Stihl MS 251 C-Q Instruction Manual

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STIHL MS 251 C-Q

Instruction Manual

Contents

English

QuickStop Super Chain Brake System 2

Guide to Using this Manual 2 Safety Precautions 3 Reactive Forces 8 Working Techniques 10 Cutting Attachment 18 Mounting the Bar and Chain (quick

chain tensioner) 19

Original Instruction ManualPrinted on chlorine-free paper

Tensioning the Saw Chain (quick chain tensioner) 21

Checking Chain Tension 21 Fuel 22 Fueling 23 Chain Lubricant 26 Filling Chain Oil Tank 27 Checking Chain Lubrication 27 Chain Brake 28 Winter Operation 29 Starting / Stopping the Engine 30 Operating Instructions 34 Taking Care of the Guide Bar 35

Printing inks contain vegetable oils, paper can be recycled.

Shroud 35 Air Filter System 36 Cleaning the Air Filter 36 Adjusting the Carburetor 37 Spark Arresting Screen in Muffler 38 Spark Plug 38 Storing the Machine 39 Checking and Replacing the Chain

Sprocket 39

Maintaining and Sharpening the Saw Chain 40

Maintenance and Care 44 Main Parts 46 Specifications 47 Ordering Spare Parts 48 Maintenance and Repairs 48 Disposal 49 EC Declaration of Conformity 49

Dear Customer,

Thank you for choosing a quality engineered STIHL product.

It has been built using modern production techniques and comprehensive quality assurance. Every effort has been made to ensure your satisfaction and troublefree use of the product.

Please contact your dealer or our sales company if you have any queries concerning this product.

Your

Dr. Nikolas Stihl

{

0458-740-8321-B. VA2.A17.

0000006628_005_GB

MS 251 C-Q

English

150BA000 KN

QuickStop Super Chain Brake System

This STIHL chain saw is equipped with a chain brake system that can be activated in three different ways. As before, the chain brake can be activated by the inertia of the front hand guard in certain kickback situations or manually by pushing the front hand guard towards the bar nose. In both these cases the chain is brought to a standstill within a fraction of a second. In addition, there is a coasting brake function that stops chain rotation within a second of you letting go of the rear handle. The locked chain is not released again until you press down the throttle trigger interlock lever to operate the throttle.

The chain brake can be activated in three ways:

3 Manually by releasing the rear

handle

The activating mechanism of the QuickStop Super coasting brake is integrated in throttle trigger interlock (rear handle). One of the big advantages of this system is that the saw chain is automatically locked in position when carrying the running saw with the rear handle released.

Guide to Using this Manual

This Instruction Manual refers to a STIHL chain saw, also called a machine in this Instruction Manual.

Pictograms

Pictograms that appear on the machine are explained in this Instruction Manual.

Depending on the machine and equipment version, the following pictograms may appear on the machine.

Fuel tank; fuel mixture of gasoline and engine oil

Tank for chain oil; chain oil

Engage and release chain brake

Coasting brake

1 By inertia in certain kickback

situations

2 Manually by pushing the front hand

guard towards the bar nose

WARNING

To reduce the risk of damage or personal injury during cutting, observe the characteristics that make this saw different from saws not equipped with a coasting brake. Before operating the chain saw for the first time, make sure you are familiar with how the chain brake system works. See the chapter on "Chain Brake".

Direction of chain travel

Ematic; chain oil flow adjustment

Tension saw chain

MS 251 C-Q

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Intake air baffle: winter operation

Intake air baffle: summer operation

Handle heating

Actuate decompression valve

Actuate manual fuel pump

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.

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.

Therefore, some changes, modifications and improvements may not be covered in this manual.

Safety Precautions

Special safety precautions must be observed to reduce the risk of personal injury when working with a chain saw because of the very high chain speed and very sharp cutters.

It is important that you read the instruction manual before first use and keep it in a safe place for future reference. Nonobservance of the instruction manual may result in serious or even fatal injury.

General

Observe all applicable local safety regulations, standards and ordinances.

The use of noise emitting power tools may be restricted to certain times by national or local regulations.

If you have not used this model before: Have your dealer or other experienced user show you how to operate your machine or attend a special course in its operation.

Minors should never be allowed to use a chain saw.

Keep bystanders, especially children, and animals away from the work area.

The user is responsible for avoiding injury to third parties or damage to their property.

MS 251 C-Q

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001BA115 KN

Do not lend or rent your chain saw without the instruction manual. Be sure that anyone using it understands the information contained in this manual.

To operate a chain saw you must be rested, in good physical condition and mental health. If you have any condition that might be aggravated by strenuous work, check with your doctor before operating a chain saw.

Do not operate the chain saw if you are under the influence of any substance (drugs, alcohol) which might impair vision, dexterity or judgment.

To reduce the risk of accidents or injury, put off the work in poor weather conditions (rain, snow, ice, wind).

Persons with pacemakers only: The ignition system of your chain saw produces an electromagnetic field of a very low intensity. This field may interfere with some pacemakers. To reduce health risks, STIHL recommends that persons with pacemakers consult their physician and the pacemaker manufacturer before operating this power tool.

Intended use

The machine may only be used to saw wood and wooden objects.

Do not use the machine for any other purpose – risk of accidents!

Do not modify the machine in any way – this may increase the risk of personal injury. STIHL excludes all liability for personal injury and damage to property caused while using unauthorised attachments.

Clothing and Equipment

Wear proper protective clothing and equipment.

Clothing must be sturdy but allow complete freedom of movement. Wear snug-fitting clothing with cut retardant inserts – do not wear a work coat.

Avoid clothing that could get caught on branches or brush or moving parts of the saw. Do not wear a scarf, necktie or jewelry. Tie up and confine long hair (e.g. with a hair net, cap, hard hat, etc.).

Wear steel-toed safety boots with cut retardant inserts and non-slip soles.

WARNING

To reduce the risk of eye injuries, wear snug-fitting safety glasses in accordance with European Standard EN 166. Make sure the safety glasses are a good fit.

Wear a face shield and make sure it is a good fit. A face shield alone does not provide adequate eye protection.

Wear hearing protection, e.g. earplugs or ear muffs.

Wear a safety hard hat where there is a danger of head injuries from falling objects.

Wear heavy-duty work gloves made of durable material (e.g. leather).

STIHL offers a comprehensive range of personal protective clothing and equipment.

Transport

Before any transport – even over short distances – switch off the machine, engage the chain brake and attach the chain scabbard. This avoids the risk of the saw chain starting unintentionally.

Always carry the chain saw by the handle – with the hot muffler away from your body, the guide bar must point to the rear. Avoid touching hot parts of the machine, especially the surface of the muffler – risk of burns!

In vehicles: Properly secure the machine to prevent tipping, damage and chain oil or fuel spillage.

Cleaning

Clean plastic parts with a cloth. Harsh detergents can damage the plastic.

MS 251 C-Q

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Clean the dust and dirt off the machine – do not use any grease solvents for this purpose.

Clean the ventilation slots if necessary.

Do not use a high-pressure cleaner to clean the machine. The hard jet of water can damage parts of the machine.

Accessories

Only use those tools, guide bars, chains, chain sprockets, accessories or technically equivalent components that have been approved by STIHL for this machine. If you have any questions in this respect, consult a servicing dealer. Use only high quality tools and accessories. Otherwise, there may be a risk of accidents and damage to the machine.

STIHL recommends the use of genuine STIHL tools, guide bars, chains, chain sprockets and accessories. They are specifically designed to match your model and meet your performance requirements.

Refuelling

Gasoline is an extremely flammable fuel – keep clear of naked flames and fire – do not spill any fuel – no smoking.

Switch off the engine before refuelling.

Never refuel the machine while the engine is still hot – the fuel may spill over – risk of fire!

Open the fuel filler cap carefully so that any excess pressure is relieved gradually and fuel does not splash out.

The machine may only be refuelled in a well ventilated place. Clean the machine immediately if fuel is spilled. Do not spill fuel over your clothing – contaminated clothing must be changed immediately.

The machines can be equipped with the following filler caps as standard:

Cliplock filler cap (bayonet-type)

Place the cliplock filler cap (bayonet-type) in position, turn as far as stop and fold the cliplock down.

This helps reduce the risk of unit vibrations causing an incorrectly tightened filler cap to loosen or come off and spill quantities of fuel.

Look out for leaks! Never start the engine if fuel has been spilled or is leaking – Fatal burns may result!

Before Starting Work

Check that your saw is properly assembled and in good condition – refer to appropriate chapters in the instruction manual.

– Check the fuel system for leaks,

paying special attention to visible parts such as the tank 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 servicing 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.

– Master Control lever must move

easily to STOP, 0 or †

– Check that the spark plug boot is

secure – a loose boot may cause arcing that could ignite combustible fumes and cause a fire.

– Never attempt to modify the controls

or safety devices in any way.

– Keep the handles dry and clean –

free from oil and dirt – for safe control of the saw.

– Make sure there is sufficient fuel

and chain oil in the tanks.

To reduce the risk of personal injury, do not operate your saw if it is damaged or not properly assembled.

Starting the chain saw

Always work on a level surface. Ensure a firm and secure footing. Hold the machine securely – the chain must not touch any objects or the floor – danger of injury due to the rotating saw chain.

MS 251 C-Q

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001BA087 LÄ

Your chain saw is a one-person saw. Do not allow other persons to be in the working area – not even while starting.

Do not start the chain saw if the chain is in a cut.

Move at least 3 meters away from the place where the machine was refuelled and never start the motor in enclosed spaces.

