Product Instruction Manual
Page 3
... Chain 44 Maintenance and Care 47 { Main Parts Specifications Special Accessories Ordering Spare Parts Maintenance and Repairs STIHL Incorporated Federal Emission Control Warranty Statement Trademarks MS 311, MS 391 English 49 Allow only persons who fully understand 51 this Manual to operate your chain saw. 52... Bar 35 Air Filter System 36 Cleaning the Air Filter 36 Engine Management 37 Adjusting the Carburetor 37 Spark Arresting Screen in this manual, please contact your STIHL dealer for your area if you can be made from those described in chapter "Safety Precautions...
... Chain 44 Maintenance and Care 47 { Main Parts Specifications Special Accessories Ordering Spare Parts Maintenance and Repairs STIHL Incorporated Federal Emission Control Warranty Statement Trademarks MS 311, MS 391 English 49 Allow only persons who fully understand 51 this Manual to operate your chain saw. 52... Bar 35 Air Filter System 36 Cleaning the Air Filter 36 Engine Management 37 Adjusting the Carburetor 37 Spark Arresting Screen in this manual, please contact your STIHL dealer for your area if you can be made from those described in chapter "Safety Precautions...
Product Instruction Manual
Page 24
... perform its operating characteristics. twice a year, Occasional usage - Do not operate your saw is engaged. If your STIHL chain saw to reduce the risk of dirt, grease and other factors. annually. The chain saw chain brake incurs ...saw should be returned to trained personnel such as your STIHL servicing dealer for the chain brake on the drum. Tighten all nuts, bolts and screws except the carburetor adjustment screws after each STIHL chain saw in the boot may cause a fire. ...reducing the risk of forest fires is a change in the instruction manual). 22 MS 311, MS 391
... perform its operating characteristics. twice a year, Occasional usage - Do not operate your saw is engaged. If your STIHL chain saw to reduce the risk of dirt, grease and other factors. annually. The chain saw chain brake incurs ...saw should be returned to trained personnel such as your STIHL servicing dealer for the chain brake on the drum. Tighten all nuts, bolts and screws except the carburetor adjustment screws after each STIHL chain saw in the boot may cause a fire. ...reducing the risk of forest fires is a change in the instruction manual). 22 MS 311, MS 391
Product Instruction Manual
Page 27
... (e.g., outboard motors, snowmobiles, chain saws, mopeds, etc.). When filling at authorized disposal locations. Gasoline Oil (STIHL 50:1 or equivalent high-quality oils) US gal. 1 2 1/2 5 US fl.oz 2.6 6.4 12...days work, not to the engine. Use mid-grade unleaded gasoline with the fuel. MS 311, MS 391 25 Fuel with the skin and avoid inhaling fuel vapor. This could cause ...mixing, pour oil into the mixture. Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but magnesium castings and catalytic converters as to...
... (e.g., outboard motors, snowmobiles, chain saws, mopeds, etc.). When filling at authorized disposal locations. Gasoline Oil (STIHL 50:1 or equivalent high-quality oils) US gal. 1 2 1/2 5 US fl.oz 2.6 6.4 12...days work, not to the engine. Use mid-grade unleaded gasoline with the fuel. MS 311, MS 391 25 Fuel with the skin and avoid inhaling fuel vapor. This could cause ...mixing, pour oil into the mixture. Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but magnesium castings and catalytic converters as to...
Product Instruction Manual
Page 31
... malfunction due to overheating 0001BA003 KN MS 311, MS 391 29 Chain brake maintenance Remove shroud N Move the Master Control lever to full throttle for no more than 3 seconds - r facing upwards N Refit the shroud and tighten the screws Heated air is necessary to normal wear. this helps prevent carburetor icing. Accelerate up to the... now drawn in any way. felling cut. The chain brake will operate only if it serviced and maintained regularly by trained personnel, such as your STIHL servicing dealer, at idle speed, engage the chain brake (push hand guard toward bar nose).
