STIHL MS 311, 391 2 - 39 Instruction Manual
English 26 27 28 29 30 31 32 33 Your Dr. Nikolas Stihl 1 Guide to Using this Manual This Instruction Manual refers to a STIHL chain saw, also called a machine in this Instruction Manual. 1.1 Pictograms Pictograms that appear on the machine are explained in this Instruction Manual. Depending on the machine and equipment ver‐ sion, the following pictograms may appear on the machine.
2 Safety Precautions 1.2 Symbols in text WARNING Warning where there is a risk of an accident or personal injury or serious damage to property. NOTICE Caution where there is a risk of damaging the machine or its individual components. 1.3 Engineering improvements STIHL's philosophy is to continually improve all of its products. For this reason we may modify the design, engineering and appearance of our products periodically.
English 2 Safety Precautions 2.6 WARNING To reduce the risk of eye injuries, wear tight-fitting safety goggles con‐ forming to standard EN 166 or a face shield. Make sure that the safety gog‐ gles and the face shield fit correctly. Wear "personal" hearing protection – for exam‐ ple, ear defenders. Wear a hard hat wherever there is any risk of falling objects. Wear sturdy protective gloves made of a resistant material (e.g. leather).
– – – – – – – – – cap, hose connections and the manual fuel pump (on machines so equipped). If there are any leaks or damage, do not start the engine – risk of fire. Have your saw repaired by a serv‐ icing dealer before using it again. Check operation of chain brake, front hand guard Correctly mounted guide bar Correctly tensioned chain The trigger and trigger lockout must move freely and spring back to the idle position when they are released.
English Examine the saw chain periodically at short inter‐ vals and as soon as you note any tangible changes: – Switch off the engine; wait until the saw chain is stationary – Check condition and secure fitting – Check sharpness Never touch the saw chain when the engine is running.
3 Reactive Forces The machine must be serviced regularly. Do not attempt any maintenance or repair work not described in the Instruction Manual. All other work should be carried out by a servicing dealer. STIHL recommends that maintenance and repair work be carried out only by authorised STIHL dealers. STIHL dealers receive regular training and are supplied with technical information. Use only high-quality spare parts. Otherwise, there may be a risk of accidents and damage to the machine.
English 4 Working Techniques object, e.g. when another limb is touched acci‐ dentally during limbing. – when the chain at the nose of the guide bar is pinched in the cut. 3.3 Quickstop chain brake: the chain pulls the saw forward – to reduce this risk, always engage the spiked bumper securely in the tree or limb. 3.6 Pushback (B) 3.4 To reduce the risk of kickback – Work cautiously and avoid situations which could cause kickback. – Hold the saw firmly with both hands and main‐ tain a secure grip.
English 4 Working Techniques chain saw in the vicinity of easily combustible materials, dry plants or scrub. It is mandatory that you ask the responsible forestry office about the current fire hazard. Country-specific legislation on felling technique must be complied with during felling work. 4.1 Sawing Do not operate your saw with the starting throttle lock engaged. Engine speed cannot be control‐ led with the throttle trigger in this position.
English 4 Working Techniques erwise the cutting attachment may stick in the cut or kick back – risk of injury! Preparing for felling Make sure no-one is endangered by the falling tree – the noise of your engine may drown any warning calls. 1 ► Make relieving cut at the compression side (1) ► Make bucking cut at the tension side (2) Be wary of pushback when making bucking cut from the bottom upwards (underbuck).
4 Working Techniques English 001BA146 KN Preparing work area at base of tree – First clear the tree base and work area from interfering limbs and brush to provide a secure footing. – Carefully clear the base of the trunk (e.g., with an axe) – sand, stones and other foreign objects will blunt the saw chain – Remove largest buttresses: first the largest buttress – saw first vertically, then horizontally – only if the tree is in sound condition 4.
