STIHL MS 171 181 211 CHAINSAW Workshop Service Repair Manual

STIH) STIHL MS 171, 181, 211 2007-05

1 MS 171, MS 181, MS 211 q © ANDREAS STIHL AG & Co. KG, 2007 RA_533_00_01_01 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 8 4.1 Clutch 8 4.2 Chain Drive, Chain Brake, Chain Tensioner 9 4.3 Chain Lubrication 10 4.4 Rewind Starter 11 4.5 Ignition System 12 4.6 Carburetor 14 4.7 Engine 17 5. Cutting Attachment 18 5.1 Chain Catcher 18 6. Clutch 19 6.1 Clutch Drum 21 7. Chain Brake 22 7.1 Checking Operation 22 7.2 Removing and Installing the Brake Band 22 7.3 Brake Lever 24 7.4 Flat Spring 26 7.5 Pins 26 7.6 Chain Tensioner 27 7.7 Bar Mounting Studs 27 8. Engine 28 8.1 Muffler / Spark Arresting Screen 28 8.2 Leakage Test 29 8.2.1 Preparations 29 8.2.2 Vacuum Test 30 8.2.3 Pressure Test 30 8.3 Oil Seals 31 8.4 Removing and Installing the Shroud 32 8.5 Removing and Installing the Engine 33 8.6 Crankshaft 34 8.7 Ball Bearings/ Crankshaft 36 8.8 Piston 37 8.8.1 Piston Rings 39 9. Ignition System 40 9.1 Ignition Module 40 9.1.1 Removing and Installing 40 9.2 Ignition Timing 42 9.3 Testing the Ignition Module 42 9.4 Spark Plug Boot 43 9.5 Flywheel 44 9.6 Short Circuit Wire 45 9.6.1 Testing 45 9.6.2 Removing and Installing 45 9.6.3 Ground Wire 47 9.6.4 Contact Spring 47 9.7 Ignition System Troubleshooting 49 10. Rewind Starter 52 10.1 General 52 10.2 Removing and Installing 52 10.3 Pawl 53 10.4 ErgoStart 53 10.5 Rope Rotor 55 10.6 Starter Rope / Grip 55 10.7 Tensioning the Rewind Spring 57 10.8 Replacing the Rewind Spring 58 11. Servicing the AV System 60 11.1 AV Spring on Oil Tank 60 11.2 AV Spring on Fuel Tank 60 11.3 AV Spring on Cylinder 61 11.4 Handle Frame 62 12. Master Control Lever 64 12.1 Switch Shaft 64 12.1.1 Removing and Installing 64 12.2 Throttle Trigger / Interlock Lever 66 13. Chain Lubrication 68 13.1 Pickup Body 68 13.2 Oil Suction Hose 68 13.3 Removing and Installing the Oil Pump 69 13.4 Valve 70 13.5 Oil Tank Cap 71 Contents

2 MS 171, MS 181, MS 211 Contents 14. Fuel System 72 14.1 Air Filter 72 14.2 Baffle / Filter Base 72 14.3 Removing and Installing the Carburetor 73 14.3.1 Leakage Test 74 14.4 Servicing the Carburetor 74 14.4.1 Metering Diaphragm 74 14.4.2 Inlet Needle 76 14.4.3 Fixed Jet 76 14.4.4 Valve Jet 77 14.4.5 Pump Diaphragm 77 14.4.6 Air Valve 79 14.4.7 Choke Shaft / Choke Shutter 80 14.4.8 Throttle Shaft / Throttle Shutter 82 14.4.9 Adjusting Screws 85 14.5 Adjusting the Carburetor 86 14.5.1 Basic Setting 86 14.5.2 Standard Setting 87 14.6 Choke and Throttle Rods 87 14.7 Removing and Installing the Intake Manifold 89 14.7.1 Removing and Installing the Carburetor Carrier 90 14.8 Tank Vent 92 14.8.1 Testing 92 14.8.2 Removing and Installing 93 14.8.3 Manual Fuel Pump 93 14.9 Fuel Intake 94 14.9.1 Pickup Body 94 14.9.2 Fuel Intake Hoses 95 14.9.3 Fuel Hoses, Tank Vent / Manual Fuel Pump 96 14.9.4 Fuel Tank Cap 97 15. Special Servicing Tools 98 16. Servicing Aids 100

3 MS 171, MS 181, MS 211 1. Introduction 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" for all assemblies. 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) IIn 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 machine is mounted to assembly stand (3) 5910 890 3100. To do this, secure the mounting plate (2) 5910 850 1650 to the assembly stand with two screws (1) and washers. The screws must not project since they, depending on the machine, may damage housings when the machine is clamped in position. The above operation is not necessary with the new assembly stand 5910 890 3101 since the mounting plate is already fitted. 1 2 3 219RA000 TG

4 MS 171, MS 181, MS 211 After disengaging the chain brake and removing the chain sprocket cover, bar and chain, the powerhead’s bar stud is pushed through the outer hole in the mounting plate and secured with the nut (arrow). The machine is held in position on the mounting plate by the two screw heads on the engine housing. 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. Storing and disposing of oils and fuels Collect fuel or lubricating oil in a clean container and dispose of it properly in accordance with local environmental regulations. 533RA000 TG 2. 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 warnings in the instruction manual. Gasoline is an extremely flammable fuel and can be explosive in certain conditions. Always wear suitable protective gloves for operations in which components are heated for assembly or disassembly. Improper handling may result in burns or other serious injuries. 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. Always perform leakage test after working on the fuel system and the engine.