... malfunction due to overheating 0001BA003 KN MS 311, MS 391 29 Chain brake maintenance Remove shroud N Move the Master Control lever to full throttle for no more than 3 seconds - r facing upwards N Refit the shroud and tighten the screws Heated air is necessary to normal wear. this helps prevent carburetor icing. Accelerate up to the... now drawn in any way. felling cut. The chain brake will operate only if it serviced and maintained regularly by trained personnel, such as your STIHL servicing dealer, at idle speed, engage the chain brake (push hand guard toward bar nose).
Product Instruction Manual
Page 32
...n - engine off Operating position F - ignition is usually also necessary to adjust the idle speed adjusting screw (LA), see "Setting the carburetor". after starting the warm engine - When the cover plate is running or can start Warm start l - engine is used, the slide ... this position is necessary 4903BA004 KN 001BA140 KN Starting / Stopping the Engine Positions of the cover plate is for starting the cold engine 30 MS 311, MS 391 English At temperatures below +14 °F (-10 °C) Attach cover plate Under extreme winter conditions (temperatures below +14 °F...
...n - engine off Operating position F - ignition is usually also necessary to adjust the idle speed adjusting screw (LA), see "Setting the carburetor". after starting the warm engine - When the cover plate is running or can start Warm start l - engine is used, the slide ... this position is necessary 4903BA004 KN 001BA140 KN Starting / Stopping the Engine Positions of the cover plate is for starting the cold engine 30 MS 311, MS 391 English At temperatures below +14 °F (-10 °C) Attach cover plate Under extreme winter conditions (temperatures below +14 °F...
Product Instruction Manual
Page 36
...) will quickly damage the shortblock and chain drive (clutch, chain brake). Retension if necessary - This protects enginemounted components (ignition, carburetor) from sources of the bar but can damage the crankshaft and bearings. This avoids unnecessarily high loads during work N Slacken off the...this period. Running the engine at high revs (full throttle off the bar. Long-term storage See "Storing the machine" 34 MS 311, MS 391 English Operating Instructions During the break-in period A factory new machine should not be run for a while at operating temperature ...
...) will quickly damage the shortblock and chain drive (clutch, chain brake). Retension if necessary - This protects enginemounted components (ignition, carburetor) from sources of the bar but can damage the crankshaft and bearings. This avoids unnecessarily high loads during work N Slacken off the...this period. Running the engine at high revs (full throttle off the bar. Long-term storage See "Storing the machine" 34 MS 311, MS 391 English Operating Instructions During the break-in period A factory new machine should not be run for a while at operating temperature ...
Product Instruction Manual
Page 39
... standard setting. N Check the spark arresting screen (country-specific) in the muffler and clean or replace if necessary. 37 With this carburetor it is a risk of engine damage due to correct the adjusting screws within fine limits. If the setting is too lean there is...the shroud and tighten the screws Engine Management English Adjusting the Carburetor Exhaust emissions are controlled by the design of any major hardware. This setting provides an optimum fuel-air mixture under most operating conditions. Standard setting MS 311, MS 391 LA N Shut off the engine N Check the air...
... standard setting. N Check the spark arresting screen (country-specific) in the muffler and clean or replace if necessary. 37 With this carburetor it is a risk of engine damage due to correct the adjusting screws within fine limits. If the setting is too lean there is...the shroud and tighten the screws Engine Management English Adjusting the Carburetor Exhaust emissions are controlled by the design of any major hardware. This setting provides an optimum fuel-air mixture under most operating conditions. Standard setting MS 311, MS 391 LA N Shut off the engine N Check the air...
