Stihl MS440 chainsaw

STIH) STIHL MS 440 2006-05

1 MS 440, MS 440 C q © ANDREAS STIHL AG & Co. KG, 2006 Contents 1. Introduction 3 2. Safety Precautions 4 3. Specifications 5 3.1 Engine 5 3.2 Fuel System 5 3.3 Ignition System 5 3.4 Chain Lubrication 5 3.5 Tightening Torques 6 4. Troubleshooting Chart 7 4.1 Clutch, Chain Drive, Chain Brake, Chain Tensioner 7 4.2 Rewind Starter 8 4.3 Chain Lubrication 9 4.4 Ignition System 10 4.5 Carburetor 11 4.6 Engine 13 5. Clutch, Chain Drive, Chain Brake and Chain Tensioner 14 5.1 Clutch Drum / Chain Sprocket 14 5.2 Replacing the Chain Catcher 15 5.3 Clutch 15 5.4 Chain brake 17 5.4.1 Checking correct operation 17 5.4.2 Removing 18 5.4.3 Installing 20 5.5 Chain Tensioner 22 5.6 Bar Mounting Studs 23 6. Engine 24 6.1 Muffler / Spark Arresting Screen 24 6.2 Leakage Test 25 6.2.1 Preparations 26 6.2.2 Pressure Test 27 6.2.3 Vacuum Test 27 6.3 Oil Seals 28 6.4 Removing the shroud 30 6.5 Cylinder and Piston 30 6.5.1 Removing 30 6.5.2 Installing 32 6.6 Piston Rings 35 6.7 Crankcase 35 6.7.1 Removing the crankshaft 35 6.7.2 Installing the crankshaft 38 6.8 Decompression Valve 43 7. Ignition System 44 7.1 Ignition Module 44 7.1.1 Ignition Timing 44 7.1.2 Removing and Installing 45 7.1.3 Testing the ignition system 46 7.2 Ignition Lead / Spark Plug Boot 47 7.3 Flywheel 48 7.3.1 Removal 48 7.3.2 Installation 49 7.4 Stop switch 49 7.5 Wiring harness 49 7.5.1 Testing Wiring Harness 50 7.6 Ignition System Troubleshooting 51 8. Rewind Starter 54 8.1 General 54 8.2 Removing and Installing 54 8.3 Pawls 54 8.4 Rope Rotor 55 8.5 Starter rope 55 8.5.1 Tensioning 56 8.6 Starter Rope Guide Bushing 57 8.7 Replacing the Rewind Spring 58 9. AV handle system 59 10. Single lever master control / handle system 60 10.1 Switch shaft 60 10.2 Throttle Trigger / Interlock Lever 61 11. Chain Lubrication 62 11.1 Pickup Body / Suction Hose 62 11.2 Valve 63 11.2.1 Cleaning 63 11.2.2 Replacing 63 11.3 Oil pump 64 11.3.1 Removing and installing 64 11.3.2 Servicing 64 12. Fuel System 65 12.1 Air Filter 65 12.2 Carburetor 66 12.2.1 Removing and Installing 66 12.2.2 Leakage Test 68 12.3 Servicing the Carburetor 68 12.3.1 Metering Diaphragm 68 12.3.2 Inlet Needle 69 12.3.3 Fixed Jet 70 12.3.4 Pump Diaphragm 70 12.4 Adjustment (carburetor without limiter caps) 71 12.4.1 Adjustment (carburetor with limiter cap) 72 12.4.2 Basic Setting (carburetor with limiter cap) 73 12.5 Tank Vent 74 12.6 Pickup Body 74 12.7 Fuel Hose 75 12.8 Tank housing 76

2 MS 440, MS 440 C Contents 13. Carburetor Heating 79 13.1 Troubleshooting Chart 80 13.2 Heating element with thermostatic switch 81 14. Handle Heating System 81 14.1 Troubleshooting 81 14.1.1 Troubleshooting Chart 83 14.1.2 Test Connections and Test Values 85 14.2 Heater switch 86 14.3 Heating element in front handle 86 14.4 Heating element in front handle 87 14.5 Generator 88 15. Special Servicing Tools 89 16. Servicing Aids 91

