Online version - not for reprint

Contents
3
Specifications
5
3.1
3.2
3.3
3.4
3.5
Engine
Fuel System
Ignition System
Chain Lubrication
Tightening Torques
5
5
5
5
6
5.3
5.4
5.4.1
5.4.2
5.4.3
5.5
5.5.1
5.5.2
5.5.3
5.5.4
5.5.5
5.5.6
5.6
5.7
5.8
7
Ignition System
7.1
7.1.1
7.1.2
Ignition Module
Ignition Timing
Removing and
Installing
Testing the Ignition
Coil
Spark Plug Boot
Flywheel
Short Circuit Wire/
Ground Wire
Stop Contact
Ignition System
Troubleshooting
7.1.3
7.2
7.3
7.4
17
7.5
7.6
17
18
18
20
20
21
23
25
25
26
28
29
29
8.7
30
AV Handle System
60
9.1
9.2
Handlebar
Replacing Annular
Buffers
Crankcase
Tank Housing
Spring
60
9.2.1
9.2.2
9.3
10
44
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5.2
Clutch Drum/Chain
Sprocket
Replacing the Chain
Catcher
Clutch
Chain Brake
Checking Operation
Removing
Installing
Chain Brake with
QuickStop Super
Removing
Installing
Checking Play
Adjusting Play
Brake Cable
Checking Operation
of Coasting Brake
Brake Spring Anchor
Pin
Chain Tensioner
Bar Mounting Studs
6.2
6.2.1
6.2.2
6.2.3
6.3
6.4
6.5
6.5.1
6.5.2
6.6
6.7
6.7.1
6.8
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5.1
Clutch, Chain Drive,
Chain Brake and
Chain Tensioner
8
10
11
12
13
16
33
33
33
34
35
36
37
38
38
39
42
43
43
44
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5
Clutch, Chain Drive,
Chain Brake, Chain
Tensioner
Rewind Starter
Chain Lubrication
Ignition System
Carburetor
Engine
Muffler/Spark
Arresting Screen
Leakage Test
Preparations
Pressure Test
Vacuum Test
Oil Seals
Shroud
Cylinder and Piston
Removing
Installing
Piston Rings
Crankcase
Crankshaft
Decompression Valve
45
45
Master Control/
Handle System
10.1
10.2
Switch Shaft
Throttle Trigger/
Interlock Lever
10.2.1 Machines without
QuickStop Super
10.2.2 Machines with
QuickStop Super
61
61
62
63
64
64
65
65
66
11
Chain Lubrication
67
45
11.1
46
48
48
11.2
11.3
11.4
11.5
Pickup Body/
Suction Hose
Delivery Hose
Valve
Oil Pump
Fan Housing
67
68
69
70
70
12
Fuel System
71
12.1
Air Filter
12.2
Carburetor
12.2.1 Removing and
Installing
12.2.2 Leakage Test
12.3
Servicing the
Carburetor
12.3.1 Metering Diaphragm
12.3.2 Inlet Needle
12.3.3 Fixed Jet
12.3.4 Pump Diaphragm
12.3.5 Accelerator Pump
12.4
Adjusting
12.4.1 Standard Setting
12.5
Tank Vent
12.6
Pickup Body
12.7
Fuel Hose
71
72
49
50
51
8
Rewind Starter
54
8.1
8.2
8.3
8.4
8.5
8.5.1
8.5.2
8.6
General
Fan Cover
Pawls
Rope Rotor
Starter Rope
ElastoStart
Tensioning
Starter Rope Guide
Bush
Replacing the Rewind
Spring
54
54
54
55
56
57
57
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4.2
4.3
4.4
4.5
4.6
8
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4.1
Troubleshooting
Chart
On
4
6.1
9
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33
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Safety Precautions
Engine
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3
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Introduction
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1
58
59
72
73
73
73
74
75
76
77
79
80
81
82
82
30
31
32
q
© 2002 Andreas Stihl AG & Co., Waiblingen
MS 270, MS 280
1
Contents
13
83
Servicing Aids
84
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14
Special Servicing
Tools
2
MS 270, MS 280
Introduction
The special tools mentioned in the
descriptions are listed in chapter
"Special Servicing Tools" of this
manual. Use the part numbers to
identify the tools in the "STIHL
Special Tools" manual.
The manual lists all special
servicing tools currently available
from STIHL.
This service manual contains
detailed descriptions of all the
typical repair and servicing
procedures for this power tool.
You should make use of the
illustrated parts lists while carrying
out repair work. They show the
installed positions of the individual
components and assemblies.
Refer to the latest edition of the
relevant parts list to check the part
numbers of any replacement parts.
Symbols are included in the text and
pictures for greater clarity.
The meanings are as follows:
= Action to be taken as
shown in the illustration
(above the text)
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Pointer
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In the illustrations:
Direction of movement
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Refer to the "Technical Information"
bulletins for engineering changes
which have been introduced since
publication of this service manual.
Technical information bulletins also
supplement the parts list until an
updated edition is issued.
– = Action to be taken that is
not shown in the illustration
(above the text)
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In the descriptions:
A fault on the machine may have
several causes. To help locate the
fault, consult the troubleshooting
charts for all assemblies and
systems in this manual and the
"STIHL Service Training System".
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Service manuals and all technical
Information bulletins are intended
exclusively for the use of STIHL
servicing dealers. They must not be
passed to third parties.
To service the underside of the
machine, turn it upside down and
mount it in the assembly stand.
Pull the hand guard back against
the front handle for this purpose.
Always use original STIHL
replacement parts.
They can be identified by the
STIHL part number,
the STIH) logo
and the STIHL parts symbol (
This symbol may appear alone on
small parts.
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Servicing and repairs are made
considerably easier if the clamp (1)
5910 890 2000 is used to mount the
machine on assembly stand (2)
5910 890 3100 so that one clamp
screw engages the outer 10 mm
bore (3) in the assembly stand.
The chainsaw can then be swivelled
to the best position for the ongoing
repair.
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1
MS 270, MS 280
3
2
Safety Precautions
If the engine is started up in the
course of repairs or maintenance
work, observe all local and countryspecific safety regulations as well
as the safety precautions and
warnings in the owner’s manual.
Gasoline is an extremely flammable
fuel and can be explosive in certain
conditions.
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Improper handling may result in
burns or other serious injuries.
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Warning!
Do not smoke or bring any fire,
flame or other source of heat near
the fuel. All work with fuel must be
performed outdoors only. Spilled
fuel must be wiped away
immediately.
4
MS 270, MS 280
3.1
Specifications
Engine
Displacement:
Bore:
Stroke:
Engine power to ISO 7293:
Max. permissible engine
speed (with bar and chain):
Idle speed:
Clutch:
MS 280
49.6 cm3
44.0 mm
32.6 mm
2.6 kW (3.54 HP)
at 9,500 rpm
54.2 cm3
46.0 mm
32.6 mm
2.8 kW (3.81 HP)
at 9,500 rpm
13,500 ± 150 rpm
2,800 rpm
Three-shoe centrifugal
clutch without linings
3,300 rpm
13,500 ± 150 rpm
2,800 rpm
Three-shoe centrifugal
clutch without linings
3,300 rpm
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Clutch engages at:
Crankcase leakage test
– at gauge pressure:
– under vacuum:
MS 270
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3
60 kPa (0.6 bar)
40 kPa (0.4 bar)
Fuel System
Ignition System
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3.3
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Air gap between ignition
module and fanwheel:
Spark plug (resistor type):
Electrode gap:
80 kPa (0.8 bar)
30 kPa (0.3 bar)
see owner’s manual
30 kPa (0.3 bar)
see owner’s manual
0.20 – 0.30 mm
NGK BPMR 7A
0.5 mm
0.20 – 0.30 mm
NGK BPMR 7A
0.5 mm
Chain Lubrication
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3.4
80 kPa (0.8 bar)
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Carburetor leakage test
at gauge pressure:
Tank vent operates
at gauge pressure:
Fuel:
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3.2
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60 kPa (0.6 bar)
40 kPa (0.4 bar)
On
Fully automatic speed-controlled oil pump with rotary piston
MS 270, MS 280
Oil delivery rate:
10 cc/min at 10,000 rpm 10 cc/min at 10,000 rpm
5
3.5
Tightening Torques
DG and P screws (Plastoform) are used in polymer and light-alloy components. These screws form a
permanent thread when they are installed for the first time. They can be removed and installed as often as
necessary without detrimentally affecting the strength of the screwed assembly, providing the specified
tightening torque is observed.