English 4.4 4 Working Techniques Sapwood cuts – With rotten trunks, leave a wider strip Sapwood cuts in long-fibered softwood help pre‐ vent sapwood splintering when the tree falls. Make cuts at both sides of the trunk at same height as bottom of felling notch to a depth of about 1/10 of trunk diameter. On large diameter trees, cut to no more than width of guide bar. Do not make sapwood cuts if wood is diseased. Basic information on felling cut C C 1/10 Ø E G 3. 2.
4 Working Techniques English Select suitable felling wedges dependent on the trunk diameter and the width of the kerf (ana‐ logue to felling cut (E)). Contact the STIHL dealer for the selection of the felling wedge (suitable length, width and height). 4.6 Selecting the appropriate felling cut The selection of the appropriate felling cut is dependent on the same tree characteristics that must be noted when determining the direction of fall and the escape paths.
English 4 Working Techniques – Do not cut into the stabilizing strap – Cut horizontally – Do not cut into the holding strap. The felling cut must be continued on the oppo‐ site side of the trunk. 001BA266 KN Ensure that the second cut is at the same level as the first cut.
5 Cutting Attachment English Shout a second warning immediately before the tree falls. ► With outstretched arms, cut through the hold‐ ing strap at a downward angle from outside. Cutting Attachment Depending on the model, the scabbard exten‐ sion either comes standard with the saw or is available as a special accessory. 2 5.2 001BA248 KN 3 – The pitch (t) of the saw chain (1), chain sprocket and the nose sprocket of the Rollo‐ matic guide bar must match.
English 6 Mounting the Bar and Chain 6.3 Fitting the chain Removing the chain sprocket cover 143BA034 KN 143BA003 KN 6.1 6 Mounting the Bar and Chain ► Unscrew the nuts and take off the chain sprocket cover. WARNING Wear work gloves to protect your hands from the sharp cutters. ► Fit the chain – start at the bar nose. 1 ► Turn the screw (1) counterclockwise until the tensioner slide (2) butts against the left end of the housing slot. Disengaging the chain brake. 001BA186 KN 6.
8 Checking Chain Tension English Retensioning during cutting work: ► Shut off the engine. ► Loosen the nuts. ► Hold the bar nose up. ► Use a screwdriver to turn the tensioning screw (1) clockwise until the chain fits snugly against the underside of the bar. ► While still holding the bar nose up, tighten down the nuts firmly. ► Go to "Checking Chain Tension". STIHL MotoMix uses STIHL HP Ultra two-stroke engine oil for an extra long engine life. MotoMix is not available in all markets. 9.
English 9.3 10 Fueling 10.2 Storing Fuel Opening Store fuel only in approved safety-type fuel can‐ isters in a dry, cool and safe location protected from light and the sun. STIHL MotoMix may be stored for up to 2 years without any problems. ► Thoroughly shake the mixture in the canister before fueling your machine. 001BA236 KN Fuel mix ages – only mix sufficient fuel for a few weeks work. Do not store fuel mix for longer than 30 days.
10 Fueling 10.3 English Filling Up with Fuel Take care not to spill fuel while fueling and do not overfill the tank. 10.4 001BA235 KN STIHL recommends you use the STIHL filler noz‐ zle for fuel (special accessory). ► Fill the fuel tank. Closing Grip must be vertical: ► Fit the cap – marks on tank cap and fuel tank must line up. ► Press the cap down as far as stop. 001BA241 KN 001BA234 KN ► Fold the grip down. Tank cap is locked. 10.
English 11 Chain Lubricant WARNING 001BA239 KN Do not use waste oil. Renewed contact with waste oil can cause skin cancer. Moreover, waste oil is environmentally harmful. ► Place the cap on the opening and rotate it counterclockwise until it engages the filler neck. ► Continue rotating the cap counterclockwise (about a quarter turn) – this causes the bottom of the cap to be turned to the correct position. ► Turn the cap clockwise and lock it in position – see section on "Closing".
