the screws withwashers (fit ground wire under upperscrew) but do not tighten down yet.
Important! A washer must be fittedunder each screw head.
- Slide the setting gauge between thearms of the ignition module and theflywheel magnets.
- Press the ignition module against theflywheel. Tighten down the mountingscrews to a torque of 9 Nm (6.6 Ibf.ft)and withdraw the setting gauge.
- Fit the fan housing.
To remove the flywheel:- Use the locking strip to block the pis-
ton - see 3.2.- Take out the fan housing mounting
screws and remove the fan housing.- Rotate the flywheel so that the magnet
poles are opposite the ignition mod-ule.
- Use 13 mm socket wrench to unscrewthe flywheel mounting nut from thecrankshaft.
Top:Pulling unscrewed ignition lead out Top: Top:of ignition module Setting gauge 1111 890 6400 Locking strip 0000 893 5901
in positionBottom: Bottom:Removing wire retainer from ignition Setting gauge inserted between Bottom:module flywheel and ignition module Releasing flywheel mounting nut
STIHL 044 56
Important! Clean the stub of thecrankshaft and the flywheel hub borewith a suitable standard commercial,solvent-based degreasant. Fit theflywheel in position and tighten downthe mounting nut to a torque of 33 Nm(24.5 Ibf.ft).
Assembly of the remaining parts isnow a reversal of the disassemblysequence.
- Inspect the flywheel and magnetpoles for any signs of cracks or otherdamage. Fit a new flywheel if youfind any damage.
To install the flywheel:
- Check that Woodruff key is correctlypositioned.
- Screw the puller into the flywheel.- Hold the puller steady with a 24 mm
open-end wrench and tighten downthe thrust bolt until the flywheelcomes away from its seat on thecrankshaft.
- Take off the flywheel.
Top:Puller 1110 890 4500
Bottom:Removing the flywheel
Top:1 = Flywheel2 = Magnet poles
Bottom:Woodruff key for flywheel Tightening flywheel mounting nut
STIHL 044 57
6.2 Rope Rotor/Pawls
- Use a screwdriver or suitable pair ofpliers to carefully remove the springclip from the starter post.
- Take the washer and rope rotor withpawls off the starter post.
- Remove the pawls and check to seeif they are in good condition, replaceif necessary.
- Replace the broken or worn starterrope - see 6.3.
Installing the rope rotor
- Coat the bore in the rope rotor withSTIHL low temperature lubricate. Fitthe rotor on the starter post so thattheinner spring loop slides into the lugon the rotor.
Note: Check that the spring loop hasengaged by turning the rope rotorslightly and letting it go - it must springback.
- Fit the pawls.
- Fit the washer and install the springclip in the starter post groove.
Note: Make sure the spring clip en-gages on the pawl guide pegs andpoints them in the clockwise direction.
- The spring clip must be treated verycarefully. If it is bent during disas-sembly or assembly, the rewindstarter might malfunction.
- Tension the rewind spring - see 6.5.
Removing rope rotor
Troubleshooting chart - see 2.4.
The fan housing has to be removed foraccess to the starter mechanism - see4.6.1.
Relieve tension of rewind spring:
- Pull out the starter rope to a length ofapprox. 30 cm (1 ft) and hold the roperotor steady.
- Use a screwdriver to catch the starterrope between the rope guide bushand the rope rotor.
- While still holding the rope rotorsteady, take three full turns off therope rotor.
- Pull out the rope with the starter gripand then let go of the rope rotor.
Note: The rope rotor will spin back andthus relieve the tension on the rewindspring. The rewind spring will not beunder tension if the starter rope is bro-ken.
If the action of the starter rope becomesvery stiff and the rope rewinds veryslowly or nor completely, it can be as-sumed that the starter mechanism is inorder but plugged with dirt. At very lowoutside temperatures the lubricating oilon the rewind spring may thicken andcause the spring windings to stick to-gether. This has a detrimental effect onthe function of the starter mechanism. Insuch a case it is sufficient to apply a fewdrops of paraffin (kerosine) to the rewindspring.
Then carefully pull out the starter ropeseveral times and allow it to rewind untilits normal smooth action is restored.
If clogged with dirt or pitch, the entirestarter mechanism, including the rewindspring, must be removed and disas-sembled. Take special care when re-moving the spring.
Wash all parts in paraffin or white spirit.
Lubricate the rewind spring and starterpost with STIHL low temperature lubri-cant, see 12.2, before installing.
6. REWIND STARTER
6.1 Routine Maintenance
Removing spring clip
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6.3 Replacing the StarterRope
6.4 Replacing the RewindSpring
Top:Starter rope correctly positioned in Top:rope rotor 1 = Special knots
2 = Rope guide bushBottom:Starter rope secured in rope rotor Bottom:with knot Special knots used Rewind spring fitted in position
- Remove the rope rotor, see 6.2, andtake out the spring housing. Use apair of pliers to remove the bits of thebroken spring from the starter cover.
- The replacement spring is suppliedwith spring housing ready for installa-tion. It should be lubricated with a fewdrops of STIHL low temperature lubri-cant before installation.
