Stihl FS120, FS200, FS300, FS350, FS400, FS450, FR350 FR450 Full Service & Repair Manual

STIHL FR 350, 450 2003-04 STIH) STIHL FS 120, 200, 300, 350, 400, 450, STIH) chodina@live.co.uk chodina@live.co.uk

1. Introduction 2 2. Specifications 3 2.1 Engine 3 2.2 Fuel System 3 2.3 Ignition System 4 2.4 Gearhead 4 2.5 Special Accessories 4 2.5.1 For User 4 2.5.2 For Service 4 2.6 Tightening Torques 5 3. Clutch 7 3.1 Removing and Installing 7 3.2 Clutch Carrier 8 4. Engine 9 4.1 Exhaust Muffler/ Spark Arresting Screen 9 4.2 Leakage Test 10 4.2.1 Preparations 10 4.2.2 Pressure Test 11 4.2.3 Vacuum Test 11 4.3 Oil Seals 12 4.4 Exposing the Cylinder 13 4.5 Cylinder and Piston 14 4.5.1 Removal 14 4.5.2 Installation 15 4.6 Piston Rings 17 4.7 Crankcase 17 4.7.1 Removing Crankshaft 17 4.7.2 Installing Crankshaft 20 4.8 Decompression Valve 23 5. Ignition System 23 5.1 Spark Plug Boot 23 5.2 Ignition Lead (FS 400/450, FR 450) 24 5.3 Ignition Module 25 5.3.1 Ignition Timing 26 5.3.2 Removing and Installing (FS 120...350, FR 350) 26 5.3.3 Removing and Installing (FS 400/450, FR 450) 27 5.4 Flywheel 28 5.5 Short Circuit Wire 29 6. Rewind Starter 30 6.1 General 30 6.2 Rewind Spring 30 6.2.1 Replacing 30 6.2.2 Tensioning 31 6.3 Starter Rope/Starter Grip (ElastoStart) 32 7. Throttle Control 33 7.1 Throttle Trigger/Interlock Lever (Bike Handle) 33 7.2 Contact Springs/Detent Spring in Control Handle (Bike Handle) 34 7.3 Throttle Trigger/Interlock Lever (Loop Handle) 34 7.4 Slide Control (Loop Handle) 35 7.5 Throttle Cable 36 7.5.1 Replacing 36 7.5.2 Adjusting 37 8. Fuel System 38 8.1 Air Filter 38 8.2 Carburetor 39 8.2.1 Removing and Installing (FS 120...350, FR 350) 39 8.2.2 Removing and Installing (FS 400/450, FR 450) 40 8.2.3 Leakage Test 41 8.2.4 Adjusting (three screws) 42 8.2.5 Adjusting (one screw) 43 8.3 Tank Vent 44 8.4 Pickup Body 44 8.5 Fuel Tank/ Hoses 45 8.6 Manual Fuel Pump 47 9. AV System 47 9.1 Repair (FS 120/200) 47 9.2 Repair (FS 300...450) 48 9.3 Repair (FR 350/450) 50 10. Shaft 51 10.1 Bike Handle (FS 120/200) 51 10.2 Bike Handle (FS 300...450) 51 10.3 Loop Handle 52 10.4 Drive Shaft/ Flexible Liner 52 10.5 Flexible Shaft (FR 350/450) 53 10.6 Drive Tube 54 10.7 Housing (FR 350/450) 56 11. Cutting Tool Drive 56 11.1 Gearhead 56 11.2 Clutch Drum 57 12. Support Frame (FR 350/450) 58 12.1 Repair 58 13. Special Servicing Tools and Aids 59 13.1 Special Servicing Tools 59 13.2 Servicing Aids 61 © 2000, Andreas Stihl AG & Co., Waiblingen CONTENTS qS FS 120, 200, 300, 350, 400, 450, FR 350, 450 1 chodina@live.co.uk chodina@live.co.uk