13 Checking Chain Lubrication Checking Chain Lubrica‐ tion due to kickback: Saw chain is blocked - and stops running. 14.2 Disengage the chain brake. The saw chain must always spin off a small amount of oil. ► Pull the hand guard back towards the front handle. NOTICE Never operate your machine without chain lubri‐ cation. If the saw chain runs dry, the cutting attachment may very quickly be damaged beyond repair. Before starting work, always check the chain lubrication and oil level in the tank.
English 15 Winter Operation 15 15.1 ► Place the slide in the position r (winter oper‐ ation) – r facing upwards ► Refit the shroud and tighten the screws every six months annually Winter Operation Heated air is now drawn in from around the cylin‐ der and circulates around the carburetor – this helps prevent carburetor icing.
16 Starting / Stopping the Engine 16 16.1 English Starting / Stopping the Engine Positions of the Master Control lever 16.2.2 Position starting acceleration n – if engine is warm (once the engine has been running for approx. one minute) – when Engine Begins to Fire – after ventilation of the combustion chamber, if the engine was flooded 16.3 STOP Holding the Chain Saw There are two methods of starting the saw. 0 On the ground 001BA140 KN 16.3.
English Actuating 0 1 ► Pull the starter grip slowly with your right hand until you feel it engage – and then give it a brisk strong pull and push down the front han‐ dle at the same time. Do not pull out the starter rope to full length – it might otherwise break. Do not let the starter grip snap back. Guide it slowly back into the housing so that the starter rope can rewind properly.
17 Operating Instructions 16.7 English 16.10 If Engine Does Not Start As Soon As the Engine Runs STOP 0 2 0001BA023 KN 1 ► Press down trigger lockout and the blip the throttle trigger (2) – the Master Control lever (1) moves to the run position (F) and the engine settles down to idling speed The master control lever was not returned from the position choke shutter closed l to starting acceleration n in time, the engine may be floo‐ ded.
English 18 Oil Quantity Control pulled along the bar by hand. Retension if neces‐ sary – see "Tensioning the Saw Chain". Chain at operating temperature The chain stretches and begins to sag. The drive links must not come out of the bar groove on the underside of the bar – the chain may otherwise jump off the bar. Retension the chain – see "Ten‐ sioning the Saw Chain". 001BA157 KN 17.2.3 1 NOTICE The chain contracts as it cools down.
20 Cleaning the Air Filter 1/4“ 3/8" P 3/8“; 0.325“ 0.404“ ► Rotate the air filter a 1/4 turn counterclockwise and lift it away in the direction of the rear han‐ dle. ► Always replace a damaged filter. 4.0 mm 5.0 mm 6.0 mm 7.0 mm If groove depth is less than specified: ► Replace the guide bar 20.1.3 Cleaning the air filter ► Wash the filter in STIHL special cleaner (spe‐ cial accessory) or a clean, non-flammable sol‐ ution (e.g. warm soapy water).
English 21.3 21 Adjusting the Carburetor 21.5 Different Standard Settings Standard Setting B These chain saws are equipped with carburetors that have different standard settings: L 21.3.1 Standard setting A – High speed screw (H) = 3/4 – Low speed screw (L) = 1 21.3.3 0001BA027 KN 21.3.2 Standard setting B – High speed screw (H) = 3/4 – Low speed screw (L) = 1/4 Determining standard setting ► Turn high speed screw (H) counterclockwise as far as stop (no more than 3/4 turn).
22 Spark Plug English ► Turn the low speed screw (L) counterclock‐ wise until the engine runs and accelerates smoothly. It is usually necessary to change the setting of the idle speed screw (LA) after every correction to the low speed screw (L). Fine Tuning for Operation at High Altitude 4903BA007 KN 21.7 A slight correction of the setting may be neces‐ sary if the engine does not run satisfactorily: ► Carry out standard setting. ► Warm up the engine.