- Position the replacement spring withspring housing (bottom facing upward)in the starter cover. Make sure theouter spring loop engages the recessin the starter cover.
Important! If the rewind spring pops outand uncoils during installation, it mustbe refitted in the spring housing asfollows:
- Thread the other end of the ropethrough the guide bush from inside thestarter cover and through the startergrip. Secure with one of the specialknots shown.
- Install the rope rotor - see 6.2.
- Remove the rope rotor - see 6.2.
- Remove the remaining rope from therope rotor. Thread one end of a new3.5 mm (9/64") dia. and 960 mm(37 3/4") long rope through the sideof the rope rotor and then, from theunderside, into the inner hole andpull it up to the top side. Secure therope with a simple overhand knot.
- Pull the rope back so that the knotlocates in the recess in the rope ro-tor.
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6.5 Tensioning the RewindSpring
- Position the outer spring loop about20 mm (3/4") from the edge of thespring housing.
- Refit the rewind spring in the springhousing in the counterclockwise di-rection, starting from the outsideand working inwards.
Note: The wooden assembly blockcan be placed over the spring hou-sing to simplify refitting.
- Install the rope rotor - see 6.2.
- Pull the starter rope out to fulllength. Rotate the rope rotor coun-terclockwise to wind on the ropeuntil the starter grip is about 20 cm(8") from the fan housing.
- Make a loop in the rope betweenthe rope rotor and starter cover.
- Grip the rope close to the rotor anduse it to turn the rope rotor three fullturns clockwise.
- Hold the rope rotor steady.
- Pull out rope with starter grip andstraighten it out.
- Hold the starter grip firmly to keepthe rope tensioned.
- Let go of the rope rotor and slowlyrelease the starter grip.
Top:Position of outer spring loopa = 20 mm (3/4") Top: Top:
Winding starter rope onto rotor Tensioning rewind springBottom:Fitting rewind spring with aid of wooden Bottom: Bottom:assembly block 1108 893 4800 Loop in rope Straightening twisted rope
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Note: The rewind spring is correctlytensioned when the starter grip sitsfirmly in the rope guide bush withoutdrooping to one side. If this is not thecase, tension the spring by one ad-ditional turn.
When the starter rope is fully extendedit must still be possible to rotate therope rotor at least another half turnbefore maximum spring tension isreached. If this is not the case, pull therope out, hold the rope rotor steadyand take off one turn of the rope.
Do not overtension the rewindspring as this will cause it to break.
- Refit the fan housing.
The wear on the guide bush is accel-erated by the starter rope being pulledsideways. The wall of the guide busheventually wears through, becomesloose and has to be replaced.
- Remove the fan housing.- Relieve tension on rewind spring, see
6.5, and remove the starter grip.
- Use a suitable tool to pry the old bushout of the fan housing.
To install the new rope bush:
- Place the new bush in its seat in thefan housing.
- Insert the screw spindle of the in-stalling tool through the bush from in-side the housing.
- Fit the thrust sleeve, tapered end first,and the hexagon nut.
- Tighten down the hexagon nut untilthe bush is firmly seated.
Note: The installing tool flares the lowerend of the rope bush.
- Refit the starter rope and the startergrip.
- Tension the rewind spring - see 6.5.
- Fit the fan housing.
6.6 Replacing StarterRope Guide Bush
Starter grip on fan housing Starter rope guide bush
Top:Fitting new rope bush with installing tool0000 890 2201 (schematic)1 = Screw spindle2 = Fan housing3 = Rope guide bush4 = Thrust sleeve5 = Hexagon nut
Bottom:Flaring the new rope bush
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Note: Push the stop buffer into its seat.Make sure the tabs locate behind thehousing face.Push the annular buffers (tapered sidefirst) into position until their annulargrooves engage the inner rib.
- Remove the tank housing, see 11.8.1,for access to the other annular buff-ers.
- Carefully pry all three annular buffersout of their seats and remove themfrom the crankcase.
Assembly is then a reversal of the dis-assembly sequence.
The crankcase and tank housing areconnected by vibration damping rubberbuffers. Damaged rubber buffers (an-nular buffers) must always be replaced.- Remove the air filter - see 11.1.- Remove the shroud - see 4.3.- Unscrew the center screw and re-
move it along with the sleeve.- Remove the mounting screws and lift
away the annular buffer.
7. AV HANDLE SYSTEM
7.1 Repair
Top:Remove center screw
Bottom:1 = Annular buffer2 = Mounting screws
Top:Prying out annular buffer
Bottom:Prying out stop buffer
Top:Fitting stop buffer
Bottom:Fitting annular buffer
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8. MASTER CONTROL
8.1 Removing and Installing
The main part of the Master Control isthe switch shaft with an integrallymolded multi-function operating lever,a molded seat for the switch actuatorand two other levers.
The thumb-operated Master Controllever moves the switch shaft to selectthe required function.
The following positions can be se-lected with the Master Control lever(from bottom upward):
- Take out the handle molding fasteningscrew. Lift away the handle molding.