Lock the chain with the chain brake before starting – risk of injury due to rotating chain!

Do not drop-start the engine – start as described in the Instruction Manual.

During operation

Ensure you always have a firm and safe footing. Take special care when the bark is wet – danger of slipping!

Always hold the chain saw firmly with both hands: Right hand on the rear handle – even if you are left-handed. To ensure reliable control, wrap your thumbs tightly around the handlebar and handle.

In the event of impending danger or in an emergency, switch off the engine immediately by moving the Master Control lever / stop switch to STOP, 0 or †.

Never let the machine run unattended.

Exercise caution with slippery surfaces, water, snow, ice, steep slopes, uneven ground or green wood that has just been stripped of its bark – danger of slipping!

Use caution with tree stumps, roots, ditches – danger of stumbling!

Do not work alone – keep within calling distance of others who are trained in emergency procedures and can provide help in an emergency. Helpers at the cutting site must also wear protective clothing (helmet!) and stand well clear of the branches being cut.

More care and attention than usual are required when wearing ear protection, as warning sounds (shouts, beeps, etc.) cannot be heard properly.

Take a break in good time to avoid tiredness or exhaustion – risk of accidents!

Dust (e. g., sawdust), fumes and smoke produced while using the machine may be hazardous to health. If dust is generated, wear a dust mask.

When the engine is running: Note that the saw chain continues to rotate for a short period after you let go of the throttle trigger – coasting effect.

No smoking when working with or near the chain saw - risk of fire! Combustible fuel vapour may escape from the fuel system.

Examine the saw chain periodically at short intervals 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. If the saw chain becomes jammed by an object, switch off the engine immediately before attempting to remove the object – risk of injury!

Always turn off the engine before leaving the machine unattended.

To change the saw chain, switch off the engine. Risk of injury from the motor starting unintentionally!

Keep easily combustible materials (e. g., wood chips, bark, dry grass, fuel) away from hot exhaust gases and hot mufflers – risk of fire! Mufflers with catalytic converters can become especially hot.

Never work without chain lubrication – monitor the oil level in the oil tank. Stop work immediately if the oil level in the oil tank is too low and top up with chain oil – see also "Topping up with chain oil" and "Check chain lubrication".

If the machine is subjected to unusually high loads for which it was not designed (e. g., heavy impact or a fall), always check that it is in good condition before continuing work – see also "Before starting work".

Check the fuel system for leaks and make sure the safety devices are working properly. Never continue using

MS 251 C-Q

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a machine that is not in perfect working order. In case of doubt, have the unit checked by your servicing dealer.

Check for correct idling, so that the saw chain stops moving when the throttle trigger is released. Check the idle setting regularly and correct when possible. Have the machine repaired by a STIHL servicing dealer if the saw chain still continues to move during idling.

The chain saw produces poisonous exhaust gases as soon as the engine starts. These gases may be colourless and odourless and may contain unburnt hydrocarbons and benzene. Never work with the machine indoors or in poorly ventilated areas, even if your machine is equipped with a catalytic converter.

Ensure proper ventilation when working in trenches, hollows or other confined locations – risk of fatal injury from breathing toxic fumes!

If you feel sick, have a headache, vision problems (e. g., your field of vision gets smaller), hearing problems, dizziness or inability to concentrate, stop work immediately. Such symptoms may be caused by an excessively high concentration of exhaust emissions – risk of accident!

After finishing work

Switch off the motor, engage the chain brake and attach the chain scabbard.

Storage

When the machine is not in use, it should be stored in such a way that noone is endangered. Secure the machine against unauthorised use.

Store the machine in a safe, dry room.

Vibrations

Prolonged use of the power tool may result in vibration-induced circulation problems in the hands (whitefinger disease).

No general recommendation can be given for the length of usage because it depends on several factors.

The period of usage is prolonged by:

– Hand protection (wearing warm

gloves)

– Work breaks

The period of usage is shortened by:

– Any personal tendency to suffer

from poor circulation (symptoms: frequently cold fingers, tingling sensations).

– Low outside temperatures.

– The force with which the handles

are held (a tight grip restricts circulation).

Continual and regular users should monitor closely the condition of their hands and fingers. If any of the above symptoms appear (e.g. tingling sensation in fingers), seek medical advice.

Maintenance and repairs

Always switch off the engine before any repair, cleaning or maintenance work and any work on the chain. Risk of injury if the engine starts inadvertently!

Exception: adjustment of carburettor and idle speed.

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. If you have any questions in this respect, consult a servicing dealer.

Do not modify the machine in any way – this may increase the risk of personal injury –risk of accidents!

To reduce the risk of fire due to ignition outside the cylinder, move the master control level to STOP, 0 or † before turning the engine over on the starter when the spark plug boot is removed or the spark plug is unscrewed!

Do not service or store the machine near a naked flame – risk of fire due to the fuel.

Check fuel cap regularly for tightness.

Use only spark plugs that are in perfect condition and have been approved by STIHL – see "Specifications".

MS 251 C-Q

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001BA036 KN

Check ignition lead (insulation in good condition, secure connection).

Check that the muffler is in perfect working condition.

Do not use the machine if the muffler is damaged or missing – risk of fire, damage to hearing!

Never touch a hot muffler – risk of burns!

The condition of the anti-vibration elements influences vibration behaviour – inspect anti-vibration elements periodically.

Inspect chain catcher – replace if damaged.

Switch off the engine

– To check the chain tension

– To retension the chain

– To replace the chain

– For remedying malfunctions

Observe sharpening instructions – for safe and proper handling, always keep the chain and guide bar in flawless condition. Keep the chain properly sharpened, tensioned and well lubricated.

Change chain, guide bar and chain sprocket in due time.

Regularly check that the clutch drum is in perfect working condition.

Always store fuel and chain lubricant only in the specified type of containers and ensure they are correctly labelled. Store in a dry, cool and secure place protected against light and sunlight.

In the event of a chain brake malfunction, switch off the machine immediately – risk of injury! Consult a

servicing dealer – do not use the machine until the malfunction has been remedied, see "Chain brake".

Reactive Forces

The most common reactive forces are: kickback, pushback and pull-in.

Dangers of kickback

Kickback can result in fatal cuts.

Kickback occurs when the saw is suddenly thrown up and back in an uncontrolled arc towards the operator.

MS 251 C-Q

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001BA257 KN

001BA037 KN

001BA038 KN

Kickback occurs if, for example,

– The saw chain in the area of the

upper quarter of the guide bar nose unintentionally comes into contact with wood or a solid object – e. g., unintentionally touches another limb during limbing

– The saw chain at the nose of the

guide bar is briefly pinched in the cut

QuickStop chain brake:

This device reduces the risk of injury in certain situations – it cannot prevent kickback. If activated, the brake stops the saw chain within a fraction of a second – refer to chapter "Chain brake" in this Instruction Manual.

Reducing the risk of kickback

– Work cautiously and methodically

– Hold the chain saw firmly with both

hands and maintain a secure grip

– Always cut at full throttle

– Be aware of the location of the guide

bar nose

– Do not cut with the guide bar nose

– Be especially careful with small,

tough limbs, undergrowth and offshoots – the saw chain may become caught in them

– Never cut several limbs at once

– Do not lean too far forward

– Do not cut above shoulder height

– Use extreme caution when re-

entering a previous cut

– Do not attempt plunge cuts if you

are not experienced in this cutting technique

– Be alert for shifting of the log or

other forces that may cause the cut to close and pinch the chain

– Always cut with a correctly

sharpened, properly tensioned saw chain – the depth gauge setting must not be too large

– Use low-kickback saw chains as

well as narrow-radius guide bars

Pull-in (A)

When the chain on the bottom of the bar – overbucking – is suddenly pinched, caught or encounters a foreign object in the wood, the chain saw may suddenly

be drawn forward toward the log – to avoid this, engage the bumper spike firmly in the wood.

Pushback (B)

When the chain on the top of the bar – underbucking – is suddenly pinched, caught or encounters a foreign object in the wood, the chain saw may suddenly be driven straight back toward the operator – to avoid this:

– Do not allow the top of the guide bar

to become jammed

– Do not twist the guide bar in the cut

Be very careful

– With freely hanging limbs

– With trunks that are under tension

between other trees because they fell unfavourably

– When working in windbreaks

In these cases, do not use a chain saw – use a hoist, winch or dragline instead.

Pull out trunks that are lying about and have been cut free. Whenever possible, deal with them in open areas.

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001BA082 KN

Dead wood (brittle, rotten or dead wood) poses a significant, highly unpredictable hazard. It is extremely difficult or even practically impossible to recognise the danger. Use aids such as winches or draglines.

When felling close to roads, rail lines, power lines, etc., work with particular care. If necessary, notify police, power companies or railway authorities.

Working Techniques

Sawing and felling work, including all related work (plunge cutting, limbing, etc.) may only be carried out by persons who have been specially trained and instructed. Persons who are not experienced chain saw users should not carry out any such work – increased risk of accidents!

Country-specific legislation on felling technique must be complied with during felling work.

Cutting

Do not operate your saw with the starting throttle lock engaged. Engine speed cannot be controlled with the throttle trigger in this position.

Work calmly and carefully – in daylight conditions and only when visibility is good. Ensure you do not endanger others – stay alert at all times.

First-time users are advised to practice cutting logs on a sawhorse – see "When cutting small logs".

Use the shortest possible guide bar: The chain, guide bar and chain sprocket must match each other and your saw.