For this reason always use a torque wrench.
Torque Remarks
Nm
Spline screw
Countersunk screw
Spline screw
Spline screw
Spline screw
Collar screw
Collar screw
Spline screw
Decompression
valve
Collar nut
Spline screw
Spline screw
Spline screw
Spline screw
Spline screw
Spline screw
Spline screw
IS-M4x8
IS-PT4x12
IS-B3.9x13
IS-M8x22
IS-P4x10
IS-M10/M8
IS-M8x21.5
IS-DG4x16
Cover plate, chain tensioner/crankcase
Cover plate/chain sprocket cover
Cover plate/fan cover
Brake band/crankcase
Brake cable, support/tank housing
Guide bar/crankcase
Guide bar/crankcase
Cover/crankcase
IS-M10x1
M5
IS-B4.2x9.5
IS-DG5x24
IS-DG5x24
IS-DG5x24
IS-DG5x18
IS-DG5x18
IS-DG5x24
Decompression valvel
Filter base/baffle/carburetor
Screen/muffler
Hand guard, sleeve/fan cover
Shroud/crankcase
Shroud/fan housing
Chain catcher/crankcase
Spiked bumper/crankcase
Fan cover/fan housing
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14.0
5.0
2.0
4.0
4.5
4.5
9.0
9.0
4.0
1)
2)
3)
4)
2) 5) 6)
7) 3) 8)
9)
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3.0
2.5
1.5
10.0
1.0
30.0
23.0
3.0
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For component
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Thread
size
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Fastener
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Remarks:
1) Special accessory
2) Only machines with quick chain adjuster
3) Secure screw with Loctite 243
4) Only machines with QuickStop Super
5) Secure screw with Loctite 270
6) With quick chain adjuster
7) Only machines without quick chain adjuster
8) Without quick chain adjuster
9) Only muffler with spark arresting screen
6
MS 270, MS 280
For component
Torque Remarks
Nm
Spline screw
Spline screw
Clutch carrier
Spline screw
Nut
Pan head screw
Collar screw
Spline screw
Spark plug
Spline screw
Spline screw
IS-DG5x24
IS-DG5x24
M12x1L
IS-DG5x18
M8x1
M4x8
M8SK6
IS-M5x28
M14x1.25
IS-DG4x20
IS-DG4x16
Fan housing/crankcase
Fan housing/bearing plug
Carrier/crankshaft
Muffler/cylinder
Flywheel/crankshaft
Inner side plate
Dihedral sleeve/crankcase/bar guide
Cylinder/crankcase
Spark plug
Ignition module/cylinder
Oil pump/crankcase
9.0
4.0
50.0
9.0
28.0
3.0
30.0
9.0
25.0
4.0
3.0
1)
1) 6)
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Fastener
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Remarks:
1) Only machines with quick chain adjuster
6) Secure screw with Loctite 270
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Screws secured with adhesive are easier to loosen if the adhesive is heated first with a hot air blower.
Exercise caution on polymer components.
Use the following procedure to fit a P (Plastoform) screw in an existing thread:
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– Place the P screw in the hole and rotate it counterclockwise until drops down slightly.
– Tighten the screw clockwise to the specified torque.
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This procedure ensures that the screw engages properly in the existing thread and does not form a new thread,
which would weaken the assembly.
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– P screws: max. 500 rpm
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Power screwdriver speed setting for polymer:
MS 270, MS 280
7
4
4.1
Troubleshooting Chart
Clutch, Chain Drive, Chain Brake, Chain Tensioner
Cause
Remedy
Saw chain stops under load at full
throttle
Clutch shoes badly worn
Replace clutch shoes or install new
clutch
Clutch drum badly worn
Install new clutch drum
Brake band stuck
Check freedom of movement
and function of brake band. If
necessary, adjust brake cable of
QuickStop Super (option)
QuickStop Super brake cable
broken (option)
Replace the brake cable
Engine idle speed too high
Readjust with idle speed screw
(counterclockwise)
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Saw chain rotates at idle speed
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Condition
Replace the clutch springs
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Clutch spring hooks broken
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Clutch springs stretched or fatigued Replace the clutch springs
Clutch springs stretched or fatigued Replace all clutch springs
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Loud noises
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Needle cage damaged
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Clutch shoe retainer broken
Chain not properly tensioned
ev
Chain sprocket wears rapidly
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Clutch shoes and carrier worn
Fit new retainer
Install new clutch
Tension chain as specified
Fit chain of correct pitch
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Wrong chain pitch
Fit new needle cage
8
MS 270, MS 280
Cause
Remedy
Saw chain does not stop
immediately when brake is
activated
Brake spring stretched or broken
Fit new brake spring
Brake band stretched/worn/broken
Fit new brake band
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Condition
MS 270, MS 280
9
4.2
Rewind Starter
Cause
Remedy
Starter rope broken
Rope pulled out too vigorously as
far as stop or over edge, i.e. not
vertically
Fit new starter rope
Normal wear
Fit new starter rope
Spring overtensioned – no reserve
when rope is fully extended
Fit new rewind spring
Very dirty or corroded
Clean or replace rewind spring
Guide peg on pawls or pawls
themselves are worn
Fit new pawls
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Starter rope can be pulled out
almost without resistance
(crankshaft does not turn)
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Rewind spring broken
(rope does not rewind)
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Condition
Starter mechanism is very dirty
ot
Starter rope is difficult to pull
and rewinds very slowly
Fit new spring clip
fo
Spring clip fatigued
Apply a few drops of kerosine
(paraffin) to spring, then pull rope
carefully several times until normal
action is restored
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Lubricating oil on rewind spring
becomes viscous at very low
outside temperatures (spring
windings stick together)
Thoroughly clean complete starter
mechanism
10
MS 270, MS 280
4.3
Chain Lubrication
In the event of trouble with the chain
lubrication system, check and
rectify other sources of faults before
disassembling the oil pump.
Cause
Remedy
Chain receives no oil
Oil tank empty
Fill up with oil
Oil inlet hole in guide bar is
blocked
Clean oil inlet hole
Intake hose or pickup body
(strainer) clogged or intake hose
ruptured
Wash intake hose and pickup body
(strainer) in fresh STIHL cleaner or
replace if necessary
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Condition
Clean or replace valve
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Valve in oil tank blocked
fo
Teeth on pump piston and/or worm
worn
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Oil pump hoses blocked/damaged
Oil pump hoses porous/ruptured
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Machine losing chain oil
Clean or replace hoses
Fit new hoses
Fit new oil pump
Fit new oil pump
Oil pump hoses not installed
correctly/leaking/ruptured/blocked
Check correct installation of hoses
or clean/replace hoses
Bore in pump housing worn
Fit new oil pump
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Pump piston worn
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Oil pump delivers insufficient oil
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Bore in pump housing worn
Install new oil pump and/or new
worm
MS 270, MS 280
11
4.4
Ignition System
Exercise extreme caution while
carrying out maintenance and
repair work on the ignition system.
The high voltages which occur can
cause serious or fatal accidents!
Cause
Remedy
Engine runs roughly, misfires,
temporary loss of power
Spark plug boot is loose
Press boot firmly onto spark plug
and fit new spring if necessary
Spark plug sooted, smeared
with oil
Clean the spark plug or replace if
necessary
Weak spark or no spark
Faulty insulation on ignition lead or
short circuit wire. Use ohmmeter to
check ignition lead for break. If
break is detected or high resistance
measured, fit a new ignition lead
Set air gap correctly
fo
Incorrect air gap between ignition
coil and flywheel
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Condition
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Flywheel cracked or has other
damage
Clean or replace spark plug,
replace faulty parts of ignition
system
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Check operation of spark plug.