Note: Slide the switch housing into itsguide before fitting the switch shaft inits mount.Attach the throttle rod and then pushthe grommet into position so that itsnipple fits in the hole in the baffle plateand its rubber tabs locate on the edgeof the housing.
- Remove switch shaft mountingscrew.
- Carefully pry the switch shaft out ofthe left-hand pivot mount and pullthe switch housing out of its guideon the right.
Installation is a reversal of the re-moval sequence.
Top:Switch shaft mounting screw
Bottom:Prying switch shaft out of pivot mount Handle molding fastening screw
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Note: The torsion spring must be underthe interlock lever and engage thenotch.
Press the interlock lever downward.Push the throttle trigger upward andmove the Master Control lever to the"CHOKE" position.
Push the throttle trigger fully upwardand position the handle molding so thatengages behind the lugs as shown inthe illustration.
- Use a 5 mm (3/16") drift to drive outthe cylindrical pin. Remove the throttletrigger and torsion spring.
Installation is a reversal of the removalsequence.
- Move Master Control lever to "RUN"position.
- Pull the throttle interlock lever out ofits seat.
- Detach the throttle rod from the trig-ger.
Top:1 = Cylindrical pin2 = Throttle trigger3 = Torsion spring
Bottom:1 = Interlock lever2 = Throttle trigger3 = Master Control lever Fitting handle molding
Top:Withdrawing interlock lever
Bottom:Detaching throttle rod from trigger
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9. ELECTRIC HANDLEHEATING SYSTEM
9.1 Troubleshooting
The entire handle heating system ismaintenance-free and subject topractically no wear. Faults in the gen-erator, heating elements and wiringare generally caused by mechanicaldamage from outside.
There are two reasons for failures inthe heating system:
- A break in the circuit due to a faultywire or component.
- A short circuit resulting from dam-age to the insulation.
Important! The heating element inthe rear handle may fail as a result ofoverheating if it is not bonded firmly inposition without creases.
To trace the cause of a fault:
- Remove the air filter - see 11.1.
- Take out the handle molding fas-tening screw.
- Carefully lift the handle moldingaway from the rear handle.
- Slide the insulating tube off the plugconnection of the wire from the gen-erator to the handle heating ele-ment.
- Separate the plug connection be-tween the two wires.
Heating element in rear handle(handle molding and pressure padremoved)
Top:Handle molding fastening screw
Bottom:Removing handle molding
Top:Insulating tube over connector
Bottom:Disconnecting wires
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- Set the heater switch to "I".
- Set the ohmmeter to " Ω x1".
- Clip one of the two test leads to thegenerator wire and the other testlead to the heating element wire.
- The torsion spring must be under theinterlock lever and engage the notch.
- Press the interlock lever downward.Push the throttle trigger upward andmove the Master Control lever to the"CHOKE" position.
- Push the throttle trigger fully upwardand position the handle molding sothat engages behind the lugs asshown in the illustration.
- Fit the air filter - see 11.1.
Note: All electrical components of theheating system are connected in serieswith the ohmmeter.
If the system is intact, the ohmmetershould indicate a value of around 2.5 Ωin measuring range " Ω x1". If noreading is obtained, there is a break inthe circuit. If the ohmmeter shows avalue of less than 2.5 Ω, there is ashort circuit in one of the components.
In either case it is necessary to checkeach component separately. The gen-erator wire remains disconnected fromthe heating element during this check.
- After completing the test, reconnectthe wires and slide the insulatingtube over the connector.
Top:1 = Interlock lever2 = Throttle trigger3 = Master Control lever
Bottom:Fitting the handle moldingOhmmeter (reading 2.5 Ω)
Top:Heater switch on "I"
Bottom:Ohmmeter connected
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9.1.1 Troubleshooting Chart
Start
Do both handles warm up?
Heater switch on "I"?
Measure resistance of individual componentswith ohmmeter
Check generator.Resistance between generatorconnection (1) and engine ground
= 0.6 Ω?
Check ground wire between tankhousing and crankcase.
Resistance between switch housingand crankcase approx. 0 Ω?
System in order
Turn on switch
R
Fibet
Re
no
no
no
no
no
no
yes
yes
yes
yes
yes
yes
no
yes
Check heater switch.Closed: approx. 0 Ω?Open: high reading?
Check front handle heating element.Resistance between 1.6 and 2.2 Ω?
Disconnect plug connectionat heater switch.
Switch has to be partly removedfor this purpose.
no
yes
Resistancebetween 0.25 and 0.3 Ω?
(depending of type of heating element)
Check rear handle heating element.In good condition?
Bonding ok?
Replace rear
handle heatingelement
eplace generator
t new ground wireween heater switchand crankcase
place front handle
Fit new switch
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9.1.2 Test ConnectionsandTest Values
The plug and socket connections of wires 1 to4 must be disconnected to test the individualcomponents.