Position the saw so that your body is clear of the cutting attachment.

Always pull the saw out of the cut with the chain running.

Use your chain saw for cutting only. It is not designed for prying or shoveling away limbs, roots or other objects.

Do not underbuck freely hanging limbs.

Take care when cutting scrub and young trees. The saw chain may catch and throw thin shoots in your direction.

To reduce the risk of injury, take special care when cutting shattered wood because of the risk of injury from slivers being caught and thrown in your direction.

Make sure your saw does not touch any foreign materials: Stones , nails , etc. m ay be flung off and damage the saw chain. The saw may kick back unexpectedly – risk of accidents.

If the rotating chain makes contact with a rock or other solid object there is a risk of sparking which may cause easily combustible material to catch fire under certain circumstances. Dry plants and scrub are also easily combustible, especially in hot and dry weather conditions. If there is a risk of fire, do not use your chainsaw near combustible

MS 251 C-Q

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001BA033 KN

001BA151 KN

001BA152 KN

materials, dry plants or scrub. Always contact your local forest authority for information on a possible fire risk.

If on a slope, stand on the uphill side of the log. Watch out for rolling logs.

When working at heights:

– Always use a lift bucket

– Never work on a ladder or in a tree

– Never work on an insecure support

– Do not work above shoulder height

– Never operate your power tool with

one hand

Begin cutting with the saw at full throttle and engage the spiked bumper firmly in the wood, and then continue cutting.

Never work without the spiked bumper because the saw may pull you forwards and off balance. Always engage the spiked bumper securely in the tree or limb.

Note when reaching the end of a cut that the saw is no longer supported in the kerf. You have to take the full weight of the machine since it might otherwise go out of control.

When cutting small logs:

– Use a sturdy and stable support –

sawhorse.

– Never hold the log with your leg or

foot.

– Never allow another person to hold

the log or help in any other way.

Limbing:

– Use a low kickback chain.

– Work with the saw supported

wherever possible.

– Do not stand on the log while

limbing it.

– Do not cut with the bar nose.

– Watch for limbs which are under

tension.

– Never cut several limbs at once.

Lying or standing logs under tension:

Always make cuts in the correct sequence (first at the compression side (1), then at the tension side (2), the saw may otherwise pinch or kick back – risk of injury.

N Make relieving cut at the

compression side (1)

N Make bucking cut at the tension

side (2)

Be wary of pushback when making bucking cut from the bottom upwards (underbuck).

NOTICE

Do not cut a lying log at a point where it is touching the ground because the saw chain will otherwise be damaged.

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001BA189 KN

001BA088 LÄ

1 1

001BA040 KN

45°

Ripping cut:

Cutting technique in which the spiked bumper is not used – risk of pull-in – start the cut with the guide bar at the shallowest possible angle – take extra care since there is an increased danger of kickback.

Preparations for Felling

Check that there are no other persons in the felling area – other than helpers.

Make sure no-one is endangered by the falling tree – the noise of your engine may drown any warning calls.

Maintain a distance of at least 2 1/2 tree lengths from the next felling site.

Determine direction of fall and escape path.

Select gap in stand into which you want the tree to fall.

Pay special attention to the following points:

– The natural lean of the tree

– Any unusually heavy limb structure,

damage

– The wind direction and speed – do

not fell in high winds

– Sloping ground

– Neighboring trees

– Snow load

– Soundness of tree – take special

care if trunk is damaged or in case of deadwood (dry, decayed or rotted wood)

A Direction of fall B Escape path (or retreat path)

– Establish paths of escape for

everyone concerned – opposite to direction of fall at about 45°.

– Remove all obstacles from escape

paths.

– Place all tools and equipment a safe

distance away from the tree, but not on the escape paths.

– Always keep to the side of the falling

tree and only walk away along the preplanned escape path.

– On steep slopes, plan escape

routes parallel to the slope.

– When walking away along the

escape path, watch out for falling limbs and watch the top of the tree.

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001BA146 KN

001BA271 KN

001BA153 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.

– Clean lower portion of tree base

(e.g. with an axe) – sand, stones and other foreign objects will dull the saw chain.

– Make the vertical cut first, then the

horizontal – but only if the wood is sound

Felling Notch

Preparing felling notch

The felling notch (C) determines the direction of fall.

Important:

– Make felling notch at a right angle to

the planned direction of fall.

– Cut close to the ground.

– Cut to a depth of about 1/5 to 1/3 of

the trunk diameter.

Determine direction of fall with gunning sight on shroud and fan housing

Your chainsaw has a gunning sight on the shroud and fan housing. Use this gunning sight.

Making Felling Notch

Posit ion t he sa w so that the f elli ng no tch is at a right angle to the direction you want the tree to fall.

The sequence in which the felling notch is made with a horizontal cut (bottom) and angled cut (top) is defined in country-specific regulations.

N Make horizontal cut (bottom) N Make the angled cut (top) at about

45°- 60° to the horizontal cut.

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001BA153 KN

001BA150 KN

001BA259 KN

1/10

001BA269 KN

Check direction of fall

N Position the saw in the horizontal

cut. The gunning sight must point in the planned direction of fall – if necessary, correct direction of fall by re-cutting the felling notch.

Sapwood cuts

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

Stump dimensions

The tree is felled with the felling cut (E).

– Cut horizontally.

– 1/10 (at least 3 cm) of width of

hinge (D) higher than bottom of felling notch (C).

The holding strap (F) or stabilizing strap (G) supports the tree and helps prevent it from falling prematurely.

– Width of strap: about 1/10 to 1/5 of

tree diameter.

– Do not cut into the strap while

making the felling cut.

– Leave a broader strap on rotten

trees.

Plunge cutting

– For relieving cuts during bucking

– For wood carving

Sapwood cuts in long-fibered softwood help prevent sapwood splintering when the tree falls. Make cuts at both sides of the trunk at same height as bottom of

The felling notch (C) determines the direction of fall.

The hinge (D) helps control the falling tree.

– Width of hinge: about 1/10 of tree

diameter.

– To reduce the risk of accidents, do

not cut through the hinge – you could lose control of the direction of fall.

– Leave a broader hinge on rotten

trees.

N Use a low kickback chain and

exercise particular caution

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001BA270 KN

001BA260 KN

001BA261 KN

1. Begin cut by applying the lower portion of the guide bar nose – do not use upper portion because of – risk of kickback. Start cutting at full throttle until depth of kerf is twice the width of the guide bar.

2. Swing saw slowly into plungecutting position – take care because of the risk of kickback or pushback.

3. Make the plunge cut very carefully. Danger of pushback.

Use the plunge-cutting sight if possible. The plunge-cutting sight and the top and bottom of the guide bar are parallel.

When making the plunge cut, the sight helps keep the hinge horizontal, i.e. the same thickness all round. To do this, hold the plunge-cutting sight parallel to the chord of the felling notch.

Felling wedges

Make use of wedges as soon as possible, i.e. providing they do not interfere with cutting. Drive wedge into felling cut with a suitable tool.

Use only aluminum or plastic wedges – never steel. Steel wedges can seriously damage the saw chain and cause dangerous kickback.

Select felling wedges that suit the diameter of the tree and width of the kerf (felling cut (E)).

Contact your STIHL dealer for advice on selecting the right felling wedge (length, width and height).

Choosing Right Felling Cut

The criteria for choosing the right felling cut are the same as those for determining the direction of fall and the escape path.

There are many different variations of these characteristics. Only the two most common characteristics are described in this manual:

Left: Normal tree – vertical trunk

with uniform tree crown.

Right: Leaner – tree crown leans in

direction of fall.

Felling Cut with Stabilizing Strap (Normal Tree)

A) Small diameter trees

Perform this felling cut when the tree diameter is smaller than the length of the guide bar.

Shout a warning before starting the felling cut.

N Start felling cut (E) using plunge-cut

method – insert full length of guide bar in the trunk.

N Engage the spiked bumper behind

the hinge and use it as a pivot – avoid repositioning the saw more than necessary.

N Enlarge felling cut as far as

hinge (1).

– Do not cut into the hinge. N Enlarge felling cut as far as

stabilizing strap (2).

– Do not cut into the stabilizing strap.

MS 251 C-Q

English

001BA273 KN

001BA263 KN

001BA274 KN

N Start felling cut using plunge-cut

method.

N Enlarge felling cut as far as

hinge (4).

– Do not cut into the hinge. N Enlarge felling cut as far as

stabilizing strap (5).

– Do not cut into the stabilizing strap.

N Insert a felling wedge (3).

Shout a second warning immediately before the tree falls.

N Holding the saw with outstretched

arms, cut through the stabilizing strap horizontally at the same level as the felling cut.

B) Large diameter trees

Perform this felling cut when the tree diameter is greater than the length of the guide bar.

Shout a warning before starting the felling cut.

N Engage the spiked bumper at the

required height of the felling cut and use it as a pivot – avoid repositioning the saw more than necessary.

N The guide bar nose enters the

wood (1) before it reaches the hinge – hold the saw horizontally and swing it as far as possible.

N Enlarge felling cut as far as

hinge (2).

– Do not cut into the hinge. N Enlarge felling cut as far as

stabilizing strap (3).

– Do not cut into the stabilizing strap.

Continue the felling cut on the other side of the trunk.

Make sure the second cut is at the same height as the first cut.

N Insert a felling wedge (6).

Shout a second warning immediately before the tree falls.

N Holding the saw with outstretched

arms, cut through the stabilizing strap horizontally at the same level as the felling cut.