Inspect Master Control lever,
ignition coil/lead for damage
insulation and leakage current
Install new flywheel
Check operation of Master Control
lever and ignition module
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No ignition spark
12
MS 270, MS 280
4.5
Carburetor
Cause
Remedy
Carburetor floods;
engine stalls
Inlet needle not sealing. Foreign
matter in valve seat or cone
damaged
Remove and clean or replace the
inlet needle, clean the fuel tank,
pickup body and fuel line if
necessary
Inlet control lever sticking on
spindle
Free off inlet control lever
Helical spring not located on nipple
of inlet control lever
Remove the inlet control lever and
refit it correctly
Perforated disc on diaphragm is
deformed and presses constantly
against the inlet control lever
Fit a new metering diaphragm
Inlet control lever too high
(relative to correct installed
position)
Set inlet control lever flush with top
edge of housing
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Idle jet too lean
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Poor acceleration
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Main jet too lean
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Inlet control lever too low
(relative to correct installed
position)
ev
Inlet needle sticking to valve seat
Rotate low speed screw (L)
counterclockwise (richer), no
further than stop
Rotate high speed screw (H)
counterclockwise (richer), no
further than stop
Set inlet control lever flush with top
edge of housing
Remove inlet needle, clean and
refit
Diaphragm gasket leaking
Fit a new diaphragm gasket
Metering diaphragm damaged or
shrunk
Fit a new metering diaphragm
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Condition
MS 270, MS 280
13
Cause
Remedy
Engine speed drops quickly under
load – low power
Air filter dirty
Clean the air filter
Tank vent faulty
Replace tank vent
Leak in fuel line between tank
and fuel pump
Seal connections or install a new
fuel line
Pump diaphragm damaged or
fatigued
Fit a new pump diaphragm
Main jet bores or ports blocked
Clean the bores and ports
Fuel pickup body dirty
Clean the pickup body, fit a new
filter
Fuel strainers dirty
Clean the fuel strainers
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Setting of high speed screw (H)
too rich
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Throttle shutter not opened fully
Reset high speed screw (H)
correctly
Check linkage
Throttle shutter opened too wide
by idle speed screw (LA)
Reset idle speed screw (LA)
correctly
Engine leaking
Seal the engine
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Engine will not idle,
idle speed too high
Clean or replace spark arresting
screen
fo
Spark arresting screen dirty
rr
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Condition
14
MS 270, MS 280
Cause
Remedy
Engine stalls at idle speed
Idle jet bores or ports blocked
Clean jet bores and ports and blow
clear with compressed air
Idle jet too rich or too lean
Set low speed screw (L) correctly
Setting of idle speed (LA)
incorrect – throttle shutter
completely closed
Set idle speed screw (LA) correctly
Small plastic plate in valve jet
does not close
Clean or renew valve jet
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Condition
MS 270, MS 280
15
4.6
Engine
Always check and, if necessary,
repair the following parts before
looking for faults on the engine:
–
–
–
–
Air filter
Fuel system
Carburetor
Ignition system
Cause
Remedy
Engine does not start easily, stalls
at idle speed, but operates normally
at full throttle
Oil seals in crankcase damaged
Replace the oil seals
Crankcase leaking or damaged
(cracks)
Seat or replace the crankcase
Muffler leaking
Replace the muffler
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Piston rings worn or broken
Fit new piston rings
fo
Engine does not deliver full power
or runs erratically
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Condition
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Air filter element dirty
ot
Muffler/spark arresting screen
carbonized
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Fuel/impulse line severely kinked or
damaged
Replace air filter element
Replace lines or position them free
from kinks
Decompression valve sticking
Replace the decompression valve
Insufficient cylinder cooling. Air
inlets in fan housing blocked or
cooling fins on cylinder very dirty
Thoroughly clean all cooling air
openings and the cylinder fins
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Engine overheating
Clean the muffler (inlet and
exhaust), replace spark arresting
screen
16
MS 270, MS 280
5
5.1
Clutch, Chain Drive, Chain Brake and Chain Tensioner
Clutch Drum/Chain Sprocket
1
– Remove the bar an chain – wear
work gloves to protect your hands
from injury.
– Inspect the needle cage for
damage.
148RA101 VA
!
Inspect the clutch drum (1) for
signs of wear.
If there are noticeable wear marks
on the inside diameter of the clutch
drum (1), check its wall thickness. If
it is less than 80% of the original
wall thickness, fit a new clutch
drum.
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Pull off the clutch drum (1) with
needle cage (2).
80%
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1
– Remove the chain sprocket
cover.
On machines with
QuickStop Super:
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Disengage the chain brake by
pulling the hand guard towards
the front handle.
100%
148RA062 VA
143RA004 VA
2
If the clutch drum has to be
replaced, also check the brake band
– see 5.4.2.
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– Press down the throttle trigger
interlock to disengage the
coasting brake and then pull off
the clutch drum (1) with needle
cage (2).
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2
138RA003 VA
146RA188 VA
On
3
Remove the E-clip (1),
washer (2) and, if fitted, the rim
sprocket (3).
1
Pull off the chain sprocket (1) or
clutch drum (2).
– Remove the needle cage.
MS 270, MS 280
17
5.2
Replacing the Chain
Catcher
5.3
Clutch
Troubleshooting chart – see 4.1.
1
– Remove the clutch drum or chain
sprocket – see 5.1.
146RA001 VA
2
3
4
Reassemble in the reverse
sequence.
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– Remove the chain sprocket
cover.
– Remove the bar and chain – wear
work gloves to protect your hands
from injury.
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If the clutch drum is still serviceable,
use No. 120 emery paper or emery
cloth (grain size approx. 120 µm) to
clean and roughen its friction
surface.
Take out the slotted screw (1).
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2
1
fo
Take out the screw (3).
Remove the chain catcher (4).
Release the twist lock (1) and lift
away the carburetor box
cover (2).
1
146RA003 VA
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146RA002 VA
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Install in the reverse sequence.
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– Rotate clutch drum/chain
sprocket and apply slight
pressure at the same time until
the oil pump drive spring
engages the notch (see arrow).
Remove the side plate (2).
ot
Clean stub of crankshaft. Wash
needle cage in clean white spirit and
lubricate with STIHL multipurpose
grease – see 14.
Remove the spark plug boot (1).
– Unscrew the spark plug.
18
MS 270, MS 280
TOP
1
Take the cover washer (1) off the
crankshaft stub.
Push the locking strip (1)
0000 893 5903 into the spark
plug hole so that "OBEN-TOP"
faces up.
208RA026 VA
146RA209 VA
– Close the decompression valve,
if fitted.
– Clean all parts with STIHL
cleaner – see 14.
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146RA004 VA
1
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2
Assembling the clutch
n
Disassembling the clutch
208RA029 VA
146RA205 VA
-n
ot
fo
1
ep
– Replace any damaged parts.
Slip the retainers onto the clutch
shoes.
er
sio
Use hook (2) 5910 890 2800 to
remove the clutch springs (1).
1
3
Unscrew the clutch from the
crankshaft clockwise (left-hand
thread).
MS 270, MS 280
– Pull the clutch shoes off the
carrier.
146RA208 VA
208RA031 VA
148RA068 VA
On
lin
ev
2
Fit the clutch shoes (2) over the
arms (1) of the clutch carrier (3).
Pull the retainers off the clutch
shoes.
19
5.4
5.4.1
Clamp the clutch in a vise.
146RA204 VA
146RA206 VA
1
Push cover washer (1), "TOP"
(arrow) facing outward, onto the
crankshaft.
Contamination (with chain oil, chips,
fine particles of abrasion, etc.) and
smoothing of the friction surfaces of
the brake band and clutch drum
impair the coefficient of friction.
This, in turn, reduces the frictional
forces and thus prolongs the
braking time. A fatigued or stretched
brake spring has the same negative
effect.
ep
Use protective jaws so as not to
damage the clutch.
The chain brake is one of the most
important safety devices on the
chainsaw. Its efficiency is measured
in terms of the chain braking time,
i.e. the time that elapses between
activating the brake and the saw
chain coming to a complete
standstill. The shorter the braking
time, the better the efficiency and
protection offered against being
injured by the rotating chain.
rin
t
TOP
Chain Brake
Checking Operation
rr
2
fo
– Start the engine.