Lead 2
Ground
Connectoron wire 4
Ground
Ground
Actual(reading)
-
approx.0.25
approx.1.6
-
0
approx.0.6
-
0
Resistance ΩOhmmeter connection(use either test lead)
If faulty
Cause
Switch faulty
Heating elementokay
Break in wire, heatingelement damaged
Short circuit- damaged insulation
Heating elementokay
Break in wire, heatingelement damaged
Short circuit- damaged insulation
Generator okay
Break in wire,generator damaged
Short circuit- damaged insulation
Remedy
Replace switch
Replace heatingelement
Repair insulation
Replace fronthandle
Repair insulation
Replace generator
Repair insulation
Spec.
0
0.25
1.6
0.6
Lead 1
Switchterminal 1)
Connectoron wire 3
Connectoron wire 2
Connectoron wire 1
Switch
Heatingelementin rearhandle
Heatingelementin fronthandle
Generator
Compo-nent
1) Remove wire for this purpose
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9.2 Switch
- Slip the washer over the nut. Securethe switch in position with the nut.
- Plug the wire's connector sleeveinto the switch.
- Push the rubber boot back onto theswitch.
- Install the carburetor - see 11.2.
- Remove the switch from inside thecarburetor box.
- Fit the new switch in the terminaland ring.
- Remove the carburetor - see 11.2.
- Push the rubber boot back a little anduse pliers to pull the wire's connectorsleeve out of the switch.
- Unscrew the switch mounting nut.
Top:Withdrawing connector sleeve
Bottom:Switch mounting nut
Top:Removing switch
Bottom:1 = Switch2 = Ring terminal3 = Ring
Top:Fitting washer
Bottom:Rubber boot
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9.3 Heating Element inRear Handle
- Fit a new expanded rubber pressurepad on top of the heating element.The heating element must be com-pletely covered.
- Reconnect the two wires.
- Slide the insulating tubes over theplug connectors.
- Refit the handle molding - see 9.1.
- Fit the air filter - see 11.1.
To check operation of heating ele-ment:
- Run the saw at maximum revs forno more than 30 seconds with theheating switched on.
Note: The heat generated during thisprocess also helps the element'sadhesive set faster.
Important! Before fitting the newheating element, clean the surfaceinside the handle so that it is free fromgrease, dirt and moisture.
- Remove the backing paper from thenew heating element.
- Press the heating element firmly anduniformly into position, taking specialcare at the corners and along theedges.
Important! Creases must be avoided.If the heating element is not fittedperfectly flat, heat transfer will beinterrupted and the element may failas a result of overheating. The ambi-ent temperature during installationshould not be less than +15 °C(60 °F).
- Remove the handle molding - see9.1.
- Slide the two insulating tubes off theplug connectors.
- Separate the plug connectors of thehandle heating system.
- Take the pressure pad and heatingelement out of the handle recess.
Top:Insulating tubes
Bottom:Separating plug connectors Heating element in rear handle Fitting pressure pad
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The heating element in the front han-dle (handlebar) is not replaceable. Anew handle must be fitted if the heat-ing element is faulty.
- Remove the carburetor - see 11.2.- Separate the plug connectors - see
9.3.- Pull off the insulating tube.- Remove the throttle trigger interlock
lever - see 8.2.- Pull the wire out of the rubber
grommet.- Disconnect wire from the switch -
see 9.2.
Important! The special screws usedfor polymer joints are secured withadhesive. Always heat the screwedjoint before loosening, e.g. with a hairdryer. Take care not to overheat thepolymer.
- Remove the mounting screws at theright side and underside of the fronthandle. Lift the handle away.
- Pull the two connecting wires out ofthe bore.
Reverse the above sequence to fit thenew front handle.
Note: Secure the handle mountingscrews with Loctite threadlockingadhesive - see 12.2.
- Plug the connector sleeve into theswitch and then slide the rubber bootback into position.
Check that the wire of the front handleheating element and the generator wireare properly positioned in the rear han-dle.
- Fit the throttle trigger interlock leverand handle molding - see 8.2.
9.4 Heating Element inFront Handle
Top:Pulling wire out of grommet
Bottom:Front handle mounting screwson side of tank housing Withdrawing wire
Impurities gradually clog the finepores of the filter with tiny particles ofdirt. This prevents the oil pump fromsupplying sufficient oil to the bar andchain. In the event of problems withthe oil supply, first check the oil tankand the pickup body. Clean the oiltank if necessary.
- Remove the oil filler cap togetherwith the cap retainer.
- Drain the oil tank.
- Use assembly hook to withdraw thepickup body from the oil tank.
Note: Do not stretch the oil hose toomuch when withdrawing the pickupbody.
- Pull the pickup body out of the oilhose.
- Grip the strainer between thumband forefinger, squeeze it slightlyand work it out of the pickup body.
- Wash the strainer and pickup bodyin white spirit and, if possible, blowout with compressed air.
- Flush out the oil tank.
Reassemble by reversing the disas-sembly sequence.
- Rotate the worm and spring clock-wise and pull them off the crank-shaft stub.
- Remove the oil pump mountingscrews.
- Pull off the pickup body - see 10.1.- Remove the oil pump - see 10.4.- Use pointed nose pliers to grip the
tab of the oil hose and pull it out ofthe crankcase.
- Use a blunt tool to push the suctionhose into the crankcase so that thetab locates it its seat at the bottomright.