MS 251 C-Q

English

001BA265 KN

001BA266 KN

001BA267 KN

Felling Cut with Holding Strap (Leaner)

A) Small diameter trees

Perform this felling cut when the tree diameter is smaller than the length of the guide bar.

N Plunge the guide bar into the trunk

until it emerges at the other side.

N Enlarge the felling cut (E) in

direction of hinge (1).

– Cut horizontally.

– Do not cut into the hinge.

N Enlarge the felling cut in direction of

– Cut horizontally.

holding strap (2).

– Do not cut into the holding strap.

Shout a second warning immediately before the tree falls.

N Cut through the holding strap at a

downward angle from outside with outstretched arms.

B) Large diameter trees

Perform this felling cut when the tree diameter is greater than the length of the guide bar.

N Engage the spiked bumper behind

the holding strap and use it as a pivot – avoid repositioning the saw more than necessary.

N The guide bar nose enters the

wood (1) before it reaches the hinge – hold the saw horizontally and swing it as far as possible.

– Do not cut into the holding strap or

hinge.

N Enlarge felling cut as far as

hinge (2).

– Do not cut into the hinge. N Enlarge felling cut as far as holding

strap (3).

– Do not cut into the holding strap.

MS 251 C-Q

English

001BA268 KN

001BA248 KN

Continue the felling cut on the other side of the trunk.

Make sure the second cut is at the same height as the first cut.

N Engage the spiked bumper behind

the hinge and use it as a pivot – avoid repositioning the saw more than necessary.

N The guide bar nose enters the

wood (4) before it reaches the holding strap – hold the saw horizontally and swing it as far as possible.

N Enlarge felling cut as far as

hinge (5).

– Do not cut into the hinge. N Enlarge felling cut as far as holding

strap (6).

– Do not cut into the holding strap.

N Cut through the holding strap at a

downward angle from outside with outstretched arms.

Cutting Attachment

A cutting attachment consists of the saw chain, guide bar and chain sprocket.

The cutting attachment that comes standard is designed to exactly match the chain saw.

– The pitch (t) of the saw chain (1),

chain sprocket and the nose sprocket of the Rollomatic guide bar must match.

– The drive link gauge (2) of the saw

chain (1) must match the groove width of the guide bar (3).

If non-matching components are used, the cutting attachment may be damaged beyond repair after a short period of operation.

Shout a second warning immediately before the tree falls.

MS 251 C-Q

English

001BA244 KN

2310BA013 KN

2310BA014 KN

2310BA015 KN

2310BA016 KN

2310BA017 KN

Chain Scabbard

Your saw comes standard with a chain scabbard that matches the cutting attachment.

If guide bars of different lengths are mounted to the saw, always use a chain scabbard of the correct length which covers the complete guide bar.

The length of the matching guide bars is marked on the side of the chain scabbard.

Mounting the Bar and Chain (quick chain tensioner)

Removing the chain sprocket cover

N Swing grip (1) into position (until it

engages)

N Turn the wing nut (2) to the left until

it hangs loosely in the chain sprocket cover (3)

N Remove chain sprocket cover (3)

Mounting the tensioning gear

N Remove screw (2)

N Position tensioning gear (1) and

guide bar (3) relative to one another

MS 251 C-Q

N Insert and tighten screw (2)

N Remove and reverse tensioning

gear (1)

English

001BA186 KN

181BA012 KN

181BA013 KN

135BA011 KN

2310BA018 KN

Releasing the chain brake

N Pull hand guard towards the front

handle until it engages audibly – chain brake is released

Fitting the saw chain

N Fit the saw chain – starting at the

nose of the guide bar – pay attention to the position of the tensioning gear and the cutting edges

N Turn tensioning gear (1) to the right

as far as possible

N Turn the guide bar so that the

tensioning gear faces the user

N Place the saw chain on the chain

sprocket (2)

N Slide the guide bar over the collar

screw (3); the head of the rear collar screw must protrude into the oblong hole

N Press the throttle trigger lockout to

release the chain brake

N Guide the drive link into the bar

groove (see arrow) and turn the tensioning gear to the left as far as possible

N Fit chain sprocket cover, sliding the

guide lugs into the engine housing openings

WARNING

Put on protective gloves – risk of injury by the sharp cutters.

When fitting the chain sprocket cover, the teeth of the adjusting wheel and the tensioning gear must mesh; if necessary,

MS 251 C-Q

English

001BA112 KN

142BA064 KN

N turn the adjusting wheel (4) a little

until the chain sprocket cover can be slid completely against the engine housing

N Swing grip (5) into position (until it

engages)

N Fit wing nut and tighten lightly N Next step: see "Tensioning the Saw

Chain"

Tensioning the Saw Chain (quick chain tensioner)

Retensioning during cutting work:

N Shut off the engine. N Pull out the hinged clip and loosen

the wingnut.

N Turn the adjusting wheel (1)

clockwise as far as stop.

N Tighten down the wingnut (2) firmly

by hand.

N Fold down the hinged clip. N Go to "Checking Chain Tension"

A new chain has to be retensioned more often than one that has been in use for some time.

N Check chain tension frequently –

see chapter on "Operating Instructions".

Checking Chain Tension

N Switch off the engine N Put on protective gloves N Press the throttle trigger lockout to

release the chain brake

N The saw chain must lie against the

bottom of the bar – and it must be possible to pull it across the guide bar by hand when the chain brake is released

N If necessary, retension saw chain

A new saw chain must be retensioned more frequently than one that has been in use already for an extended period.

N Check chain tension frequently –

see "Operating Instructions"

MS 251 C-Q

English

Fuel

Your engine requires a mixture of gasoline and engine oil.

WARNING

For health reasons, avoid direct skin contact with gasoline and avoid inhaling gasoline vapor.

STIHL MotoMix

STIHL recommends the use of STIHL MotoMix. This ready-to-use fuel mix contains no benzol or lead, has a high octane rating and ensures that you always use the right mix ratio.

STIHL MotoMix uses STIHL HP Ultra two-stroke engine oil for an extra long engine life.

MotoMix is not available in all markets.

Mixing Fuel

NOTICE

Unsuitable fuels or lubricants or mix ratios other than those specified may result in serious damage to the engine. Poor quality gasoline or engine oil may damage the engine, sealing rings, hoses and the fuel tank.

Gasoline

Use only high-quality brand-name gasoline with a minimum octane rating of 90 – leaded or unleaded.

If your machine is equipped with a catalytic converter, you must use unleaded gasoline.

NOTICE

A few tankfuls of leaded gasoline will greatly reduce the efficiency of the catalytic converter.

Gasoline with an ethanol content of more than 10% can cause running problems in engines with a manually adjustable carburetor and should not be used in such engines.

Engines equipped with M-Tronic deliver full power when run on gasoline with an ethanol content of up to 25% (E25).

Engine oil

Use only high-quality two-stroke engine oil – preferably STIHL HP, HP Super or HP Ultra, which are specially formulated for use in STIHL engines. HP Ultra guarantees high performance and a long engine life.

These engine oils are not available in all markets.

Use only STIHL 50:1 two-stroke engine oil for the fuel mix in models with a catalytic converter.

Mix Ratio

STIHL 50:1 two-stroke engine oil: 50 parts gasoline to 1 part oil

Examples

Gasoline STIHL engine oil 50:1 Liters Liters (ml) 1 0.02 (20) 5 0.10 (100) 10 0.20 (200) 15 0.30 (300) 20 0.40 (400) 25 0.50 (500)

N Use a canister approved for storing

fuel. Pour oil into canister first, then add gasoline and mix thoroughly.

Storing Fuel

Store fuel only in approved safety-type fuel canisters in a dry, cool and safe location protected from light and the sun.

Fuel mix ages – only mix sufficient fuel for a few weeks work. Do not store fuel mix for longer than 30 days. Exposure to light, the sun, low or high temperatures can quickly make the fuel mix unusable.

STIHL MotoMix may be stored for up to 2 years without any problems.

N Thoroughly shake the mixture in the

canister before fueling your machine.

WARNING

Pressure may build up in the canister – open it carefully.

N Clean the fuel tank and canister

from time to time.

MS 251 C-Q

English

001BA229 KN

001BA240 KN

001BA218 KN

001BA219 KN

Dispose of remaining fuel and cleaning fluid properly in accordance with local regulations and environmental requirements.

Fueling

Preparing the machine

Left: Tank cap without symbols Right: Tank cap with markings and

symbols on cap and tank

Tank cap without symbols

Opening

N Before fueling, clean the cap and

the area around it to ensure that no dirt falls into the fuel tank

N Always position the machine so that

the cap is facing upwards

Tank cap markings

MS 251 C-Q

Tank caps and fuel tanks may be marked in different ways

Depending on the version, your machine may be equipped with a tank cap and fuel tank with or without symbols.

N Swing the grip to the upright

position.

N Rotate the tank cap about a quarter

turn counterclockwise.

English

001BA224 KN

001BA220 KN

001BA221 KN

001BA222 KN

001BA223 KN

001BA225 KN

001BA227 KN

N Remove the cap.

Filling up with fuel

Take care not to spill fuel while fueling and do not overfill the tank.

STIHL recommends you use the STIHL filler nozzle for fuel (special accessory).

N Fill up with fuel.

Closing

Grip must be vertical: N Fit the cap – positioning marks on

tank cap and filler neck must be in alignment.

N Press the cap down as far as stop.

N While holding the cap depressed,

turn it clockwise until it engages in position.

N Fold the grip flush with the top of the

cap.