135RA024 VA
-n
146RA207 VA
ot
1
Screw on the clutch and tighten it
down – see 3.5.
Use the hook (2) 5910 890 2800
to attach other ends of springs
and press them firmly into the
clutch shoes.
– Remove locking strip from the
cylinder.
sio
n
Attach one end of each spring (1)
to the clutch shoes.
– With the chain brake released,
open the throttle wide and
activate the brake manually – the
chain must come to an abrupt
stop.
The braking time is in order if
deceleration of the saw chain is
imperceptible to the eye.
ev
er
– Screw home spark plug and
tighten it down – see 3.5.
– With the chain brake activated
(locked), open the throttle wide
for a brief period (max.
3 seconds) – the chain must not
rotate.
– Fit boot on the spark plug.
lin
– Fit the shroud.
On
– Install clutch drum/chain sprocket
– see 5.1.
20
MS 270, MS 280
5.4.2
Removing
Troubleshooting chart – see 4.1.
1
– Remove the chain sprocket
cover, bar and chain – wear work
gloves to protect your hands from
injury.
146RA009 VA
146RA006 VA
– Remove the clutch drum/chain
sprocket – see 5.1.
Pry the brake band out of the
crankcase.
Remove the cover (1).
ep
– Relieve tension of brake spring
by pushing hand guard forward.
rr
1
2
rin
t
Take out the screws (arrows).
2
n
146RA010 VA
Remove the brake band (1) from
the lugs on the crankcase.
Disconnect the brake band from
the bell crank (2).
146RA008 VA
On
lin
ev
– Engage the chain brake by
pushing the hand guard away
from the front handle.
sio
Remove the side plate (2).
Carefully ease the brake
spring (1) off the anchor pin and
take it off the bell crank (2).
1
er
Take out the screw (1).
-n
138RA004 VA
ot
1
146RA007 VA
fo
2
Take out the screw (arrow).
MS 270, MS 280
21
4
2
146RA202 VA
Remove the E-clip (1).
rin
t
Remove the E-clip (arrow).
1
Detach the spring (2).
Pull off the cam lever (3).
ep
Install a new brake band if there are
noticeable signs of wear (large
areas on inside diameter and/or
parts of outside diameter) and its
remaining thickness is less than
0.6 mm.
146RA201 VA
146RA200 VA
3
– Inspect parts and replace if
damaged.
rr
Important:
Thickness of brake band must not
be less at any point.
fo
– Clean the entire housing recess
for the chain brake.
– If the groove in the pin (4) is worn,
fit a new pin – see 5.6.
-n
1
146RA012 VA
ot
2
sio
n
Carefully pry the hand guard (1)
and bell crank (2) off their pivot
pins and remove them together.
er
Pull the bell crank out of the hand
guard.
lin
146RA011 VA
On
2
ev
1
Take out the screw (1) together
with the bushing (2).
22
MS 270, MS 280
5.4.3
Installing
146RA016 VA
Push the bell crank into the side
of the hand guard.
Check that cam lever is properly
located on face (arrow) of hand
guard bearing boss.
ep
The short arm of the bell crank must
point to the top of the hand guard.
rin
t
146RA014 VA
If the brake spring anchor pin was
removed because it was worn, it
must be installed before starting the
following operations – see 5.6.
rr
1
Push the cam lever (1) into
position.
3
sio
n
Position the bearing boss of the
hand guard (1) against the pivot
pin and fit the other side of the
hand guard over the housing.
Fit the E-clip (2).
– Coat the brake band with chain
oil to protect it from corrosion and
help reduce "snatching" during
the first few brake applications.
Press the cam lever (3) slightly
downward and push the hand
guard and bell crank onto their
pivot pins.
ev
2
lin
1
– Tighten down the hand guard
mounting screw – see 3.5.
146RA210 VA
On
3
Secure bell crank with E-clip.
er
Position the bell crank (2) against
the pivot pin.
146RA017 VA
-n
146RA211 VA
2
ot
1
146RA015 VA
fo
2
Attach spring (1) to pivot pin (2)
and cam lever (3).
MS 270, MS 280
23
1
ep
– Fit chain brake cover.
1
n
Fit the side plate (2) over the
collar screws and push it against
the crankcase.
sio
– Coat the screw with Loctite 243
– see 14.
Fit the screw (1) and tighten it
down firmly.
er
– Fit the screw and tighten it down
firmly – see 3.5.
138RA004 VA
-n
146RA019 VA
Push brake band into the slot in
the crankcase.
ev
– Install the clutch drum/chain
sprocket – see 5.1.
– Fit the bar, chain and chain
sprocket cover. Tighten down
nuts on the chain sprocket cover
– see 3.5.
146RA212 VA
lin
On
2
ot
fo
Check correct position of
protective tube:
a = 20 mm
b = 32 mm
Use assembly tool (2)
1117 890 0900 to attach the
brake spring (1) to the anchor pin.
rin
t
Turns of brake spring must be
tightly against one another in the
relaxed condition. If this is not the
case, replace the brake spring.
2
rr
Attach the brake band to the bell
crank.
176RA046 VA
146RA018 VA
b
176RA048 VA
a
– Check operation of chain brake
– see 5.4.1.
Hook the brake spring to the bell
crank (arrow).
24
MS 270, MS 280
5.5
Chain Brake with
QuickStop Super
5.5.1 Removing
Troubleshooting chart – see 4.1.
2
– Remove the chain sprocket
cover.
1
3
2
fo
rr
2
2
Carefully pry the spring (1) off the
pivot pin.
ep
Carefully ease the brake
spring (1) off the anchor pin and
take it off the brake lever (2).
rin
t
1
148RA073 VA
148RA071 VA
– Remove the clutch drum/chain
sprocket – see 5.1.
Take out the screw (1).
Remove the side plate (2).
Pry the brake band (2) out of the
crankcase and disconnect it from
the brake lever (3).
Pull the hand guard (2) and brake
lever (1) off their pivot pins.
ev
er
sio
n
Take out the screw (1).
148RA074 VA
1
1
146RA040 VA
-n
138RA004 VA
ot
1
1
2
Take out the screw (1).
Remove the cover (1).
Remove the bushing (2).
– Relieve tension of brake spring
by pushing hand guard forward.
148RA075 VA
146RA011 VA
Take out the screws (arrows).
MS 270, MS 280
1
2
146RA006 VA
On
lin
1
Unhook coasting brake cable (1)
from the brake lever (2).
– Pull the brake lever out of the
hand guard.
25
5.5.2
Installing
If the brake spring anchor pin was
removed because it was worn, it
must be installed before starting the
following operations – see 5.6.
1
2
2
4
Attach the coasting brake
cable (1) to the hole (arrow) in the
brake lever (2).
rin
t
Disconnect spring (1) from
lever (2).
Clean all disassembled parts in
STIHL cleaner – see 14.
Replace any damaged or worn
parts.
rr
ep
Pry the E-clip (3) off the pin and
remove the lever with spring.
1
If the groove in the pin (4) is worn,
fit a new pin – see 5.6.
fo
1
146RA213 VA
-n
3
Fit the lever (2) and spring (1).
n
Position bearing boss of the hand
guard (1) against the pivot pin
and fit the other side of the hand
guard over the fan cover.
sio
Fit the E-clip (3).
ev
er
Press the lever (1) slightly
downward and push the hand
guard and brake lever (2) onto
their pivot pins.
– Fit hand guard mounting screw at
fan cover side and tighten it down
firmly – see 3.5.
148RA077 VA
lin
On
2
ot
2
148RA078 VA
3
148RA075 VA
146RA203 VA
1
Coat all sliding and bearing points
with STIHL multipurpose grease
– see 14. Do not lubricate the brake
band.
Push the lever into the side of the
hand guard.
26
MS 270, MS 280
a
rin
t
Use the assembly tool
1117 890 0900 to attach the
brake spring (1) to the anchor pin.
Assemble all other parts in the
reverse sequence.
ep
Check correct position of
protective tube:
a = 30 mm
b = 40 mm
3
n
ev
Install screw (1) with Loctite 243
and tighten it down firmly
– see 3.5.
er
First attach the brake band (2) to
the brake lever (3) and then push
it into the slot in the crankcase.
sio
1
-n
146RA041 VA
ot
fo
2
Turns of brake spring must be
tightly against one another in the
relaxed condition. If this is not the
case, replace the brake spring.
