Home

Online version - not for reprint

1. 33RA122 VA e Use screwdriver bit 1 0812 542 2104 to tighten screws alternately in a diagonal pattern to 9 Nm 6 6 lbf ft 31 Note Trim away any excess gasket material in the area of the cylinder mounting face Coat sealing lips of oil seals with grease see 13 2 Apply thin coating of sealant see 13 2 to outside diameter of oil seals Slide the oil seal open side facing the crankcase over the ignition end of the crankshaft 133RA123 VA e Press it fully home with press sleeve 1 1121 893 2400 133RA124 VA e Fit the assembly sleeve 1 1118 893 4602 over the clutch end of the crankshaft 32 e Slide the oil seal 2 open side facing the crankcase over the assembly sleeve 133RA125 VA e Press it home with press sleeve 1 1118 893 2401 Remove the assembly sleeve Wait about one minute and then turn the crankshaft several times Reassemble remaining parts in the reverse sequence _ l 133RA040 VA On machines with a catalytic converter it is necessary to stick a heat reflecting foil on the crankcase Clean and degrease surface first Remove the backing from the new heat reflecting foil e Press heat reflecting foil firmly into position so there are no creases a 8 mm 0 3 024 026 5 9 Decompression Valve Zar KLAX WS N lt MNO lt i KO HK Remove the shroud see 4 2
2. 133RA184 VA e Remove the side plate 1 e Remove the cover 2 WE NS hia 185 VA e Pull the insulating tube and wires out of the lower hole in the tank housing 133RA186 VA e Pull the insulating tube and wires out of the upper hole in the tank housing Install in the reverse sequence 133RA187 VA e Install wire to rear handle heating element in carburetor box as shown 49 10 5 Generator 133RA188 VA 133RA189 VA 133RA191 VA Remove the flywheel see 6 6 e Pull the connecting wire out of Machines from serial number the grommet X 33 339 218 All versions Note On machines with carb e Remove the insulating tube 1 uretor heating pull the terminal e Inspect magnet ring in flywheel socket housing off the printed e Pull pin 2 out of socket 3 for cracks or other damage If circuit board and pull the copper damage is found replace the colored wire out of the housing flywheel see 6 3 Note Flywheels with a more powerful magnet are installed from serial number X 33 339 218 Flywheels can be identified by the width of the magnet Previous New 11 mm 0 4 6 mm 0 24 133RA192 VA If a new flywheel has to be installed in a machine up to All versions serial number X 33 339 217 the front handle and the rear handle e Take out the screws heating element must be replaced at the same time Note The screws are
3. e Pull out the spur gear 145RA049 VA e Inspect the teeth on the spur gear and adjusting screw 1 If the teeth are damaged pull off the thrust pad 2 take the adju sting screw out of the tensioner slide 3 and replace both parts Note The adjusting screw and spur gear must be replaced together Install in the reverse sequence Coat teeth of adjusting screw and spur gear with grease see 13 2 before installing w 145RA050 VA e Check that O ring is fitted in spur gear and lubricate it with a little oil before installing 024 026 5 ENGINE 5 1 133RA036 VA Troubleshooting chart see Standard Repairs Trouble shooting handbook e Take out the screws Remove the exhaust casing 133RA037 VA Inspect the spark arresting screen 1 if fitted If necessary take out the screw 2 and re move the spark arresting screen from the exhaust casing Clean the spark arresting screen or fit a new one 024 026 Muffler Spark Arresting Screen 133RA038 VA e Take out the screws Remove the muffler e Remove the gasket e On machines with catalytic converter check condition of heat reflecting foil and replace if necessary a 8 mm 0 3 fi 133RA040 VA Reassemble in the reverse sequence Install new gasket so that its bead 3 points towards the
4. 133RA085 VA e On new service tool ZS 5910 890 2200 first screw the sleeve 1 5910 890 1800 into the plate 2 5910 893 2101 26 Unscrew spindle 3 a little left hand thread e Fit service tool ZS against ignition side of crankcase so that number 6 4 is at bottom Note Cylinder flange is at top e Insert three M5x72 screws 9022 341 1190 in the holes marked 6 and tighten them down against the drilled plate 133RA086 VA e Turn spindle counterclockwise until the crankshaft is pushed out of the ball bearing lt x gt i e q c oO ise e The crankshaft 1 connecting rod 2 and needle bearing are an inseparable unit Always replace as a complete unit When fitting a replacement crankshaft always install new oil seals and ball bearings 133RA088 VA e Ease the oil seal out of the clutch side of the crankcase e Use press arbor 1 1118 893 7200 to remove the ball bearing 024 026 133RA090 VA 133RA092 VA e Carefully knock the oil seal out of the ignition side of the crankcase 1 lt gt 3 lt a B e Use press arbor 1 1120 893 7200 to remove the ball bearing Inspect both halves of the crank case for cracks and replace if necessary Note The crankcase must be replaced as a complete unit even if only one half is damaged All other parts which are still serviceable can be transferred to the new crankcase
5. Clean away any loose dirt from around the air filter and filter cover Remove the carburetor box cover 133RA213 VA e Loosen the slotted nuts and remove the air filter Separate the two halves of the filter 133RA214 VA e Lift the choke shutter and remove the baffle Note There is no separate baffle in 026 machines with the new filter system Wash both halves of the filter in a fresh non flammable cleaning solution e g warm soapy water Soften encrusted dirt by soaking the filter for a while in cleaning solution Note If filter mesh is damaged replace filter immediately Important Flocked air filters must not be cleaned with compressed air brushes or rags lt gt w g i 5 e Disconnect the spring 2 to replace the choke shutter 1 Install in the reverse sequence 55 12 2 Carburetor Preheating 133RA057 VA e 024 machines up to serial number X 36 348 619 have a rectangular opening at the top of the carburetor box which is covered by a spring steel shutter 133RA217 VA The retaining lug in the tank housing may be damaged if force is used to pry the shutter out of its seat without pressing down the sprung tab In sucha case the shutter will no longer snap back into position e A sealing plug 1121 791 1400 can be fitted in place of the shut ter to avoid the need to replace an otherwise intact tank hou
6. Heating element Remove the shroud see 4 2 Remove the air filter see 12 1 e Clip one of the two test leads to a cylinder fin and the other to the heating element contact If the heating element is in good condition the ohmmeter will indicate 8 Q in measuring range Ox 1 If the reading is outside this tolerance replace the heating element see 12 5 2 133RA227 VA Thermostatic switch Remove the carburetor see 12 5 2 e Clip one of the two test leads to the carburetor body and the other to the flag terminal on the thermostatic switch wire Note The switch must open at temperatures above 21 C 70 F e g hold it in your closed hand for a few moments The ohmmeter must indicate an infinite value in measuring range Q x 1 no deflection Cool the switch to below 12 C 54 F The ohmmeter should indicate a value of around 0 Q in measuring range Q x 1 Replace faulty thermostatic switch Install the carburetor see 12 5 2 024 026 12 3 3 Troubleshooting Chart Measure resistance between carburetor body and one cooling fin on cylinder ambient temperature at least 21 C 70 F Remove carburetor Resistance approx 4 8 Q gt Measure resistance on heating element no Resistance approx 4 8 Q Replace carburetor yes Replace printed circuit board Check thermos
7. e Pull the pickup body 1 off the suction hose 2 Install in the reverse sequence a gt o is q lt q a i ie Insert suction hose in bore e Use a blunt tool to push the end of the suction hose into the crankcase so that the tab locates it its seat at the bottom right This operation is easier if the bead of the hose is lubricated with a little oil 024 026 11 2 Valve A valve is installed in the tank wall to keep internal tank pressure equal to atmospheric pressure Cleaning the valve Unscrew the oil filler cap Drain the oil tank Note Collect chain oil in a clean container or dispose of properly Observe safety precautions see 1 Remove the side plate Blow valve clear with compres sed air from outside to inside of tank Flush out the oil tank Fit the oil filler cap Fit the side plate Replacing the valve Unscrew the oil filler cap Remove the side plate 133RA203 VA e Use a 7 mm 9 32 drift to care fully drive the vent valve into the crankcase and take it out of the oil tank 024 026 e Use a 7 mm 9 32 drift to care fully press in the new valve until itis about 1 mm 3 64 below the face of the crankcase dimension a Fit the oil filler cap Fit the side plate S D A Fd 5 11 3 Oil Pump 133RA204 VA Remove the clutch and brake
8. gt 3 T 5 8 e Slide the setting gauge 1 1111 890 6400 between the arms of the ignition module and the flywheel magnets Press the ignition module against the setting gauge and tighten down the mounting screws to a torque of 7 0 Nm 5 2 Ibf ft Assemble all other parts in the reverse sequence 35 6 3 Short Circuit Wire Ground Wire The complete wiring harness has to be replaced on machines with carburetor heating from serial number X 32 611 639 and machines with heated handles from serial number X 37 055 376 see 6 4 Remove the shroud see 4 2 Remove the air filter see 12 1 lt gt wo 3 9 2 e Pull ground wire 1 out of the contact spring e Pull short circuit wire 2 out of the switch shaft 133RA136 VA Note The ground wire 1 is soldered to the printed circuit board 2 on machines with carburetor heating up to serial number X 32 611 638 36 133RA137 VA e Pull both wires out of the grommet e To change the ground wire on machines with carburetor heating up to serial number X 33 339 217 pull the connector housing 1 off the printed circuit board e Use a small screwdriver to carefully press down the retaining lug of the terminal socket 2 in the connector housing Remove the terminal socket 133RA139 VA Remove the short circuit wire and ground wire from the ignition module see 6 2 2 e Pull the short
9. yes Check heater switch Closed approx 0 Q Open high reading Fit new switch yes System in order 10 1 2 Test Connections and Test Values The plug and socket connections of the wires in the rear handle must be disconnected to test the individual components Component Ohmmeter connection Resistance Q If faulty use either test lead Remedy terminal switch Heating Connector Connector approx Heating element okay element on wire from on wire from 0 26 old 0 22 in rear rear handle rear handle approx handle heating heating 0 9 element element 5 Break in wire heating Replace heating element damaged element Short circuit Repair damaged insulation insulation Heating Connector Ground approx Heating element okay element on wire from 6 3 in front front handle approx handle heating 1 5 element Break in wire heating Replace front element damaged handle Short circuit Repair damaged insulation insulation Generator Connector Ground approx Generator okay on wire from generator Break in wire Replace generator damaged generator Short circuit Repair damaged insulation insulation 1 Pull out wire to make connection 47 10 2 Heater Switch Remove the front handle and put it to one side see 10 4 e Take the ground wire ring terminal off the heater switch a S Beyer y ee EE g SS JEEN