Checking security of cap

– The lug on the grip must fully

engage the recess (arrow).

N Grip the cap – it is properly locked if

it cannot be turned or removed.

If the cap can be turned or removed

Bottom of cap is twisted in relation to top:

Left: Bottom of cap twisted Right: Bottom of cap correctly

positioned

MS 251 C-Q

Closing

001BA226 KN

001BA236 KN

001BA232 KN

001BA234 KN

001BA237 KN

001BA234 KN

001BA233 KN

001BA231 KN

English

N Place the cap on the opening and

rotate it counterclockwise until it engages the filler neck.

N Continue rotating the cap

counterclockwise (about a quarter turn) – this causes the bottom of the cap to be turned to the correct position.

N Turn and lock the cap clockwise –

see sections on "Closing" and "Checking security of cap".

Tank cap with markings and symbols

Opening

N Raise the grip until it is upright.

N Turn the cap counterclockwise

(about a quarter turn).

Marks on tank cap and fuel tank must line up.

N Remove the cap.

Filling up with fuel

Take care not to spill fuel while fueling and do not overfill the tank.

STIHL recommends you use the STIHL filler nozzle for fuel (special accessory).

N Fill up with fuel.

Grip must be vertical: N Fit the cap – marks on tank cap and

fuel tank must line up.

N Press the cap down as far as stop.

N While holding the cap depressed,

turn it clockwise until it engages in position.

The marks on the tank cap and fuel tank are then in alignment.

MS 251 C-Q

English

001BA235 KN

001BA241 KN

001BA238 KN

001BA239 KN

N Fold the grip down so that it is flush

with the top of the cap.

Tank cap is locked.

If the tank cap cannot be locked in the fuel tank opening

Bottom of cap is twisted in relation to top.

N Remove the cap from the fuel tank

and check it from above.

Left: Bottom of cap is twisted –

inner mark (1) in line with outer mark.

Right: Bottom of cap in correct posi-

tion – inner mark is under the grip. It is not in line with the outer mark.

N Place the cap on the opening and

rotate it counterclockwise until it engages the filler neck.

N Continue rotating the cap

counterclockwise (about a quarter turn) – this causes the bottom of the cap to be turned to the correct position.

N Turn the cap clockwise and lock it in

position – see section on "Closing".

Chain Lubricant

For automatic and reliable lubrication of the chain and guide bar – use only an environmentally compatible quality chain and bar lubricant. Rapidly biodegradable STIHL BioPlus is recommended.

NOTICE

Biological chain oil must be resistant to aging (e.g. STIHL BioPlus), since it will otherwise quickly turn to resin. This results in hard deposits that are difficult to remove, especially in the area of the chain drive and chain. It may even cause the oil pump to seize.

The service life of the chain and guide bar depends on the quality of the lubricant. It is therefore essential to use only a specially formulated chain lubricant.

WARNING

Do not use waste oil. Renewed contact with waste oil can cause skin cancer. Moreover, waste oil is environmentally harmful.

NOTICE

Waste oil does not have the necessary lubricating properties and is unsuitable for chain lubrication.

MS 251 C-Q

English

001BA158 KN

143BA024 KN

Filling Chain Oil Tank

Preparations

N Thoroughly clean the oil filler cap

and the area around it to ensure that no dirt falls into the tank.

N Position the machine so that the

filler cap is facing up.

N Open the filler cap.

Fill up with chain oil.

N Refill the chain oil tank every time

you refuel.

Take care not to spill chain oil while refilling and do not overfill the tank.

STIHL recommends you use the STIHL filler nozzle for chain oil (special accessory).

N Close the filler cap.

There must still be a small amount of oil in the oil tank when the fuel tank is empty.

If the oil level in the tank does not go down, the reason may be a fault in the oil supply system: Check chain lubrication, clean the oilways, contact your dealer for assistance if necessary STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer.

Checking Chain Lubrication

The saw chain must always throw off a small amount of oil.

NOTICE

Never operate your saw without chain lubrication. If the chain runs dry, the whole cutting attachment will be irretrievably damaged within a very short time. Always check chain lubrication and the oil level in the tank before starting work.

Every new chain has to be broken in for about 2 to 3 minutes.

After breaking in the chain, check chain tension and adjust if necessary – see "Checking Chain Tension".

MS 251 C-Q

English

Chain Brake

The chain brake system has two functions:

N Standard STIHL chain brake N STIHL coasting brake

The coasting brake stops chain rotation as soon as you release the saw's rear handle.

Coasting brake is activated

Disengaging the coasting brake

N Press down the throttle trigger

interlock lever. This releases the clutch drum and allows the chain to rotate.

Chain brake is activated

Disengaging the chain brake

N Pull the hand guard back toward the

front handle.

NOTICE

Always disengage chain brake before accelerating the engine (except when checking its operation) and before starting cutting work.

High revs with the chain brake engaged (chain locked) will quickly damage the powerhead and chain drive (clutch, chain brake).

Chain brake is activated by inertia

N When you let go of the rear handle.

N When the hand guard is pushed

towards the bar nose by the left hand or by inertia in certain kickback situations.

The chain is stopped and locked.

If the kickback force of the saw is high enough.

The hand guard is accelerated towards the bar nose – even if your left hand is not behind the hand guard, e.g. during the felling cut.

The chain brake will operate only if the front hand guard has not been modified in any way.

MS 251 C-Q

English

2310BA000 KN

2310BA001 KN

Checking operation of the coasting brake

Before starting work: Open the throttle wide and then release the rear handle. The chain must stop moving within less than a second.

Checking operation of the chain brake

Before starting work: Run engine at idle speed, engage the chain brake (push hand guard towards bar nose) and open the throttle wide for no more than 3 seconds – the chain must not rotate. The hand guard must be free from dirt and move freely.

In case of doubt about the above functions, contact your servicing dealer for assistance. STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer.

Chain brake maintenance

The chain brake is subject to normal wear. It is necessary to have it serviced and maintained regularly by trained personnel. STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer. Maintain the following servicing intervals:

Full-time usage: every 3

months

Part-time usage: every 6

months

Occasional usage: every 12

months

Winter Operation

Pre-heating carburetor

N Remove the shroud – see "Shroud"

At temperatures below +10 °C

N Using a screwdriver, pry the shutter

out of the s (summer operation) position

N Place the shutter with the opening in

the direction of the chain saw in the r position (winter operation) – shutter must audibly snap into place

N Fit the shroud – see "Shroud"

Heated air is now drawn in from around the cylinder and circulates around the carburetor – this helps prevent carburetor icing.

At temperatures above +20 °C N Ensure that the shutter is always

returned to position s (summer operation), otherwise the engine may malfunction due to overheating

At temperatures below -10 °C

N if the chain saw is extremely cold

(frost formation) – after starting, bring the engine up to operating temperature at increased idle speed (disengage chain brake!)

In case of erratic idling behavior or poor acceleration

N Turn the low speed screw (L)

1/4 turn counterclockwise

Whenever the low speed screw (L) has been adjusted, it is usually also necessary to adjust the idle speed adjusting screw (LA), see "Setting the carburetor".

Air filter system

N Retrofit new air filter if necessary –

see "Air filter system"

MS 251 C-Q

English

STOP

001BA140 KN

Starting / Stopping the Engine

Positions of Master Control Lever

Stop 0 – engine off – the ignition is switched off

Normal run position F – engine runs or can fire.

Starting throttlen – this position is used to start a warm engine. The Master Control lever moves to the normal run position as soon as the throttle trigger is squeezed.

Choke shutter closed l – this position is used to start a cold engine.

Setting the Master Control Lever

To move the Master Control lever from the normal run position (F) to choke closed (l), press down the throttle trigger lockout and squeeze the throttle trigger at the same time and hold them in that position – now set the Master Control lever.

To select the starting throttle position (n), move the Master Control lever to choke closed (l) first, then push it into the starting throttle position (n).

The Master Control lever must be in the choke closed position (l) for the changeover to the starting throttle position (n).

The Master Control lever moves from the starting throttle position (n) to the run position (F) when you press down the throttle trigger lockout and blip the throttle trigger at the same time.

To switch off the engine, move the Master Control lever to Stop (0).

Choke shutter closed (l)

– if the engine is cold

– if the engine stalls when you open

the throttle after starting.

– if the fuel tank was run until empty

(engine stopped).

Starting throttle position (n)

– if the engine is warm, i.e. if it has

been running for about one minute.

– When the engine begins to fire

– after clearing a flooded combustion

chamber.

Fuel pump

Press the manual fuel pump bulb several times – even if the bulb is already filled with fuel:

– When starting for the first time.

– if the fuel tank was run until empty

(engine stopped).

Holding the Saw

There are two ways of holding the saw when starting.

MS 251 C-Q

English

2310BA008 KN

2310BA009 KN

231BA010 KN

On the ground

N Place your saw on the ground.

Make sure you have a firm footing – check that the chain is not touching any object or the ground.

N Hold the saw firmly on the ground

with your left hand on the front handle – your thumb should be under the handle.

N Put your right foot into the rear

handle and press down.

Between knees or thighs

N Hold the rear handle tightly between

your legs, just above the knees.

N Hold the front handle firmly with

your left hand – your thumb should be under the handle.

Cranking

Standard versions

N 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 handle 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.

Machines without additional manual fuel pump: If the engine is new or after a long out-of-service period, it may be necessary to pull the starter rope several times to prime the fuel system.

