Stihl Ms 250 C Manual

							MS 250
English
39 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 engine-
mounted components (ignition, 
carburetor) from thermal overload.
After finishing work
NSlacken 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"
NTurn the guide bar over – every time 
you sharpen the chain and every 
time you replace the chain –  this 
helps avoid one-sided wear, 
especially at the nose and 
underside of the bar.
NRegularly clean the oil inlet hole (1), 
the oilway (2) and the bar groove 
(3).
NMeasure the groove depth – with the 
scale on the filing gauge (special 
accessory) – in the area used most 
for cutting.
Taking Care of the Guide Bar
Chain 
typeChain pitch Minimum 
groove depth
Picco 1/4" P 0.16" (4.0 mm)
Rapid 1/4" 0.16" (4.0 mm)
2
3 1
143BA026 KN 
						

							MS 250
English
40 If groove depth is less than specified:
NReplace the guide bar.
The drive link tangs will otherwise 
scrape along the bottom of the groove – 
the cutters and tie straps will not ride on 
the bar rails.The air filter system can be adapted to 
suit different operating conditions by 
installing a choice of filters. Changing 
the filter is quick and simple.
The saw comes standard with either a 
fabric filter or a fleece filter.
Fabric filter
For normal operating conditions and 
winter operation.
Fleece filter
For dry and very dusty work areas.If there is a noticeable loss of engine 
power
NPress down the throttle trigger 
lockout and move the Master 
Control lever to choke closedl.
NTurn the knob 90° to the left.
NLift off the carburetor box cover 
vertically.
NAlways replace damaged filters.
NClean away loose dirt from around 
the filter.
NPlace fingers behind the air filter (1), 
press thumbs against the housing 
and swing the filter in direction of 
rear handle.  Picco 3/8" P 0.20" (5.0 mm)
Rapid 3/8"; 0.325" 0.24" (6.0 mm)
Rapid 0.404" 0.28" (7.0 mm)
Air Filter System
208BA001 KN
&OHDQLQJWKH$LU)LOWHU
208BA005 KN
1
135BA035 KN 
						

							MS 250
English
41
NOTICE
To avoid damaging the filter, do not use 
tools for removing and installing the air 
filter.
NBlow out the filter with compressed 
air from the clean air side.
If the filter fabric is caked with dirt or no 
compressed air is available:
NWash the filter in a clean, non-
flammable solution (e.g. warm 
soapy water) and then dry.
NReinstall the air filter.Exhaust emissions are controlled by the 
design of the fundamental engine 
parameters and components (e.g. 
carburation, ignition, timing and valve or 
port timing) without the addition of any 
major hardware.
General Information
The carburetor comes from the factory 
with a standard setting.
This setting provides an optimum fuel-air 
mixture under most operating 
conditions.
Preparations
NShut off the engine.
NCheck the air filter and clean or 
replace if necessary.
NCheck the spark arresting screen 
(not in all models, country-specific) 
i n t he m uf f ler  an d c le an o r r e plac e  if  
necessary.
Standard setting
NTurn high speed screw (H) 
counterclockwise as far as stop (no 
more than 3/4 turn).
NTurn the low speed screw (L) 
carefully clockwise as far as stop, 
then turn it back 1/4 turn.
Engine ManagementAdjusting the Carburetor
208BA024 KN
HL 
						