This service manual contains de- tailed descriptions of all the repair and servicing procedures specific to this power tool series. There are separate handbooks for servicing procedures for stand- ardized parts and assemblies that are installed in several STIHL power tool models. Reference is made to these handbooks in the appropriate chapters in this manual. As the design concept of models FS 120, FS 200, FS 300, FS 350, FS 400, FS 450 and FR 350, FR 450 is almost identical, the descriptions and servicing procedures in this manual generally apply to all models. Differences are described in detail. 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 power tool may have several causes. Consult the troubleshooting charts for all assemblies in the "Standard Repairs, Troubleshooting" handbook. Refer to the "Technical Informa- tion" bulletins for engineering changes which have been intro- duced since publication of this service manual. Technical information bulletins also supplement the parts list until a revised edition is issued. The special servicing tools mentio- ned in the descriptions are listed in the last chapter of this manual. 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: • = 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. Servicing and repairs are made considerably easier if the machine is mounted on assembly stand (2) 5910 890 3100 with the aid of clamp (1) 5910 890 8800. Secure the clamp to the assembly stand with two washers and two M8 nuts. Servicing and repairs to the powerhead are considerably easier if it is mounted on assembly stand (2) 5910 890 3100 with the aid of clamping plate (1) 5910 890 2101. First remove the clutch housing and secure the powerhead to the stand with two M6x20 and two M10x25 hex. head screws. The machine or powerhead can then be swivelled to the best position for the ongoing repair and this leaves both hands free. Always use original STIHL replacement parts. They can be identified by the STIHL part number, the and the STIHL parts symbol The symbol may appear alone on small parts. 1. INTRODUCTION 250RA228 1 2 VA 250RA227 VA 2 1 2 FS 120, 200, 300, 350, 400, 450, FR 350, 450 chodina@live.co.uk chodina@live.co.uk

2.1 Engine STIHL single cylinder two-stroke engine with special impregnated cylinder bore FS 120/300 FS 200/350 FS 400 FS 450 FR 350 FR 450 Displacement: 30.8 cm 3 36.3 cm 3 40.2 cm 3 44.3 cm 3 1.88 cu.in 2.21 cu.in 2.45 cu.in 2.70 cu.in Bore: 35 mm 38 mm 40.0 mm 42.0 mm 1.38 in 1.49 in 1.57 in 1.65 in Stroke: 32 mm 32 mm 32 mm 32 mm 1.26 in 1.26 in 1.26 in 1.26 in Power output: 1.3 kW (1.8 bhp) 1.6 kW (2.2 bhp) 1.9 kW (2.6 bhp) 2.1 kW (2.8 bhp) at 9,000 rpm Max. permissible engine speed without cutting tool (cut-off speed): 12,500 ± 1000 rpm 12,500 ± 800 rpm Idle speed: 2,800 rpm Bearings: Crankshaft supported in heavy-duty ball bearings, needle cages on small and big ends Piston pin diameter: 10 mm (0.39 in) Rewind starter: ElastoStart Pawls: Single pawl system Reserve pull on rope rotor: min. 1/2 turn Starter rope: 3.0 mm (0.12 in) dia. x 800 mm (31.5 in) Clutch: Centrifugal clutch without linings Clutch engages at: 4,300 rpm Crankcase leakage test at gauge pressure: 0.5 bar (7.25 psi) under vacuum: 0.5 bar (7.25 psi) 2.2 Fuel System Carburetor: Diaphragm carburetor Standard setting on carburetors with three adjusting screws High speed screw H: Open approx. 1 turn Low speed screw L: Open approx. 1 turn Carburetor leakage test at gauge pressure: 0.8 bar (11.6 psi) Function of tank vent at gauge pressure: ≤ 0.3 bar (4.35 psi) under vacuum: ≤ 0.05 bar (0.725 psi) Fuel tank capacity: 0.64 l (1.35 US pt) 0.68 l (1.44 US pt) Octane rating: min. 90 RON (US/CAN; pump octane min. 87) Fuel mixture: Regular brand name gasoline and two-stroke engine oil Mix ratio: 50:1 with STIHL two-stroke engine oil 25:1 with other brand name two-stroke, air-cooled engine oils Air filter: Paper filter 2. SPECIFICATIONS FS 120, 200, 300, 350, 400, 450, FR 350, 450 3 chodina@live.co.uk chodina@live.co.uk

2.3 Ignition System Type: Electronic magneto ignition (breakerless) with integral trigger unit and electronic speed governor Air gap: 0.2 - 0.5 mm (0.008 - 0.020 in) Length of ignition lead: 305 mm * (12 in)* Spark plug (suppressed): Bosch WSR 6F, NGK BPMR 7 A or Champion RCJ 6Y Electrode gap: 0.5 mm (0.020 in) Splark plug thread: M14x1.25 Length of thread: 9.5 mm (0.37 in) 2.4 Gearhead Type: Spiral-toothed bevel gear drive Gear ratio: 1:1.4 ** 1:1.235 Bearings: Deep groove ball bearings Lubrication: STIHL gear lubricant 0781 120 1117 (7 g / 0.25 oz) 2.5 Special Accessories 2.5.1 For User Full harness Safety glasses Transport guard for metal cutting tools STIHL gear lubricant (80 g/3 oz tube) 0781 120 1109 STIHL gear lubricant (80 g/3 oz tube) 0781 120 1117 2.5.2 For Service Carburetor parts kit 4134 007 1060 Set of gaskets for FS 120, 200, 300, 350, FR 350 4134 007 1050 Set of gaskets for FS 400, 450, FR 450 4128 007 1050 * FS 400/450 only ** FS 120, 200, 350 and 450 4 FS 120, 200, 300, 350, 400, 450, FR 350, 450 chodina@live.co.uk chodina@live.co.uk