- Fit the pickup body - see 10.1.- Install the oil pump - see 10.4.
Top:Vent valve
Bottom:Installed position of valvea = approx. 1 mm (3/64")
Top:Removing worm with spring
Bottom:Oil pump mounting screws
Top:Withdrawing the suction hose
Bottom:Correct position of suction hose
There is vent valve in the tank wallwhich keeps the internal pressure inthe oil tank equal to atmospheric pres-sure.- Remove the inner side plate.- Drain the oil tank.- Use a 7 mm (9/32") dia. drift to
carefully drive the vent valve into thecrankcase and then remove it fromthe oil tank.
- Carefully press in the new valve untilit is about 1 mm (3/64") below theface of the crankcase.
- Refit the inner side plate.
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10.5 Servicing the Oil Pump
Always check the suction hose andpickup body before disassembling theoil pump.
- Remove the oil pump - see 10.4.
- Use a 2 mm (5/64") dia. drift to driveout the pin. Pull the adjusting screwout of the housing and remove the0-rings.
- Pry the plug out of the housing andwithdraw the pump piston with heli-cal spring and washers.
- Wash all parts in white spirit. In-spect the parts for damage and re-place as necessary.
Assembly is a reversal of the disas-sembly sequence.
Note: Always install new 0-rings.Coat the pump piston and worm withgrease, see 12.2, before installing.
Note: Fit a new 0-ring in the spacerbush and lubricate it with a few dropsof oil.
- Fit a new 0-ring in the groove on theoil pump delivery line. Coat the wormwith grease, see 12.2.Tighten the oil pump mountingscrews to 3.5 Nm (2.6 Ibf.ft). Installworm with spring as far as stop (ro-tate counterclockwise).
- Carefully pull oil pump out of is seatand lift away.
- Remove the spacer bush from thecrankshaft stub and take the 0-ringout of the bush.
Installation is a reversal of the re-moval sequence.
The air filter's function is to remove dustand dirt sucked in with the combustionair and thus help reduce wear on enginecomponents to a minimum.
Dirty and clogged air filters reduce en-gine power, increase fuel consumptionand make starting more difficult.
The air filter should always becleaned when engine power beginsto drop off.
- Before removing the air filter, closethe choke shutter to prevent dirt fal-ling into the carburetor.
- Take off the carburetor box cover.- Pull off the outer filter element.- Remove the slotted nuts and pull
away the baffle and inner filter ele-ment.
- Thoroughly wash the two elementsin a fresh, non-inflammable cleaningsolution (e.g. warm soapy water).Carefully shake dry. Encrusted dirtshould be softened by immersingthe filter in the cleaning solution.
Note: If the filter fabric is damaged,replace the part concerned immedi-ately.
Installation is a reversal of the removalsequence.
Note: When installing the outer filterelement make sure that the integrallymolded ledges on the element engageunder the retaining lugs on the carbu-retor box.
11. FUEL SYSTEM
11.1 Air Filter
Top:Master Control lever in cold startposition -choke shutter closed
Bottom:Twist lock on carburetor box cover
Top:Outer filter element
Bottom:1 = Slotted nuts2 = Baffle3 = Inner filter element
Top:Ledges on outer filter element
Bottom:Retaining lugs on carburetor box
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11.2 Removal and Installationof Carburetor
- Unscrew the carburetor mountingnuts.
- Pull the baffle off the studs.
- Pull the carburetor off the studs andremove the fuel hose from the elbowconnector at the same time.
Installation is a reversal of the re-moval sequence.
- Remove the air filter - see 11.1.
- Push the lateral grommet off theadjusting screws and out of thecarburetor box.
- Pry the throttle rod out of the throt-tle trigger.
- Pull the front grommet out of thebaffle.
- Detach throttle rod from the throttleshaft and pull it out.
The all-position diaphragm carburetorconsists of a fuel pump and the actualcarburetor. Although the fuel pumpshares a common housing with thecarburetor, it operates as a com-pletely separate and independent unit.
Troubleshooting chart - see 2.6.
Top:1 = Mounting nuts2 = Baffle
Bottom:1 = Carburetor2 = Fuel hose
Top:Removing front grommet
Bottom:Throttle rod in throttle shaft
Top:Pushing out lateral grommet
Bottom:Detaching throttle rod
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Note: Before fitting the carburetor onthe studs, check that the sleeve (inmanifold) and washer are in positionand push the fuel hose onto the elbowconnector.
After fitting the carburetor, check thatthe elbow connector is properly posi-tioned in the impulse hose.
- Tighten down the mounting nuts to atorque of 3.5 Nm (2.6 Ibf.ft).
The carburetor can be tested for leakswith the carburetor and crankcasetester.
- Remove the carburetor - see 11.2.- Connect up the tester's pressure
hose. Note that a separate nippleand a length of fuel line are requiredas an adapter to make this connec-tion.
- Close the vent screw on the rubberbulb and pump air into the carburetoruntil the pressure gauge shows areading of approx. 0.4 bar (5.7 psi).