MS 251 C-Q

English

2310BA021 KN

2310BA002 KN

Versions with ErgoStart

WARNING

This machine is extremely simple and easy to start, even for children – risk of accidents.

Do not allow children or other unauthorized persons to attempt to start or otherwise use the machine:

– Never leave the machine

unattended during work breaks.

– After work, store the machine in a

safe, secure location.

The ErgoStart stores the energy required to start the saw. For this reason there may be a delay of a few seconds between cranking the engine and it actually starting.

There are two ways of starting with the ErgoStart:

N Hold the starter grip with your right

hand and pull it out slowly and steadily – or – hold the starter grip with your right hand and give it several short pulls, using only a short length of rope for each pull.

N Push down the handle while

cranking. Do not pull out the rope to its full length – it might otherwise break.

N Do not let the starter grip snap back.

Guide it slowly back into the housing so that the starter rope can rewind properly.

Starting the Saw

WARNING

Bystanders must be well clear of the general work area of the saw.

N Observe safety precautions.

Versions with manual fuel pump

N Press the manual fuel pump bulb at

least five times – even if the bulb is already filled with fuel.

All models

N Push the hand guard (1) forward –

the chain is locked.

N Press down the trigger lockout (2)

and pull the throttle trigger (3) at the same time. Set Master Control lever (4) to:

Choke shutter closed (l)

– if the engine is cold (also use this

position if the engine stopped when you opened the throttle after starting)

Starting throttle position (n)

– if the engine is warm, i.e. if it has

been running for about one minute.

N Hold and start your saw as

described.

MS 251 C-Q

English

2310BA003 KN

STOP

2310BA004 KN

STOP

001BA186 KN

When engine begins to fire

N Set the Master Control lever (4) to

the starting throttle position (n).

N Hold and start your saw as

described.

As soon as the engine runs

N Press down trigger lockout and the

blip the throttle trigger (3) – the Master Control lever (4) moves to the run position (F) and the engine settles down to idling speed.

NOTICE

As the chain brake is still engaged, the engine must be returned to idling speed immediately – or the engine housing and chain brake might otherwise be damaged.

N Pull the hand guard back towards

the front handle.

The chain brake is now disengaged – your saw is ready for operation.

NOTICE

Always disengage chain brake before accelerating the engine. High revs with the chain brake engaged (chain locked) will quickly damage the clutch and chain brake.

At very low outside temperatures

N Allow engine to warm up at part

throttle.

N Change over to winter operation if

necessary – see “Winter Operation”.

Stopping the engine

N Move the Master Control lever to the

stop position (0).

If the engine does not start

If you did not move the Master Control lever from the choke closed position (l) to the starting throttle

position (n) quickly enough after the engine began to fire, the combustion chamber may be flooded.

N Move the Master Control lever to the

stop position (0).

N Remove the spark plug – see

"Spark Plug".

N Dry the spark plug. N Crank the engine several times with

the starter to clear the combustion chamber.

N Refit the spark plug – see "Spark

Plug".

N Set Master Control lever to the

starting throttle position (n) – even if the engine is cold.

N Now start the engine.

MS 251 C-Q

English

Operating Instructions

During the break-in period

A factory new machine should not be run at high revs (full throttle off load) for the first three tank fillings. This avoids unnecessarily high loads during the break-in period. As all moving parts have to bed in during the break-in period, the frictional resistances in the shortblock are greater during this period. The engine develops its maximum power after about 5 to 15 tank fillings.

During work

NOTICE

Do not make the mixture leaner to achieve an apparent increase in power – this could damage the engine – see "Adjusting the Carburetor".

NOTICE

Open the throttle only when the chain brake is off. Running the engine at high revs with the chain brake engaged (chain locked) will quickly damage the shortblock and chain drive (clutch, chain brake).

Check chain tension frequently

A new saw chain must be retensioned more frequently than one that has been in use already for an extended period.

Chain cold

Tension is correct when the chain fits snugly against the underside of the bar but can still be pulled along the bar by hand. Retension if necessary – 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 "Tensioning the Saw Chain".

NOTICE

The chain contracts as it cools down. If it is not slackened off, it can damage the crankshaft and bearings.

After a long period of full-throttle operation

After a long period of full-throttle operation, allow engine to run for a while at idle speed so that the heat in the engine can be dissipated by flow of cooling air. This protects enginemounted components (ignition, carburetor) from thermal overload.

After finishing work

N Slacken off the chain if you have

retensioned it at operating temperature during work.

NOTICE

Always slacken off the chain again after finishing work. The chain contracts as it cools down. If it is not slackened off, it can damage the crankshaft and bearings.

Short-term storage

Wait for engine to cool down. Keep the machine with a full tank of fuel in a dry place, well away from sources of ignition, until you need it again.

Long-term storage

See "Storing the machine"

MS 251 C-Q

English

143BA026 KN

2710BA003 KN

Taking Care of the Guide Bar

N Flip the bar – after each sharpening

and each time the chain is changed – to avoid uneven wear, especially at the sprocket nose and on the bottom

N Periodically clean the oil inlet

hole (1), oil outlet channel (2) and bar groove (3)

N Measure groove depth – using the

measuring tool on the file gauge (special accessory) – in the area with the greatest wear

Picco 3/8“ P 5.0 mm Rapid 3/8“; 0.325“ 6.0 mm Rapid 0.404“ 7.0 mm

If the groove is not at least this deep: N Replace guide bar

Otherwise the drive links will grind against the base of the groove – the bottoms of the cutters and the tie straps will not lie against the bar.

Shroud

Remove shroud

N Move the Master Control Lever to

the stop position 0

N Push the front hand guard forwards

– the saw chain is blocked

N Loosen screws (1) N Remove the shroud (2)

Refitting the shroud

N Refit the shroud and tighten the

screws

Chain type Chain pitch Minimum

groove depth Picco 1/4“ P 4.0 mm Rapid 1/4“ 4.0 mm

MS 251 C-Q

English

5902BA009 KN

5902BA008 KN

2710BA000 KN

2710BA001 KN

Air Filter System

The air filter system can be adapted to suit different operating conditions by installing different filters. Changing the filter is quick and simple.

Fleece filter

N Fleece filter for normal operating

conditions and dry work areas.

HD2 filter

N HD2 filter (black filter frame, pleated

filter material) for extreme wintry conditions (e.g. powder or drifting snow) or very dusty work areas.

Cleaning the Air Filter

If there is a noticeable loss of engine power

N Remove the shroud – see "Shroud"

Removing the air filter N Clean away loose dirt from around

the filter

NOTICE

Do not use tools to remove and install the air filter – the air filter could be damaged in the process.

N Turn air filter 1/4 turn

counterclockwise and remove in the direction of the rear handle

N Always replace a damaged filter

Cleaning the air filter N Knock out the filter or blow it clear

with compressed air from the inside outwards

If knocking-out or blowing-out does not suffice, or in the case of stubborn dirt or stuck filter fabric, the filter must be subjected to a thorough cleaning.

Thorough filter cleaning N Wash the filter in STIHL special-

purpose cleaner (special accessory) or a clean, nonflammable cleaning liquid (e. g., warm soapy water) – rinse the filter from inside to out under a water jet – do not use high-pressure cleaners

N Dry all f ilt er parts – do not expo se to

extreme heat

N Do not oil the filter N Reinstall filter

Installing the air filter

N Fit air filter N Press the air filter in the direction of

the filter housing and simultaneously turn it clockwise until the air filter engages – the "STIHL" logo must be horizontal

N Fit the shroud – see "Shroud"

MS 251 C-Q

English

2310BA027 KN

2310BA028 KN

Adjusting the Carburetor

Basic information

The carburetor comes from the factory with a standard setting.

The carburetor has been adjusted for optimum performance and fuel efficiency in all operating states.

Standard setting

N Switch off the engine N Check the air filter – clean or replace

it if necessary

N Turn the high speed adjusting

screw (H) counterclockwise as far as possible (max. 3/4 turn)

N Turn the low speed adjusting

screw (L) clockwise until it is firmly in its seat – then back off 1/4 turn

Setting the idle speed

N Make standard setting N Start engine and let it warm up

Engine stops when idling N Turn the idle speed adjusting screw

(LA) clockwise until the saw chain begins to run – then turn it back 2 3/4 turn.

Saw chain rotates at idle speed N Turn the idle speed screw (LA)

counterclockwise until the saw chain stops turning – then turn another 2 3/4 turns in the same direction

WARNING

If the saw chain continues to keep rotating in idle even after adjustment, have the chain saw checked by a servicing dealer.

Speed erratic when idling; poor acceleration (despite standard setting of low speed adjusting screw)

The idle setting is too lean. N Carefully turn the low speed

adjusting screw (L) counterclockwise until the engine runs smoothly and accelerates properly.

Whenever the low speed adjusting screw (L) has been adjusted, it is usually also necessary to readjust the idle speed adjusting screw (LA).

Correcting the carburetor setting for use at high altitudes

The setting may have to be marginally corrected if engine performance is unsatisfactory at high altitudes:

N Make standard setting N Let the engine warm up N Turn the high speed adjusting

screw (H) slightly clockwise (leaner) – max. up to the stop

NOTICE

After descending from a high altitude, restore the carburetor setting to the standard setting.

If you make the setting too lean it will increase the risk of engine damage through lack of lubrication and overheating.