10. 133RA010 VA e Remove the grommet lt gt A lt d a 2 e Use standard 13 mm socket to unscrew the decompression valve Fit new decompression valve and torque down to 14 Nm 10 3 Ibf ft Fit the grommet Fit the shroud 024 026 6 IGNITION SYSTEM Warning Exercise extreme caution when carrying out maintenance and repair work on the ignition system The high voltages which occur can cause serious or even fatal accidents Troubleshooting on the ignition system should always begin at the spark plug See Standard Repairs Troubleshooting handbook Note The electronic breakerless ignition system basically consists of an ignition module 1 and flywheel 2 6 1 Spark Plug Boot Ignition Lead Remove the shroud see 4 2 Remove the carburetor box cover Remove the ignition module see 6 2 2 Remove boot from the spark plug Note An angled spark plug boot is installed on model 026 from serial number X 19 830 900 e Pull grommet if fitted off the ignition lead e Pull the ignition lead out of the insulating tube 33 145RA170 VA e Use suitable pliers to grip the spring and pull it out of the spark plug boot Unhook the leg spring from the ignition lead Slip the spark plug boot off the ignition lead Cut new ignition lead to length see parts list or cut to same length as old lead Coat end of the igni
11. muffler Coat threads of muffler mounting screws with Loctite see 13 2 Tighten down screws to 10 0 Nm 7 5 Ibf ft 15 5 2 Catalytic Converter 5 2 1 Construction and Function 133RA264 VA The catalytic converter is integrated in the muffler casing and helps reduce the amount of noxious emissions in the exhaust gas by means of a chemical reaction afterburning The main emissions are unburnt hydrocarbons and carbon monoxi de The nitrogen oxide content is negligible in two stroke engines Hydrocarbon emissions are reduced approximately 70 by a process of catalytic combustion of the exhaust gases in the converter The metal carrier catalyst in these machines provides less flow re sistance than the ceramic carrier catalyst commonly found in motor vehicles There is therefore no loss of engine power compared to machines without a catalyst Furthermore this catalytic con verter reaches operating tempera ture in a relatively short 20 to 30 seconds and is temperature resistant up to approx 1300 C 2375 F Afterburning the exhaust gases in the muffler generates tempera tures in the region of 1200 C 2200 F 16 133RA265 VA Inside the catalytic converter very thin flat and corrugated stainless steel sheets are rolled together in a spiral shape to produce a honey comb structure which is enclosed in a round steel jacket The honeycomb cells are coated with the noble meta
12. outside this tolerance replace the carburetor lt gt N a lt ira oO i Thermostatic switch e Clip one of the two test leads to the carburetor body and the ot her to the tag on the thermo static switch Note The switch must open at temperatures above 21 C 70 F e g hold it in your closed hand for a few moments The ohmmeter must indicate an infinite value in measuring range Q x 1 no deflection Cool the switch to below 12 C 54 F The ohmmeter should indicate a value of around 0 Q in measuring range Q x 1 Replace faulty thermostatic switch Printed circuit board Remove the printed circuit board see 12 4 133RA223 VA e Connect the ends of the ground wire and handle heating connecting wire e g with a crocodile clip 57 133RA224 VA e In the first test hold the test leads against the two upper connector tags Note If the printed circuit board is in good condition the ohmmeter will show a reading of 0 Q in measuring range Q x 1 e In the second test hold the test leads against the riveted contact and the bent contact see illustration Note If the printed circuit board is in good condition the ohmmeter will show a reading of 0 Q in measuring range Q x 1 Replace faulty printed circuit bo ard Install the printed circuit board see 12 4 58 Perform the following tests on 026 machines from serial number X 33 339 218
13. 111 1101 0786 111 1109 0781 120 1109 0781 120 1110 Oil seals oil pump drive chain sprocket bearing chain tensioner Cleaning crankshaft stub and flywheel taper Bearing bore in rope rotor rewind spring in fan housing Peg on pawl Sliding and bearing points on brake band Protects brake band against corrosion Securing screws see 3 6 Securing screws see 3 6 High voltage output on ignition module 024 026
14. 2905 to nipple on test flange 143RA046 VA e Close the vent screw 1 on the rubber bulb Pump air into the crankcase with rubber bulb until the gauge indicates a pressure of 0 5 bar 7 25 psi If this pressure remains constant for at least 20 seconds the crankcase or decompression valve is airtight 18 e However if the indicated pres sure drops the leak must be located and the faulty part replaced Note To find the leak coat the suspect area with oil and pressurize the crankcase again Bubbles will appear if a leak exists If the decompression valve is leaking install a new one see 53 Repeat the pressure test Carry out the vacuum test see 5 3 3 After finishing the test open the vent screw and disconnect the hose Remove the test flange Install the carburetor see 12 5 2 Loosen muffler screws and pull out the sealing plate Take out one screw and coat its thread with Loctite see 13 2 Refit screw and tighten down to 10 Nm 7 5 Ibf ft Note Remove and install the second screw in the same way Fit the upper casing 5 3 3 Vacuum Test Oil seals tend to fail when sub jected to a vacuum i e the sealing lip lifts away from the crankshaft during the piston s induction stroke because there is no internal counterpressure An additional test can be carried out with the vacuum pump to detect this kind of fault Carry
15. If the ohmmeter shows a value of less than 3 5 Q or 0 9 Q there is a short circuit in one of the com ponents In either case it is necessary to check each component separate ly The generator wire remains disconnected from the heating element during this check After completing the test re connect the wires and slide the insulating tube over the pin and socket connector Fit the interlock lever see 9 2 45 10 1 1 46 Troubleshooting Chart Start Do both handles warm up i Heater switch on I no yes Measure resistance of individual components with ohmmeter Turn on switch Check rear handle heating element In good condition Bonding OK no yes no Resistance zwischen 0 22 and 0 26 Q or 0 9 and 1 1 Q Replace rear handle heating element yes Check generator Resistance between generator connection and engine ground 0 6 Q no Replace generator yes Check ground wire between tank housing and crankcase Resistance between switch housing and crankcase approx 0 Q no yes Fit new ground wire between heater switch and crankcase Disconnect plug connection at heater switch Check front handle heating element Resistance between 1 44 and 1 76 Q or 6 3 and 7 7 Q Replace front handle
16. e Place ball bearing in position with flush side up and push it home as far as stop Note This operation must be carried out very quickly because the bearing absorbs heat immedi ately and begins to expand 133RA102 VA e If it is not possible to heat the crankcase use the press arbor 1 1118 893 7200 to press in the ball bearing as far as stop Remove the oil pump and refit the plastic plug a gt 2 i lt aas el ce e After the crankcase has cooled down push the two annular buffers tapered end first into position so that the annular groove 1 engages the housing rib 2 024 026 133RA104 VA e Push the oil suction hose into the crankcase bore Ka N 133RA10 e Use a blunt tool to push the oil suction hose into the bore so that its tab locates in the recesss at the bottom right 133RA106 VA e Install the cam lever 1 and secure it with the E clip 2 e Attach the spring 3 024 026 e Install the oil delivery hose 4 see 11 3 e Install chain tensioner 5 see 4 4 or 4 5 Heat area of bearing seat on ignition side of crankcase to approx 150 C 300 F e Place ball bearing in position with open side up and push it home by hand as far as stop Note This operation must be carried out very quickly because the bearing absorbs heat immedi ately and begins to expand 133RA107 VA e If it is not pos
17. ft Assemble all other parts in the reverse sequence 024 026 7 REWIND STARTER 7 1 General If the action of the starter rope becomes very stiff and the rope rewinds very slowly or not com pletely it can be assumed that the starter mechanism is in order but plugged with dirt At very low outside temperatures the lubri cating oil on the rewind spring may thicken and cause the spring windings to stick together This has a detrimental effect on the function of the starter mechanism In such a case it is sufficient to apply a few drops of paraffin kerosine to the rewind spring Then carefully pull out the starter rope several times and allow it to rewind until its normal smooth action is restored If clogged with dirt or pitch the entire starter mechanism inclu ding the rewind spring must be removed and disassembled Take special care when removing the spring Wash all parts in paraffin kerosine or white spirit Lubricate the rewind spring and starter post with STIHL special lubricant see 13 2 before installation 024 026 7 2 Rewind Spring 7 2 1 Replacing Troubleshooting chart see Standard Repairs Trouble shooting handbook Remove the fan housing with rewind starter Remove the rope rotor see Standard Repairs Trouble shooting handbook After removing the spring hous ing take remaining pieces of rewind spring out of fan housing Note The replacement spring comes rea
18. locate properly in the crankcase notch 2 so that it is clear of the flywheel e Position the connecting wire behind the retainer 3 Assemble all other parts in the reverse sequence 51 11 CHAIN LUBRICATION 11 1 Pickup Body Suction Hose Impurities gradually clog the fine pores of the filter with tiny particles of dirt This prevents the oil pump from supplying sufficient oil to the bar and chain In the event of problems with the oil supply system first check the oil tank and the pickup body Clean the oil tank if necessary Troubleshooting chart see Standard Repairs and Troubleshooting handbook Pickup Body Unscrew oil filler cap and drain the oil tank Note Collect chain oil in a clean container or dispose of properly Observe safety precautions see 1 133RA198 VA e Use hook 1 5910 893 8800 to pull the pickup body out of the oil tank Note Avoid stretching the oil hose 52 2 WT AVANT 133RA199 VA e Pull the pickup body out of the oil suction hose Wash the pickup body in white spirit and if possible blow out with compressed air Always replace a damaged pickup body Flush out the oil tank Install in the reverse sequence Suction hose Remove the oil pump see 11 3 Use pliers to grip the tab of the oil hose and pull it out of the bore e Pull suction hose and pickup body out of the crankcase 133RA201 VA
19. new pins see 4 3 4 and 4 3 5 024 026 4 3 3 Assembling Lubricate sliding and bearing points of chain brake with STIHL multipurpose grease or prefer ably molybdenum grease e g Molykote see 13 2 e Push the cam lever 1 onto the pivot pin e Install the E clip 2 e Attach the spring 1 to the pivot pin 2 and cam lever 024 026 133RA020 VA e Insert the bell crank in the side of the hand guard so that the short arm of the bell crank points up e Position the hand guard 1 against the pivot pin and fit the other side of the hand guard over the fan housing e Position the bell crank 2 against the pivot pin e Press the cam lever 3 downwards and push the hand guard and bell crank onto their pi vot pins Fit hand guard mounting screw and tighten to 4 0 Nm 3 0 Ibf ft e Check that cam lever is properly located on face of hand guard bearing boss JO 133RA023 VA A e Secure bell crank with E clip Coat brake band with chain oil STIHL Bioplus see 12 2 to protect it from corrosion and help reduce brake snatching during the first few applications 11 e Hook the brake spring onto the bell crank e Press brake band into slot lt gt A 6 lt ra 9 6 e Coils of brake spring must locate tight against one another in relaxed condition Install a new brake spring if necessary 12 e Check that pr