Product Instruction Manual
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...N Position the replacement spring with frame in a well ventilated area. this helps prevent the carburetor diaphragms sticking together. N Remove the saw chain and guide bar, clean them and spray with local environmental requirements. STIHL BioPlus, completely fill the chain oil tank. English The starter grip must be possible to turn...fan housing N Apply suitable tools (screwdriver, punch, etc.) to the cylinder fins and air filter. risk of children and other unauthorized persons. 42 MS 311, MS 391 the anchor loop (arrow) must be drawn firmly into its seat in the fan housing -
...N Position the replacement spring with frame in a well ventilated area. this helps prevent the carburetor diaphragms sticking together. N Remove the saw chain and guide bar, clean them and spray with local environmental requirements. STIHL BioPlus, completely fill the chain oil tank. English The starter grip must be possible to turn...fan housing N Apply suitable tools (screwdriver, punch, etc.) to the cylinder fins and air filter. risk of children and other unauthorized persons. 42 MS 311, MS 391 the anchor loop (arrow) must be drawn firmly into its seat in the fan housing -
Product Instruction Manual
Page 50
...adjusting screws) 3) Retighten Sparl arresting screen4) in all versions, market-specific X X X X X X X X X X 48 MS 311, MS 391 If your daily working time is longer or operating conditions are difficult (very dusty work or daily after 10 to normal operating conditions...STIHL servicing dealer. 2) see chapter on "Chain Brake" 3) Firmly tighten down the cylinder base screws of professional saws (3.4 kW or more) after each refueling stop weekly monthly every 12 months if problem if damaged if required Cooling inlets Clean X Cylinder fins Clean X X Preseparator port and carburetor...
...adjusting screws) 3) Retighten Sparl arresting screen4) in all versions, market-specific X X X X X X X X X X 48 MS 311, MS 391 If your daily working time is longer or operating conditions are difficult (very dusty work or daily after 10 to normal operating conditions...STIHL servicing dealer. 2) see chapter on "Chain Brake" 3) Firmly tighten down the cylinder base screws of professional saws (3.4 kW or more) after each refueling stop weekly monthly every 12 months if problem if damaged if required Cooling inlets Clean X Cylinder fins Clean X X Preseparator port and carburetor...
Product Instruction Manual
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Main Parts 3 5 2 4 # 1 6 11 7 12 8 10 9 13 16 17 15 18 20 22 19 23 21 14 24 English 1 Shroud Lock 2 Carburetor Adjusting Screws 3 Spark Plug Boot 4 Shutter (Summer and Winter Operation) 5 Decompression Valve (Automatically Resetting) 6 Chain Brake 7 Chain Sprocket 8 Chain Sprocket Cover 9 Chain Catcher 10 Side ... Fuel Filler Cap 20 Master Control Lever 21 Throttle Trigger 22 Throttle Trigger Lockout 23 Rear Handle 24 Rear Hand Guard # Serial Number 4903BA003 KN MS 311, MS 391 49
Main Parts 3 5 2 4 # 1 6 11 7 12 8 10 9 13 16 17 15 18 20 22 19 23 21 14 24 English 1 Shroud Lock 2 Carburetor Adjusting Screws 3 Spark Plug Boot 4 Shutter (Summer and Winter Operation) 5 Decompression Valve (Automatically Resetting) 6 Chain Brake 7 Chain Sprocket 8 Chain Sprocket Cover 9 Chain Catcher 10 Side ... Fuel Filler Cap 20 Master Control Lever 21 Throttle Trigger 22 Throttle Trigger Lockout 23 Rear Handle 24 Rear Hand Guard # Serial Number 4903BA003 KN MS 311, MS 391 49
Product Instruction Manual
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.... (not illustrated) 50 MS 311, MS 391 when activated. 6 Chain Brake A device to operator's right hand. It also serves as the lever for chain brake activation. 17 Front Handle (Handlebar) Handlebar for the left hand from operator. English Definitions 1 Shroud Lock Lock for the shroud. 2 Carburetor Adjusting Screws For tuning the carburetor. 3 Spark Plug Boot...
