Instruction Manual
Table Of Contents
- STIHL MS 231, 251
- 1 Guide to Using this Manual
- 2 Safety Precautions
- 3 Reactive Forces
- 4 Working Techniques
- 5 Cutting Attachment
- 6 Mounting the Bar and Chain (side chain tensioner)
- 7 Mounting the Bar and Chain (quick chain tensioner)
- 8 Tensioning the Saw Chain (side chain tensioner)
- 9 Tensioning the Saw Chain (quick chain tensioner)
- 10 Checking Chain Tension
- 11 Fuel
- 12 Fueling
- 13 Chain Lubricant
- 14 Filling Chain Oil Tank
- 15 Checking Chain Lubrication
- 16 Chain Brake
- 17 Winter Operation
- 18 Starting / Stopping the Engine
- 18.1 Positions of Master Control Lever
- 18.2 Setting the Master Control Lever
- 18.3 Fuel pump
- 18.4 Holding the Saw
- 18.5 Cranking
- 18.6 Starting the Saw
- 18.7 When engine begins to fire
- 18.8 As soon as the engine runs
- 18.9 At very low outside temperatures
- 18.10 Stopping the engine
- 18.11 If the engine does not start
- 19 Operating Instructions
- 20 Taking Care of the Guide Bar
- 21 Shroud
- 22 Air Filter System
- 23 Cleaning the Air Filter
- 24 Adjusting the Carburetor
- 25 Spark Plug
- 26 Storing the Machine
- 27 Checking and Replacing the Chain Sprocket
- 28 Maintaining and Sharpening the Saw Chain
- 29 Maintenance and Care
- 30 Minimize Wear and Avoid Damage
- 31 Main Parts
- 32 Specifications
- 33 Ordering Spare Parts
- 34 Maintenance and Repairs
- 35 Disposal
- 36 EC Declaration of Conformity
► Remove saw chain and guide bar; clean and
spray with protective oil
► Thoroughly clean the machine - pay special
attention to the cylinder fins and air filter
► When using biological chain oil (e.g. STIHL
BioPlus), fill the lubricant oil tank
► Store the machine in a dry and secure location
Keep out of the reach of children and other
unauthorized persons
27 Checking and Replacing
the Chain Sprocket
► Remove chain sprocket cover, saw chain and
guide bar.
► Release chain brake – pull hand guard against
the front handle
27.1 Fit new chain sprocket
001BA121 KN
–
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 pre‐
serve the chain sprocket.
STIHL recommends use of original STIHL chain
sprockets in order to ensure optimal functioning
of the chain brake.
001BA122 KN
1
2
4
5
6
1
2
3
6
► Use a screwdriver to remove the E-clip (1)
► Remove the washer (2)
► Remove rim sprocket (3)
► Inspect transport profile on the clutch drum (4)
– if there are also heavy signs of wear, also
replace the clutch drum
► Remove clutch drum or spur chain
sprocket (5) including needle cage (6) from the
crankshaft – with QuickStop Super chain
brake, press throttle trigger lockout before‐
hand
27.2 Install spur chain sprocket / rim
sprocket
► Clean crankshaft stub and needle cage and
lubricate with STIHL lubricant (special acces‐
sory)
► Slide needle cage onto the crankshaft stub
► After refitting, turn the clutch drum and/or spur
chain sprocket approx. 1 full turn so that the
carrier for the oil pump drive engages – with
QuickStop Super chain brake, press throttle
trigger lockout beforehand
► Refit the rim sprocket – cavities toward the
outside
► Refit washer and E-clip on the crankshaft
27 Checking and Replacing the Chain Sprocket English
0458-737-0121-C 33