Stihl Ms 250 C Manual

							MS 250
English
19
Bucking
Bucking is cutting a log into sections.
WARNING
When bucking, do not stand on the log. 
Make sure the log will not roll downhill. If 
on a slope, stand on the uphill side of the 
log. Watch out for rolling logs.
Cut only one log at a time.
Shattered wood should be cut very 
carefully. Sharp slivers of wood may be 
caught and flung in the direction of the 
operator of the saw.When cutting small logs, place log 
through "V"-shaped supports on top of a 
sawhorse. Never permit another person 
to hold the log. Never hold the log with 
your leg or foot.Logs under strain:
Risk of pinching! Always start relieving 
cut (1) at compression side.Then make 
bucking cut (2) at tension side. If the saw 
pinches, stop the engine and remove it 
from the log.
Only properly trained professionals 
should work in an area where the logs, 
limbs and roots are tangled. Working in 
"blow down" areas is extremely 
hazardous. Drag the logs into a clear 
area before cutting. Pull out exposed 
and cleared logs first.
Felling
Felling is cutting down a tree.
Before felling a tree, consider carefully 
all conditions which may affect the 
direction of fall.
001BA033 KN
001BA051 LÄ
1
001BA151 KN
2
1
001BA152 KN
2 
						

							MS 250
English
20
WARNING
There are a number of factors that may 
affect and change the intended direction 
of fall, e.g. wind direction and speed, 
lean of tree, surrounding trees and 
obstacles, sloping ground, one-sided 
limb structure, wood structure, decay, 
snow load, etc. To reduce the risk of 
severe or fatal injury to yourself or 
others, look for these conditions prior to 
beginning the cut, and be alert for a 
change in direction while the tree is 
falling.
WARNING
Always observe the general condition of 
the tree. Inexperienced users should 
never attempt to cut trees that are 
decayed or rotted inside or that are 
leaning or otherwise under tension. 
There is an increased risk that such 
trees could snap or split while being cut 
and cause serious or fatal injury to the 
operator or bystanders. Also look for 
broken or dead branches which could 
vibrate loose and fall on the operator. 
When felling on a slope, the operator 
should stand on the uphill side if 
possible.Felling Instructions
When felling, maintain a distance of at 
least 2 1/2 tree lengths from the nearest 
person.
When felling in the vicinity of roads, 
railways and power lines, etc., take extra 
precautions. Inform the police, utility 
company or railway authority before 
beginning to cut.
WARNING
The noise of your engine may drown any 
warning call.Escape Path
First clear the tree base and work area 
from interfering limbs and brush and 
clean its lower portion with an ax.
Then, establish two paths of escape (B) 
and remove all obstacles. These paths 
should be generally opposite to the 
planned direction of the fall of the tree 
(A) and about at a 45° angle. Place all 
tools and equipment a safe distance 
away from the tree, but not on the 
escape paths.
001BA088 LÄ2/1
211/1
2
B
001BA040 KN
A
45°
45°
B 
						

							MS 250
English
21 Buttress Roots
If the tree has large buttress roots, cut 
into the largest buttress vertically first 
(horizontally next) and remove the 
resulting piece.
Gunning Sight
When making the felling notch, use the 
gunning sight on the shroud and housing 
to check the desired direction of fall:
Position the saw so that the gunning 
sight points exactly in the direction you 
want the tree to fall.Conventional Cut
Felling notch (C) – determines the 
direction of the fall
For a conventional cut:
NProperly place felling notch 
perpendicular to the line of fall, 
close to the ground.
NCut down at approx. 45° angle to a 
depth of about 1/5 to 1/4 of the trunk 
diameter.
NMake second cut horizontal.
NRemove resulting 45° piece.Open-face Technique
Felling notch (C) – determines the 
direction of the fall
For an open-face cut:
NProperly place felling notch 
perpendicular to the line of fall, 
close to the ground.
NCut down at approx. 50° angle to a 
depth of approx.1/5 to 1/4 of the 
trunk diameter.
NMake second cut from below at 
approx. 40 degree angle.
NRemove resulting 90° piece.
001BA146 KN
001BA153 KN
001BA143 KN
C
C 
						