DG and P screws (Plastoform) are used in polymer and lightmetal components. These screws form a perma- nent thread when they are installed for the first time. They can be removed and installed as often as necessary 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 lbf.ft Self-tapping screw IS-B3.5x6.5 Rewind spring/fan housing 1.5 1.1 Self-tapping screw IS-B4.2x9.5 Muffler/spark arresting screen 2.5 1.8 1) 2) Spline screw IS-DG4x20 Ignition module/crankcase 4.5 3.3 3) 4) 5) Spline screw IS-DG5x24 Ignition module/crankcase 6.0 4.4 1) 2) Spline screw IS-DG5x12 AV sleeve/drive tube (fixing screw) 2.5 1.8 3) Spline screw IS-DG5x12 Guard ring/gear housing 5.0 3.7 1) 4) Spline screw IS-DG5x20 Fan housing/crankcase 6.0 4.4 Spline screw IS-DG5x20 Fan housing/shroud/crankcase 6.0 4.4 Spline screw IS-DG5x20 Carburetor housing/crankcase/ cylinder 6.0 4.4 Spline screw IS-DG5x20 Filter housing/ground wire/ crankcase 6.0 4.4 Spline screw IS-DG5x20 Ground wire/crankcase 6.0 4.4 1) 2) Spline screw IS-DG5x26 Fuel tank/crankcase 6.0 4.4 Spline screw IS-DG5x24 Bracket/crankcase 6.0 4.4 1) Spline screw IS-DG5x20 Shroud/clutch housing 6.0 4.4 Spline screw IS-DG5x26 Guard plate/fuel tank/ crankcase 6.0 4.4 1) 2) Spline screw IS-DG5x28 Cylinder/crankcase 10.5 7.5 Spline screw IS-DG5x24 Muffler/crankcase 8.5 6.3 Spline screw IS-DG5x24 Muffler/cylinder 8.5 6.3 Spline screw IS-DG5x24 Crankcase 8.5 6.3 Spline screw IS-DG5x24 Clutch housing/crankcase 8.5 6.3 1) 2) 4) 5) Spline screw IS-DG5x24 Clutch housing/crankcase 6.0 4.4 3) Spline screw IS-DG6x28 Clutch housing/drive tube 12.0 8.8 1) 6) Spline screw IS-DG5x24 Clutch housing/drive tube 8.5 6.3 4) Spline screw IS-DG5x24 Gear housing/drive tube 8.5 6.3 2) 3) 5) Spline screw IS-DG5x25 Gear housing/drive tube Stage 1 1.5 1.1 1) 4) Stage 2 7.5 5.5 1) 4) Collar nut M5 Filter housing/carburetor housing 3.5 2.6 Collar screw M5/P6 Carburetor housing 4.0 3.0 Spline screw IS-M5x12 Clamp/control handle/ drive tube (loop handle) 2.0 1.5 3) 4) Spline screw IS-M5x16 AV sleeve/drive tube (clamp screw) 5.5 4.0 3) Spline screw IS-M5x12 Clamp/control handle/drive tube 2.0 1.5 2) 5) Spline screw IS-M5x16 Clamp/drive tube (for harness) 4.5 3.3 3) Spline screw IS-M5x30 Control handle (bike handle) 2.0 1.5 6) 2.6 Tightening Torques FS 120, 200, 300, 350, 400, 450, FR 350, 450 5 chodina@live.co.uk chodina@live.co.uk