5 MS 171, MS 181, MS 211 3. Specifications 3.1 Engine MS 171 MS 181, MS 181 C MS 211, MS 211 C Displacement: 30.1 cm 3 31.8 cm 3 35.2 cm 3 Bore: 37 mm 38 mm 40 mm Stroke: 28 mm 28 mm 28 mm Engine power to ISO 7293: 1.3 kW (1.8 PS) at 9,500 rpm 1.5 kW (2.0 PS) at 9,500 rpm 1.7 kW (2.3 PS) at 9,500 rpm Max. permissible engine speed with bar and chain: 13,500 rpm 13,500 rpm 13,500 rpm Idle speed: 2,800 rpm 2,800 rpm 2,800 rpm Clutch: Centrifugal clutch without linings Clutch engages at: 5,100 rpm 5,100 rpm 5,100 rpm Crankcase leakage test at gauge pressure: 0.5 bar under vacuum: 0.5 bar 3.2 Fuel System Carburetor leakage test at gauge pressure: 0.8 bar Operation of tank vent at gauge pressure: 0.5 bar Fuel: as specified in instruction manual 3.3 Ignition System Air gap between ignition module and fanwheel: 0.15...0.35 mm Spark plug (suppressed): NGK CMR 6H Electrode gap: 0.5 mm 3.4 Chain Lubrication Fully automatic, speed-controlled oil pump with reciprocating piston Oil delivery rate: 7.0 cm³/min at 10,000 rpm

6 MS 171, MS 181, MS 211 3.5 Tightening Torques DG and P (Plastoform) 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 Screw P 4x12 Cover plate, chain sprocket cover 2.5 Screw B 3.9x13 Cover plate (special accessory) 1.0 Screw D 4x15 Chain tensioner cover/engine housing 2.5 Collar screw D 8x18 Collar screw, engine housing/guide bar, rear 16.0 1) Collar screw D 8x18 Collar screw engine housing/guide bar, front 16.0 1) Screw P 4x16 Cover, chain brake/engine housing (repair solution) 2.0 Screw D 5x16 Cover, chain brake/engine housing (repair solution) 2.0 Countersunk screw M 6x14 Replacement chain catcher (repair solution) 4.0 Screw P 5x20 Filter base/engine housing 4.0 Screw P 5x20 Filter base/engine housing/carburetor carrier 4.0 Screw D 5x16 Spiked bumper/engine housing 3.5 Screw D 4x12 Manifold/cylinder 4.0 Screw P 5x20 AV bearing plug, front bottom/engine housing 4.0 Screw P 5x20 AV bearing plug, rear bottom/handle frame 4.0 Screw P 5x20 AV bearing plug, rear bottom/engine housing 4.0 Screw D 5x18 AV bearing plug/cylinder 8.0 Screw P 5x25 Fan housing/hand guard/engine housing 4.0 Screw P 5x20 Fan housing/engine housing 4.0 M 12x1 L Clutch/crankshaft 50.0 Screw D 5.3x41 Crankcase/engine pan/cylinder 11.0 Collar nut M 5 Baffle/filter base/collar screw, carburetor 3.5 Screw D 5x18 Muffler/cylinder 8.0 Nut M 8x1 Flywheel/crankshaft 28.0 2) M 10x1 Spark plug 12.0 Screw D 4x18 Ignition module/cylinder 4.0

7 MS 171, MS 181, MS 211 Remarks: 1) Loctite 243 medium strength 2) Degrease crankshaft/flywheel faces and mount oil-free Use the following procedure when refitting a DG or P screw in an existing thread: Place the screw in the hole and rotate it counterclockwise until it drops down slightly. Tighten the screw clockwise to the specified torque. This procedure ensures that the screw engages properly in the existing thread and does not form a new thread and weaken the assembly. Power screwdriver setting for polymer: DG and P screws max. 500 rpm Do not use a impact wrench for releasing or tightening screws. Do not mix up screws with and without binding head

8 MS 171, MS 181, MS 211 4. Troubleshooting 4.1 Clutch Condition Cause Remedy Saw chain stops under load at full throttle Clutch shoes badly worn Install new clutch Clutch drum badly worn Install new clutch drum Saw chain rotates at idle speed Engine idle speed too high Readjust with idle speed screw (LA) (counterclockwise) Clutch springs stretched or fatigued Replace the clutch springs or install new clutch Clutch spring hooks broken Replace the clutch springs Clutch shoe bores worn Replace clutch shoes or install new clutch 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

9 MS 171, MS 181, MS 211 4.2 Chain Drive, Chain Brake, Chain Tensioner Condition Cause Remedy 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 stops under load at full throttle Clutch shoes badly worn Install new clutch Clutch drum badly worn Install new clutch drum Brake band blocked Check freedom of movement and operation of brake band Saw chain does not stop immediately when brake is activated Brake spring stretched or broken Fit new brake spring Brake band stretched or worn Fit new brake band Clutch drum worn Fit new clutch drum

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STIHL MS 171 181 211 CHAINSAW Workshop Service Repair Manual

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