							MS 250
English
22 Making Sapwood Cuts
NFor medium sized or larger trees 
make cuts at both sides of the trunk, 
at same height as subsequent 
felling cut.
NCut to no more than width of guide 
bar.
This is especially important in softwood 
in summer – it helps prevent sapwood 
splintering when the tree falls.D =Felling Cut 
Conventional and open-face technique:
NBegin 1 to 2 inches (2,5 to 5 cm) 
higher than center of felling notch.
NCut horizontally towards the felling 
notch.
NLeave approx.1/10 of diameter 
uncut. This is the hinge.
NDo not cut through the hinge – you 
could lose control of the direction of 
the fall.
Drive wedges into the felling cut where 
necessary to control the fall.
WARNING
If the tip of the bar contacts a wedge, it 
may cause kickback. Wedges should be 
of wood or plastic – never steel, which 
can damage the chain.E = Hinge
NHelps control the falling tree.
NDo not cut through the hinge – you 
could lose control of the direction of 
the fall.
001BA150 KN001BA144 KN
D
D
001BA145 KN
E
E 
						

							MS 250
English
23 Felling Cut for Small Diameter Trees: 
Simple Fan Cut
Engage the bumper spikes of the chain 
saw directly behind the location of the 
intended hinge and pivot the saw around 
this point only as far as the hinge. The 
bumper spike rolls against the trunk.Felling Cut for Large Diameter Trees
WARNING
Felling a tree that has a diameter greater 
than the length of the guide bar requires 
use of either the sectioning felling cut or 
plunge-cut method. These methods are 
extremely dangerous because they 
involve the use of the nose of the guide 
bar and can result in kickback. Only 
properly trained professionals should 
attempt these techniques.
Sectioning Method
For the sectioning method make the first 
part of the felling cut with the guide bar 
fanning in toward the hinge. Then, using 
the bumper spike as a pivot, reposition 
the saw for the next cut.Avoid repositioning the saw more than 
necessary. When repositioning for the 
next cut, keep the guide bar fully 
engaged in the kerf to keep the felling 
cut straight. If the saw begins to pinch, 
insert a wedge to open the cut. On the 
last cut, do not cut the hinge.
Plunge-cut Method
Timber having a diameter more than 
twice the length of the guide bar requires 
the use of the plunge-cut method before 
making the felling cut.
First, cut a large, wide felling notch. 
Make a plunge cut in the center of the 
notch.
001BA147 KN
001BA148 KN
14
2 
						

							MS 250
English
24 The plunge cut is made with the guide 
bar nose. Begin the plunge cut by 
applying the lower portion of the guide 
bar nose to the tree at an angle. Cut until 
the depth of the kerf is about the same 
as the width of the guide bar. Next, align 
the saw in the direction in which the 
recess is to be cut.
With the saw at full throttle, insert the 
guide bar in the trunk.
Enlarge the plunge cut as shown in the 
illustration.
WARNING
There is an extreme danger of kickback 
at this point. Extra caution must be taken 
to maintain control of the saw. To make 
the felling cut, follow the sectioning 
method described previously.
If you are inexperienced with a chain 
saw, plunge-cutting should not be 
attempted. Seek the help of a 
professional.
WARNING
In order to reduce the risk of personal 
injury, never stand directly behind the 
tree when it is about to fall, since part of 
the trunk may split and come back 
towards the operator (barber-chairing), 
or the tree may jump backwards off the 
stump. Always keep to the side of the 
falling tree. When the tree starts to fall, 
withdraw the bar, shut off the engine and 
walk away on the preplanned escape 
path. Watch out for falling limbs.
WARNING
Be extremely careful with partially fallen 
trees which are poorly supported. When 
the tree hangs or for some other reason 
does not fall completely, set the saw 
aside and pull the tree down with a cable 
winch, block and tackle or tractor. If you 
try to cut it down with your saw, you may 
be injured.
MAINTENANCE, REPAIR AND 
STORING
Maintenance, replacement, or repair of 
the emission control devices and 
systems may be performed by any 
nonroad engine repair establishment or 
individual. However, if you make a 
warranty claim for a component which 
has not been serviced or maintained 
properly or if nonapproved replacement 
parts were used, STIHL may deny 
coverage.
WARNING
Use only identical STIHL replacement 
parts for maintenance and repair. Use of 
non-STIHL parts may cause serious or 
fatal injury.
Strictly follow the maintenance and 
repair instructions in the appropriate 
section of your instruction manual. 
Please refer to the maintenance chart in 
this manual.
WARNING
Always stop the engine and make sure 
that the cutting tool is stopped before 
doing any maintenance or repair work or 
cleaning the power tool.
WARNING
Do not attempt any maintenance or 
repair work not described in your 
instruction manual. Have such work 
performed by your STIHL servicing 
dealer only. For example, if improper 
tools are used to remove the flywheel or 
if an improper tool is used to hold the 
flywheel in order to remove the clutch, 
structural damage to the flywheel could 
occur and could subsequently cause the 
flywheel to burst.
Wear gloves when handling or 
performing maintenance on saw chains.
WARNING
Use the specified spark plug and make 
sure it and the ignition lead are always 
clean and in good condition. Always 
press spark plug boot snugly onto spark 
plug terminal of the proper size. (Note: If 
terminal has detachable SAE adapter  
						