20. pletely cover the heating element Reconnect the two wires Slide the insulating tubes over the pin and socket connectors Fit the interlock lever see 9 2 Check operation of heating element Run the saw at maximum revs for no more than 30 seconds with the heating switched on Note The heat generated during this process also helps the element s adhesive set faster 024 026 10 4 The heating element in the front handle handlebar is not replace able A new handle must be fitted if the heating element is faulty A heating element with a higher resistance is installed in the front handle of machines from serial number X 33 339 218 Previous version 1 44 1 76 Q New version 6 3 7 7 Q The flywheel and heating element in the rear handle have to be replaced if a new heating element with a higher resistance is installed in the front handle Remove carburetor see 12 5 2 Separate the pin and socket connector the thicker wire in the rear handle and pull wire out of channel in the tank housing see 6 4 e Remove front handle mounting screws from underside of machine 024 026 133RA181 VA Heating Element in Front Handle e Remove front handle mounting screws from side of machine Lift away the front handle and put it to one side 133RA183 VA e Pull the grommet off the connec ting wire Pull the connecting inwards through the opening
21. secured with Loctite and may be difficult Remove the ignition module to remove see 6 2 2 Machines up to serial number X 33 339 217 Separate the generator connec ting wire at the connector in the rear handle and pull it out of the insulating tube see 6 4 lt x aR oO D q aa a bse e Pull the connecting wire out of e Remove the generator the insulating tube e Pull the retainer out of the crankcase 50 024 026 133RA194 VA e Inspect generator and poles for cracks or other damage If damage is found replace the generator Place the generator in position with the connecting wire facing the crankcase The connecting wire and must be at same side as the crank case recess Push the retainer into the crankcase Install screws with Loctite 242 see 13 2 lt gt fe z a oO iz e Fit the centering tool 1 1118 893 3500 on the crankshaft so that its groove engages the key 024 026 Tighten the screws to a torque of 2 Nm 1 5 Ibf ft Remove the centering tool e If necessary use puller 1 1107 893 4500 to remove the centering tool from the crank shaft 133RA197 VA e Reconnect the pin and socket machines from serial number X 33 339 218 and slide the insulating tube 1 over the connector Important The insulating tube must completely cover the connector e The connecting wire must
22. slip into the cylinder 24 Remove the clamping strap and wooden assembly block e To fit the manifold in the tank housing intake opening wind a piece of string about 15 cm 6 long around the back of the manifold flange and pass the ends of the string through the intake opening e Push the manifold down 133RA077 VA e Pull the ends of the string outward Note The manifold flange is pulled through the tank housing intake opening in this way without damaging the manifold lt a o R is Xd a i ise Carefully line up the cylinder and gasket e Use screwdriver bit 1 0812 542 2104 to torque down cylinder base screws to 10 5 Nm 7 7 lbf ft alternately in diagonal pattern Assembly is now a reversal of the disassembly sequence 024 026 5 7 Piston Rings Remove the piston see 5 6 1 Note To avoid carbon residue falling into the crankcase always remove the piston to install the piston rings and clean the ring grooves Remove rings from piston Check thickness of piston rings e Use a piece of old piston ring to scrape the grooves clean 133RA079 VA Install the new piston rings in the grooves so that the radii 1 face the fixing pin 2 Install the piston see 5 6 2 024 026 5 8 Crankcase 5 8 1 Removing the Crankshaft Remove the clutch see 4 2 Remove the chain brake see 4 3 2 Remove the c
23. strip from the chain tensioner 133RA013 VA e Take out the screws Remove the cover 133RA014 VA e Carefully pry the brake spring off the anchor pin and unhook it from the bell crank 133RA015 VA e Lever the brake band out of the crankcase Unhook the brake band from the bell crank U i 133RA017 VA C 170RA014 VA e Replace the brake band if e Ease the E clip off the bell crank pivot pin there are noticeable signs of wear large areas on inside diameter and or parts of outside diameter and its remaining thickness is less than 0 6 mm 0 024 Important Thickness of brake band must not be less at any point e f the brake band is still service able use No 120 emery paper or emery cloth grain size approx 120um to clean and roughen its entire friction surface inside diameter A 133RA018 e Carefully ease the hand guard 1 and bell crank 2 off the pivot pins and lift them away together Pull the bell crank out of the hand guard lt gt mu fo lt a oO ie 133RA016 VA e Take out the screw e Remove the E clip 1 10 e Unhook the spring 2 and take it away e Pull off the cam lever 3 Inspect parts Replace any worn or damaged parts Clean chain brake seat in crankcase If the brake spring anchor pin or the hand guard pivot pin are worn install
24. tank vent Check function by performing pressure and vacuum tests on the tank via the fuel hose Up to serial number X 30 976 774 SS Remove the carburetor box cover e Pull off the tank vent vertically a o aD 133RA248 VA e Unscrew the self tapping screw 1 and grub screw 2 from the tank vent 64 Wash all parts in fresh white spirit and blow out with compressed air Assemble in the reverse sequence Make sure the grub screw is fitted squarely 145RA276 VA From serial number X 30 976 775 Equalization of pressure from the outside inwards takes place via the sintered filter 1 and the valve 2 Note The sintered filter helps prevent dirt entering the valve or the tank The cap 3 protects the sintered filter from damage and contamina tion 145RA277 VA Equalization of pressure from the inside outwards takes place via the bore in the tank the valve and sintered filter 133RA249 VA Remove the air filter see 12 1 e Pull off the cap lt S S wo 2 5 isc e Pull the sintered filter 1 and valve 2 out of the tank Install a new valve 024 026 133RA251 VA From serial number X 36 348 620 e The previous vent valve 1 has been replaced by valve 2 The new valve only allows air to enter the fuel tank To equalize pressure from the inside outwards always
25. use installing tool see Standard Repairs Troubleshooting handbook Fit new cylinder gasket e Lubricate the piston and piston rings with oil and place the 133RA070 VA piston 1 on the wooden assem bly block 2 1108 893 4800 e Position piston rings in the grooves so that the radii at the ring gap meet at the fixing pin 133RA071 VA A 133RA072 VA e Push the manifold onto the intake port e Note installed position 133RA073 VA Push the hose clamp over the manifold The screw head must point upwards to the right e Tighten the hose clamp Ends of clamp must point down to the right at angle a of 45 degrees Note Tighten the screw until the gap b between the two ends of the hose clamp is 5 6mm 0 20 0 24 in On 026 push cap onto stud and screw home the decompression valve if fitted see 5 9 23 _ 133RA074 VA e Use the clamping strap 1 0000 893 2600 to compress the piston rings around the piston Check that the piston rings are correctly positioned Lubricate the inside of the cylinder with oil and line it up so that it is positioned as it will be in the installed condition It is important to observe this point as the piston rings might other wise break lt x gt ire N is q c oO ise e Slide the cylinder over the piston the clamping strap is pushed downward as the piston rings
26. with a hot air blower hair dryer Take care on polymer components Power screwdriver setting for use in polymer max 600 rpm for Plastoform screws 024 026 4 CLUTCH CHAIN DRIVE CHAIN BRAKE AND CHAIN TENSIONER 4 1 Clutch Drum and Chain Sprocket Remove the chain sprocket cover e Disengage the chain brake by pulling the hand guard toward the front handle e Remove the E clip 1 e Remove the washer 2 143RA004 VA 133RA002 VA If a rim sprocket is fitted pull it off e Pull off the clutch drum chain sprocket 024 026 lt x gt foo i e lt oc oO ise 143RA007 VA e Remove the needle cage Clean and inspect the clutch drum chain sprocket 145RA006 VA Important If there are noticeable wear marks on the inside diameter of the clutch drum check its wall thickness If it is less than 80 of the original wall thickness fit a new clutch drum Note If the clutch drum has to be replaced also check the brake band see 4 3 2 170RA005 VA e f the clutch drum is still service able use No 120 emery paper or emery cloth grain size approx 120um to clean and roughen its friction surface Reassemble in the reverse sequence Clean stub of crankshaft Wash needle cage in clean white spirit and lubricate with grease see 13 2 Replace damaged needle cage On 026 rotate clutch drum chain sprocket and apply slight p
27. with fuel must be performed outdoors only Spilled fuel must be wiped up immediately Wash hands thoroughly after every contact with waste oil Do not pour waste oil down the drain or allow it to soak into the ground Collect waste oil and take it to an official disposal site for environ ment friendly disposal STIHL 1999 Andreas Stihl AG amp Co Waiblingen 1 2 INTRODUCTION This service manual contains detailed descriptions of all the repair and servicing procedures specific to this power tool series There are separate handbooks for servicing procedures for standardized parts and assem blies that are installed in several STIHL power tool models Reference is made to these handbooks in the appropriate chapters of this manual As the design concept of model 024 and 026 chainsaws is almost identical the descriptions and servicing procedures generally apply to both Differences are described in detail Servicing procedures on the carburetor are described in the Carburetors handbook You should make use of the illustrated parts lists while carrying out repair work They show the installed positions of the individual components and assemblies Refer to the latest edition of the relevant parts list to check the part numbers of any replacement parts needed Parts lists on microfiche and CD ROM are always more up to date than printed lists A fault on the machine may have several causes To he
28. 024 026 CONTENTS 1 Safety Precautions 2 Introduction 3 Specifications 3 1 Engine 3 2 Fuel System 3 3 Ignition System 3 4 Cutting Attachment 3 5 Special Accessories 3 5 1 For User 3 5 2 For Service 3 6 Tightening Torques 4 Clutch Chain Drive Chain Brake and Chain Tensioner 4 1 Clutch Drum and Chain Sprocket 4 2 Clutch 4 3 Chain Brake 4 3 1 Checking Function 4 3 2 Disassembling 4 3 3 Assembling 4 3 4 Anchor Pin for Brake Spring 4 3 5 Pin for Hand Guard 4 4 Front Chain Tensioner 024 4 5 Side Chain Tensioner Engine 5 1 Muffler Spark Arresting Screen 5 2 Catalytic Converter 5 2 1 Construction and Function 5 3 Leakage Test 5 3 1 Preparations 5 3 2 Pressure Test 5 3 3 Vacuum Test 5 4 Oil Seals 5 5 Exposing the Cylinder 5 6 Cylinder and Piston 5 6 1 Removing 5 6 2 Installing 5 7 Piston Rings 5 8 Crankcase 5 8 1 Removing the Crankshaft 5 8 2 Installing the Crankshaft 5 9 Decompression Valve Ignition System 6 1 Spark Plug Boot Ignition Lead 024 026 aAnkKARAWW O N 0 O0O ON 6 2 6 2 1 6 2 2 6 3 6 4 6 6 9 1 9 2 10 10 1 10 1 1 10 1 2 10 2 10 3 10 4 10 5 11 11 1 11 2 11 3 11 3 1 12 12 1 12 2 12 3 12 3 1 12 3 2 12 3 3 12 4 Ignition Module Ignition Timing 34 35 Removing and Installing 35 Short Circuit Wire Ground Wire Wiring Harness Contact Spring Flywheel Rewind Starter General Rewind S
29. 890 4400 with No 3 1 jaws 0000 893 3706 Clamp the arms Pull out the oil seal Important Take special care not to damage crankshaft stub Clean sealing face on crankshaft stub with standard commercial solvent based degreasant containing no chlorinated or halogenated hydrocarbons see 13 2 Lubricate sealing lips of oil seal with grease see 13 2 Thinly coat the outside diameter of the oil seal with sealant see 13 2 lt gt o D e lt a oO ise e Slip assembly sleeve 1 1118 893 4602 over the crank shaft stub e Push the oil seal 2 open side facing the crankcase over the assembly sleeve 19 e Press oil seal home with press sleeve 1 1118 893 2401 After about one minute turn the crankshaft several times Remove the assembly sleeve Install the oil pump see 11 3 Fit the brake band see 4 3 3 Install the clutch see 4 2 Ignition side Remove the flywheel see 6 6 e On machines with heated handles remove the generator and put it to one side 20 133RA051 VA e Remove key from crankshaft stub Use a suitable pipe or punch to carefully tap the oil seal and free it off lt S 3 e lt fra N ise e Apply puller 1 5910 890 4400 with No 6 jaws 0000 893 3711 Clamp the arms Pull out the oil seal Important Take special care not to damage crankshaft stub Cl