1
rr
Attach spring (1) to the pivot pin.
176RA046 VA
148RA073 VA
b
146RA043 VA
1
1
146RA042 VA
On
lin
2
Hook the brake spring (1) to the
brake lever (2).
MS 270, MS 280
27
5.5.3
Checking Play
– Pull the hand guard towards the
front handle.
1
1
– Remove the chain sprocket
cover.
146RA191 VA
– Remove the cutting attachment –
wear work gloves to protect your
hands from injury.
A
1
rin
t
Reassemble in the reverse
sequence.
fo
3
rr
A
4
– Check free travel by slowly
squeezing the interlock lever (1).
Play must be within the mark (B)
at the front end of the interlock
lever.
The brake lever must not move. If
it does, adjust play – see 5.5.4.
A
1
2
Take out the screw (1) and
remove the side plate (2).
ot
A
-n
146RA179 VA
A
A
148RA081 VA
3
Let go of the interlock lever (1).
ep
Press down interlock lever (1) all
the way and hold it in that
position.
146RA192 VA
B
sio
n
The brake band (1) must locate
without any play at the points
shown (A) in the crankcase.
148RA079 VA
1
On
lin
ev
er
Take out the screws (3) and
remove the cover (4).
The brake cable (1) must hang
loosely in the crankcase when
the brake is disengaged.
28
MS 270, MS 280
Adjusting Play
5.5.5
Brake Cable
Machines with QuickStop Super
have an additional brake cable.
2
146RA002 VA
1
– Remove the switch shaft
– see 10.1.
2
– Remove brake cable from switch
lever – see 10.2.2.
1
148RA075 VA
5.5.4
– Separate crankcase and tank
housing – see 9.2.2.
Disconnect coasting brake
cable (1) from the brake lever (2).
1 2
ep
rin
t
Release twist lock (1) and
lift away the carburetor box
cover (2).
1
146RA177 VA
146RA178 VA
n
Reassemble in the reverse
sequence.
ev
Turn wrench to left to increase
play.
Pull the brake cable (1) out of the
crankcase in the direction of the
rear handle.
sio
Turn wrench to right to reduce
play.
Ease the support (1) upwards
and push it in the direction of the
cylinder.
er
Use a 6mm open-end wrench to
adjust play on nut (1).
-n
146RA038 VA
ot
fo
rr
1
lin
Remove the switch shaft (2),
see 10.1, if it gets in the way of
adjustments.
1
146RA175 VA
On
Reassemble in the reverse
sequence.
Pull the cable (1) out of the tank
housing in the direction of the
cylinder.
– Remove the brake spring
– see 5.5.1.
MS 270, MS 280
29
Checking Operation of
Coasting Brake
5.6
Check operation of the brake with
the bar and chain mounted.
Brake Spring Anchor Pin
1
When starting the machine observe
country-specific safety regulations
and the safety precautions in the
owner’s manual.
If the brake does not operate
properly, service the sliding and
bearing points shown in the
illustrations as follows:
Lubricate brake lever bearing
points (1) with grease – see 14.
Coat outside diameter of clutch
drum (2) with chain oil – see 14.
Removing
The anchor pin (1) must be replaced
if it is worn or damaged:
If lightly contaminated:
– Remove the fan cover
– see 8.2.
– Clean all parts with a brush and
STIHL cleaner – see 14.
– Remove the chain brake spring
– see 5.4.2 or see 5.5.1.
If heavily contaminated or
clogged with resin:
– Remove the shroud – see 6.4.
ep
The chain must come to a standstill
in less than one second.
1
rr
– Release the rear handle.
2
146RA194 VA
2
rin
t
– With the engine running, open
the throttle wide.
148RA048 VA
1
fo
5.5.6
ot
– Remove the parts concerned and
clean in STIHL cleaner – see 14.
Use a suitable punch to drive the
anchor pin (1) out of the
crankcase in the direction of the
arrow.
-n
– Replace worn or damaged parts.
sio
n
– Before re-installing parts, clean
machine recesses and seats with
STIHL cleaner – see 14.
148RA047 VA
On
lin
ev
er
If a biological chain oil is preferred,
STIHL recommends the use of
rapidly biodegradable STIHL
Bioplus.
To guarantee troublefree operation,
use only original STIHL replacement parts as per the latest parts
list.
Do not drive out the pin in the other
direction as this would damage the
annular bead which was formed in
the crankcase bore when the pin
was originally installed. In such a
case neither the new anchor pin nor
the brake spring would locate
properly. Furthermore, the
crankcase could be damaged in this
way and possibly impair correct
operation of the chain brake.
Lubricate bearing points (arrows)
of interlock and switch levers with
Mobilplex grease – see 14.
30
MS 270, MS 280
5.7
Chain Tensioner
Installing
2
1
176RA054 VA
– Position the new pin in the bore
so that the knurling on the pin
meshes with the existing knurling
in the bore. Turn pin back and
forth as necessary.
176RA052 VA
– Before installation, coat the
knurled area of the new pin with
Loctite 243 – see 14.
Remove the cover plate.
rin
t
– Remove the inner side plate
– see 5.4.2.
rr
ep
Rotate the spur gear clockwise
until tensioner slide (1) butts
against the thrust pad (2).
176RA055 VA
n
Pull out the retainer (1).
Take out the screw (2).
MS 270, MS 280
176RA056 VA
2
176RA053 VA
On
lin
– Fit the shroud – see 6.4.
1
ev
– Fit the fan cover – see 8.2.
Pull out the spur gear.
sio
– Coat all sliding and bearing
points with STIHL multipurpose
grease – see 14.
er
Carefully tap home the pin
squarely to obtain dimension "a"
(about 4 mm).
-n
176RA036 VA
ot
fo
a
Take out the tensioner slide with
adjusting screw and thrust pad.
31
5.8
2
Bar Mounting Studs
3
176RA117 VA
Wear work gloves to protect your
hands from injury.
Push stud puller 5910 893 0501
over the collar stud as far as it will
go. Use a 15 mm wrench to
unscrew the collar stud counterclockwise.
– Machines with quick chain
adjuster: Before installing, coat
thread of collar stud with
Loctite 270 – see 14.
– Machines without quick chain
adjuster: Before installing, coat
thread of collar stud with
Loctite 243 – see 14.
– Install and tighten down the collar
studs – see 3.5.
On
lin
ev
er
sio
n
-n
ot
fo
Assemble all other parts in the
reverse sequence.
rin
t
– Coat teeth of adjusting screw and
spur gear with grease, see 14,
before refitting.
– Remove the chain sprocket cover
and cutting attachment.
rr
The adjusting screw and spur gear
must be replaced as a matching
pair.
When reassembling, check that
O-ring (arrow) is fitted in spur
gear and coat with oil before
fitting the spur gear.
ep
Inspect the teeth on the spur gear
and adjusting screw (1), replace
both parts if necessary. To do
this, pull off the thrust pad (2) and
unscrew the tensioner slide (3).
176RA058 VA
1
176RA057 VA
1
32
MS 270, MS 280
6
6.1
Engine
Muffler/Spark Arresting
Screen
Always check and, if necessary,
repair the fuel system, carburetor,
air filter and ignition system before
looking for faults on the engine.
6.2
Leakage Test
6.2.1
Preparations
Defective oil seals and gaskets or
cracks in castings are the usual
causes of leaks. Such faults allow
supplementary air to enter the
engine and upset the fuel-air
mixture.
Troubleshooting chart – see 4.6.
1
– Remove the decompression
valve, if fitted – see 6.8.
fo
sio
1
2
146RA214 VA
On
lin
Reassemble in the reverse
sequence.
ev
Inspect spark arresting
screen (2) for damage, clean or
replace if necessary.
er
Take out the screw (1), if fitted,
and pull out the spark arresting
screen (2).
n
Take out the screws (arrows).
– Remove the muffler.
– Remove the muffler – see 6.1.