MS 251 C-Q

English

2310BA023 KN

2310BA006 KN

000BA039 KN

000BA045 KN

Spark Arresting Screen in Muffler

N If engine performance deteriorates,

check the spark arresting screen in the muffler

N Let the muffler cool down

N Unscrew the screw (1) N Pull out spark arresting screen (2) N Clean the dirty spark arresting

screen, replace if damaged or heavily carbonized

N Refit the spark arresting screen N Fit screw

Spark Plug

N If the engine is down on power,

difficult to start or runs poorly at idle speed, first check the spark plug.

N Fit a new spark plug after about 100

operating hours – or sooner if the electrodes are badly eroded. Install only suppressed spark plugs of the type approved by STIHL – see "Specifications".

Removing the spark plug

N Remove the shroud – see "Shroud"

Checking the Spark Plug

N Clean dirty spark plug. N Check electrode gap (A) and

readjust if necessary – see "Specifications".

N Rectify the problems which have

caused fouling of the spark plug.

Possible causes are:

– Too much oil in fuel mix.

– Dirty air filter.

– Unfavorable running conditions.

N Pull off the spark plug boot N Unscrew spark plug

WARNING

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 injuries or damage to property.

MS 251 C-Q

English

2310BA012 KN

001BA121 KN

N Use resistor type spark plugs with a

properly tightened adapter nut.

Installing the spark plug

N Fit spark plug by hand N Tighten the spark plug and press on

the spark plug boot firmly

N Fit the shroud – see "Shroud"

Storing the Machine Checking and Replacing the

Chain Sprocket

For periods of 3 months or longer N Drain and clean the fuel tank in a

well ventilated area.

N Dispose of fuel properly in

accordance with local environmental requirements.

N Run the engine until the carburetor

is dry – this helps prevent the carburetor diaphragms sticking together.

N Remove the saw chain and guide

bar, clean them and spray with corrosion inhibiting oil.

N Thoroughly clean the machine – pay

special attention to the cylinder fins and air filter.

N If you use a biological chain and bar

lubricant, e.g. STIHL BioPlus, completely fill the chain oil tank.

N Store the machine in a dry, high or

locked location, out of the reach of children and other unauthorized persons.

N Remove chain sprocket cover, saw

chain and guide bar.

N Release chain brake – pull hand

guard against the front handle

Fit new chain sprocket

– after use of two saw chains or

earlier

– if the wear marks (arrows) are

deeper than 0.5 mm – otherwise the service life of the saw chain is reduced – use check gauge (special accessory) to test

Using two saw chains in alternation helps preserve the chain sprocket.

STIHL recommends use of original STIHL chain sprockets in order to ensure optimal functioning of the chain brake.

MS 251 C-Q

English

001BA122 KN

N Use a screwdriver to remove the E-

clip (1)

N Remove the washer (2) N Remove rim sprocket (3) N Inspect transport profile on the

clutch drum (4) – if there are also heavy signs of wear, also replace the clutch drum

N Remove clutch drum or spur chain

sprocket (5) including needle cage (6) from the crankshaft – with QuickStop Super chain brake, press throttle trigger lockout beforehand

Install spur chain sprocket / rim sprocket

N Clean crankshaft stub and needle

cage and lubricate with STIHL lubricant (special accessory)

N Slide needle cage onto the

crankshaft stub

N After refitting, turn the clutch drum

and/or spur chain sprocket approx. 1 full turn so that the carrier for the oil pump drive engages – with QuickStop Super chain brake, press throttle trigger lockout beforehand

N Refit the rim sprocket – cavities

toward the outside

N Refit washer and E-clip on the

crankshaft

Maintaining and Sharpening the Saw Chain

Sawing effortlessly with a properly sharpened saw chain

A properly sharpened saw chain cuts through wood effortlessly even with very little pushing.

Never use a dull or damaged saw chain – this leads to increased physical strain, increased vibration load, unsatisfactory cutting results and increased wear.

N Clean the saw chain N Check the saw chain for cracks and

damaged rivets

N Replace damaged or worn chain

components and adapt these parts to the remaining parts in terms of shape and level of wear – rework accordingly

Carbide-tipped (Duro) saw chains are especially wear-resistant. For an optimal sharpening result, STIHL recommends STIHL servicing dealers.

WARNING

Compliance with the angles and dimensions listed below is absolutely necessary. An improperly sharpened saw chain – especially depth gauges that are too low – can lead to increased kickback tendency of the chain saw – risk of injury!

MS 251 C-Q

English

689BA027 KN

689BA021 KN

689BA025 KN

001BA203 KN

Chain pitch

The chain pitch marking (a) is embossed in the area of the depth gauge of each cutter.

Marking (a) Chain pitch

Inches mm 7 1/4 P 6.35 1 or 1/4 1/4 6.35 6, P or PM 3/8 P 9.32 2 or 325 0.325 8.25 3 or 3/8 3/8 9.32 4 or 404 0.404 10.26

The diameter of file to be used depends on the chain pitch – see table "Sharpening tools".

The angles of the cutter must be maintained during resharpening.

Sharpening and side plate angles

A Sharpening angle

STIHL saw chains are sharpened with a 30° sharpening angle. Ripping chains, which are sharpened with a 10° sharpening angle, are exceptions. Ripping chains have an X in the designation.

B Side plate angle

The correct side plate angle results automatically when the specified file holder and file diameter are used.

Tooth shapes Angle (°)

Micro = semi-chisel tooth,

30 75 e. g., 63 PM3, 26 RM3, 36 RM

Super = full chisel tooth,

30 60 e. g., 63 PS3, 26 RS, 36 RS3

Ripping chain, e. g.,

10 75 63 PMX, 36 RMX

The angles must be identical for all cutters in the saw chain. Varying angles: Rough, uneven running of the saw chain, increased wear – even to the point of saw chain breakage.

File holder

N Use a file holder

Always use a file holder (special accessory, see table "Sharpening tools") when sharpening saw chains by hand. File holders have markings for the sharpening angle.

Use only special saw chain files! Other files are unsuitable in terms of shape and type of cutting.

To check the angles

STIHL filing gauge (special accessory, see table "Sharpening tools") – a universal tool for checking sharpening and side plate angles, depth gauge setting, and tooth length, as well as cleaning grooves and oil inlet holes.

MS 251 C-Q

English

689BA018 KN

90°

689BA043 KN

689BA023 KN

689BA061 KN

Proper sharpening

N Select sharpening tools in

accordance with chain pitch

N Clamp guide bar if necessary N Block saw chain – push the hand

guard forward

N To advance the saw chain, pull the

hand guard toward the handlebar: The chain brake is disengaged. With the Quickstop Super chain brake system, additionally press the throttle trigger lockout

N Sharpen frequently, removing little

material – two or three strokes of the file are usually sufficient for simple resharpening

markings on the file holder – rest the file holder on the tooth head and the depth gauge

N File only from the inside outward N The file only sharpens on the

forward stroke – lift the file on the backstroke

N Do not file tie straps and drive links N Rotate the file a little periodically in

order to avoid uneven wear

N To remove file burr, use a piece of

hardwood

N Check angle with file gauge

All cutters must be equally long.

With varying cutter lengths, the cutter heights also vary and cause rough running of the saw chain and chain breakage.

N All cutters must be filed down equal

to the length of the shortest cutter – ideally, one should have this done by a servicing dealer using an electric sharpener

a Required distance between depth

gauge and cutting edge

When cutting softwood outside of the frost season, the distance can be increased by up to 0.2 mm (0.008").

Chain pitch Depth gauge

Distance (a) Inches (mm) mm (Inches) 1/4 P (6.35) 0.45 (0.018) 1/4 (6.35) 0.65 (0.026) 3/8 P (9.32) 0.65 (0.026)

0.325 (8.25) 0.65 (0.026) 3/8 (9.32) 0.65 (0.026)

0.404 (10.26) 0.80 (0.031)

Lowering the depth gauges

The depth gauge setting is lowered when the cutter is sharpened.

N Check the depth gauge setting after

each sharpening

N Guide the file: horizontally (at a right

angle to the side surface of the guide bar) in accordance with the specified angle – according to the

Depth gauge setting

The depth gauge determines the depth to which the cutter penetrates the wood and thus the chip thickness.

N 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 protrudes past the file gauge, the depth gauge must be reworked

MS 251 C-Q

English

689BA051 KN

689BA044 KN

689BA052 KN

Saw chains with humped drive link (2) – upper part of the humped drive link (2) (with service mark) is lowered at the same time as the depth gauge of the cutter.

WARNING

The rest of the humped drive link must not be filed; otherwise, this could increase the tendency of the chain saw to kick back.

N Afterwards, dress the leading edge

of the depth gauge parallel to the service mark (see arrow) – when doing this, be careful not to further lower the highest point of the depth gauge

N Lay the file gauge on the saw chain

– the highest point of the depth gauge must be flush with the file gauge

N After sharpening, clean the saw

chain thoroughly, removing any filings or grinding dust – lubricate

WARNING

Depth gauges that are too low increase the kickback tendency of the chain saw.

the saw chain thoroughly

N In the event of extended periods of

disuse, store saw chains in cleaned and oiled condition

N Rework the depth gauge so that it is

flush with the file gauge

Sharpening tools (special accessories) Chain pitch Round file ^ Round file File holder File gauge Taper square file Sharpening set Inches (mm) mm (Inches) Part number Part number Part number Part number Part number 1/4P (6.35) 3.2 (1/8) 5605 771 3206 5605 750 4300 0000 893 4005 0814 252 3356 5605 007 1000 1/4 (6.35) 4.0 (5/32) 5605 772 4006 5605 750 4327 1110 893 4000 0814 252 3356 5605 007 1027 3/8 P (9.32) 4.0 (5/32) 5605 772 4006 5605 750 4327 1110 893 4000 0814 252 3356 5605 007 1027

0.325 (8.25) 4.8 (3/16) 5605 772 4806 5605 750 4328 1110 893 4000 0814 252 3356 5605 007 1028 3/8 (9.32) 5.2 (13/64) 5605 772 5206 5605 750 4329 1110 893 4000 0814 252 3356 5605 007 1029

0.404 (10.26) 5.5 (7/32) 5605 772 5506 5605 750 4330 1106 893 4000 0814 252 3356 5605 007 1030

consisting of file holder with round file, taper square file and file gauge

MS 251 C-Q

English

Maintenance and Care

The following information applies under normal operating conditions. The specified intervals must be shortened accordingly when working for longer than normal each day or under difficult conditions (extensive dust, highly resinous lumber, lumber from tropical trees, etc.). If the machine is only used occasionally, the intervals can be extended accordingly.

