Stihl Ms 250 C Manual

							MS 250
English
29 STIHL MotoMix uses STIHL HP Ultra 
two-stroke engine oil suited for high 
performance engines.
For further details, see 
www.STIHLusa.com/ethanol
If not using MotoMix, use only STIHL 
two-stroke engine oil or equivalent high-
quality two-stroke engine oils that are 
designed for use in air cooled two-cycle 
engines.
The use of non-seasonal gasoline 
blends may increase the potential for 
pressure to build in the fuel tank during 
operation. For example, using a winder 
blend during the summer will increase 
pressure in the fuel tank. Always use 
gasoline blends appropriate to the 
season, altitude and other 
environmental factors.
Do not use BIA or TCW rated (two-
stroke water cooled) mix oils or other 
mix oils that state they are for use in both 
water cooled and air cooled engines 
(e.g., outboard motors, snowmobiles, 
chain saws, mopeds, etc.).
WARNING
Take care when handling gasoline. 
Avoid direct contact with the skin and 
avoid inhaling fuel vapor. When filling at 
the pump, first remove the container 
from your vehicle and place the 
container on the ground before filling. To 
reduce the risk of sparks from static 
discharge and resulting fire and/or 
explosion, do not fill fuel containers that 
are sitting in or on a vehicle or trailer.
The container should be kept tightly 
closed in order to limit the amount of 
moisture that gets into the mixture.The machine‘s fuel tank should be 
cleaned as necessary.
Fuel mix ages
If not using MotoMix, only mix sufficient 
fuel for a few days of work, not to exceed 
30 days of storage. Store in approved 
fuel-containers only. When mixing, pour 
oil into the container first, and then add 
gasoline. Close the container and shake 
it vigorously by hand to ensure proper 
mix of oil and gasoline.
Dispose of empty mixing-oil containers 
only at authorized disposal locations.
Preparations
NBefore fueling, clean the filler cap 
and the area around it to ensure that 
no dirt falls into the tank.
Always thoroughly shake the mixture in 
the canister before fueling your 
machine.
NPosition the machine so that the 
filler cap is facing up.
WARNING
In order to reduce the risk of fire and 
other personal injury from escaping gas 
vapor and fumes, remove the fuel filler 
cap carefully so as to allow any pressure 
build-up in the tank to release slowly Gaso-
lineOil (STIHL 50:1 or equiva-
lent high-quality oils)
US gal. US fl.oz.
12.6
2 1/2 6.4
5 12.8
Fueling
001BA229 KN 
						

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30
Opening
NRaise handle.
NTwist filler cap counterclockwise 
(approx. 1/4 turn).
Markings on filler cap and housing must 
align.NRemove the filler cap.
Refueling
Take care not to spill fuel while fueling 
and do not overfill the tank – leave 
approx. 1/2" (13 mm) air space.
Closing
Handle is in an upright position:
NPosition filler cap – markings on filler 
cap and housing must align.
NPush the filler cap down as far as it 
will go.NPush the filler cap down and twist it 
clockwise until it engages.
Then the markings on filler cap and 
housing will align.
NFlip the handle down.
001BA236 KN
001BA232 KN
001BA234 KN
001BA237 KN
001BA234 KN
001BA233 KN
001BA231 KN
001BA235 KN 
						

							MS 250
English
31 Filler cap is now closed.
If the filler cap will not engage into the 
tank housing
The base of the filler cap is rotated in 
relation to the upper part.
NLook at the black alignment marks 
on the top of the filler cap.NWith the filler cap in the filling neck, 
twist it counterclockwise until it 
drops into its seat.
NContinue to twist the filler cap 
counterclockwise (approx. 1/4 turn) 
– this will twist the base of the cap 
into the correct position.
NWhile pushing down on the cap, 
twist the filler cap clockwise and 
close it – see section "Closing."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. Left: Base of filler cap is rotated – 
interior marking (1) is aligned 
with the exterior marking.
Right: Base of filler cap is in the cor-
rect position – interior 
marking is below the clip. It 
does not align with the exte-
rior marking.
001BA241 KN
1
001BA238 KN
001BA239 KN
&KDLQ/XEULFDQW 
						

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32
Preparations
NThoroughly clean the oil filler cap 
and the area around it to ensure that 
no dirt falls into the tank.
NPosition the machine so that the 
filler cap is facing up.
NOpen the filler cap.
Filling chain oil tank
NRefill the chain oil tank every time 
you refuel.
Take care not to spill chain oil while 
refilling and do not overfill the tank.
NClose 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.
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".
Filling Chain Oil Tank
001BA158 KN
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143BA024 KN 
						