-n
146RA026 VA
1
– Make sure spark plug is properly
tightened down – see 3.5.
ot
2
Install plug (1) 1122 025 2200
and tighten down to 25 Nm.
ep
rr
The crankcase can be checked
thoroughly for leaks with the
carburetor and crankcase tester
and the vacuum pump.
– Remove the shroud – see 6.4.
rin
t
Moreover, the transition from idle
speed to part or full throttle is not
smooth.
146RA028 VA
This makes adjustment of the
prescribed idle speed difficult, if not
impossible.
Remove the heat shield (1) from
the muffler (2).
MS 270, MS 280
33
6.2.2
3
Pressure Test
2
1
146RA063 VA
Close vent screw (1) on the
rubber bulb.
Fit sleeves (2) 1124 893 7100.
– Pump air into the crankcase with
rubber bulb until the gauge
indicates a pressure of 0.6 bar. If
this pressure remains constant
for at least 20 seconds, the
crankcase is airtight.
Fit nuts (3) and tighten them
down firmly.
Connect pressure hose of tester
1106 850 2905 to nipple on test
flange (arrow).
– Remove the carburetor
– see 12.2.1.
fo
rr
The sealing plate must completely
cover the opening in the heat shield.
Fit the test flange
1119 850 4201 (1).
rin
t
Fit sealing plate (1)
0000 855 8106 between the heat
shield and cylinder exhaust port
and tighten down the heat shield
with the muffler mounting screws.
ep
1
146RA180 VA
146RA215 VA
1
er
sio
n
-n
ot
– Set the piston to top dead center
(T.D.C.).
146RA031 VA
2
On
lin
ev
1
Check that the sleeve (1) and
washer (2) are in place.
34
MS 270, MS 280
6.2.3
Vacuum Test
If the vacuum reading remains
constant, or rises to no more than
0.3 bar within 20 seconds, it can be
assumed that the oil seals are in
good condition. However, if the
pressure continues to rise (reduced
vacuum in the crankcase), the oil
seals must be replaced.
146RA034 VA
Oil seals tend to fail when subjected
to a vacuum, i.e. the sealing lip lifts
away from the crankshaft during the
piston's induction stroke because
there is no internal counterpressure.
An additional test can be carried out
with vacuum pump to detect this
kind of fault. Carry out the same
preparations as for the pressure test
– see 6.2.1.
If the pressure drops, the leak
must be found and the faulty part
replaced.
– After finishing the test, open the
vent screw and disconnect the
hose.
rin
t
– Remove the test flange.
– Install the carburetor
– see 12.2.1.
rr
ep
To find the leak, coat the suspect
area with oil and pressurize the
crankcase again. Bubbles will
appear if a leak exists.
-n
146RA033 VA
ot
fo
– Continue with vacuum test
– see 6.2.3
– Remove the screws from the
cylinder. Remove the sealing
plate.
– Mount the muffler – see 6.1.
– On engines with decompression
valve, unscrew the plug from the
cylinder, see 6.2.1, and install the
decompression valve – see 6.8.
3
2
1
146RA035 VA
On
lin
ev
er
sio
n
Connect suction hose (arrow) of
vacuum pump 0000 850 3501 to
nipple of test flange.
Close the vent screw (1) on the
pump.
Operate lever (2) until the
pressure gauge (3) indicates a
vacuum of 0.4 bar.
MS 270, MS 280
35
6.3
Oil Seals
It is not necessary to disassemble
the complete crankcase to replace
the oil seals.
– Install the flywheel – see 7.3.
– Clean sealing face with STIHL
cleaner – see 14.
– Fit the fan cover – see 8.2.
– Lubricate sealing lip of oil seal
with grease – see 14.
Flywheel side
– Remove the flywheel
– see 7.3.
Clutch side
– Remove the clutch – see 5.3.
1
fo
rr
ep
rin
t
– Thinly coat the outside diameter
of the oil seal with sealant
– see 14.
1
146RA052 VA
Remove the drive spring (1) with
worm.
n
Use the press sleeve (1)
1108 893 2405 to install the oil
seal.
– Remove the oil pump – see 11.4.
er
– Clamp the puller arms.
146RA047 VA
Apply puller (1) 0000 890 4400
with No. 3.1 jaws.
– Slip the oil seal, open side facing
the crankcase, over the
crankshaft stub.
sio
– Free off the oil seal in its seat by
tapping it with a punch.
-n
146RA046 VA
ot
1
The seating face must be flat and
free from burrs.
ev
– Pull out the oil seal.
– Wait about one minute, then
rotate the crankshaft several
times.
146RA048 VA
On
lin
Take care not to damage the
crankshaft stub.
Remove the retaining ring
(arrow).
– Free off the oil seal in its seat by
tapping it with a punch.
36
MS 270, MS 280
6.4
Shroud
2
1
1
Apply puller (1) 0000 890 4400
with No. 3.1 jaws.
– Slip the oil seal, open side facing
the crankcase, over the
crankshaft stub.
– Clamp the puller arms.
Take care not to damage the
crankshaft stub.
146RA002 VA
rr
– Remove the installing sleeve.
ep
Use press sleeve (1)
1118 893 2405 to install the oil
seal.
Pull out the oil seal (2).
Release twist lock (1) and
remove the carburetor box
cover (2).
– Wait about one minute, then
rotate the crankshaft several
times.
fo
– Clean sealing face with STIHL
cleaner – see 14.
– Lubricate sealing lip of oil seal
with grease – see 14.
ot
– Install retaining ring in crankshaft
groove.
– Thinly coat the outside diameter
of the oil seal with sealant
– see 14.
146RA070 VA
2
rin
t
146RA049 VA
146RA051 VA
1
-n
If the retaining ring is fatigued, fit a
new one.
n
– Install the oil pump – see 11.4.
Take out the shroud mounting
screws (arrows).
– Remove the shroud upwards.
Reassemble in the reverse
sequence.
On
1
146RA050 VA
lin
ev
er
sio
Reassemble in the reverse
sequence.
– Pull off the spark plug boot.
Fit the installing sleeve (1)
1118 893 4602 on the crankshaft.
MS 270, MS 280
37
6.5
6.5.1
Cylinder and Piston
Removing
– Remove the handlebar – see 9.1.
– Remove the muffler – see 6.1.
– Remove the shroud – see 6.4.
1
– Remove the carburetor
– see 12.2.1.
Disconnect the hose (1) from the
cylinder.
rin
t
Take out the cylinder base
screws through the holes
(arrows) in the cylinder.
146RA060 VA
146RA054 VA
– Remove the spark plug – see 5.3.
ep
– Pull the cylinder off the piston.
1
Take the washer (2) off the studs.
146RA059 VA
146RA055 VA
Carefully lift the cylinder and, at
the same time, push the manifold
through the tank housing
opening.
n
Remove the sleeve (1) from the
manifold.
Unscrew the decompression
valve (1), if fitted.
sio
2
-n
146RA031 VA
ot
fo
rr
1
Caution:
Do not use pointed or sharp-edged
tools for this job.
3
Remove the screw (1) with
washer and ground wire (2).
Disconnect the short circuit
wire (3) and take the wires out of
the guide (arrow).
2
1
146RA061 VA
146RA053 VA
On
lin
1 2
ev
er
– Remove the fan cover.
Remove the clamp ring (1).
Pull the manifold (2) off the intake
port.
– Inspect the cylinder for damage
and replace it if necessary.
38
MS 270, MS 280
6.5.2
– If a new cylinder has to be
installed, always fit a new
matching piston.
2
Installing
1
– Remove the clutch – see 5.3.
– Remove the flywheel – see 7.3.
Use the assembly drift (2)
1108 893 4700 to push the piston
pin (1) out of the piston.
176RA077 VA
Note installed position of piston:
1 = Arrow
2 = Flywheel
The arrow mark must point towards
the muffler.
rr
ep
If the piston pin is stuck, tap the end
of the drift lightly with a hammer if
necessary.
Hold the piston steady during this
process to ensure that no jolts are
transmitted to the connecting rod.
2
rin
t
– Before removing the piston,
decide whether or not the
crankshaft has to be removed as
well. The crankshaft has to
blocked to remove the flywheel
and clutch by resting the piston
on the wooden assembly block
with the cylinder removed or
loosened.