3 MS 440, MS 440 C This service manual contains detailed descriptions of all the typical repair and servicing procedures for this power tool. 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. A fault on the machine may have several causes. To help locate the fault, consult the chapter on "Troubleshooting" and the "STIHL Service Training System". Refer to the "Technical Information” bulletins for engineering changes which have been introduced since publication of this service manual. Technical information bulletins also supplement the parts list until an updated edition is issued. The special tools mentioned in the descriptions are listed in chapter "Special Servicing Tools" of this manual. Use the part numbers to identify the tools in the "STIHL Special Tools" manual which lists all the 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: : = 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) += Situation applies as from serial No. *= Situation applies up to serial No. In the illustrations: A Pointer aDirection of movement b 4.2 Reference to another chapter, i.e. chapter 4.2 in this example. Service manuals and technical information bulletins are intended exclusively for the use of properly equipped repair shops. They must not be passed to third parties. Servicing and repairs are made considerably easier if the clamp (1) 5910 890 2000 is used to mount the machine on assembly stand (2) 5910 890 3100 so that one clamp screw engages the outer 10 mm (0.39 in) hole (3) in the assembly stand. To service the underside of the machine (e.g. remove the front handle), turn it upside down and mount it so that one clamp screw engages the inner 10 mm (0.39 in) hole in the assembly stand. Pull the hand guard back against the front handle for this purpose. Always use original STIHL replacement parts. They can be identified by the STIHL part number, the STIH) logo and the STIHL parts symbol ( This symbol may appear alone on small parts. 1. Introduction

4 MS 440, MS 440 C 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 warnings in the instruction manual. Gasoline is an extremely flammable fuel and can be explosive in certain conditions. Improper handling may result in burns or other serious injuries. Warning! Do not bring any fire, flame, spark or other source of heat near the fuel. All work with fuel must be performed outdoors only. Spilled fuel must be wiped away immediately. 2. Safety Precautions

5 MS 440, MS 440 C 3. Specifications 3.1 Engine Displacement: 70.7 cm 3 (4.31 cu.in) Bore: 50 mm (1.97 in) Stroke: 36 mm (1.42 in) Engine power to ISO 7293: 4 kW (5.4 bhp) at 9,500 rpm Max. permissible engine speed with bar and chain: 13,500 ± 150 rpm Idle speed: 2,500 1 rpm Clutch: Centrifugal clutch with three unlined clutch shoes Clutch engages at: 3,500 rpm Crankcase leakage test at gauge pressure: p ü = 0.5 bar (7.25 psi) under vacuum: p u = 0.5 bar (7.25 psi) 3.2 Fuel System Carburetor leakage test at gauge pressure: p ü = 0.8 bar (11.6 psi) Operation of tank vent at gauge pressure: p ü = 0.3 bar (4.35 psi) Fuel: as specified in instruction manual 3.3 Ignition System Air gap between ignition module and fanwheel: 0.15...0.3 mm (0.006...0.12in) Spark plug (suppressed): Bosch WSR 6F NGK BPMR 7A Electrode gap: 0.5 mm (0.02 in) 3.4 Chain Lubrication Fully automatic, speed-controlled oil pump with rotary piston Oil delivery rate: 8...18 cm 3 /min (0.49...1.1 cu.in/min) at 10,000 rpm

6 MS 440, MS 440 C 3.5 Tightening Torques DG screws are used in polymer and light metal components. These screws form a permanent thread when they are installed for the first time. They can be removed and installed as often as necessary without impairing 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 size For component Torque Remarks Nm (lbf ft) Screw IS-M5x20 Crankcase 11.5 (8.48) Screw IS-M5x20 Cylinder 11.5 (8.48) Screw IS-M5x16 Muffler, lower casing to cylinder 11.0 (8.11) 1) Screw IS-M5x6 Muffler, upper casing top 6.5 (4.79) 1) Screw IS-M5x16 Muffler top 11.0 (8.11) 1) Screw IS-M5x18 Muffler bottom 15.0 (11.06) 1) Screw IS-M5x20 Ignition module 7.0 (5.16) 2)3) Screw IS-M4x16 Shroud 4.0 (2.95) M12x1 L Carrier (clutch) 50.0 (36.88) M14x1,25 Spark plug 25.0 (18.44) Nut M5 Carburetor 3.5 (2.58) Screw IS-M4x16 Annular buffer plate 5.0 (3.69) Screw IS-M5x12 Spiked bumper top (with nut) 7.5 (5.53) Screw IS-M5x16 Spiked bumper bottom (chain catcher) 7.5 (5.53) Screw IS-M3,5x12 Generator 2.0 (1.48) 1) Screw M4x8 Cover, chain tensioner 3.0 (2.21) Screw IS-M4x12 Oil pump 3.5 (2.58) Screw IS-M4x12 Cover, chain brake 3.0 (2.21) Screw IS-M4x12 Brake band 3.0 (2.21) 1) Screw IS-M4x16 Fan housing 4.0 (2.95) 2) Screw M4x8 Side plate, inner 3.0 (2.21) Nut M8x1 Crankshaft (flywheel) 33.0 (24.34) M10x1 Decompression valve 14.0 (10.33) Collar stud M8x21,5 Bar mounting 23.0 (16.96) 1) Polymer screw IS-P6x26,5 Annular buffer, top 5.5 (4.06) Polymer screw IS-P6x19 Annular buffer, bottom 5.5 (4.06) Polymer screw IS-P6x19 Front handle, top 8.0 (5.90) 4) Polymer screw IS-P6x19 Front handle, bottom 8.0 (5.90) 4) Screw assy. IS-M4x16 Hand guard left, fan housing 4.0 (2.95) Remarks: 1) Secure screw with Loctite 270 2) Secure screw with Loctite 242 3) A washer must be fitted under the screw head