30. A256 VA 133RA257 VA 133RA259 VA e On machines with heated e Pull the tank housing forward e Remove tank vent 1 contact handles take out screw of and push the manifold flange out spring 2 switch shaft 3 ground wire for heater switch of the tank housing at the same throttle trigger 4 fuel hose 5 time and impulse hose 6 Remove screws from annular buffers see 8 x v 32 e Pull the impulse hose off the e On machines from serial number nipple X 36 348 620 pry stop buffer out of wall of carburetor box On machines up to serial number X 36 348 619 remove Note If a screw thread is stripped cover on 026 shroud carb box in one of the mounting holes for cover and shutter on 024 special self threading screws the tank housing can be repaired by On machines with heated installing a thread insert handles remove heating element from rear handle see 10 3 and pull heater switch ground wire out of tank housing 133RA043 VA e Take sleeve 1 out of manifold e Slip the washer 2 off the studs 66 024 026 145RA206 VA e The stripped thread must be drilled out to a diameter of a 8 5 mm and a depth of b 15 mm Caution Do not exceed the specified hole depth of 15 mm 145RA207 VA e Fit an M6x10 screw with washer in the thread insert Screw the thread insert into the tank housing An M6
31. If only the ball bearings have to be replaced remove all rubber and plastic components first Carry out the following operations for this purpose 024 026 e Take out the screws 1 e Remove the annular buffer 2 e Push the annular buffers out of the clutch side of the crankcase e Pull out the oil suction hose with pickup body 133RA093 VA e Remove the oil delivery hose 1 To replace the crankcase e Unhook the spring 2 and remove the cam lever 3 133RA096 VA e Remove the complete chain tensioner see 4 4 or 4 5 133RA097 VA e Use stud puller 1 5910 893 0501 to unscrew the collar studs not on machines with quick chain tensioner 27 5 8 2 Installing the Crankshaft New crankcases come with preassembled ball bearings Stamp the serial number on the crankcase with 2 5 mm 0 1 figure stamps If the original crankcase is used again remove the gasket residue and clean the mating surfaces they must be cleaned very thoroughly to ensure a perfect seal 133RA098 VA e Check that dowel pin is in position If necessary drive dowel pin into crankcase e Pull plastic plug out of oil pump 28 133RA100 VA e Place oil pump in position Insert screws and tighten down fingertight lt gt 5 iv 6 Heat area of bearing seat on clutch side of crankcase to approx 150 C 300 F
32. M8 5910 893 0501 Removing guide bar mounting studs 30 Service tool AS 5910 890 2205 Removing crankshaft clutch side 31 Screw sleeve 5910 893 2409 Assembling crankcase 32 Service tool ZS 5910 890 2220 Removing crankshaft ignition side 33 Screw sleeve 5910 893 2421 Installing crankshaft 34 Press arbor 1118 893 7200 Removing and installing main bearings 35 Press arbor 1120 893 7200 Removing main bearing clutch side 36 Centering tool 1118 893 3500 Centering the generator 37 Puller 1107 893 4500 Removing centering tool 38 Pliers A19 0811 611 8380 Removing driver from worm 39 Assembly stand 5910 890 3100 Holds chainsaw for repairs Remarks 1 Equivalent to puller 0000 890 4400 but with longer spindle 5910 890 8400 2 DG screws must always be tightened with a torque wrench 3 Wrench has optical acoustic signal 4 Only use for releasing DG screws 024 026 69 13 2 No 10 70 Servicing Aids Lubricating grease 370 g 13 oz tube Standard commercial solvent based degreasant containing no chlorinated or halogenated hydrocarbons STIHL special lubricant 100 ml 3 5 fl oz bottle Ignition lead HTR 10 m 33 Graphite grease Molykote grease STIHL Bioplus 1 liter 34 fl oz bottle Medium strength threadlocking Loctite 242 High strength threadlocking Loctite 270 STIHL gear lubricant 80 g 2 8 oz tube 225 g 8 oz tube 0781 120 1111 0781 417 1315 0000 930 2251 0781 516 3331 0786
33. Pull the switch out of its seat in the tank housing 133RA180 VA e Push back the rubber grommet 1 e Pull the connector sleeve 2 out of the heater switch 3 Assemble in the reverse sequence 48 10 3 Heating elements with a higher resistance are installed from serial number X 33 339 218 Previous version 0 225 0 275 Q New version 0 9 1 1 Q If a heating element with a higher resistance is installed the flywheel and front handle must be replaced at the same time 145RA237 VA Remove the interlock lever see 9 2 e Slide the two insulating tubes 1 off the pin and socket connectors e Separate the connectors of the handle heating system lt gt o f 2 ira re e Remove pressure pad and heat ting element from handle recess Important Make sure inside of handle is free from grease dirt and moisture Heating Element in Rear Handle Remove the backing from the new heating element Press the heating element firmly and uniformly into position taking special care at the corners and along the edges Important Avoid creases If the heating element is not fitted perfectly flat heat transfer will be interrupted and the element may fail as a result of overheating The ambient temperature during installation should not be less than 15 60 F 145RA239 VA e Fit a new expanded rubber pressure pad on top of the heating element It must com
34. Sealing plate 18 Test flange 19 Setting gauge 20 Socket 13 mm 21 Socket 19 mm long 22 Torque wrench 23 Torque wrench 24 Screwdriver bit T27x125 25 Hook 26 Installing tool 27 Assembly tube 68 0000 893 5903 1118 893 2401 1118 893 4602 1121 893 2400 5910 890 4400 0000 893 3706 0000 893 3711 1110 890 4500 5910 890 8210 1110 893 4700 1108 893 4800 0000 893 2600 1106 850 2905 0000 855 9200 1110 141 8600 0000 850 3501 0000 855 8106 1118 850 4200 1111 890 6400 5910 893 5608 5910 893 5613 5910 890 0301 5910 890 0302 5910 890 0311 5910 890 0312 0812 542 2104 5910 893 8800 5910 890 2210 1117 890 0900 Blocking crankshaft Installing oil seal clutch side Protecting oil seal at clutch side Installing oil seal ignition side Removing oil seals 1 Removing flywheel Attaching connectors to electrical wires Removing and installing piston pin Fitting piston Compressing piston rings Testing carburetor and crankcase for leaks Testing carburetor for leaks Sealing export port for leakage test Leakage test Setting air gap between ignition module and flywheel Flywheel nut Clutch 0 5 18 Nm 2 0 4 13 5 Ibf ft 3 6 80 Nm 2 4 4 60 Ibf ft 3 IS screws Removing pickup bodies Fitting hookless snap rings in piston Attaching the brake spring 024 026 28 T handle screwdriver QI T27x150 5910 890 2400 For all IS screws 4 29 Stud puller
35. Such faults allow supplementary air to enter the engine and thus upset the fuel air mixture This makes adjustment of the prescribed idle speed difficult if not impossible Moreover the transition from idle speed to part or full throttle is not smooth The engine can be checked thoroughly for leaks with the carburetor and crankcase tester and the vacuum pump 024 026 5 3 1 Preparations lt gt 3 lt c 5 8 Remove the shroud see 4 2 e Make sure spark plug 1 is properly tightened down e Pull out knob 2 of decompres sion valve if fitted 133RA042 VA Remove muffler upper casing and back off the muffler moun ting screws half way see 5 1 e Fit the sealing plate 1 0000 855 8106 between the muffler and exhaust port and then retighten the screws moderately Note The sealing plate must completely fill the space between the two screws Remove the carburetor see 12 5 2 Set the piston to top dead center T D C This can be checked through the intake port 133RA043 VA e Check that sleeve 1 and washer 2 are in position 133RA044 VA e Fit the test flange 1 1118 850 4200 on the carburetor studs Check tester 1106 850 2905 and vacuum pump 0000 850 3501 for leaks 17 5 3 2 Pressure Test 133RA045 VA Carry out preparations see 5 3 1 e Connect pressure hose of tester 1106 850
36. ary without detrimentally affecting the strength of the screwed assembly providing the specified tightening torque is observed For this reason it is essential to use a torque wrench Fastener Thread For component Torque Remarks size Nm Ibf ft Pan head screw M4x8 Cover plate chain tensioner 3 0 2 2 Countersunk screw PT4x12 Cover plate chain sprocket cover 2 5 1 8 1 Collar screw M8x21 5 Bar mounting 23 0 17 0 2 Collar screw M10 M8 Bar mounting 30 0 22 0 1 3 Spline screw IS M4x12 Cover to crankcase sprocket side 3 0 2 2 M10x1 Decompression valve 140 10 3 4 Self tapping screw B4 2x9 5 Spark arresting screen 2 0 1 5 Spline screw M3 5x12 Generator 2 0 1 5 2 Self tapping screw IS P6x19 Front handle top bottom W version 7 0 5 2 Self tapping screw IS P6x32 5 Front handle top polymer 5 0 3 7 Self tapping screw IS P6x21 5 Front handle bottom polymer 5 0 3 7 Self tapping screw B3 9x19 Handle molding 1 6 1 2 Screw assembly IS M4x16 Hand guard left 4 0 3 0 Slotted nut M5 Shroud to cylinder 3 5 2 6 Self tapping screw IS P6x19 Chain catcher plug 2 8 2 1 Spline screw IS M5x12 Spiked bumper with self locking nut 7 5 5 5 Spline screw IS M5x20 Crankcase 9 0 6 6 Mutter M5 Air filter 2 0 1 5 Spline screw IS M4x16 Fan housing 4 0 3 0 M12x1L Clutch carrier 50 0 37 0 Self tapping screw IS P6x26 5 Annular buffer to tank housing left 5 0 3 7 Self tapping screw IS P6x19 Annular buffer to tank housing right 5 0 3 7 024 026 Fasten
37. band see 4 2 and 4 3 2 Adjustable oil pump e Pull off the worm and driver 133RA205 VA e If necessary use pliers 1 0811 611 8380 to remove the driver from the worm LI at tlc e Slip the ring 1 and washer 2 off the end of the crankshaft 53 Non adjustable oil pump e Remove the worm 1 All versions e Take out the screws 2 e Remove the oil pump 3 e Pull the oil delivery hose off the oil pump nipple 54 133RA207 VA lt gt o 3 ira oO sd ERO agar e To remove the oil delivery hose 1 pry the sleeve 2 out of the bore The hose is damaged in this process and must be replaced 9 V 133RA20 An oil pump with a stroke of 0 5 mm instead of 0 65 mm is installed in 024 machines from serial number 1 42 721 934 Install in the reverse sequence Before installing a new or over hauled oil pump on 026 pry the polymer plug out of the pump housing and lubricate the control edge of the pump piston with a thin coating of grease 133RA210 VA Fit the plug Lubricate worm on pump piston with grease Installing oil delivery hose Coat ends of hose with oil e Use modified flat nosed pliers see illustration to push the oil delivery hose onto the oil pump nipple a 5 5 mm 7 32 Push the oil delivery hose through the bore in the bar moun ting flange from the inside out wards so that it pro
38. bure tor heating remove the hot plate 1 and heating element 2 61 DY e Detach throttle rod from the throttle trigger e Remove the carburetor Take the throttle rod off the throttle shaft Install in the reverse sequence e On machines with compensator inspect O ring on stub and install a new one if necessary 62 133RA239 VA 133RA240 VA lt gt pi c o bd 133RA043 VA 0 1 i e Check that sleeve 1 and washer 2 are in place e On machines with carburetor heating up to serial number X 33 339 217 lift thermostatic switch connecting tag while pushing home the carburetor lt gt 2 g ira oO s e After fitting the carburetor check that elbow connector is correctly seated in the impulse hose 133RA244 VA e On machines with carburetor heating from serial number X 33 339 218 connect thermo static switch s flag terminal 1 to tag on contact spring e Push the heating element 2 into position e Fit hot plate 3 with TOP 1121 facing upwards and outwards Tighten down nuts to 3 5 Nm 2 6 Ibf ft Machines with carburetor heating up to serial number X 33 339 217 Run machine at full throttle and operate the stop switch If the machine does not stop the wires are not properly connected at the top of the carburetor box cover Connect the green yellow wire gr