.... (not illustrated) 50 MS 311, MS 391 when activated. 6 Chain Brake A device to operator's right hand. It also serves as the lever for chain brake activation. 17 Front Handle (Handlebar) Handlebar for the left hand from operator. English Definitions 1 Shroud Lock Lock for the shroud. 2 Carburetor Adjusting Screws For tuning the carburetor. 3 Spark Plug Boot...
Product Instruction Manual
Page 53
... RSC3) Pitch: 3/8" (9.32 mm) Drive link gauge: 0.050 in. (1.3 mm) or 0.063 in. (1.6 mm) MS 311, MS 391 51 or 11-tooth Saw chains 3/8" STIHL reduced kickback saw chains (with Sec. 5.11 of operating hours for which the engine has been shown to ISO 7293: 4.4...Fuel system All position diaphragm carburetor with integral fuel pump Fuel tank capacity: 20.3 oz (0.60 l) Chain lubrication Fully automatic, speed-controlled oil pump with reciprocating piston - Category A = 300 hours B = 125 hours C = 50 hours Engine STIHL single cylinder two-stroke engine MS 311 Displacement: 3.60 cu. ...
... RSC3) Pitch: 3/8" (9.32 mm) Drive link gauge: 0.050 in. (1.3 mm) or 0.063 in. (1.6 mm) MS 311, MS 391 51 or 11-tooth Saw chains 3/8" STIHL reduced kickback saw chains (with Sec. 5.11 of operating hours for which the engine has been shown to ISO 7293: 4.4...Fuel system All position diaphragm carburetor with integral fuel pump Fuel tank capacity: 20.3 oz (0.60 l) Chain lubrication Fully automatic, speed-controlled oil pump with reciprocating piston - Category A = 300 hours B = 125 hours C = 50 hours Engine STIHL single cylinder two-stroke engine MS 311 Displacement: 3.60 cu. ...
Product Instruction Manual
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... U.S. Your emission control system includes parts such as the part numbers of the parts. MS 311, MS 391 53 Original STIHL parts can be performed only by an authorized STIHL servicing dealer using original STIHL replacement parts. new 1997 and later model year small off -road equipment engine at no... Spare Parts Please enter your saw model, serial number as well as the carburetor and the ignition system. EPA regulations for the period of engine use from defects in some cases, by the STIHL part number, the { logo and, in materials and workmanship which cause it...
... U.S. Your emission control system includes parts such as the part numbers of the parts. MS 311, MS 391 53 Original STIHL parts can be performed only by an authorized STIHL servicing dealer using original STIHL replacement parts. new 1997 and later model year small off -road equipment engine at no... Spare Parts Please enter your saw model, serial number as well as the carburetor and the ignition system. EPA regulations for the period of engine use from defects in some cases, by the STIHL part number, the { logo and, in materials and workmanship which cause it...
Product Instruction Manual
Page 57
...require shorter maintenance intervals. Carburetor - Magneto or Electronic Ignition System (Ignition Module) - Fuel Line Fittings - Fasteners Where to make a Claim for required maintenance at and after the first scheduled replacement point. Trademarks English STIHL Registered Trademarks STIHL® { K The ...Deviations from this manual are based on the application of parts and other engine components caused by STIHL Incorporated, and N replacement of the recommended 2-stroke fuel-oil MS 311, MS 391 55 Fuel Cap - Choke (Cold Start Enrichment System) - and #3,400,476) 4-...
...require shorter maintenance intervals. Carburetor - Magneto or Electronic Ignition System (Ignition Module) - Fuel Line Fittings - Fasteners Where to make a Claim for required maintenance at and after the first scheduled replacement point. Trademarks English STIHL Registered Trademarks STIHL® { K The ...Deviations from this manual are based on the application of parts and other engine components caused by STIHL Incorporated, and N replacement of the recommended 2-stroke fuel-oil MS 311, MS 391 55 Fuel Cap - Choke (Cold Start Enrichment System) - and #3,400,476) 4-...