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33
Locking chain with chain brake
–in an emergency
–when starting
–at idling speed
The chain is stopped and locked when 
the hand guard is pushed toward the bar 
nose by the left hand – or when brake is 
activated by inertia in certain kickback 
situations.
Releasing the chain brake
NPull the hand guard back toward the 
front handle.
NOTICE
Always disengage chain brake before 
accelerating engine and before starting 
cutting work. The only exception to this 
rule is when you check operation of the 
chain brake.
High revs with the chain brake engaged 
(chain locked) will quickly damage the 
powerhead and chain drive (clutch, 
chain brake).
The chain brake is designed to be 
activated also by the inertia of the front 
hand guard
if the forces are sufficiently high. The 
hand guard is accelerated toward the 
bar nose - even if your left hand is not 
behind the hand guard, e.g. during a felling cut. The chain brake will operate 
only if it has been properly maintained 
and the hand guard has not been 
modified in any way.
Check operation of chain brake
Before starting work: Run engine at idle 
speed, engage the chain brake (push 
hand guard toward bar nose). 
Accelerate up to full throttle for no more 
than 3 seconds – the chain must not 
rotate. The hand guard must be free 
from dirt and move freely.
Chain brake maintenance
The chain brake is subject to normal 
wear. It is necessary to have it serviced 
and maintained regularly by trained 
personnel, such as your STIHL servicing 
dealer, at the following intervals:
Chain Brake
143BA011 KN
143BA012 KN
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34
At temperatures below +50°F (+10°C):
NSqueeze the throttle trigger lockout 
and move the Master Control lever 
to l (cold start).
NTurn the knob above the rear handle 
90° counterclockwise.
NLift off the carburetor box cover 
vertically.NLift out the shutter (in front of spark 
plug) vertically.
NTurn the shutter 180°.
NRefit the shutter.
NRefit the carburetor box cover and 
secure it with the knob.
Heated air is now drawn in from around 
the cylinder to warm the carburetor – this 
helps prevent carburetor icing.
NOTICE
At temperatures above +70 °F (+ 20°C), 
always close the shutter again. This is 
necessary to avoid engine running 
problems and overheating.
Positions of Master Control Lever
Stop 0 – engine off – the ignition is 
switched off
Normal run position(F) – engine runs or 
can fire.
Starting throttle(n) – 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.
Winter Operation
208BA005 KN135BA029 LÄ
6WDUWLQJ6WRSSLQJWKH
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STOP
0
001BA140 KN 
						

							MS 250
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35
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.
–after engine begins to fire,
–after clearing a flooded combustion 
chamber.Manual 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.On the ground 
NPlace your saw on the ground. 
Make sure you have a firm footing – 
check that the chain is not touching 
any object or the ground.
NHold the saw firmly on the ground 
with your left hand on the front 
handle – your thumb should be 
under the handle.
NPut your right foot into the rear 
handle and press down.
143BA018 KN 
						

							MS 250
English
36 Between knees or thighs
NHold the rear handle tightly between 
your legs, just above the knees.
NHold the front handle firmly with 
your left hand – your thumb should 
be under the handle.
Cranking
NPull 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.Starting the Saw
WARNING
Bystanders must be well clear of the 
general work area of the saw.
NObserve safety precautions.
Versions with manual fuel pump
NPress the manual fuel pump bulb at 
least five times – even if the bulb is 
already filled with fuel.
143BA019 KN
143BA020 KN
135BA027 KN 
						

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37 Versions with decompression valve
NPress in the button to open the 
decompression valve.
The decompression valve closes as 
soon as the engine fires.
NFor this reason you must press in 
the button before each starting 
attempt.All models
NPush the hand guard (1) forward – 
the chain is locked.
NPress down the trigger lockout (2) 
and pull the throttle trigger at the 
same time. Set Master Control 
lever (3) 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.
NHold and start your saw as 
described.
When engine begins to fire
NSet the Master Control lever to the 
starting throttle position (n ).
NHold and start your saw as 
described.
As soon as the engine runs
NPress down trigger lockout and the 
blip the throttle trigger (4) – the 
Master Control lever (3) 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.
135BA015 KN
2 1
208BA000 KN
0
3
3
45
0
208BA001 KN 
						

							MS 250
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38 NPull the hand guard back toward 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
NAllow engine to warm up at part 
throttle.
Stopping the Engine
NMove the Master Control lever to the 
stop position (0).
If 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.
NMove the Master Control lever to the 
stop position (0).
NRemove the spark plug – see 
"Spark Plug".
NDry the spark plug.
NCrank the engine several times with 
the starter to clear the combustion 
chamber.
NRefit the spark plug – see "Spark 
Plug".
NSet Master Control lever to the 
starting throttle position (n) – even 
if the engine is cold.
NNow start the engine.
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.
143BA012 KN
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