							MS 250
English
42
Adjusting Idle Speed
NCarry out the standard setting.
NStart and warm up the engine.
Engine stops while idling
NTurn the idle speed screw (LA) 
clockwise until the chain begins to 
run –  then back it off 1/4 turn.
Saw chain runs while engine is idling
NTurn the idle speed screw (LA) 
counterclockwise until the chain 
stops moving –  then turn it another 
1/4 turn in the same direction.
WARNING
If the chain continues moving when the 
engine is idling, have your saw checked 
and repaired by your servicing dealer.
Erratic idling behavior, poor acceleration 
(even though standard setting of low 
speed screw is correct)
Idle setting is too lean
NTurn the low speed screw (L) 
counterclockwise, no further than 
stop, until the engine runs and 
accelerates smoothly.It is usually necessary to change the 
setting of the idle speed screw (LA) after 
every correction to the low speed 
screw (L).
Fine Tuning for Operation at High 
Altitude
A slight correction of the setting may be 
necessary if engine does not run 
satisfactorily:
NCarry out the standard setting.
NWarm up the engine.
NTurn high speed screw (H) slightly 
clockwise (leaner) – no further than 
stop.
NOTICE
After returning from high altitude, reset 
the carburetor to the standard setting.
If the setting is too lean there is a risk of 
engine damage due to insufficient 
lubrication and overheating.If the engine is down on power, difficult 
to start or runs poorly at idling speed, 
first check the spark plug.
Install a new spark plug after approx. 
100 operating hours or earlier if the 
electrodes are badly eroded/corroded.
The wrong fuel mix (too much engine oil 
in the gasoline), a dirty air filter and 
unfavorable running conditions (mostly 
at part throttle etc.) affect the condition 
of the spark plug. These factors cause 
deposits to form on the insulator nose 
which may degrade performance.
Removing the Spark Plug
NDepress throttle trigger lockout and 
throttle trigger at the same time and 
move the Master Control lever to 
choke closedl.
NTurn the knob 90° to the left.
NLift off the carburetor box cover 
vertically.
208BA025 KN
LA
6SDUN3OXJ
208BA005 KN 
						

							MS 250
English
43 NPlace fingers behind the air filter (3), 
press thumbs against the housing, 
swing the filter in the direction of the 
rear handle and remove it. 
NRemove the shutter (4).
NPull off the spark plug boot.
NUnscrew the spark plug.
Checking the spark plug
NClean the spark plug if it is dirty
NCheck the electrode gap (A) and 
readjust if necessary – see 
"Specifications"
NUse only resistor type spark plugs of 
the approved range
Correct the problems that have caused 
fouling of the spark plug:
–too much oil in fuel mix,
–dirty air filter,
–unfavorable running conditions, e.g. 
operating at part throttle.
WARNING
T o  r e d u c e  t h e  r i s k  o f  f i r e  a n d  b u r n  i n j u r y ,  
use only spark plugs authorized by 
STIHL. Always press the spark plug 
boot (1) snugly onto the spark plug 
terminal (2).
Do not use a spark plug with a 
detachable SAE adapter terminal (3). 
Arcing may occur that could ignite 
combustible fumes and cause a fire. 
This can result in serious injuries or 
damage to property. 
NOnly use resistor type spark plugs 
with solid, non-threaded terminals
Installing the spark plug
NScrew home the spark plug, fit the 
boot and press it down firmly.
NInstall the shutter and air filter.
NFit the carburetor box cover.
4
3
135BA001 KN
208BA020 KN
000BA039 KNA
2
0000-GXX-1830-A0
3
1 
						

							MS 250
English
44 If engine running behavior is 
unsatisfactory even though the air filter 
is clean and the carburetor is properly 
adjusted, the cause may be the muffler.
Have the muffler checked for 
contamination (carbonization) by your 
servicing dealer.
STIHL recommends that you have 
servicing and repair work carried out 
exclusively by an authorized STIHL 
servicing dealer.For periods of 3 months or longer
NDrain and clean the fuel tank in a 
well ventilated area.
NDispose of fuel properly in 
accordance with local 
environmental requirements.
NRun the engine until the carburetor 
is dry – this helps prevent the 
carburetor diaphragms sticking 
together.
NRemove the saw chain and guide 
bar, clean them and spray with 
corrosion inhibiting oil.
NThoroughly clean the machine – pay 
special attention to the cylinder fins 
and air filter.
NIf you use a biological chain and bar 
lubricant, e.g. STIHL BioPlus, 
completely fill the chain oil tank.
NStore the machine in a dry, high or 
locked location, out of the reach of 
children and other unauthorized 
persons.NRemove chain sprocket cover, saw 
chain and guide bar.
NRelease 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 0.02 in (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.
Use only STIHL original chain sprockets 
to help ensure reliable functioning of the 
chain brake.
Engine Running BehaviorStoring the MachineChecking and Replacing the 
Chain Sprocket
001BA121 KN 
						