176RA075 VA
1
ot
fo
– Remove the piston from the
connecting rod and take the
needle cage out of the small end.
2
146RA181 VA
146RA186 VA
1
Remove the hookless snap rings
from the piston.
Thoroughly clean the gasket
seating surface (1).
Wear safety glasses to protect
your eyes when working with snap
rings.
Lubricate the needle cage (2)
with oil and fit it in the small end.
Push the assembly drift
1108 893 4700, small diameter
first, through the piston and small
end (needle cage) and line up the
piston.
MS 270, MS 280
176RA074 VA
On
lin
ev
er
sio
n
-n
– Inspect the piston rings and
replace if necessary – see 6.6.
1
39
Push the large slotted diameter of
the sleeve over the magnet and
snap ring. Position the sleeve so
that the inner pin (1) points
toward the flat face (2) of tool's
shank.
249RA148 VA
249RA146 VA
Fit the piston pin (1) on the
assembly drift (2) and slide it into
the piston.
Remove the sleeve and slip it
onto the other end of the shank.
Inner pin must again point toward
flat face.
Apply the installing tool
5910 890 2210 to the piston
boss, hold the piston steady,
center the tool shank exactly and
press home until the snap ring
slips into the groove.
Attach the snap ring (1) to the
magnet (2) so that the snap ring
gap is on the flat side of the tool's
shank.
40
249RA147 VA
1
249RA145 VA
2
On
lin
ev
er
sio
n
Remove the sleeve from
installing tool 5910 890 2210.
249RA149 VA
-n
249RA144 VA
ot
fo
rr
1
rin
t
146RA187 VA
1
ep
2
2
Stand the installing tool, sleeve
downward, on a flat surface
(wooden board) and press
vertically downwards until the
sleeve butts against the tool's
shoulder.
MS 270, MS 280
Wind a piece of string (1) (about
15 cm long) around the back of
the manifold flange and pass the
ends of the string through the
intake opening.
rin
t
– Push the manifold on to the
intake port.
Fit the clamping ring, note the
installed position (arrow).
ep
Fit the snap rings so that their gaps
are on the piston's vertical axis (they
must point either up or down – see
arrow).
146RA064 VA
249RA150 VA
176RA083 VA
1
Press the manifold down.
rr
– Make sure the piston rings are
properly positioned.
-n
146RA216 VA
ot
fo
– Lubricate the inside of the
cylinder with oil and line it up so
that it is positioned as it will be in
the installed condition.
Position the piston rings in the
grooves so that the radii at the
ring gaps engage the fixing pins
(arrows) in the piston grooves.
upward.
MS 270, MS 280
146RA063 VA
146RA065 VA
1
138RA035 VA
On
lin
ev
er
sio
n
Coat cylinder sealing face with
Dirko red – see 14.
Carefully slide the cylinder (1)
over the piston.
Pull the ends of the string
outward.
The manifold flange is pulled
through the tank housing intake
opening without damaging the
manifold.
41
6.6
– Make sure the flange is properly
seated in the tank housing.
Piston Rings
– Remove the piston – see 6.5.1.
1
146RA031 VA
– Remove the piston rings from the
piston.
2
rin
t
Fit sleeve (1) in the manifold.
Push the washer (2) onto the
studs.
sio
Use a piece of old piston ring to
scrape the grooves clean.
er
Fit the cylinder base screws and
torque down in a diagonal pattern
– see 3.5.
n
– Line up the cylinder.
176RA091 VA
-n
146RA062 VA
ot
fo
rr
ep
Reassemble all other parts in the
reverse sequence.
Install and tighten down the
decompression valve (1) firmly
(if fitted) – see 3.5.
176RA092 VA
146RA059 VA
On
lin
ev
1
Install the new piston rings in the
grooves so that the radii at the
ends of the rings face upward.
– Install the piston – see 6.5.2.
42
MS 270, MS 280
6.7
6.7.1
Crankcase
Crankshaft
Removing
If the ball bearings are damaged,
remove them as follows:
– Remove the chain catcher
– see 5.2.
– Drain the oil tank.
– remove the oil pump – see 11.4.
– Remove the flywheel – see 7.3
fo
rr
ep
Position the piston rings so that
the radii at the ring gaps meet at
the fixing pins (arrows) in the
piston groove when the rings are
compressed.
– Remove the cylinder – see 6.5.1.
rin
t
138RA035 VA
– Remove the chain brake
– see 5.4.2.
2
Heat the ball bearing (arrow) to
about 50°C and pull it off the
crankshaft.
– Pull off the oil seals.
The crankshaft and connecting rod
form an inseparable unit. This
means that the crankshaft must
always be replaced as a complete
unit in the event of damage to either
part.
ev
er
sio
n
Lift the crankshaft (1) with
piston (2) out of the
crankcase (3).
1
If the crankshaft has to be replaced,
remove the piston – see 6.5.1.
146RA072 VA
lin
On
135RA100 VA
146RA071 VA
-n
1
ot
3
Check the ball bearings (arrows)
on crankshaft (1) for damage and
replace if necessary.
MS 270, MS 280
43
Decompression Valve
7
Exercise extreme caution when
troubleshooting or carrying out
maintenance and repair work on the
ignition system. The high voltages
that occur can cause serious or
even fatal accidents.
135RA100 VA
146RA059 VA
1
Removing
If a new crankshaft has been
installed, fit the piston – see 6.5.2.
– remove the carburetor box cover
and shroud – see 6.4.
Heat the ball bearings to about
50°C and push them on, closed
side facing outwards, as far as
stop.
Unscrew the decompression
valve (1).
1
rr
Installing
fo
– Fit the decompression valve and
tighten it down firmly – see 3.5.
– Fit the carburetor box cover and
shroud – see 6.4.
2
The electronic ignition system
basically consists of an ignition
module (1) and flywheel (2).
On
lin
ev
er
sio
n
-n
– Install the cylinder – see 6.5.2.
146RA073 VA
ot
– Coat cylinder with 'Dirko red'
before installation – see 14.
Troubleshooting on the ignition
system should always begin at the
spark plug – see 4.4.
ep
Installing
Reassemble all other parts in the
reverse sequence.
Ignition System
rin
t
6.8
44
MS 270, MS 280
Ignition Module
7.1.1
7.1.2
146RA074 VA
– Remove the fan cover with
rewind starter – see 8.2.
ep
The ignition module accommodates
all the components required to
control ignition timing. There are
two electrical connections on the
coil body:
Since there is no mechanical wear
in these systems, ignition timing
cannot get out of adjustment.
However, an internal fault in the
circuit can alter the switching point
in such a way that a spark test will
still show the system to be in order
although timing is outside the
permissible tolerance. This will
impair engine starting and running
behavior.
Removing and Installing
– Remove the shroud – see 6.4.
Ignition timing is permanently set
according the design specification
cannot be adjusted during repair
work.
2
High voltage output with ignition
lead (1).
1
fo
rr
Connector tag (2) for short
circuit wire.
Pull the short circuit wire (1) off
the connector tag on the ignition
module.
1
1
146RA076 VA
On
lin
ev
er
sio
n
-n
ot
Testing in the workshop is limited to
a spark test.
A new ignition module must be
installed if no ignition spark is
obtained (after checking that wiring
and stop switch are in good
condition).
146RA075 VA
1
Ignition Timing
rin
t
7.1
Take out the screws (1) and
washers and remove the wires
from the guide (arrow).
– Remove the ignition module.
MS 270, MS 280
45
7.1.3
If the ignition lead is damaged,
install a new ignition module.
Testing the Ignition Coil
To test the ignition module, use
either the ZAT 4 ignition system
tester 5910 850 4503 or the ZAT 3
ignition system tester
5910 850 4520.
If the spark plug boot is damaged,
install a new one – see 7.2.
1
146RA078 VA
Reassemble in the reverse
sequence.
The ignition test refers only to a
spark test, not to ignition timing.
rin
t
– Rotate the flywheel until the pole
shoes are under the ignition
module.
rr
1
ep
Slide the setting gauge (1)
1111 890 6400 between the arms
of the ignition module and the
flywheel pole shoes.
er
ev
lin
On
2
3
208RA053 VA
ot
-n
– Fit the fan cover and tighten
down the screws – see 3.5.