If this pressure remains constant, thecarburetor is airtight. However, if itdrops, there are two possible causes:
1. The inlet needle is not sealing(foreign matter in valve seat orsealing cone of inlet needle isdamaged or inlet control leversticking).
2. The metering diaphragm is dam-aged.
In either of these cases the carburetormust be removed and serviced.
11.3 Leakage Testing theCarburetor
Top:Pressure testing carburetor with carburetor/crankcase tester 1106 850 2905
Bottom:Damaged inlet needle
Top:Fuel line 1110 141 8600 fittedon nipple 0000 855 9200
Bottom:Fuel line fitted on elbow connector
Top1 = Washer2 = Sleeve
Bottom:1 = Fuel hose2 =Impulse hose
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11.4 Servicing theCarburetor
- To disassemble the carburetor, un-screw the metering diaphragm endcover and lift it away.
- Remove the metering diaphragmand gasket from the carburetor bodyand cover.
- If the fuel strainer in the pump sideof the carburetor body is dirty, use ascriber to pry it out and then clean it.
Important! If the fuel strainer is dam-aged, always fit a new one.
In such a case the fuel pickup headshould also be inspected and re-placed if necessary - see 11.7.
It is advisable to check the service-ability of the fuel pump whenever thecarburetor is removed for repair.- Remove the carburetor - see 11.2.- Unscrew the fuel pump end cover
and remove the gasket and pumpdiaphragm.
Note: The diaphragm and gasketoften stick to the cover or carburetorbody. If this is the case, take particularcare when separating them.
Top:Fastening screws of meteringdiaphragm end cover
Bottom:Metering diaphragm and gasket oncarburetor
Top:Pump diaphragm on carburetor body
Bottom:Fuel strainer in carburetor body
Top:Fuel pump end cover fastening screw
Bottom:Fuel pump end cover with gasket
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- Carefully separate the diaphragmand gasket.
Note: The diaphragms are the mostdelicate parts of the carburetor. Theyare subjected to continuous alternat-ing stresses and the material eventu-ally shows signs of fatigue, i.e. thediaphragms distort and swell. Theyhave to be replaced when this stage isreached.- The inlet needle valve is located in a
recess in the metering diaphragmchamber. Take out the round headretaining screw.
- Remove the inlet control lever withspindle, helical spring and inlet nee-dle. If there is an annular indentationon the sealing cone of the inlet nee-dle, it will be necessary to replacethe inlet needle because it will nolonger seal properly. This is indi-cated by constant flooding of thecarburetor even though the needle isclean.
- Use a 5 mm (approx. 3/16") dia. driftto press the valve jet out of its seat inthe direction of the venturi and washit in white spirit.
- Remove the carburetor adjustingscrews.
Top:Pressing out valve jet
Bottom:Carburetor adjusting screws
Top:1 = Round head screw2 = Inlet control lever3 = Spindle4 = Helical spring5 = Inlet needle
Bottom:Damaged inlet needle
Top:Separating gasket and diaphragm
Bottom:Retaining screw on inlet controllever spindle
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Top:Locating pegs on body
Bottom:Locating pegs on cover
Correct position of inlet control lever"a" = approx. 0.8 mm (1/32")
- Fit the gasket, metering diaphragmand end cover. The metering dia-phragm and gasket are held in po-sition by the integrally cast pegs onthe body.
- Insert the fuel strainer at the pumpside. Fit the pump diaphragm, gas-ket and end cover and tighten downsecurely. The pump diaphragm andgasket are held in position by theintegrally cast pegs on the endcover.
- Pry the sealing plug out of the me-tering chamber.
Caution! The sealing plug is de-stroyed during removal. It should,therefore, only be removed if a re-placement is available.
Wash the carburetor body and allserviceable parts in fresh white spiritand blow clear with compressed air,paying special attention to the boresand ports.
- When inserting the valve jet, makesure that it is exactly vertical in thebore. The lower edge of the valve jetmust be flush with the venturi wall.
- Fit the inlet needle and the helicalspring in their respective bores. Insertspindle in the inlet control lever, en-gage clevis in annular groove on thehead of the inlet needle and tightendown the round head screw. Makesure that the helical spring locates onthe control lever's nipple.
- Check easy action of the inlet controllever.
Important! The distance between theupper edge of the inlet control lever andthe metering diaphragm seating facemust be approx. 0.8 mm (1/32"). If nec-essary, use suitable pliers to carefullybend the lever.
Top:Sealing plug
Bottom:Valve jet in position - lower edge ofjet flush with venturi wall
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Note: Fit end cover so that both theelbow connectors point in the samedirection.
- Refit the carburetor adjustingscrews.
- Carry out leakage test, see 11.3,before installing the carburetor.
To remove the throttle shaft:
- Remove the throttle shutter fasten-ing screw.
- Use suitable pliers to pull the throt-tle shutter out of the throttle shaft.
- Take out the idle speed adjustingscrew.
- Pry the E-clip off the throttle shaft.
- Withdraw the throttle shaft from thecarburetor.
- Remove the torsion spring.
- Slide the throttle shaft into the car-buretor and check that the torsionspring is correctly positioned.