English 23 Storing the Machine 24.1 WARNING Fit new chain sprocket Arcing may occur if the adapter nut (1) is loose or missing. Working in an easily combustible or explosive atmosphere may cause a fire or an explosion. This can result result in serious inju‐ ries or damage to property. 22.3 001BA121 KN ► Use resistor type spark plugs with a properly tightened adapter nut. Install spark plug 4903BA008 KN – after use of two saw chains or earlier – if the wear marks (arrows) are deeper than 0.
25 Maintaining and Sharpening the Saw Chain Install spur chain sprocket / rim sprocket ► Clean crankshaft stub and needle cage and lubricate with STIHL lubricant (special acces‐ sory) ► Slide needle cage onto the crankshaft stub ► After refitting, turn the clutch drum and/or spur chain sprocket approx.
English 25 Maintaining and Sharpening the Saw Chain exceptions. Ripping chains have an X in the des‐ ignation. B Side plate angle The correct side plate angle results automatically when the specified file holder and file diameter are used. Tooth shapes Micro = semi-chisel tooth, e. g., 63 PM3, 26 RM3, 36 RM Super = full chisel tooth, e. g., 63 PS3, 26 RS, 36 RS3 Ripping chain, e. g., 63 PMX, 36 RMX Angle (°) A B 30 75 30 60 10 75 The angles must be identical for all cutters in the saw chain.
25 Maintaining and Sharpening the Saw Chain English ► Lay the appropriate file gauge (1) for the chain pitch on the saw chain and press it against the cutter to be checked – if the depth gauge pro‐ trudes past the file gauge, the depth gauge must be reworked With varying cutter lengths, the cutter heights also vary and cause rough running of the saw chain and chain breakage.
English 25 Maintaining and Sharpening the Saw Chain WARNING 689BA052 KN Depth gauges that are too low increase the kick‐ back tendency of the chain saw.
26 Maintenance and Care Complete machine Visual inspection (condition, leaks) Clean Throttle trigger, throttle trigger Function test lockout, choke lever, stop switch, master control lever (dependent on equipment) Chain brake Function test Have checked by dealer1) Manual fuel pump (if present) check Have repaired by a specialist dealer1) Fuel pick-up body / filter in fuel check tank Clean, replace filter insert replace Fuel tank Clean Lubricating oil tank Clean Chain lubrication check Saw chain Check, pay
Carburetor Spark plug Accessible screws and nuts (except adjusting screws) Chain catcher Safety information label 27 Check idle adjustment – saw X chain must not rotate Set the idle speed; if required have the chainsaw repaired by a specialist dealer1) Adjust electrode gap Replace after 100 hours of operation X X X X Tighten2) check replace replace Minimize Wear and Avoid Damage Observing the instructions in this manual helps reduce the risk of unnecessary wear and dam‐ age to the power tool.
28 Main Parts 27.2 English Parts Subject to Wear and Tear Some parts of the power tool are subject to nor‐ mal wear and tear even during regular operation in accordance with instructions and, depending on the type and duration of use, have to be replaced in good time.
English 30 Ordering Spare Parts Oil tank capacity: 29.5 350 cc (0.35 l) Weight Weight (dry, without bar and chain): MS 311: MS 391: 29.6 6.2 kg 6.2 kg Cutting Attachment Actual cutting length may be less than the speci‐ fied length 29.6.1 Rollomatic E guide bars Cutting lengths: Pitch: Groove width: Nose sprocket: 29.6.2 37, 40, 45 cm 3/8" (9.32 mm) 1.
32 Disposal English MS 391: courses and are supplied with the necessary technical information. When repairing the machine, only use replace‐ ment parts which have been approved by STIHL for this power tool or are technically identical. Only use high-quality replacement parts in order to avoid the risk of accidents and damage to the machine. STIHL recommends the use of original STIHL replacement parts.
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