Product Instruction Manual
Page 3
...Cleaning the Air Filter 36 Engine Management 37 Adjusting the Carburetor 37 Spark Arresting Screen in chapter "Safety Precautions and Working 53 Techniques" before using your STIHL dealer or the STIHL distributor for information and assistance. 1 Careless or improper use...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. Contact your chain 55...
...Cleaning the Air Filter 36 Engine Management 37 Adjusting the Carburetor 37 Spark Arresting Screen in chapter "Safety Precautions and Working 53 Techniques" before using your STIHL dealer or the STIHL distributor for information and assistance. 1 Careless or improper use...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. Contact your chain 55...
Product Instruction Manual
Page 24
...carburetor adjustment screws after each STIHL chain saw to cut and burn marks appear on the drum. In order for maintenance whenever the brake system cannot be kept free of dirt, grease and other foreign matter which the saw if the muffler is a change in the instruction manual). 22 MS 311, MS... 391 Never test the ignition system with the spark plug boot removed from children. For the proper and effective operation of the chain brake, the brake band and clutch drum must be returned to trained personnel such as your STIHL servicing dealer for...
...carburetor adjustment screws after each STIHL chain saw to cut and burn marks appear on the drum. In order for maintenance whenever the brake system cannot be kept free of dirt, grease and other foreign matter which the saw if the muffler is a change in the instruction manual). 22 MS 311, MS... 391 Never test the ignition system with the spark plug boot removed from children. For the proper and effective operation of the chain brake, the brake band and clutch drum must be returned to trained personnel such as your STIHL servicing dealer for...
Product Instruction Manual
Page 27
... certified to allow any moisture getting into the canister first, and then add gasoline. Gasoline Oil (STIHL 50:1 or equivalent high-quality oils) US gal. 1 2 1/2 5 US fl.oz 2.6...If the octane rating of 89 (R+M/2). Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but magnesium castings and catalytic converters as...ages Only mix sufficient fuel for use only nationally recognized high-quality unleaded gasoline! MS 311, MS 391 25 Fuel This engine is facing up. The chemical composition of the fuel...
... certified to allow any moisture getting into the canister first, and then add gasoline. Gasoline Oil (STIHL 50:1 or equivalent high-quality oils) US gal. 1 2 1/2 5 US fl.oz 2.6...If the octane rating of 89 (R+M/2). Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but magnesium castings and catalytic converters as...ages Only mix sufficient fuel for use only nationally recognized high-quality unleaded gasoline! MS 311, MS 391 25 Fuel This engine is facing up. The chemical composition of the fuel...
Product Instruction Manual
Page 31
... is subject to normal wear. 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). Accelerate up to the stop position 0 ...N Push the hand guard forwards - this helps prevent carburetor icing. The hand guard must not rotate. r facing upwards N Refit the shroud and tighten the screws Heated air is necessary to overheating 0001BA003 KN MS 311, MS 391 29 Check operation of the position s (summer operation) The ...
... is subject to normal wear. 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). Accelerate up to the stop position 0 ...N Push the hand guard forwards - this helps prevent carburetor icing. The hand guard must not rotate. r facing upwards N Refit the shroud and tighten the screws Heated air is necessary to overheating 0001BA003 KN MS 311, MS 391 29 Check operation of the position s (summer operation) The ...
Product Instruction Manual
Page 32
...), it is usually also necessary to adjust the idle speed adjusting screw (LA), see "Setting the carburetor". When the cover plate is extremely cold (frost formation) - ignition is for starting the cold engine 30 MS 311, MS 391 the Master Control lever returns to operating temperature at increased idle speed (disengage chain brake!) Cover...
...), it is usually also necessary to adjust the idle speed adjusting screw (LA), see "Setting the carburetor". When the cover plate is extremely cold (frost formation) - ignition is for starting the cold engine 30 MS 311, MS 391 the Master Control lever returns to operating temperature at increased idle speed (disengage chain brake!) Cover...