Parts Diagram
Page 18
... shroud 2 Pan head self-tapping screw IS-P4x12 1 Shutter 1 Sleeve 1 Washer 1 Carburetor WTE-9 1 Grommet 1 O-ring 9x1.5 1 Filter housing 2 Buffer 1 Baffle 2 Hexagon nut M5 1 Air filter, fleece 1 Air filter PA (B) 1 Prefilter (B) 1 Shroud ☐ 20 3 Spline screw IS-M6x20 1 Warning pictogram Filler cap (2,4) USA, CDN (1) MS 311, (2) MS 311-Z, (3) MS 391, (4) MS 391-Z MS 311, MS 391 18 SCS 01-2010 3.29
... shroud 2 Pan head self-tapping screw IS-P4x12 1 Shutter 1 Sleeve 1 Washer 1 Carburetor WTE-9 1 Grommet 1 O-ring 9x1.5 1 Filter housing 2 Buffer 1 Baffle 2 Hexagon nut M5 1 Air filter, fleece 1 Air filter PA (B) 1 Prefilter (B) 1 Shroud ☐ 20 3 Spline screw IS-M6x20 1 Warning pictogram Filler cap (2,4) USA, CDN (1) MS 311, (2) MS 311-Z, (3) MS 391, (4) MS 391-Z MS 311, MS 391 18 SCS 01-2010 3.29
Parts Diagram
Page 19
Drawing K Carburetor WTE-9 MS 311, MS 391 19 SCS 01-2010 3.29
Drawing K Carburetor WTE-9 MS 311, MS 391 19 SCS 01-2010 3.29
Parts Diagram
Page 20
... 31 1140 122 3201 32 1140 120 7200 33 1140 121 3500 34 1140 122 3202 35 1140 121 3502 1140 007 1004 Qty Description 1 Carburetor WTE-9 ☐ 1 - 35 1 Inlet needle 1 Spring 1 Inlet control lever 1 Spindle 1 Round head screw 1 Gasket 1 Metering diaphragm 1 Gasket 1 Pump diaphragm 1 Air valve housing 4 Screw...Pump piston kit 3 E-clip 1 Choke shutter 2 Round head screw 1 Torsion spring 1 Choke shaft with lever 1 Throttle lever 1 Torsion spring 1 Throttle lever 1 Set of carburetor parts ☐ 6 - 9 (1) MS 311, (2) MS 311-Z, (3) MS 391, (4) MS 391-Z MS 311, MS 391 20 SCS 01-2010 3.29
... 31 1140 122 3201 32 1140 120 7200 33 1140 121 3500 34 1140 122 3202 35 1140 121 3502 1140 007 1004 Qty Description 1 Carburetor WTE-9 ☐ 1 - 35 1 Inlet needle 1 Spring 1 Inlet control lever 1 Spindle 1 Round head screw 1 Gasket 1 Metering diaphragm 1 Gasket 1 Pump diaphragm 1 Air valve housing 4 Screw...Pump piston kit 3 E-clip 1 Choke shutter 2 Round head screw 1 Torsion spring 1 Choke shaft with lever 1 Throttle lever 1 Torsion spring 1 Throttle lever 1 Set of carburetor parts ☐ 6 - 9 (1) MS 311, (2) MS 311-Z, (3) MS 391, (4) MS 391-Z MS 311, MS 391 20 SCS 01-2010 3.29
User Manual
Page 2
... Torques 6 6.9 Decompression Valve 38 9.7 Handlebar 59 3. Control Levers 61 3.1 Clutch 3.2 Chain Drive, Chain Brake, Chain Tensioner 3.3 Chain Lubrication 3.4 Rewind Starter 3.5 Ignition System 3.6 Carburetor 3.7 Engine 4. Ignition System 39 10. Clutch 4.1 Clutch Drum 5. Engine 27 9. Specifications 5 6.3 Oil Seals 30 9.4 AV Spring on 6.2.3 Pressure Test 29 Fuel Tank 57 2....Studs 26 8.4 Rope Rotor 52 8.5 Starter Rope / Grip 53 8.6 Tensioning the Rewind Spring 54 8.7 Replacing the Rewind Spring 55 RA_542_00_01_01 MS 311, MS 391 q © ANDREAS STIHL AG & Co.