7 MS 440, MS 440 C 4. Troubleshooting Chart 4.1 Clutch, Chain Drive, Chain Brake, Chain Tensioner Condition Cause Remedy Saw chain stops under load at full throttle Clutch shoes badly worn Replace clutch shoes Clutch drum badly worn Install new clutch drum Brake band stuck Check freedom of movement and function of brake band. Saw chain rotates at idle speed Engine idle speed too high Adjust idle speed screw (counterclockwise) Clutch springs stretched or fatigued Replace clutch springs Clutch spring hooks broken Replace clutch springs Loud noises Clutch springs stretched or fatigued Replace all clutch springs Needle cage damaged Fit new needle cage Clutch shoe retainer broken Fit new retainer Clutch shoes and carrier worn Install new clutch Chain sprocket wears rapidly Chain not properly tensioned Tension chain as specified Wrong chain pitch Fit chain of correct pitch Insufficient chain lubrication Check chain lubrication Chain sprocket worn Fit new chain sprocket Saw chain does not stop immediately when brake is activated Brake spring stretched or broken Fit new brake spring Brake band stretched, worn or broken Fit new brake band

8 MS 440, MS 440 C 4.2 Rewind Starter Condition Cause Remedy Starter rope broken Rope pulled out too vigorously as far as stop or over edge, i.e. not vertically Fit new starter rope Normal wear Fit new starter rope Starter rope does not rewind Rewind spring broken Fit new rewind spring Spring overtensioned – no reserve when rope is fully extended Fit new rewind spring Very dirty or corroded Clean or replace rewind spring Starter rope can be pulled out almost without resistance (crankshaft does not turn) Guide peg on pawls or pawls themselves are worn Fit new pawls Spring clip fatigued Fit new spring clip Starter rope is difficult to pull and rewinds very slowly Starter mechanism is very dirty Thoroughly clean complete starter mechanism Lubricating oil on rewind spring becomes viscous at very low outside temperatures (spring windings stick together) Coat rewind spring with a little standard solvent-based degreasant (containing no chlorinated or halogenated hydrocarbons), then pull rope carefully several times until normal action is restored

9 MS 440, MS 440 C 4.3 Chain Lubrication Warning! In the event of trouble with the chain lubrication system, check and rectify other sources of faults before disassembling the oil pump. Condition Cause Remedy Chain receives no oil Oil tank empty Fill up with oil O-ring on oil line to crankcase defective or oil line damaged Remove oil pump, fit a new O-ring and refit or replace the oil pump Oil inlet hole in guide bar is blocked Clean oil inlet hole Intake hose or pickup body (strainer) clogged or intake hose ruptured Clean intake hose and pickup body (strainer) with standard solvent- based degreasant not containing chlorinated or halogenated hydrocarbons / replace intake hose and pickup body Valve in oil tank blocked Clean or replace valve Teeth on pump piston and/or worm worn Install new oil pump and/or new worm Machine losing chain oil O-ring on oil line to crankcase defective or oil line damaged Remove oil pump, fit a new O-ring and refit or replace the oil pump Piston bore in pump housing worn Install new oil pump Oil pump delivers insufficient oil Adjusting screw and/or control edge on pump piston worn Fit new adjusting screw and/or oil pump Piston bore in pump housing worn Install new oil pump

Stihl MS440 chainsaw

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