Before starting work

At the end of work and/or

daily

Whenever tank is refilled

Weekly

Complete machine

Throttle trigger, throttle trigger lockout, choke lever, choke control, stop switch, master control lever (dependent on equipment)

Chain brake

Manual fuel pump (if present)

Fuel pick-up body / filter in fuel tank

Fuel tank Clean X

Lubricating oil tank Clean X

Chain lubrication Check X

Saw chain

Guide bar

Chain sprocket Check X

Air filter

Visual inspection (condition, leaks) XX

Clean X

Function tests XX

Have checked by a specialist dealer

Check X

Have repaired by a specialist dealer

Check X

Clean, replace filter insert XX

Replace XXX

Check, pay attention to sharpness XX

Check chain tension XX

Sharpen X

Check (wear, damage) X

Clean and turn over X

Deburr X

Replace XX

Clean XX

Replace X

Monthly

Yearly

If faulty

If damaged

As required

MS 251 C-Q

English

Before starting work

At the end of work and/or

daily

Whenever tank is refilled

Weekly

Monthly

Yearly

If faulty

If damaged

As required

Anti-vibration elements

Air intake on fan housing Clean XX X

Cylinder fins Clean XX

Carburetor

Spark plug

All accessible screws, nuts and bolts (not adjusting screws)

Spark arresting screen in muffler

Chain catcher

Exhaust bore

Safety information label Replace X

STIHL recommends STIHL servicing dealers

During initial use of professional chain saws (with a power output of 3.4 kW or more), tighten the cylinder block screws after 10 to 20 hours of operation

Check XX

Have them replaced by a servicing dealer

Check idle adjustment – saw chain must not rotate

Set the idle speed, have the chain saw repaired by a servicing dealer

Adjust electrode gap X

Replace after 100 hours of operation

Tighten

Have checked by a specialist dealer

Have cleaned by a specialist dealer, or replaced if necessary

Check X

Replace X

Decarbonise after 139 hours of operation, subsequently after every 150 hours of operation

MS 251 C-Q

English

Main Parts

1 Shroud lock 2 Carburetor adjusting screws 3 Fuel pump 4 Shutter (summer and winter

operation) 5 Chain brake 6 Chain sprocket

7 Chain sprocket cover 8 Chain catcher 9 Spiked bumper 10 Guide bar 11 Oilomatic chain 12 Adjusting wheel (quick chain

tensioner) 13 Handle of wingnut (quick chain

adjuster) 14 Oil filler cap 15 Muffler 16 Front hand guard 17 Front handle (handlebar) 18 Spark plug boot 19 Starter grip 20 Fuel filler cap 21 Master Control lever 22 Throttle trigger 23 Coasting brake lever (throttle trigger

lockout) 24 Rear handle 25 Rear hand guard # Serial number

2310BA030 ST

MS 251 C-Q

English

Specifications

Engine

STIHL single cylinder two-stroke engine

MS 251 C

Displacement: 45.6 cc Bore: 44 mm Stroke: 30 mm Engine power to

ISO 7293: Idle speed:

to ISO 11681 +/- 50 rpm

Ignition System

Electronic magneto ignition

Spark plug (resistor type): NGK CMR6H

Electrode gap: 0.5 mm

Fuel System

All position diaphragm carburetor with integral fuel pump

Fuel tank capacity: 390 cc (0.39 l)

Chain Lubrication

Fully automatic, speed-controlled oil pump with rotary piston

Oil tank capacity: 200 cc (0.2 l)

2.2 kW (3.0 bhp) at 10,000 rpm

2,800 rpm

Weight

Weight (dry, without bar and chain): MS 251 C: 5.3 kg

Cutting attachment

The actual cutting length can be less than the specified cutting length.

.325" Rollomatic E guide bars

Cutting lengths: 35, 40, 45 cm Pitch: .325" (8.25 mm) Groove width: 1.6 mm Nose sprocket: 11-tooth

3/8" P Rollomatic E guide bars

Cutting lengths: 30, 35, 40, 45 cm Pitch: 3/8" P (9.32 mm) Groove width: 1.3 mm Nose sprocket: 9-tooth

.325" chain

Rapid Micro 3 (26 RM3) Type 3634 Rapid Duro 3 (26 RD3) Type 3667 Pitch: .325" (8.25 mm) Drive link gauge: 1.6 mm

3/8" P chain

Picco Micro 3 (63 PM3) Type 3636 Picco Super 3 (63 PS3) Type 3616 Picco Duro 3 (63 PD3) Type 3612 Pitch: 3/8" P (9.32 mm) Drive link gauge: 1.3 mm

Chain sprocket

7-tooth for .325" Max. chain velocity to

ISO 11681 25.6 m/s

6-tooth for 3/8" P Max. chain velocity to

ISO 11681 24.8 m/s

As a rule, the mean chain velocity in operation is about 20% lower than the maximum chain velocity in accordance with ISO 11681. Contact your STIHL servicing dealer for advice on personal protective equipment.

Noise and Vibration Data

For further details on compliance with Vibration Directive 2002/44/EC see www.stihl.com/vib.

Sound pressure level L

to ISO 22868

MS 251 C: 103 dB(A)

Sound power level Lw to ISO 22868

MS 251 C: 114 dB(A)

Vibration measurement a

hv, eq

ISO 22867

Handle, left Handle, right

MS 251 C: 3.9 m/s

3.9 m/s

The K-factor in accordance with Directive 2006/42/EC is 2.5 dB(A) for the sound pressure level and sound power level; the K-factor in accordance with Directive 2006/42/EC is 2.0 m/s

for the vibration measurement.

MS 251 C-Q

English

REACH

REACH is an EC regulation and stands for the Registration, Evaluation, Authorisation and Restriction of Chemical substances.

For information on compliance with the REACH regulation (EC) No. 1907/2006 see www.stihl.com/reach.

Ordering Spare Parts

Please enter your saw model, serial number as well as the part numbers of the guide bar and saw chain in the spaces provided. This will make reordering simpler.

The guide bar and saw chain are subject to normal wear and tear. When purchasing these parts, always quote the saw model, the part numbers and names of the parts.

Model

Serial number

Guide bar part number

Chain part number

Maintenance and Repairs

Users of this machine may only carry out the maintenance and service work described in this user manual. All other repairs must be carried out by a servicing dealer.

STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer. STIHL dealers are regularly given the opportunity to attend training courses and are supplied with the necessary technical information.

When repairing the machine, only use replacement parts which have been approved by STIHL for this power tool or are technically identical. Only use highquality replacement parts in order to avoid the risk of accidents and damage to the machine.

STIHL recommends the use of original STIHL replacement parts.

Original STIHL parts can be identified by the STIHL part number, the { logo and the STIHL parts symbol K (the symbol may appear alone on small parts).

MS 251 C-Q

English

000BA073 KN

Disposal

Observe all country-specific waste disposal rules and regulations.

STIHL products must not be thrown in the garbage can. Take the product, accessories and packaging to an approved disposal site for environmentfriendly recycling.

Contact your STIHL servicing dealer for the latest information on waste disposal.

EC Declaration of Conformity

ANDREAS STIHL AG & Co. KG Badstr. 115 D-71336 Waiblingen

Germany

declare in exclusive responsibility that the product

Category: Chainsaw Make: STIHL Model: MS 251 C-BEQ Serial identification: 1143 Displacement 45.6 cc

conforms to the relevant provisions of Directives 2006/42/EC, 2014/30/EU and 2000/14/EC and has been developed and manufactured in compliance with the following standards in the versions valid on the date of production:

EN ISO 11681-1, EN 55012, EN 61000-6-1

The measured and guaranteed sound power levels were determined according to Directive 2000/14/EC, Annex V, using the ISO 9207 standard.

Measured sound power level

DPLF Deutsche Prüf- und Zertifizierungsstelle für Land- und Forsttechnik (NB 0363) Max-Eyth-Weg 1 D-64823 Gross-Umstadt

Certification No. K-EG-2010/5605

Technical documents deposited at:

ANDREAS STIHL AG & Co. KG Produktzulassung (Product Licensing)

The year of manufacture and serial number are applied to the product.

Done at Waiblingen, 28.10.2016

ANDREAS STIHL AG & Co. KG

pp.

Thomas Elsner

Director Product Management and Services

MS 251 C-Q

114 dB(A)

Guaranteed sound power level

116 dB(A)

The EC type examination was carried out by

0458-740-8321-B

AUS

www.stihl.com

*04587408321B*

0458-740-8321-B

Stihl MS 251 C-Q Instruction Manual

Specifications and Main Features

Frequently Asked Questions

User Manual