39. carburetor preheating see arrow Reassemble in the reverse sequence 5 6 Cylinder and Piston 5 6 1 Removing x 4 N Y N YL A Q on ws X o NO 3N 133RA058 VA Preparations see 5 5 e Unscrew the cylinder base screws through the throughholes in the cylinder 133RA059 VA e Carefully lift the cylinder up and at the same time push the manifold through the tank housing opening Important Do not use pointed or sharp edged tools Pull the cylinder off the piston 21 133RA060 VA 2 1 e Release the hose clamp 1 e Pull the manifold 2 off the intake port Inspect the cylinder and replace it if necessary If a new cylinder has to be in stalled always fit the matching piston New cylinders are only supplied complete with piston for this reason Before removing the piston decide whether or not the crank shaft has to be removed as well To remove the flywheel block the crankshaft by sliding the wooden assembly block between the piston and crankcase Remove the cylinder gasket If the cylinder is changed on the 026 pull the cap off the stud 133RA061 VA e Ease the hookless snap rings out of the grooves in the piston bosses 22 133RA062 VA e Use the assembly drift 2 1110 893 4700 to push the piston pin 1 out of the piston Note If the piston pin is stuck tap the end of the drift light
40. circuit wire and ground wire out the insulating tube Install in the reverse sequence 024 026 6 4 Wiring Harness The wiring harness includes the ground wire short circuit wire and connecting wire to the generator and rear handle heating element Remove the carburetor see 12 5 2 Remove the interlock lever see 9 2 OAs 133RA140 VA e Pull back the insulating tube on the thinner wire from generator to rear handle heating element to expose connector lt x gt lt as oO e Disconnect the pin 1 and socket connector 2 024 026 e Pull wire with tube 1 out of channel in tank housing e Pull wire 2 out of tube e Pull back insulating tube 1 to expose connector e Disconnect the wires e Pull the ground wire 2 out of the contact spring e Pull the short circuit wire 3 out of the switch shaft Disconnect wire from generator see 10 5 KOA y A A NI les Ss 4 aA e Ease the grommet 1 out of the tank housing 133RA144 VA e Pull the wiring harness 2 out of the tank housing and the insulating tube 3 Install in the reverse sequence e Make a loop 1 in the wire from the generator to the rear handle heating element and push it behind the retainers 133RA146 VA e Also push the ground wire 1 and short circuit wire 2 behind the retainers e Note correct
41. ck condition of heat shield foil and fit a new one if necessary Fit the shroud 024 026 4 3 Chain Brake 4 3 1 Checking Function The chain brake is one of the most important safety devices on the chain saw Its efficiency is measu red in terms of braking time i e the time that elapses between activating the brake and the saw chain coming to a standstill The shorter the braking time the better the efficiency and protection offered Contamination with chain oil chips fine particles of abrasion etc and smoothing of the friction surfaces of the brake band and clutch drum impair the coefficient of friction This in turn reduces the frictional forces and thus pro longs the braking time A fatigued or stretched brake spring has the same negative effect Start the engine With the chain brake activated locked open throttle wide for brief period max 3 seconds the chain must not rotate With the chain brake released open throttle wide and activate the brake manually the chain must come to an abrupt stop Note The braking time is in order if deceleration of the saw chain is imperceptible to the eye 024 026 4 3 2 Disassembling Remove clutch drum chain sprok ket see 4 1 Relieve tension of brake spring by pushing hand guard forwards 133RA011 VA e Take out the screw Remove the side plate 133RA012 VA e On 026 remove the upper bumper
42. djustable Since there is no mechanical wear in these systems ignition timing cannot get out of adjustment However an internal fault in the circuit can alter the switching point in such a way that a spark test will still show the system to be in order although timing is outside the permissible tolerance This will impair engine starting and running behavior 024 026 6 2 2 Removing and Installing 133RA132 VA Remove the fan housing e Pull the short circuit wire 1 off the connector tag and out of the retainer 2 e Take out the screws 3 133RA133 VAN Remove the ignition module e Pull off the grommet 1 e Rotate the ignition module to unscrew the ignition lead 2 from the contact pin Pull the ignition lead out of the high voltage output Pack the high voltage output with STIHL multipurpose grease see 13 2 Important Do not use graphite grease Molykote or silicone insulating paste Screw home the ignition lead Push the grommet over the high voltage output Coat threads of screws with Loctite 242 see 13 2 Place the ignition module in position insert screws with washers but do not tighten them down yet Important A washer must be fitted under each screw head Note Secure the ground wire with the upper screw On machines with heated handles position connector of generator wire under the ignition module see 10 5 lt
43. dy for installation with a spring housing It should be lubricated with a few drops of STIHL special lubricant before installation see 13 2 e Position the rewind spring with spring housing bottom plate must face up in the fan housing Engage the anchor loop over the cast lug in the fan housing Important If the rewind spring pops out and uncoils during instal lation it must be refitted in the spring housing as follows e Position the anchor loop about 20 mm 3 4 from the edge of the spring housing e Fit rewind spring in the counter clockwise direction starting out side and working inwards Place wooden block 1 1108 893 4800 over the spring housing to simplify this operation 39 e Check distance of inner spring loop from starter post a 2 mm 0 08 and correct if necessary Install the rope rotor see Standard Repairs Trouble shooting handbook Tension the rewind spring see 7 2 2 40 7 2 2 Tensioning e Make a loop in the starter rope 133RA156 VA e Grip the rope close to the rotor and use it to turn the rope rotor six full turns clockwise lt gt K D z a oO ied e Hold the rope rotor steady e Pull out the rope with the starter grip and straighten it out Hold the starter grip firmly to keep the rope tens
44. ean sealing face on crankshaft stub with standard commercial solvent based degreasant containing no chlorinated or halogenated hydrocarbons see 13 2 Lubricate sealing lips of oil seal with grease see 13 2 Thinly coat the outside diameter of the oil seal with sealant see 13 2 133RA0 Push the oil seal over the crank shaft stub the open side must face the crankcase e Use the press sleeve 1 1121 893 2400 to install the oil seal After about one minute turn the crankshaft several times Install the generator if fitted see 10 5 Install the flywheel see 6 6 024 026 5 5 Exposing the Cylinder Always check and if necessary repair the fuel system carburetor air filter and ignition system before looking for faults on the engine Troubleshooting chart see Standard Repairs Trouble shooting handbook Remove the muffler see 5 1 Remove the carburetor see 125 2 Remove the shroud see 4 2 133RA041 VA e Unscrew the spark plug 1 e On 026 remove decompression valve if fitted see 5 9 133RA043 VA e Take the sleeve 1 out of the manifold e Pull the washer 2 off the studs 024 026 133RA056 VA e On 026 up to serial number X 36 348 619 remove cover from tank housing 133RA057 VA e On 024 up to serial number X 36 348 619 it is not necessary to remove the shutter for
45. er Spline screw Spline screw Spline screw Spline screw Spline screw Spline screw Nut Spline screw Self tapping screw Stud Stud Nut Spline screw Spline screw Spline screw Use the following procedure when refitting a P screw in an existing thread Thread IS M5x12 IS M5x16 IS M5x12 IS M5x12 IS M5x12 IS M5x16 M8x1 M4x8 BM4x16 M5x8 5 M5x8 5 M5 IS M5x20 M14x1 25 IS M5x20 IS M4x12 For component size Annular buffer plate Muffler to crankcase Cat version Muffler to crankcase non Cat version Muffler to cylinder Upper casing to muffler non Cat version Upper casing to muffler Cat version Flywheel Side plate Side plate Stud to cylinder left Stud to cylinder right Carburetor Cylinder Spark plug Ignition module Oil pump Torque Nm 8 0 10 0 10 0 10 0 10 0 5 9 7 5 7 5 7 5 7 5 Place the P screw in the hole and rotate it counterclockwise until it drops down slightly Tighten the screw clockwise to the specified torque Remarks lbf ft This procedure ensures that the screw engages properly in the existing thread and does not form a new thread i e the thread is not weakened 1 On machines with quick chain tensioner 2 Secure screw with Loctite 242 3 Secure screw with Loctite 270 4 On 026 only 5 A washer must be fitted under the screw head Note Screws secured with adhesive Loctite are easier to release if they are heated
46. for richer mixture at sea level Turn screws very slowly and carefully even slight movements produce a noticeable change in engine running behavior Note the following when making corrections to high speed screw The setting of the high speed screw H affects the maximum off load engine speed If the setting is too lean the maximum permissible engine speed will be exceeded and increase the risk of engine damage 133RA246 VA Sy Adjusting engine idle speed A correction at the low speed screw L usually necessitates a change in the setting of the idle speed screw LA 3 Engine stops while idling Check standard setting Turn idle speed screw LA clock wise until the chain begins to run then turn it back one quarter turn Chain runs while engine is id ling Check standard setting Turn the idle speed screw LA counterclockwise until the chain stops running and then turn it about another quarter turn in the same direction Erratic idling behavior poor acceleration Idle setting too lean Turn the low speed screw L counterclockwise until the engine runs and accelerates smoothly 63 12 6 Tank Vent Correct operation of the carburetor is only possible if atmospheric pressure and internal fuel tank pressure are equal at all times This is ensured by the tank vent Important If problems occur on the carburetor or the fuel supply system always check and clean the
47. ft supported in heavy duty deep groove ball bearings needle cages on small and big ends 10 mm 0 39 in Single pawl system min 1 2 turn 3 5 mm 0 14 in dia Centrifugal clutch without linings 3 600 rpm 0 5 bar 7 25 psi 0 5 bar 7 25 psi Diaphragm carburetor approx 1 turn open approx 1 turn open standard setting 0 8 bar 11 6 psi lt 0 3 bar 4 35 psi lt 0 05 bar 0 725 psi 0 47 L 16 fl oz min 90 RON Regular brand name gasoline and two stroke engine oil 50 1 with STIHL 50 1 two stroke engine oil 25 1 with other brand name two stroke air cooled engine oils Large area bisectional flat filter additional prefilter in carburetor box cover 3 3 3 4 3 5 3 5 1 Ignition System Cutting Attachment Special Accessories For User Type Air gap Spark plug Suppressed Electrode gap Guide bars Bar lengths Oilomatic chain Chain sprocket Chain speed Chain lubrication Oil feed rate on non adjustable pump on adjustable pump Oil tank capacity ElastoStart Air filter fleece 024 0 325 8 tooth chain sprocket Intake air preheating kit 024 Intake air preheating kit 026 Intake air preheating kit 026 0 325 7 tooth rim sprocket kit 0 325 8 tooth rim sprocket kit 3 8 Picco 7 tooth rim sprocket kit 3 8 Picco 8 tooth rim sprocket kit 3 8 7 tooth rim sprocket kit Chain scabbard extension from 45 cm 18 in CAT mounting kit Electronic magne