- Fit the throttle shutter. Round notchmust be forward and the small boremust face the throttle lever.
- Coat fastening screw with Loctite,see 12.2, and tighten down securely.
- Refit the idle speed adjusting screw.
Top:Correctly positioned torsion spring
Bottom:Fitting the throttle shutter
Top:E-clip
Bottom:Withdrawing throttle shaft
Top:Elbow connectors
Bottom:Throttle shutter fastening screw
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Top:Choke shutter fastening screw
Bottom:Withdrawing choke shaft
Top:Correctly positioned torsion spring
Bottom:Fitting the choke shutter
Adjusting screws on carburetor1 = High speed adjusting screw2 = Low speed adjusting screw3 = Idle speed adjusting screw
11.5 Carburetor Adjustment
When the engine is tested at the factorythe carburetor is set to obtain a slightlyricher mixture to provide the cylinderbore and bearings with additional lubri-cant during the break-in period. Thissetting should be left as it is for the firstthree tank fillings. The high speed ad-justing screw may then be turned up to1/4 turn clockwise to obtain a leanermixture.
Caution! The engine's maximum per-missible speed with bar and chain mustnot be exceeded.
If the saw is used at high altitudes(mountains) or near sea level, it may benecessary to alter the carburetor settingslightly. This correction is made at thetwo adjusting screws (H and L) as fol-lows: Turn clockwise for a leaner mix-ture (at high altitudes) or counterclock-wise for a richer mixture (at sea level).
- Slide the choke shaft into the carbu-retor and check that the torsionspring is correctly positioned.
Fit the choke shutter so that the outerhole faces upward (see arrow).
- Coat fastening screw with Loctite,see 12.2, and tighten down securely.
- Install the carburetor - see 11.2.
To remove the choke shaft:
- Remove the choke shutter fasten-ing screw.
- Pry the E-clip off the choke shaftand withdraw the shaft from thecarburetor.
- Remove the torsion spring.
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Note that even very slight variations atthe adjusting screws produce a no-ticeable change in engine runningbehavior. Always make sure that theengine is warm and the air filter cleanbefore carrying out carburetor adjust-ments.
Caution! The setting of the highspeed adjusting screw not only affectsthe engine's performance but also itsmaximum off-load speed. If the settingis too lean (adjusting screw turned toofar clockwise), the maximum permissi-ble engine speed will be exceeded.This can result in damage to the en-gine being caused by a lack of lubri-cant and overheating.
Corrections to the high speed ad-justing screw may only be carried outif the maximum permissible enginespeed of 14,000 rpm (with bar andproperly tensioned chain) can bechecked with an accurate tachometer.
Saws with catalytic converter:Corrections may be carried out only ifthe engine speed at full throttle doesnot fall below a minimum of13,000 rpm.
Basic setting
If the carburetor has to be adjustedfrom scratch, carefully screw bothadjusting screws clockwise down ontotheir seats to obtain a starting point forfine tuning.
Then make the following adjustments:
High speed adjusting screw H:back off 1 full turn
Low speed adjusting screw L:back off 1 full turn
The saw must be run with the basiccarburetor setting (H = 1, L = 1) if anaccurate tachometer is not availablefor checking the engine's maximumspeed.
Notes for adjustment of idle speed
Engine stops while idling
- Turn idle speed adjusting screwclockwise until the chain begins torun.
- Then turn it back one quarter turn.
Chain runs while engine is idling
- Turn the idle speed adjusting screwcounterclockwise until the chainstops running
- Then turn it about another quarterturn in the same direction.
Erratic idling behavior, poor ac-celeration
- Idle setting too lean.
- Turn the low speed adjusting screwcounterclockwise until the engineruns and accelerates smoothly.
Exhaust smokes at idle speed
- Idle setting too rich.
- Turn the low speed adjusting screwclockwise until the engine speeddrops.
- Turn screw back one quarter turn.
- Check that the engine acceleratessmoothly when the throttle is opened.
Note: A correction at the low speedadjusting screw usually necessitates achange in the setting of the idle speedadjusting screw.
Specified engine idle speed:2,700 rpm ± 100 rpm
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Top:1 = Grub screw2 = Vent hose3 = Vent connector
Bottom:Correctly positioned grub screwsa = approx. 16 mm (5/8")
11.6 Tank Vent 11.7 Fuel Filter andFuel Hose
Correct operation of the carburetor isonly possible if atmospheric pressureand internal fuel tank pressure areequal at all times. This is ensured bythe tank vent.
Important! In the event of trouble withthe carburetor or the fuel supply sys-tem, always check and clean the tankvent.
- Remove the air filter - see 11.1.
- Remove the vent connector from thestub on the tank housing.
- Pull the tank vent out of the retainer.
- Pull the vent hose off the vent con-nector.
- Use a 3 mm (1/8") dia. drift to pushthe grub screws out of the hose.
- Wash all parts in fresh white spirit andblow out with compressed air.
Install the tank vent by reversing thedisassembly sequence.
Note: Use a drift to position the grubscrews as shown in the drawing.