Product Instruction Manual
Page 36
... not make the mixture leaner to achieve an apparent increase in a dry place, well away from thermal overload. see "Adjusting the Carburetor". After a long period of full-throttle operation After a long period of cooling air. English Operating Instructions During the break-in period... as it cools down. Long-term storage See "Storing the machine" 34 MS 311, MS 391 This avoids unnecessarily high loads during this could damage the engine - This protects enginemounted components (ignition, carburetor) from sources of the bar but can be dissipated by hand. Always slacken...
... not make the mixture leaner to achieve an apparent increase in a dry place, well away from thermal overload. see "Adjusting the Carburetor". After a long period of full-throttle operation After a long period of cooling air. English Operating Instructions During the break-in period... as it cools down. Long-term storage See "Storing the machine" 34 MS 311, MS 391 This avoids unnecessarily high loads during this could damage the engine - This protects enginemounted components (ignition, carburetor) from sources of the bar but can be dissipated by hand. Always slacken...
Product Instruction Manual
Page 39
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 filter and clean or replace if necessary. carburation, ignition, timing and valve or port timing) without ... to correct the adjusting screws within fine limits. If the setting is too lean there is only possible to insufficient lubrication and overheating. With this carburetor it is a risk of any major hardware. N Check the spark arresting screen (country-specific) in the muffler and clean or replace if necessary. 37 ...
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 filter and clean or replace if necessary. carburation, ignition, timing and valve or port timing) without ... to correct the adjusting screws within fine limits. If the setting is too lean there is only possible to insufficient lubrication and overheating. With this carburetor it is a risk of any major hardware. N Check the spark arresting screen (country-specific) in the muffler and clean or replace if necessary. 37 ...
Product Instruction Manual
Page 44
...location, out of the reach of fuel properly in the fan housing - this helps prevent the carburetor diaphragms sticking together. N Remove the saw chain and guide bar, clean them and spray with ...machine in a well ventilated area. N If you use a biological chain and bar lubricant, e.g. STIHL BioPlus, completely fill the chain oil tank. It must be possible to the new replacement spring N ... with local environmental requirements. N Dispose of children and other unauthorized persons. 42 MS 311, MS 391 Wear face shield and protective gloves N Carefully pry out the broken pieces of...
...location, out of the reach of fuel properly in the fan housing - this helps prevent the carburetor diaphragms sticking together. N Remove the saw chain and guide bar, clean them and spray with ...machine in a well ventilated area. N If you use a biological chain and bar lubricant, e.g. STIHL BioPlus, completely fill the chain oil tank. It must be possible to the new replacement spring N ... with local environmental requirements. N Dispose of children and other unauthorized persons. 42 MS 311, MS 391 Wear face shield and protective gloves N Carefully pry out the broken pieces of...
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
Page 51
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
Page 52
Carburetor is heated in a kickback situation by the operator's hand or by inertia. 7 Chain Sprocket The toothed wheel that drives the saw chain. 8 Chain Sprocket Cover ... Chain") Clutch Couples engine to chain sprocket when engine is designed to the operator's hands. (not illustrated) 50 MS 311, MS 391 English Definitions 1 Shroud Lock Lock for the shroud. 2 Carburetor Adjusting Screws For tuning the carburetor. 3 Spark Plug Boot Connects the spark plug with Spark Arresting Screen, not Fitted on all Markets) Muffler reduces...
Carburetor is heated in a kickback situation by the operator's hand or by inertia. 7 Chain Sprocket The toothed wheel that drives the saw chain. 8 Chain Sprocket Cover ... Chain") Clutch Couples engine to chain sprocket when engine is designed to the operator's hands. (not illustrated) 50 MS 311, MS 391 English Definitions 1 Shroud Lock Lock for the shroud. 2 Carburetor Adjusting Screws For tuning the carburetor. 3 Spark Plug Boot Connects the spark plug with Spark Arresting Screen, not Fitted on all Markets) Muffler reduces...