48. he ignition e To prevent the crankcase and the service tool counterclockwise side of the crankcase gasket twisting fit M5x72 screws until the drilled plate butts from service tool ZS in two against the crankcase crankcase holes as far as stop 30 024 026 Screw the spindle fully into service tool AS by turning it clockwise e Screw the threaded sleeve 1 5910 893 2409 onto the spindle as far as it will go left hand thread 133RA118 VA e Check that tensioner slide 1 is butting against thrust pad 2 If necessary rotate spur gear clockwise until slide is against thrust pad 024 026 lt gt D z d o 2 Push the threaded sleeve over the crankshaft stub e Hold the crankshaft steady rotate the spindle counter clockwise to screw the threaded sleeve onto the crankshaft Release the crankshaft Hold the service tool steady and continue turning the spindle until the tool locates against the guide bar mounting face Fit two hexagon nuts on the bar mounting studs and screw them down fingertight 133RA120 VA e Turn the spindle counterclock wise until the crankshaft locates against the ball bearing Unscrew the hexagon nuts Unscrew the spindle clockwise and take away the service tool Take out the two M5x72 screws 133RA121 VA e Use a 4 mm 0 15 drift to drive the dowel pin into the crankcase from the chain tensioner side
49. hines with a quick chain tensioning system and secure with one M8 nut and washer The complete unit can then be swivelled to the best position for the ongoing repair This leaves both hands free Always use original STIHL replacement parts They can be identified by the STIHL part number the 77JHL ogo and the STIHL parts symbol amp 2 The symbol may appear alone on small parts 024 026 3 SPECIFICATIONS 3 1 Engine STIHL single cylinder two stroke engine with special impregnated cylinder bore Displacement Bore Stroke Engine power to ISO 7293 Max permissible engine speed with bar and chain Idle speed Bearings Piston pin diameter Rewind starter Reserve pull on rope rotor Starter rope Clutch Clutch engages at Crankcase leakage test at gauge pressure under vacuum 3 2 Fuel System Carburetor Setting High speed screw H Low speed screw L Carburetor leakage test at gauge pressure Function of tank vent at gauge pressure under vacuum Fuel tank capacity Octane number Fuel mixture Mix ratio Air filter Original tank vent 024 026 024 024S 026 42 cm 2 56 cu in 44 3 cm 2 70 cu in 48 7 cm 2 97 cu in 42 mm 1 65 in 42 mm 1 65 in 44 mm 1 73 in 30 mm 1 18 in 32 mm 1 26 in 32 mm 1 26 in 2 1 kW 2 85 bhp 2 3 kW 8 1 bhp 2 6 kW 8 5 bhp at 7 000 rpm at 7 000 rpm at 7 000 rpm 13 000 rpm 13 000 rpm 14 000 rpm 2 500 rpm Cranksha
50. ioned Let go of the rope rotor and slowly release the starter grip so that the rope winds itself onto the rotor 133RA158 VA Note The starter grip must sit firmly in the rope guide bush without drooping to one side If this is not the case tension the spring by one additional turn When the starter rope is fully extended it must still be possible to rotate the rope rotor at least another half turn before maximum spring tension is reached If this is not the case pull the rope out hold the rope rotor steady and take off one turn of the rope Do not overtension the rewind spring it might break Fit the fan housing 024 026 7 3 Starter Rope Starter Grip ElastoStart Remove the fan housing with rewind starter For starter rope ElastoStart on 026 see Standard Repairs and Troubleshooting handbook Starter rope Remove the rope rotor see Standard Repairs and Troubleshooting handbook Remove starter rope from the rope rotor 362RA095 VA e Remove cap from the starter grip Pull the rope out of the starter grip N 362RA096 VA e Thread end of new rope through the underside of the starter grip Secure the end of the rope with a simple overhand knot 024 026 362RA097 VA e Pull the rope back until the knot locates in the starter grip Pres
51. jects about 10 20 mm 3 4 lt gt Be c 9 6 e Hold the projecting end with the modified flat nosed pliers Now push home the sleeve with the modified carburetor screwdriver 1 0000 890 2300 a R1 5 mm 1 16 Place oil pump in installed position Use modified carburetor screwdriver to push hose into bar mounting flange so that it is recessed about 1 2 mm 1 16 Tighten mounting screws to 3 5 Nm 2 6 Ibf ft 024 026 11 3 1 Servicing On 026 always check the suction hose and pickup body before disassembling the oil pump Remove the oil pump see 11 3 N 133RA212 VA e Use a 2 mm 5 64 drift to drive out the roll pin 1 e Pull out the control bolt 2 e Remove the O rings 3 e Pry the plug 4 out of the housing e Withdraw the pump piston 5 with spring 6 and washers 7 Wash all parts in white spirit Inspect the parts for damage and replace as necessary Reassemble in the reverse sequence Always install new O rings Coat pump piston and worm with grease see 13 2 before installing 024 026 12 FUEL SYSTEM 12 1 Air Filter Choke Shutter Dirty and clogged air filters reduce engine power increase fuel consumption and make starting more difficult 026 machines from serial number X 32 252 039 are equipped with a newly developed air filter system The air filter should always be cleaned when engine power begins to drop off
52. l platinum which acts as the actual catalyst A chemical reaction which reduces harmful emissions takes place when hot exhaust gas flows through the catalytic converter Some 70 of the hydrocarbons HC is transformed into water H20 and non poisonous carbon dioxide CO2 A catalyst is a component which initiates chemical reactions wit hout being consumed in the process The platinum coating of the honey comb cells is sensitive to lead i e lead collects on platinum This inhibits the chemical reaction If several tankfuls of leaded fuel are used the catalyst s function can be reduced by more than 50 For this reason only unleaded gasoline may be used in a chain saw with a catalytic converter In order to avoid damage to the engine the catalytic converter must be replaced if cracks are found in the honeycomb structure or if the converter s steel jacket is damaged in any way 133RA216 VA Exhaust gas leaves the internal pipe 1 and is deflected sideways and forwards by the specially shaped baffle plate 2 Additional fresh air is sucked in and used for cooling at this point The special construction of the exhaust outlet allows the exhaust gas to expand immediately so that its temperature drops rapidly in area of spiked bumper to approx 300 C 570 F 024 026 5 3 Leakage Test Defective oil seals and gaskets or cracks in castings are the usual causes of leaks
53. lp locate the fault consult the troubleshooting charts for all assemblies in the Standard Repairs Troubleshoot ing handbook Refer to the Technical Informa tion bulletins for engineering changes which have been intro duced since publication of this service manual Technical informa tion bulletins also supplement the parts list until a revised edition is issued The special servicing tools mentioned in the descriptions are listed in the last chapter of this ma nual Use the part numbers to identify the tools in the STIHL Special Tools manual The manual lists all special servicing tools currently available from STIHL Symbols are included in the text and pictures for greater clarity The meanings are as follows In the descriptions e Action to be taken as shown in the illustration above the text Action to be taken that is not shown in the illustration above the text In the illustrations Pointer Direction of movement Service manuals and all technical information bulletins describing engineering changes are intended exclusively for the use of STIHL servicing dealers They must not be passed to third parties lt x gt So e q c oO ise Servicing and repairs are made considerably easier if the machine is mounted on assembly stand 1 5910 890 3100 Remove the chain sprocket cover and secure the machine to the assembly stand with the sprocket cover nuts Mac
54. ly with a hammer if necessary Important Hold the piston steady during this process to ensure that no jolts are transmitted to the connecting rod Remove piston and take the needle cage out of the connecting rod A 133RA063 VA e Inspect piston rings and replace if necessary see 5 7 5 6 2 Installing 133RA064 VA e Thoroughly clean the gasket seating surface 1 e Lubricate the needle cage 2 with oil and fit it in the small end 133RA065 VA e With arrow 1 pointing to the right use installing tool 5910 890 2210 to fit hookless snap ring 2 in the front piston boss 133RA066 VA N e Heat the piston slightly and slip it over the connecting rod Check installed position of piston 1 Arrow exhaust side 2 Flywheel 024 026 133RA067 VA e Push the assembly drift small diameter first through the piston and small end needle cage and line up the piston X j 5 e Fit the piston pin 1 on the assembly drift 2 and slide it into the piston the pin slides home easily if the piston has been heated 133RA069 VA e Apply the installing tool 1 5910 890 2210 to the piston boss hold the piston steady center the tool shank exactly 024 026 and press home until the snap ring slips into the groove Note For instructions on how to
55. ng element 4 and hot plate 5 are installed between the carburetor and air filter Resistances at temperature of 25 C 77 F Previous heating element 4 Q New heating element 8 Q 024 026 12 3 2 Testing Tests should be carried out as follows on 026 machines up to serial number X 33 339 217 Complete system Note The printed circuit board and heating element are tested as described below The ambient temperature for the test must be at least 21 C 70 F If the temperature is much lower than 21 C 70 F the thermostatic switch may close and produce false readings Test the thermostatic switch separately Remove the air filter see 12 1 Remove the shroud see 4 2 Set ohmmeter to Q x 1 e Clip one of the two test leads to the carburetor body and the other to a cylinder fin 024 026 lt gt o qa 2 ira oO i If the system is in good condition the ohmmeter will indicate 3 8 Q in measuring range Q x 1 Note If the reading obtained is outside this tolerance test each component separately eee 133RA221 VA Heating element Remove the carburetor see 1255 2 e Hold one of the two test leads against the carburetor body and the other against the heating element s center contact If the heating element is in good condition the ohmmeter will show a reading of 3 8 Q in measuring range Q x 1 Note If the reading obtained is
56. open the tank cap slowly to release pressure and ensure that no fuel is spilled Note Valve 1 is removed and installed from above while valve 2 is removed and installed from below To replace the valve unscrew the filler cap 133RA266 VA e Pull the valve out of its seat Push new valve into position 024 026 12 7 Fuel Hose lt gt a wo a 8 12 8 Tank Housing Drain the tank housing Note Collect fuel in a clean container or dispose of at approved disposal site Remove the carburetor see 12 5 2 On machines with carburetor heating up to serial number Remove the carburetor see 12 5 2 Take off the pickup body see 11 1 Pry the flange of the fuel hose out of the fuel tank e Remove the fuel hose Reassemble in the reverse sequence Coat the flange of the fuel hose with a little oil 133RA253 VA X 33 339 217 remove the printed circuit board see 12 4 Remove the front handle see 10 4 Remove the shroud see 4 2 lt S g 8 e Pull short circuit wire and ground wire out of switch shaft and off the contact spring 133RA255 VA e Straight side 1 of flange must be in line with the web 2 and its point must face forwards e Pry rubber grommet out of tank housing and pull wires out of the bore 65 133R