Fastener Thread For component Torque Remarks size Nm lbf.ft Spline screw IS-M6x25 Clamp/loop handle 4.5 3.3 3) Spline screw IS-M6x25 Support/drive tube 6.0 4.4 1) 4) 6) Spline screw IS-M6x35 Clamp moldings/support block (handle support/bike handle) 4.5 3.3 3) M8 Carrier 24.0 17.7 Spline screw IS-M6x18 Clutch shoe/carrier 12.0 8.8 M8 Flywheel 32.0 23.6 M10 Decompression valve 14.0 10.3 1) 2) 4) 5) M14x1.25 Spark plug 20.0 15.0 Screw plug M11x10 Gearhead 8.5 6.3 Spline screw IS-M5x14 Filter cover/filter housing 6.0 4.4 1) 2) Plastoform screw IS-P4x16 Control handle/handle moldings 1.0 0.75 Collar screw IS-P3.5x10.6 Detent spring/slide control (bike handle) 1.1 0.80 1) 3) 4) Nut M12x1.5 L Cutting tool 25.0 18.5 Spline screw IS-M5x16 Cutting tool deflector/gearhead 4.3 3.2 Spline screw IS-M6x14 Spring/support plate 10.0 7.5 2) 5) Spline screw IS-M6x25 Housing/shaft clamp screw 4.5 3.3 2) 5) Spline screw IS-M6x14 Bearing housing/support frame 10.0 7.5 2) 5) Spline screw IS-M10x20 Support plate/ball bearing/ support frame 20.0 15.0 2) 5) Use the following procedure to fit a DG or P screw in an existing thread: – Place the DG or P 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. 1) FS 400/450 2) FR 450 3) FS 120/200 4) FS 300/350 5) FR 350 6) with washer Note: Power screwdriver speed settings for polymer: Plastoform screws max. 600 rpm DG screws max. 500 rpm 6 FS 120, 200, 300, 350, 400, 450, FR 350, 450 chodina@live.co.uk chodina@live.co.uk

Removal Troubleshooting chart - see "Standard Repairs, Trouble- shooting" handbook. - Remove clutch housing - see 9.1 or 11.2. All models • Inspect clutch drum. There should be no scores or signs of excessive wear. Important: If there are signs of serious wear on the inside diameter, fit a new clutch drum - see 11.2. - Remove the shroud - see 4.1. - Pull off the spark plug boot. - Unscrew the spark plug. FS 120...350, FR 350 • Fit locking strip (1) 0000 893 5903. FS 400/450, FR 450 • Fit locking strip (1) 4221 893 5900. • Take out screws (1). • Remove cover (2). • Remove clutch shoes with bushings. • Take bushings out of the clutch shoes. • Twist the clutch shoes and detach the springs. Important: Clutch shoes and springs must always be replaced in pairs. 3. CLUTCH 3.1 Removing and Installing 250RA001 1 VA 250RA002 1 VA 250RA004 1 1 2 VA 250RA003 VA 250RA005 VA 250RA230 VA 250RA229 VA FS 120, 200, 300, 350, 400, 450, FR 350, 450 7 chodina@live.co.uk chodina@live.co.uk

Installation • Fit clutch shoes with springs and bushings so that the arrows point counterclockwise. • Fit cover in position. • Insert screws and tighten down to 12 Nm (8.8 lbf.ft). - Pull locking strip out of cylinder. - Fit spark plug and tighten down to 20 Nm (15 lbf.ft). Important: If the spark plug comes with a separate terminal nut, always fit the nut on the thread and tighten it down securely. - Fit the boot on the spark plug. - Fit the shroud - see 4.1. - Fit clutch housing - see 9.1 or 11.2. - Remove clutch - see 3.1. • Unscrew carrier from end of crankshaft. • Fit the carrier and tighten it down to 24 Nm (17.7 lbf.ft). - Install the clutch - see 3.1. 3.2 Clutch Carrier 250RA232 VA 250RA231 VA 250RA234 VA 250RA235 VA 250RA233 VA 8 FS 120, 200, 300, 350, 400, 450, FR 350, 450 chodina@live.co.uk chodina@live.co.uk

Troubleshooting chart - see "Standard Repairs, Trouble- shooting" handbook. Spark arresting screen FS 120...350, FR 350 • Pull spark arresting screen out of the muffler. - Clean or replace spark arresting screen if necessary. FS 400/450, FR 450 • Take out the screw (1). • Pull spark arresting screen (2) out of the muffler. - Clean or replace spark arresting screen if necessary. - Tighten down screw to 2.5 Nm (1.8 lbf.ft). Muffler FS 400/450, FR 450 - Remove air filter cover - see 8.1. All models • Remove screws from clutch housing. • Take out screws (1). • Press down the decompression valve (2). • Remove the shroud (3). • Take out the screws. - Lift away the muffler. • Remove the gasket. Reassemble in the reverse sequence. - Use a new gasket. - Tighten down screws to 8.5 Nm (6.3 lbf.ft). 250RA006 VA 250RA011 VA 250RA009 VA 250RA012 VA 250RA007 1 2 VA 1 250RA010 1 3 2 VA 4. ENGINE 4.1 Exhaust Muffler/Spark Arresting Screen FS 120, 200, 300, 350, 400, 450, FR 350, 450 9 chodina@live.co.uk chodina@live.co.uk

Stihl FS120, FS200, FS300, FS350, FS400, FS450, FR350 FR450 Full Service & Repair Manual

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