							MS 250
English
25 nut, it must be securely attached.) A 
loose connection between spark plug 
terminal and the ignition wire connector 
in the boot may create arcing that could 
ignite combustible fumes and cause a 
fire.
WARNING
Never test the ignition system with the 
spark plug boot removed from the spark 
plug or with a removed spark plug, since 
uncontained sparking may cause a fire.
WARNING
Do not operate your power tool if the 
muffler is damaged, missing or modified. 
An improperly maintained muffler will 
increase the risk of fire and hearing loss. 
Your muffler is equipped with a spark-
arresting screen to reduce the risk of 
fire; never operate your power tool if the 
screen is missing, damaged or clogged. 
Remember that the risk of a brush or 
forest fire is greater in hot or dry 
weather.
In California, it is a violation of § 4442 or 
§ 4443 of the Public Resources Code to 
use or operate gasoline-powered tools 
on forest-covered, brush-covered or 
grass-covered land unless the engine’s 
exhaust system is equipped with a 
complying spark arrester that is 
maintained in effective working order. 
The owner/operator of this product is 
responsible for properly maintaining the 
spark arrester. Other states or 
governmental entities/agencies, such as 
the U.S. Forest Service, may have 
similar requirements. Contact your local 
fire agency or forest service for the laws 
or regulations relating to fire protection 
requirements.Keep the chain, bar and sprocket clean; 
replace worn sprockets or chains. Keep 
the chain sharp. You can spot a dull 
chain when easy-to-cut wood becomes 
hard to cut and burn marks appear on 
the wood. Keep the chain at proper 
tension.
Tighten all nuts, bolts and screws except 
the carburetor adjustment screws after 
each use.
WARNING
In order for the chain brake on your 
STIHL chain saw to properly perform its 
function of reducing the risk of kickback 
and other injuries, it must be properly 
maintained. Like an automobile brake, a 
chain saw chain brake incurs wear each 
time it is engaged.
The amount of wear will vary depending 
upon usage, conditions under which the 
saw is used and other factors. Excessive 
wear will reduce the effectiveness of the 
chain brake and can render it 
inoperable.
For the proper and effective operation of 
the chain brake, the brake band and 
clutch drum must be kept free of dirt, 
grease and other foreign matter which 
may reduce friction of the band on the 
drum.
For these reasons, each STIHL chain 
saw should be returned to trained 
personnel such as your STIHL servicing 
dealer for periodic inspection and 
servicing of the brake system according 
to the following schedule:
Heavy usage – every three months, 
Moderate usage – twice a year, 
Occasional usage – annually.The chain saw should also be returned 
immediately for maintenance whenever 
the brake system cannot be thoroughly 
cleaned or there is a change in its 
operating characteristics.
For any maintenance of the emission 
control system please refer to the 
maintenance chart and to the limited 
warranty statement near the end of the 
instruction manual.
Do not clean your machine with a 
pressure washer. The solid jet of water 
may damage parts of the machine.
S t o r e  c h a i n  s a w  i n  a  d r y  p l a c e  a n d  a w a y  
from children. Before storing for longer 
than a few days, always empty the fuel 
tank (see chapter "Storing the Machine" 
in the instruction manual). 
						

							MS 250
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26 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.
Chain scabbard
Your saw comes standard with a chain 
scabbard that matches the cutting 
attachment.
If you use guide bars of different lengths 
on the saw, the length of the chain 
scabbard must be matched to the guide 
bar to reduce the risk of injury. It should 
cover the full length of the guide bar.
The length of the matching guide bars is 
marked on the side of the chain 
scabbard.
Removing the chain sprocket cover
NUnscrew the nuts and take off the 
chain sprocket cover.
NTurn the screw (1) 
counterclockwise until the tensioner 
slide (2) butts against the left end of 
the housing slot.
Cutting Attachment
001BA248 KN
1
2
3a
001BA244 KN
0RXQWLQJWKH%DUDQG&KDLQ
143BA034 KN
1
2
001BA185 KN 
						