... Torques 6 6.9 Decompression Valve 38 9.7 Handlebar 59 3. Control Levers 61 3.1 Clutch 3.2 Chain Drive, Chain Brake, Chain Tensioner 3.3 Chain Lubrication 3.4 Rewind Starter 3.5 Ignition System 3.6 Carburetor 3.7 Engine 4. Ignition System 39 10. Clutch 4.1 Clutch Drum 5. Engine 27 9. Specifications 5 6.3 Oil Seals 30 9.4 AV Spring on 6.2.3 Pressure Test 29 Fuel Tank 57 2....Studs 26 8.4 Rope Rotor 52 8.5 Starter Rope / Grip 53 8.6 Tensioning the Rewind Spring 54 8.7 Replacing the Rewind Spring 55 RA_542_00_01_01 MS 311, MS 391 q © ANDREAS STIHL AG & Co.
User Manual
Page 3
...Filter 68 12.2 Baffle 68 12.3 Filter Base 68 12.4 Air Guide Shroud 69 12.5 Carburetor 71 12.5.1 Leakage Test 71 12.6 Servicing the Carburetor 72 12.6.1 Metering Diaphragm 72 12.6.2 Inlet Needle 73 12.6.3 Pump Diaphragm 74 12.6.4 Air...Valve 76 12.6.5 Levers on Throttle Shaft 76 12.6.6 Adjusting Screws 77 12.7 Carburetor Adjustment 79 12.7.1 Basic Setting 79 12.7.2 Standard Setting 80 12.8 Carburetor Carrier 81 12.9 Intake Manifold 82 12.10 Tank Vent 83 12.10.1 ...Hose 86 12.11.4 Tank Housing 87 13. Contents 12. Servicing Aids 90 2 MS 311, MS 391
...Filter 68 12.2 Baffle 68 12.3 Filter Base 68 12.4 Air Guide Shroud 69 12.5 Carburetor 71 12.5.1 Leakage Test 71 12.6 Servicing the Carburetor 72 12.6.1 Metering Diaphragm 72 12.6.2 Inlet Needle 73 12.6.3 Pump Diaphragm 74 12.6.4 Air...Valve 76 12.6.5 Levers on Throttle Shaft 76 12.6.6 Adjusting Screws 77 12.7 Carburetor Adjustment 79 12.7.1 Basic Setting 79 12.7.2 Standard Setting 80 12.8 Carburetor Carrier 81 12.9 Intake Manifold 82 12.10 Tank Vent 83 12.10.1 ...Hose 86 12.11.4 Tank Housing 87 13. Contents 12. Servicing Aids 90 2 MS 311, MS 391
User Manual
Page 6
... Lubrication MS 311, MS 391 MS 311 59 cm3 47 mm 34 mm 3 kW (4 bhp) at 9,500 rpm 13,000 rpm 2,800 rpm Centrifugal clutch without linings 3,500 rpm 0.5 bar 0.5 bar MS 391 64.1 cm3 49 mm 34 mm 3.2 kW (4.4 bhp) at 9,500 rpm 13,000 rpm 2,800 rpm Centrifugal clutch without linings 3,500 rpm Carburetor leakage...
... Lubrication MS 311, MS 391 MS 311 59 cm3 47 mm 34 mm 3 kW (4 bhp) at 9,500 rpm 13,000 rpm 2,800 rpm Centrifugal clutch without linings 3,500 rpm 0.5 bar 0.5 bar MS 391 64.1 cm3 49 mm 34 mm 3.2 kW (4.4 bhp) at 9,500 rpm 13,000 rpm 2,800 rpm Centrifugal clutch without linings 3,500 rpm Carburetor leakage...