The diaphragm pump draws fuel out ofthe tank and into the carburetor via thefuel hose. Any impurities mixed withthe fuel are retained by the pickupbody (filter). The fine pores of the filtereventually become clogged with min-ute particles of dirt. This restricts thepassage of fuel and results in fuelstarvation.
Important! In the event of trouble withthe fuel supply system, always checkthe fuel tank and the pickup body first.Clean the fuel tank if necessary.
To clean the fuel tank:
- Unscrew the filler cap and drain thetank.
- Pour a small amount of clean gaso-line into the tank.
- Close the tank and shake the sawvigorously.
- Open the tank again and drain it.
1 = Retainer2 = Vent connector Fuel filler cap
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To remove and install the pickupbody:- Use the assembly hook to pull the
pickup body out through the filleropening.
Note: Do not stretch the intake hosetoo much while pulling out the pickupbody.- Pull the pickup body off the fuel
hose.- Remove cap from pickup body and
take out the weight.- Take the filter out of the pickup body.
Caution! The fine mesh strainer onthe pickup body must not be dam-aged. It may be washed in white spirit.
Note: It is not advisable to clean thefilter - always fit a new one.Install by reversing the removal se-quence.
Important! The foam filter must befitted without being creased or twistedin any way.
To remove the intake hose:- Remove the carburetor - see 11.2.- Pull the pickup body off the intake
hose.- Pull the intake hose out of the tank
housing.Install by reversing the removal se-quence.
Note: Coat the hose flange with a littleoil to simplify installation. The straightface of the flange must locate againstthe tank housing.
Top:Removing the intake hose
Bottom:Hose flange correctly positionedin tank housing
Top:Removing pickup body
Bottom:1 = Pickup body2 = Filter3 = Weight4 = Cap
Top:Assembly hook 5910 893 8800
Bottom:Withdrawing the pickup body
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11.8 Tank Housing
11.8.1 Removal andInstallation
Top:Front handle mounting screwson side of tank housing
Bottom:1 = Washer2 = Sleeve
- Pry the plug out of the annular bufferat the ignition side.
- Remove the mounting screw fromthe annular buffer.
- Disconnect spade terminals fromcontact springs of short circuit andground wires.
- Remove center mounting screw fromupper annular buffer.
- Drain the tank housing.- Remove the shroud - see 4.3.- Remove mounting screws at side
and underside of front handle. Liftaway the handle.
Note: To remove front handle onmachines with handle heating see9.4.
- Remove the carburetor - see 11.2.
- Pull the washer off the studs andremove the sleeve from the mani-fold.
Top:1 = Short circuit wire2 = Ground wire
Bottom:Center mounting screw in upperannular buffer
Top:Prying out plug
Bottom:Removing mounting screw
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- Remove the chain sprocket cover.
- Take out the inner side plate mount-ing screw and remove the side plate.
- Take out the chain catcher mountingscrew and remove the chain catcher.
- Pry the plugs out of the annularbuffers at the starter side.
- Remove the annular buffer mount-ing screws.
- Pull the tank housing forward andpush the manifold flange out of thetank housing intake opening at thesame time.
- Pull the impulse hose off the nipple.
- Swing the tank housing to one side,push the grommet out of the housingand pull out the short circuit andground wires.
Assembly is a reversal of the disas-sembly sequence.
Top:Plug in annular buffer at starter side
Bottom:Pushing out the manifold flange
Top:Inner side plate mounting screw
Bottom:Chain catcher mounting screw
Top:Impulse hose
Bottom:Grommet in tank housing
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Note: If a screw thread is stripped inone of the mounting holes for specialself cutting screws, the tank housingcan be repaired by installing a threadinsert. The stripped thread must bedrilled out to a diameter of 8.5 mmand a depth of 15 mm.
Important! Do not exceed the speci-fied hole depth of 15 mm.
- Fit M6 x 10 screw with washer inthe thread insert.
- Screw the thread insert into the tankhousing. An M6 x 18 pan head screwmust then be used in place of thespecial self cutting screw.
- To install the manifold flange in thetank housing's intake opening, winda piece of string (approx. 15 cm/6"long) around the back of the manifoldflange and thread the ends of thestring through the intake opening.
- Press the tank housing against themanifold and pull the ends of thestring outward at the same time.
This procedure enables the manifoldflange to be fitted in the intake openingwithout being damaged.
- Make sure the short circuit andground wires are securely positionedunder the retainers.
Bore sizea = 8.5 mm dia.b = 15 mm (approx. 9/16")
Top:Installing thread insert 9799 543 0900
Bottom:Correct position of string for installingmanifold in tank housing
Top:Pulling manifold into tank housingintake opening
Blocking crankshaftFitting oil seal (output side)Fitting oil seal (ignition side)Removing oil seals(output side only)(ignition side only)Removing flywheelAttaching connectorsto electric wiresFitting piston pinCompressing piston ringsFitting pistonTesting carburetor andcrankcase for leaksTesting crankcase forleaksSealing exhaust port forleakage testFor leakage testSetting air gap betweenignition module and flywheelCrankshaft nut