57. ore 145RA028 VA e Carefully tap home the pin squarely to obtain dimension a i e 4 3 4 7 mm 11 64 Install the cylinder see 5 6 2 Install the chain brake see 4 3 3 4 3 5 Pin for Hand Guard 171RA032 VA e Use pliers e g pincers to pull the pin out of the crankcase Coat the knurled area of the new pin with Loctite see 13 2 before installation Position the new pin in the bore so that the knurling on the pin meshes with the existing knurling in the bore Carefully tap home the pin squarely 13 44 Front Chain Tensioner 024 133RA030 VA Remove the side plate e Wind tensioner slide 1 back till it butts against thrust pad 2 e Take out the adjusting screw 3 with thrust pad and tensioner slide 133RA031 VA e Pull the thrust pad 1 off the adjusting screw e Unscrew the adjusting screw 2 from the tensioner slide 3 Sor e Take out the screw 1 e Remove the cover plate 2 14 45 Side Chain Tensioner 133RA032 VA Remove the side plate e Rotate the spur gear clockwise until the tensioner slide 1 butts against the thrust pad 2 133RA033 VA e Take out the screw 1 e Remove the cover plate 2 e Take out the tensioner slide 3 with adjusting screw and thrust pad 4 133RA034 VA
58. otective tube is correctly positioned a 20 mm 0 8 b 33 mm 1 3 133RA027 V e Attach the brake spring to the bell crank e Use the assembly tool 2 1117 890 0900 to attach the brake spring 1 to the anchor pin Fit cover over the chain brake e On machines with handle hea ting secure ground wire for heater switch with rear screw Tighten down screws to 3 0 Nm 2 2 Ibf ft On 026 fit the upper bumper strip Install the side plate Install clutch drum chain sprocket see 4 1 Check operation of chain brake see 4 3 1 024 026 4 3 4 Anchor Pin for Brake Spring Remove the cylinder see 5 6 1 Remove the chain brake see 4 3 2 _ lt 145RA027 VA e Use a suitable punch to drive the anchor pin out of the crankcase in the direction of the arrow Important Do not drive out the pin in the other direction as this would damage the annular bead which was formed in the crank case bore when the pin was originally installed In such a case neither the new anchor pin nor the brake spring would locate properly Further more the crankcase could be damaged in this way and possibly impair correct operation of the chain brake 024 026 Coat the knurled area of the new pin with Loctite see 13 2 before installation Position the new pin in the bore so that the knurling on the pin meshes with the existing knurling in the b
59. ound wire at spark plug boot side and the copper colored wire generator wire at the air filter side 024 026 12 5 3 Adjusting SS Standard setting To readjust the carburetor start with the standard setting Carefully screw down both adjusting screws until they are against their seats Then make the following adjustments H High speed screw 1 open 1 full turn L Low speed screw 2 open 1 full turn A slight correction to this setting may be necessary at high altitudes mountains or near sea level For corrections to high speed screw H Use a tachometer do not exceed max permissible engine speed Engine can be damaged by lack of lubricant and overheating Maximum engine speed with bar and properly tensioned chain 13 000 rpm 024 14 000 rpm 026 Note If no tachometer is avail able do not turn the high speed or low speed screws beyond the standard setting to make the mixture leaner 024 026 Furthermore the engine speed of machines with catalytic converter must not be less than 12 000 or 13 000 rpm Check chain tension Check air filter and clean if necessary Inspect the spark arresting screen and clean or replace if ne cessary Start the engine and warm it up Adjust idle speed correctly chain must not rotate Turn high speed screw H and low speed screw L clockwise for leaner mixture at high altitudes or counterclockwise
60. out preparations see 5 8 1 133RA045 VA e Connect suction hose of vacuum pump 0000 850 3501 to test flange nipple lt gt N T gt lt c oO ise e Close the vent screw 1 on the pump e Operate lever 2 until pressure gauge indicates a vacuum of 0 5 bar 7 25 psi 024 026 Note If the vacuum reading remains constant or rises to no more than 0 3 bar 4 25 psi within 20 seconds it can be assumed that the oil seals are in good condition However if the pressure continues to rise reduced vacuum in the crankcase the oil seals must be replaced After finishing the test open the vent screw and disconnect the hose Remove the test flange Install the carburetor see 12 5 2 Loosen the muffler screws and pull out the sealing plate Take out one screw and coat its thread with Loctite see 13 2 Refit screw and tighten down to 10 Nm 7 5 Ibf ft Note Remove and install the second screw in the same way Fit the upper casing 024 026 5 4 Oil Seals NE 133RA048 VA It is not necessary to disassemble the complete crankcase if only the oil seals have to be replaced Clutch side Remove the clutch see 4 2 e Remove the brake band 1 see 4 3 2 e Remove the oil pump 2 see 11 3 Use a suitable pipe or punch to carefully tap the oil seal and free it off 133RA049 VA 7 e Apply puller 1 5910
61. position of wire 3 to rear handle heating element 37 6 5 Contact Spring S XQ rs 133RA147 VA Remove the air filter see 12 1 Turn switch lever so that it points up e Pull the ground wire 1 out of the contact spring e Machines with carburetor heating from serial number X 33 339 218 Pull flag terminal 2 off the contact spring lt gt o iv 6 5 e Pull contact spring out of its seat in the tank housing Reassemble in the reverse sequence 38 6 6 Flywheel Removing the flywheel Use the locking strip to block the piston see 4 2 Remove the fan housing Rotate the flywheel so that the magnet poles line up with the ignition module e Unscrew the flywheel mounting nut e Use puller 1 1110 890 4500 to release the flywheel Pull the flywheel off the crankshaft 133RA151 VA e The flywheel 1 and magnet poles 2 must not be cracked or damaged in any way Install a new flywheel if necessary For machines with heated handles see 10 5 133RA152 VA Installing the flywheel Important Clean the stub of the crankshaft and the flywheel hub bore with a standard commercial solvent based degreasant contain ing no chlorinated or halogenated hydrocarbons see 13 2 e Check that the key is correctly positioned in the crankshaft Fit the flywheel in position Fit and tighten down flywheel nut to 33 Nm 24 5 Ibf
62. pring Replacing Tensioning Starter Rope Starter Grip ElastoStart AV Handle System Master Control Handle System Switch Shaft Interlock Lever Throttle Trigger Electric Handle Heating System Troubleshooting Troubleshooting Chart Test Connections and Test Values Heater Switch Heating Element in Rear Handle Heating Element in Front Handle Generator Chain Lubrication Pickup Body Suction Hose Valve Oil Pump Servicing Fuel System Air Filter Choke Shutter Carburetor Preheating Carburetor Heater Construction and Function Testing Troubleshooting Chart Printed Circuit Board 42 43 43 43 45 45 46 47 48 48 49 50 52 55 55 56 56 56 57 59 60 12 5 Carburetor 60 12 5 1 Leakage Testing 60 12 5 2 Removing and Installing 61 12 5 3 Adjusting 63 12 6 Tank Vent 64 12 7 Fuel Hose 65 12 8 Tank Housing 65 13 Special Servicing Tools and Aids 68 13 1 Special Servicing Tools 68 13 2 Servicing Aids 70 1 SAFETY PRECAUTIONS If the engine is started up in the course of repairs or maintenance work observe all local and country specific safety regulations as well as the safety precautions and war nings in the owner s manual Gasoline is an extremely flamm able fuel and can be explosive in certain conditions Improper handling may result in burns or other serious injuries Warning Do not smoke or bring any fire or flame near the fuel All work
63. ressure at the same time until driver on oil pump worm engages the notch on the drum s circumference If machine is equipped with a rim sprocket refit it so that the cavities face outwards 4 2 Clutch Troubleshooting chart see Standard Repairs Trouble shooting handbook Remove the clutch drum chain sprocket see 4 1 Remove the air filter see 12 1 133RA004 VA e Unscrew slotted nut from the shroud Remove the shroud Pull off the spark plug boot 133RA006 VA Unscrew the spark plug e Close the decompression valve 1 where fitted e Push the locking strip 2 0000 893 5903 into the cylinder 8 e Unscrew the clutch in the direction of the arrow left hand thread Disassemble and reassemble the clutch see Standard Repairs Troubleshooting handbook On 024 if a cover washer is fitted behind the original clutch do not refit it when installing the new clutch e Screw clutch onto crankshaft and torque down to 50 Nm 37 Ibf ft Remove locking strip from cylinder Q a aK Q ON UG Z Install spark plug and torque down to 25 Nm 18 5 lbf ft e On machines with a decompres sion valve make sure the cover is properly seated 133RA035 VA e lf the shroud is replaced ona 026 machine without decompres sion valve seal the opening in the shroud with the cap lt gt Q e lt ac oO ise e Che
64. s cap into the starter grip Fit starter rope on rope rotor Install the rope rotor Starter grip The new starter grip comes with starter rope Remove the rope rotor see Standard Repairs and Troubleshooting handbook Take the knot out of the recess in the rope rotor Open the knot and pull the starter rope out of the rotor and fan housing e Thread the starter rope 1113 195 8200 through the guide bush from outside 250R e Thread other end of rope through the hole in the side of the rope rotor Secure the rope with a simple overhand knot 250RA128 VAS e Pull the rope back into the rotor so that the knot locates in the recess Install rope rotor see Standard Repairs Troubleshooting hand book Tension the rewind spring see 7 2 2 Fit fan housing with rewind starter 41 8 AV HANDLE SYSTEM Rubber anti vibration buffers are installed between the crankcase and tank housing Damaged rubber buffers annular buffers must always be replaced in sets Modified softer annular buffers are installed in 026 machines without spark arresting from serial number 1 42 567 877 All annular buffers are marked with an abbreviated version of the part number for easy identification The marking is usually molded on the end face of the buffer e g annular buffer 1121 790 9902 is marked 1121 02 Remove the
65. shroud see 4 2 Remove the side plate see 4 3 2 On quick chain tensioning system remove the lower bumper strip 133RA160 VA e Ease the plug out of the rear annular buffer 42 133RA161 VA e Remove screw 1 from chain catcher 2 e Ease expanding plug 3 out of front annular buffer 133RA162 VA e Unscrew the annular buffer mounting screws e Pry the annular buffers out of the crankcase 133RA164 VA e Push the new annular buffers into the crankcase so that the groove engages over the inner housing rib 1 133RA165 VA e Take out the screw 1 and remove the sleeve 2 e Take out the screws 3 and remove the annular buffer plate 4 e Check stop buffer from machine X 36 348 620 and install new one if necessary To do this remove tank housing see 12 8 Tightening torques see 3 6 024 026 9 MASTER CONTROL HANDLE SYSTEM 9 1 Switch Shaft The thumb operated Master Control lever moves the switch shaft to select the required function Remove the interlock lever see 9 2 e Pull the short circuit wire out of the switch shaft e Pry the switch shaft out of its pivot mount next to the contact spring 024 026 lt gt o z a oO 9 2 Interlock Lever Throttle Trigger E A Turn the switch shaft so the Mas
66. sible to heat the crankcase use the press arbor 1 1118 893 7200 to press in the ball bearing as far as stop I 133RA109 e Place annular buffer 1 in position with large opening facing outward e Install screws 2 with Loctite 242 and tighten down to 8 Nm 5 9 Ibf ft see 13 2 e Screw the spindle fully into service tool ZS 2 and then screw the threaded sleeve 1 5910 893 2420 onto the spindle as far as it will go 29 If crankcase is new install collar studs for guide bar with Loctite 242 and torque down to 23 Nm 17 Ibf ft 133RA110 VA 133RA113 VA Lubricate tapered crankshaft e Turn the spindle clockwise the stub with oil until the crankshaft locates against the ball bearing e Place tapered crankshaft stub in ball bearing at ignition side of Important The connecting rod crankcase must point toward the cylinder flange while the crankshaft is being installed 133RA111 VA 133RA114 VA 133RA116 VA e Position threaded sleeve 1 on e Release the spindle by turning it Lubricate straight crankshaft thread 2 of crankshaft stub and counterclockwise then hold the stub with oil screw it on crankshaft steady and unscrew the service tool counterclockwise Slip clutch side of crankcase over the crankshaft stub 133RA117 D 133RA112 VA 133RA115 VA e Hold the spindle steady and turn e Fit a new gasket on t