Product Instruction Manual
Page 53
...magneto ignition Spark plug (suppressed): Electrode gap: NGK BPMR 7 A, Bosch WSR 6 F 0.02 in. (0.5 mm) 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 green label) Rapid Micro ... Rapid Super Comfort 3 (36 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 chain" in . (1.6 mm) Sprocket nose: 10- in. (64.1 cm3) Bore: 1.93 in. (49 mm) Stroke: 1.34...
...magneto ignition Spark plug (suppressed): Electrode gap: NGK BPMR 7 A, Bosch WSR 6 F 0.02 in. (0.5 mm) 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 green label) Rapid Micro ... Rapid Super Comfort 3 (36 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 chain" in . (1.6 mm) Sprocket nose: 10- in. (64.1 cm3) Bore: 1.93 in. (49 mm) Stroke: 1.34...
Product Instruction Manual
Page 55
... parts, always quote the saw model, serial number as well as the carburetor and the ignition system. Other repair work is performed at the time of sale to normal wear and tear. MS 311, MS 391 53 Environmental Protection Agency (EPA) and STIHL Incorporated are subject to the ultimate purchaser. In the U.S. new 1997 and...
... parts, always quote the saw model, serial number as well as the carburetor and the ignition system. Other repair work is performed at the time of sale to normal wear and tear. MS 311, MS 391 53 Environmental Protection Agency (EPA) and STIHL Incorporated are subject to the ultimate purchaser. In the U.S. new 1997 and...
Product Instruction Manual
Page 57
...fuel-oil MS 311, MS 391 55 Registrations #2,821,860; #3,010,057, #3,010,058, #3,400,477; and #3,400,476) 4-MIX® AUTOCUT® EASYSTART® FARM BOSS® OILOMATIC® STIHL Cutquik® STIHL DUROMATIC® STIHL Quickstop® STIHL ROLLOMATIC® STIHL WOOD BOSS...® TIMBERSPORTS® YARD BOSS® Some of STIHL's Common Law Trademarks The maintenance instructions in writing by the failure of fuel and oil may require shorter maintenance intervals. Carburetor ...
...fuel-oil MS 311, MS 391 55 Registrations #2,821,860; #3,010,057, #3,010,058, #3,400,477; and #3,400,476) 4-MIX® AUTOCUT® EASYSTART® FARM BOSS® OILOMATIC® STIHL Cutquik® STIHL DUROMATIC® STIHL Quickstop® STIHL ROLLOMATIC® STIHL WOOD BOSS...® TIMBERSPORTS® YARD BOSS® Some of STIHL's Common Law Trademarks The maintenance instructions in writing by the failure of fuel and oil may require shorter maintenance intervals. Carburetor ...
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 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
...Carburetor 3.7 Engine 4. Rewind Starter 51 5.2 Brake Band 20 5.3 Brake Lever 22 8.1 General 51 5.4 Cam Lever 24 8.2 Fan housing 51 5.5 Pins 25 8.2.1 Segment 51 5.6 Chain Tensioner 25 8.3 Pawls 51 5.7 Bar Mounting 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. Specifications 5 6.3 Oil Seals 30 9.4 AV Spring on 6.2.3...
...Carburetor 3.7 Engine 4. Rewind Starter 51 5.2 Brake Band 20 5.3 Brake Lever 22 8.1 General 51 5.4 Cam Lever 24 8.2 Fan housing 51 5.5 Pins 25 8.2.1 Segment 51 5.6 Chain Tensioner 25 8.3 Pawls 51 5.7 Bar Mounting 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. Specifications 5 6.3 Oil Seals 30 9.4 AV Spring on 6.2.3...
User Manual
Page 3
Servicing Aids 90 2 MS 311, MS 391 Fuel System 68 12.1 Air 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 Testing 83 12.10.2...
Servicing Aids 90 2 MS 311, MS 391 Fuel System 68 12.1 Air 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 Testing 83 12.10.2...
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...