							MS 250
English
27
Disengaging the chain brake.
NPull the hand guarad towards the 
front handle until there is an audible 
click – the chain brake is 
disengaged.
Fitting the chain
WARNING
Wear work gloves to protect your hands 
from the sharp cutters.
NFit the chain – start at the bar nose.NFit the guide bar over the studs (1) – 
the cutting edges on the top of the 
bar must point to the right.
NEngage the peg of the tensioner 
slide in the locating hole (2) –- place 
the chain over sprocket (3) at the 
same time.
NTurn the tensioning 
screw (4)clockwise until there is 
very little chain sag on the 
underside of the bar – and the drive 
link tangs are engaged in the bar 
groove.
NRefit the sprocket cover and screw 
on the nuts only fingertight.
NGo to chapter on "Tensioning the 
Saw Chain"Retensioning during cutting work:
NShut off the engine.
NLoosen the nuts.
NHold the bar nose up.
NUse a screwdriver to turn the 
tensioning screw (1) clockwise until 
the chain fits snugly against the 
underside of the bar.
NWhile still holding the bar nose up, 
tighten down the nuts firmly.
NGo to "Checking Chain Tension".
A new chain has to be retensioned more 
often than one that has been in use for 
some time.
NCheck chain tension frequently – 
see chapter on "Operating 
Instructions".
001BA186 KN
143BA003 KN
311
24
001BA187 KN
7HQVLRQLQJWKH&KDLQ
1
133BA024 KN 
						

							MS 250
English
28 NShut off the engine.
NWear work gloves to protect your 
hands.
NThe chain must fit snugly against 
the underside of the bar and it must 
still be possible to pull the chain 
along the bar by hand.
NIf necessary, retension the chain.
A new chain has to be retensioned more 
often than one that has been in use for 
some time.
NCheck chain tension frequently – 
see chapter on "Operating 
Instructions".This engine is certified to operate on 
unleaded gasoline and the STIHL two-
stroke engine oil at a mix ratio of 50:1.
Your engine requires a mixture of high-
quality gasoline and two-stroke air 
cooled engine oil.
Use mid-grade unleaded gasoline with a 
minimum octane rating of 89 ((R+M)/2) 
and no more than 10% ethanol content.
NOTICE
Fuel with an octane rating below 89 may 
increase engine temperatures. This, in 
turn, increases the risk of piston seizure 
and damage to the engine.
The chemical composition of the fuel is 
also important. Some fuel additives not 
only detrimentally affect elastomers 
(carburetor diaphragms, oil seals, fuel 
lines, etc.), but magnesium castings and 
catalytic converters as well. This could 
cause running problems or damage the 
engine. For this reason STIHL 
recommends that you use only quality 
unleaded gasoline!
NOTICE
Gasoline with an ethanol content of 
more than 10% can cause running 
problems and major damage in engines 
and should not be used.
For further details, see 
www.STIHLusa.com/ethanol
The ethanol content in gasoline affects 
engine speed – it may be necessary to 
readjust the carburetor if you use fuels 
with various ethanol contents.
WARNING
To reduce the risk of personal injury 
from loss of control and/or contact with 
the running cutting tool, do not use your 
unit with an incorrect idle adjustment. At 
correct idle speed, the cutting tool 
should not move.
If your machine’s idle speed is 
incorrectly adjusted, have your 
authorized STIHL servicing dealer 
check your machine and make the 
proper adjustments and repairs.
The idle speed and maximum speed of 
the engine change if you switch from a 
fuel with a certain ethanol content to a 
fuel with a much higher or lower ethanol 
content.
This problem can be avoided by always 
using fuel with the same ethanol 
content.
To ensure the maximum performance of 
your STIHL engine, use a high quality 2-
cycle engine oil. To help your engine run 
cleaner and reduce harmful carbon 
deposits, STIHL recommends using 
STIHL HP Ultra 2-cycle engine oil or ask 
your dealer for an equivalent fully 
synthetic 2-cycle engine oil. 
To meet the requirements of EPA and 
CARB we recommend to use STIHL HP 
Ultra oil.
STIHL MotoMix
STIHL recommends the use of STIHL 
MotoMix. STIHL MotoMix has a high 
octane rating and ensures that you 
always use the right gasoline/oil mix 
ratio.
Checking Chain Tension
143BA007 KN
)XHO