							MS 250
English
45 NUse a screwdriver to remove the E-
clip (1)
NRemove the washer (2)
NRemove rim sprocket (3) (if so 
equipped), clutch drum (4) and 
needle cage (6).
NInspect transport profile for rim 
sprocket on the clutch drum (4) – if 
there are also heavy signs of wear, 
also replace the clutch drum
NRemove clutch drum with integrated 
spur chain sprocket (5) (if so 
equipped) including needle cage (6) 
from the crankshaft – for 
powerheads with Quickstop Plus 
chain brake system, depress 
throttle trigger lockout beforehand
Install spur chain sprocket / rim sprocket
NClean crankshaft stub and needle 
cage and lubricate with STIHL 
lubricant (special accessory)
NSlide needle cage onto the 
crankshaft stub
NAfter refitting, turn the clutch drum 
and/or spur chain sprocket approx. 
1 full turn so that the carrier for the 
oil pump drive engages
NRefit the rim sprocket – cavities 
toward the outside
NRefit washer and E-clip on the 
crankshaftSawing 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.
NClean the saw chain
NCheck the saw chain for cracks and 
damaged rivets
NReplace 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!
001BA122 KN
1 2
45
61
2 3 6
0DLQWDLQLQJDQG6KDUSHQLQJ
WKH6DZ&KDLQ 
						

							MS 250
English
46
Chain pitch
The chain pitch marking (a) is embossed 
in the area of the depth gauge of each 
cutter.
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
ASharpening 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.
BSide plate angle
The correct side plate angle results 
automatically when the specified file 
holder and file diameter are used.
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
NUse 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. 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
689BA027 KN
a
7RRWKVKDSHV $QJOHr
$%
0LFUR VHPLFKLVHOWRRWK
H J 30 50
 50 
6XSHU IXOOFKLVHOWRRWK
H J 36 56
 56 
5LSSLQJFKDLQH J
 30; 50; 
A
B
689BA021 KN689BA025 KN
001BA203 KN 
						

							MS 250
English
47
Proper sharpening
NSelect sharpening tools in 
accordance with chain pitch
NClamp guide bar if necessary
NBlock saw chain – push the hand 
guard forward
NTo advance the saw chain, pull the 
hand guard toward the handlebar: 
The chain brake is disengaged. 
With the Quickstop Plus chain brake 
system, additionally press the 
throttle trigger lockout
NSharpen frequently, removing little 
material – two or three strokes of the 
file are usually sufficient for simple 
resharpening
NGuide the file: horizontally ( a t  a  r i g h t  
angle to the side surface of the 
guide bar) in accordance with the 
specified angle – according to the markings on the file holder – rest the 
file holder on the tooth head and the 
depth gauge
NFile only from the inside outward
NThe file only sharpens on the 
forward stroke – lift the file on the 
backstroke
NDo not file tie straps and drive links
NRotate the file a little periodically in 
order to avoid uneven wear
NTo remove file burr, use a piece of 
hardwood
NCheck 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.
NAll 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
Depth gauge setting
The depth gauge determines the depth 
to which the cutter penetrates the wood 
and thus the chip thickness.aRequired 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").
Lowering the depth gauges
The depth gauge setting is lowered 
when the cutter is sharpened.
NCheck the depth gauge setting after 
each sharpening
NLay 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
689BA018 KN
90°
689BA043 KN
689BA023 KN
a
&KDLQSLWFK HSWKJDXJH
LVWDQFH D
,QFKHV PP PP ,QFKHV
3   
   
 3   
   
   
   
2
689BA061 KN
1 
						

							MS 250
English
48 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.
NRework the depth gauge so that it is 
flush with the file gaugeNAfterwards, 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
WARNING
Depth gauges that are too low increase 
the kickback tendency of the chain saw.NLay the file gauge on the saw chain 
– the highest point of the depth 
gauge must be flush with the file 
gauge
NAfter sharpening, clean the saw 
chain thoroughly, removing any 
filings or grinding dust – lubricate 
the saw chain thoroughly
NIn the event of extended periods of 
disuse, store saw chains in cleaned 
and oiled condition
689BA051 KN
689BA044 KN689BA052 KN
6KDUSHQLQJWRROVVSHFLDODFFHVVRULHV
&KDLQSLWFK 5RXQGILOH^Round file File holder File gaugeTaper square file Sharpening set 
1)
Inches (mm) mm (Inches) Part number Part number Part number Part number Part number
1/4 P (6.35) 3.2 (1/8) 5605 771 32065605 750 4300 0000 893 4005 0814 252 3356 5605 007 1000
1/4 (6.35) 4.0 (5/32) 5605 772 40065605 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
1)consisting of file holder with round file, taper square file and file gauge