67. sing 56 12 3 12 3 1 Carburetor Heater Construction and Function 133RA218 VA The carburetor heater in 024 machines up to serial number X 33 339 217 and the 026 both operate in exactly are the same way but differ slightly in construc tion The heating element 1 is a small ceramic plate bonded to the carburetor Power is supplied by the generator for the electric handle heating system Current is fed via wires to the tank housing and from there via a printed circuit board with sliding contacts to the heating element Carburetor heating is controlled automatically via the thermostatic switch 2 on the carburetor Note In the 024 the thermostatic switch is installed inside the tank housing It trips at approx 18 C 65 F The VH versions of 026 machines from serial number X 33 339 218 are equipped with a new carburetor heating system 133RA219 VA A new thermostatic switch 3 is mounted on a bracket on the new carburetor s end cover The new thermostatic switch turns off the carburetor heating at a lower temperature This means that more power is available sooner for the handle heating system The handles therefore warm up faster Cut out temperature of thermostatic switch Previous version 15 21 C 60 70 F New version 7 13 C 45 55 F The heating element 1 bonded to the previous carburetor and the printed circuit board have been deleted Instead heati
68. stem is maintenance free and subject to practically no wear Faults in the generator heating elements and wiring are generally caused by mechanical damage Heating elements with a higher resistance are installed from serial number X 33 339 218 see 10 3 or 10 4 There are two reasons for failures in the heating system 1 A break in the circuit due to a faulty wire or component 2 Ashort circuit resulting from damaged insulation Important The heating element in the rear handle may overheat and lt gt D A 3 ira re fail if it is not bonded firmly in position i e completely flat no creases To trace the cause of a fault 024 026 ELECTRIC HANDLE HEATING SYSTEM NX oS 145RA230 VA Remove interlock lever see 9 2 e Slide back the insulating tube from connector on the wire between the generator and rear handle heating element 145RA231 VA e Separate the pin and socket connector M e Set the heater switch to Set the ohmmeter to Ox1 Ss 145RA293 VA e Clip one ohmmeter test lead to the generator wire and the other test lead to the heating element wire Note All electrical components of the heating system are connected in series with the ohmmeter If the system is in order the ohm meter should indicate a value between 3 5 and 4 or 0 9 and 1 1Q If no reading is obtained there is a break in the circuit
69. tatic switch no ey Replace thermostatic switch Does switch close below approx 12 C 55 F R 0Q yes no p Replace thermostatic switch Does switch open above approx 21 C 70 F R yes System in order 59 12 4 Printed Circuit Board 133RA228 VA 026 machines up to serial number X 33 339 217 Remove the shroud see 4 2 Remove the carburetor see 12 5 2 Take boot off the spark plug e Slide the insulating tube 1 off the connector on the wire between the printed circuit board and the rear handle heating element e Separate the pin and socket connector e Take the insulating tube out of the rear handle and pull the wire out of the insulating tube 60 133RA230 VA e Pull the ground wire contact sleeve out of its seat in the contact spring 12 5 12 5 1 Carburetor Leakage Testing Troubleshooting chart see Standard Repairs and Troubleshooting Important If problems occur on the carburetor or the fuel supply system always check and clean the tank vent see 12 6 The carburetor can be tested for leaks with the carburetor and crankcase tester 1106 850 2905 Remove the air filter see 12 1 Check tester for leaks e Pull the terminal socket housing off the printed circuit board Remove the printed circuit board Install in the reverse sequence e When refi
70. ter Control lever points up e Pull the switch shaft out of the other pivot mount Install in the reverse sequence The throttle rod must be above the switch shaft e Use a screwdriver to press the switch shaft 1 into the pivot mount and ease the contact spring 2 forwards a little at the same time 133RA169 VA 133RA170 VA 133RA171 VA Remove the air filter see 12 1 Move Master Control lever to CHOKE position e Take out the screw Remove the handle molding 133RA172 VA Move Master Control lever to RUN position e Pull interlock lever out of its seat 43 133RA173 VA Vga ey e Pull the throttle rod out of the throttle trigger 133RA174 VA e Use a 5 mm 3 16 drift to drive out the cylindrical pin 1 e Take the throttle trigger 2 and torsion spring 3 out of the handle 133RA175 VA e Remove the torsion spring The torsion spring must be under the interlock lever and engage the notch 44 lt gt o lt ira oO 2 Install in the reverse sequence e Press the interlock lever 1 down e Push the throttle trigger 2 up and move Master Control lever 3 to CHOKE position lt gt S R lt iia oO fed e Fit the handle molding so that tab 1 engages the seat 2 in the tank housing 024 026 10 10 1 Troubleshooting The entire handle heating sy
71. tion lead about 20 mm 3 4 with oil Fit spark plug boot over the ignition lead Use suitable pliers to grip the end of the ignition lead inside the spark plug boot and pull it out 145RA171 VA e Pinch the hook of the spring into the center of the lead about 15 mm 5 8 from the end of the lead 34 171RA146 VA e Pull the lead back into the boot so that the spring locates properly inside it O A 338RA142 VA e Use a pointed tool awl or gimlet to pierce the center of the other end of the ignition lead which screws into the module Reassemble remaining parts in the reverse sequence 250RA008 VA e If spark plug has detachable adapter nut it must be attached and tightened down securely 6 2 Ignition Module 133RA131 VA The ignition module accommoda tes all the components required to control ignition timing There are three electrical connections on the coil body 1 the high voltage output 1 2 the ground wire 2 3 the connector tag 3 for the short circuit wire Accurate testing of the ignition module is only possible with special test equipment For this reason it is only necessary to carry out a spark test in the workshop A new ignition module must be installed if no ignition spark is obtained after checking that wiring and stop switch are in good condition 024 026 6 2 1 Ignition Timing Ignition timing is fixed and is not a
72. to ignition breakerless with integral trigger unit 0 2 0 3 mm 0 008 0 012 in Bosch WSR 6F NGK BPMR 7 A or Champion RCJ 6Y 0 5 mm 0 020 in STIHL Rollomatic with nose sprocket corrosion resistant finish and induction hardened rails 32 37 and 40 cm 13 15 18 in 0 325 8 25 mm Rapid chain 7 tooth 0 325 18 3 m s 60 ft s at 9 500 rpm Speed controlled or adjustable reciprocating pump 6 cm min 0 2 fl oz min at 6 000 rpm 9 5 cm min 0 3 fl oz min at 10 000 rpm 4 5 11 5 cm min 0 15 0 4 fl oz min at 10 000 rpm 0 32 L 11 fl oz 0000 190 3401 1121 120 1625 1121 640 2001 1 11216402005 2 1121 007 1030 1121 007 1027 up to serial number X 30 976 774 1121 007 1044 from serial number X 30 976 775 1121 007 1001 1 1121 007 1037 1121 007 1002 1121 007 1038 1121 007 1004 1121 007 1039 1121 007 1005 1121 007 1040 1121 007 1035 1121 007 1041 NSNIANANIN 0000 792 9131 1121 007 1042 024 026 3 5 2 For Service Carburetor parts kit 024 small 1118 007 1060 Tillotson Carburetor parts kit 024 large 1118 007 1065 Tillotson Carburetor parts kit 024 026 large 1121 007 1062 Walbro Carburetor parts kit 024 026 large 1118 007 1066 Walbro WT 22 Gasket set 024 026 1121 007 1050 3 6 Tightening Torques Plastoform screws are used for polymer components These screws form a permanent thread when they are installed for the first time They can be removed and installed as often as necess
73. tting make sure the bent contact locates between the housing and peg e Pull fuel hose off the carburetor s elbow connector S N fia oO e Push the fuel line 1 1110 141 8600 onto the nipple 2 0000 855 9200 024 026 If this pressure remains constant the carburetor is airtight However if it drops there are two possible causes 1 The inlet needle is not sealing foreign matter in valve seat or sealing cone of inlet needle is damaged or inlet control lever sticking 2 The metering diaphragm is e Push fuel line with nipple onto damaged carburetor elbow connector After completing test open the vent screw and pull the fuel line off the elbow connector Push the fuel hose onto the elbow connector Install the air filter P a 133RA235 A e Connect the tester s pressure hose to the nipple K 133RA236 VA e Close the vent screw 1 on the rubber bulb 2 and pump air into the carburetor until the pressure gauge 3 shows a reading of approx 0 8 bar 11 6 psi 024 026 12 5 2 Removing and Installing 133RA233 VA Remove the air filter see 12 1 Remove the interlock lever see 9 2 e Pull fuel hose off the carburetor s elbow connector 133RA237 VA e On machines with new carbure tor heating pull flag terminal off contact spring 133RA238 VA Unscrew the nuts On machines with new car
74. x18 pan head screw must then be used in place of the original special self threading screw Reassemble in the reverse sequence 024 026 133RA261 VA e A different air filter system is installed from serial number X 36 348 620 As a result of the modified air flow the cut out see arrow in the tank housing is no longer required e The cut out is now closed with a molding skin It can be re opened for machines with the original air filter system Note Carry out this work carefully so that the cover 1 or shutter 2 is an exact fit e Fit the manifold in the tank housing intake opening as follows Wind a piece of string 1 approx 15 cm 6 long around the back of the manifold flange and pass the ends of the string through the intake opening e Push the manifold down lt gt o 3 T oO ey e Pull the ends of the string outward Note The manifold flange is thus pulled through the tank housing intake opening without damaging the manifold 67 13 Special Servicing Tools and Aids 13 1 Special Servicing Tools 1 Locking strip 2 Press sleeve 3 Assembly sleeve 4 Press sleeve 5 Puller 6 Jaws No 3 1 7 Jaws No 6 8 Puller 9 Crimping tool 10 Assembly drift 11 Wooden assembly block 12 Clamping strap 13 Carburetor and crankcase tester 14 Nipple 15 Fuel line 16 Vacuum pump 17
75. ylinder see 5 6 1 Remove the flywheel see 6 6 On machines with heated handles remove the generator see 10 5 Remove the ignition module see 6 2 2 Drain the chain oil tank Drain the fuel tank Note Dispose of fuel at approved disposal site Remove the tank housing see 12 8 Remove the oil pump see 11 3 Remove the spiked bumper Remove the piston see 5 6 1 133RA080 VA e Take out the screws that join the two halves of the crankcase 133RA081 VA e Use a screwdriver to rotate the spur gear 1 clockwise until the tensioner slide 2 butts against the thrust pad 3 133RA082 VA e At the chain tensioner side of the crankcase use a 4 mm 0 15 drift to drive the dowel pin out of the two halves of the crankcase 133RA083 VA e Only the new service tool AS for machines with the quick chain tensioning system illustration shows view from below 25 lt gt po 3 q ira oO 2 e Back off spindle 1 of service tool AS 5910 890 2205 all the way e Slip service tool AS 2 over the collar studs fit the hexagon nuts 3 for sprocket cover and tighten them down by hand e Turn the spindle 1 clockwise until the crankshaft is pressed out of the ball bearing The two halves of the crankcase separate during this process Remove the service tool AS Remove crankcase gasket

Online version - not for reprint

Contents

Download Pdf Manuals

Related Search

Related Contents