– Fit the shroud – see 6.4.
46
1
– Connect the short circuit wire.
n
Use the left-hand screw with
washer (arrow) to secure the the
ground wire (1).
– Remove the setting gauge and
use a feeler gauge to check the
air gap. It should be 0.2 to
0.3 mm.
sio
146RA077 VA
fo
– Press the ignition module against
the flywheel and tighten down the
mounting screws – see 3.5.
Using the ZAT 4 ignition tester
5910 850 4503
– Before starting the test, install a
new spark plug in the cylinder
and tighten it down firmly
– see 3.5.
Pull the boot off the spark plug
and connect it to the input
terminal (1). Push the tester’s
output terminal (3) onto the spark
plug.
– Crank the engine quickly with the
rewind starter (min. 1,000 rpm)
and check spark in the tester’s
window (2).
MS 270, MS 280
Warning!
The engine may start and
accelerate during the test.
If a spark is visible, the ignition
system is in order.
– Before starting the test, install a
new spark plug in the cylinder
and tighten it down firmly
– see 3.5.
If a spark is visible, the ignition
system is in order. In case of doubt
about the result, perform additional
test with ZAT 3.
If no spark is visible in the
window (2), check the following
points:
Pull the boot off the spark plug
and connect it to the terminal (2).
Attach ground terminal (1) to the
spark plug.
IIf no spark is visible in the
window (3), check the following
points:
Use adjusting knob (3) to set
spark gap to about 2 mm.
– Check the wiring harness for
damage – see 7.4.
rin
t
– Check the wiring harness for
damage – see 7.4.
– If necessary, check ignition
system with aid of the
troubleshooting chart – see 7.6.
– Check operation of start-stop
switch – see 7.5.
– Check operation of start-stop
switch – see 7.5.
ep
– Check leg spring – see 7.2.
– Check leg spring – see 7.2.
-n
ot
fo
rr
– If necessary, check ignition
system with aid of the
troubleshooting chart – see 7.6.
er
sio
n
While using the ZAT 3, hold it only
by the handle (4) or position it in a
safe place. Keep fingers or other
parts of your body at least 1 cm
away from the spark window (3),
high voltage connection (2), ground
connection (5) and the ground
terminal (1).
Warning!
High voltage – risk of
electrocution.
lin
ZAT 3
ev
3
1
2
208RA054 VA
On
5910 850 4520
Using ZAT 3 ignition tester
5910 850 4520
– Crank the engine quickly with the
rewind starter (min. 1,000 rpm)
and check sparkover in the
tester’s window (3).
Warning!
The engine may start and
accelerate during the test.
It is necessary to use the ZAT 3
ignition system tester
5910 850 4520 to test the auxiliary
spark gap.
MS 270, MS 280
47
7.2
Spark Plug Boot
7.3
Flywheel
– Remove the fan cover with
rewind starter – see 8.2.
Use suitable pliers to pull the leg
spring out of the spark plug boot.
rin
t
– Remove the shroud – see 6.4.
Pinch the hook (arrow) of the leg
spring into the center of the lead,
i.e. about 15 mm from the end of
the lead.
ep
– Pull boot off the spark plug.
176RA160 VA
176RA159 VA
– Block the piston with the locking
strip – see 5.3.
rr
– Unhook the leg spring from the
ignition lead.
fo
– Pull the boot off the ignition lead.
Pull the lead back into the boot so
that the leg spring locates
properly inside it (see arrow).
146RA079 VA
Unscrew the flywheel nut (arrow).
sio
n
– Use pliers to grip the end of the
ignition lead inside the spark plug
boot and pull it out.
-n
– Fit spark plug boot over the
ignition lead.
366RA104 VA
ot
– Coat end of the ignition lead
(about 20 mm) with oil.
146RA080 VA
On
lin
ev
er
Reassemble in the reverse
sequence.
1
If the flywheel cannot be removed
by hand, screw on the puller (1)
4133 893 0800 and tap its end to
release the flywheel.
48
MS 270, MS 280
Short Circuit Wire/
Ground Wire
1
2
If the insulation of the short circuit
wire (1) is damaged it can cause a
short circuit to ground and upset or
completely interrupt ignition.
Replace damaged wires.
Pull off the flywheel.
To remove the short circuit wire (1)
and the ground wire (2), perform the
following operations:
Reassemble in the reverse
sequence.
– Remove the fan cover with
rewind starter – see 8.2.
Degrease crankshaft stub and bore
in flywheel with STIHL cleaner
– see 14.
– Remove the shroud – see 6.4.
ot
146RA053 VA
-n
Remove the screw (1) with
washer and ground wire (2).
Disconnect the short circuit
wire (3) and take the wires out of
the guide (arrow).
ev
er
sio
n
Check position of slot.
Assemble all other parts in the
reverse sequence.
3
– Remove the air filter/filter base
– see 12.1.
– Fit the flywheel in position.
– Fit the flywheel nut and tighten it
down firmly – see 3.5.
1 2
fo
rr
ep
Inspect flywheel and magnet poles
for cracks or other damage. If you
find any damage, install a new
flywheel.
Pull the ground wire (1) off the
contact spring (2).
rin
t
– Remove the puller from the
crankshaft.
1
146RA082 VA
146RA081 VA
2
146RA084 VA
7.4
Pull the connector sleeve of the
short circuit wire (1) out of its seat
in the switch shaft.
146RA085 VA
1
146RA083 VA
On
lin
1
Pull the grommet (1) out of the
tank housing.
– Pull the wires out of the tank
housing.
MS 270, MS 280
49
7.5
Stop Contact
3 2
Reassemble in the reverse
sequence.
The contact spring is in order if the
short circuit wire makes contact with
the connector sleeve when the
Master Control lever is in the
"STOP" position.
Replace the contact spring if it is
broken or bent.
Replace the contact spring as
follows:
fo
Important:
Make sure the wires are properly
positioned in the area of the
flywheel.
ep
– Remove the air filter/filter base
– see 12.1.
rr
Remove the wires from the
retainers (arrows).
rin
t
146RA088 VA
146RA087 VA
1
ot
Pull the wire (1) off the contact
spring (2).
-n
Pry the contact spring (2) out of
the retaining clip (3) and
remove it.
On
lin
ev
er
sio
n
Reassemble in the reverse
sequence.
50
MS 270, MS 280
7.6
Ignition System Troubleshooting
Engine does not run
ep
-n
ot
fo
rr
Check the spark plug:
– Smeared with oil, black?
– Sooted?
– Electrode gap correct?
– Contacts shorted?
Clean the plug, reset
or replace
rin
t
Master Control lever/slide control
or separate stop switch
in position "1"?
On
lin
ev
er
sio
n
Check spark plug boot:
– Firmly seated on plug (leg spring)?
– Leg spring hook in center of
ignition lead?
– Boot damaged?
If necessary, install new spark plug boot
and/or leg spring
Test ignition system with
ZAT 3 or ZAT 4
(use ZAT 3 as main spark gap
– see TI 32.94)
1
MS 270, MS 280
51
1
Powerful
spark?
yes
rin
t
no
fo
rr
ep
Check air gap
and reset if necessary
-n
ot
Check flywheel:
– Have pole shoes turned blue?
Install new flywheel
er
sio
n
Disconnect short circuit wire from
ignition module
On
lin
ev
Check ignition lead:
– Severe chafing?
– Spark plug boot: Holes/cracks?
– Resistance: spark plug boot to ground:
spec. 1.5 – 12kΩ
– Check resistance of ignition lead:
spec. < 10 Ω,
If necessary, install new spark plug boot
and/or ignition lead
2
52
3
MS 270, MS 280
2
rr
ep
Check operation of
Master Control lever/slide control
or separate stop switch
– Short circuit wire chafed?
– Contact gap (contact springs)
If necessary, install new ignition lead
and/or contact springs
Re-connect short circuit wire
rin
t
3
yes
ot
fo
Powerful
spark?
-n
no
lin
Engine
runs
no
On
yes
ev
er
sio
n
Install new
ignition module
Check ON/STOP function
on Master Control lever/
slide contro
or separate stop switch
MS 270, MS 280
Look for fault in fuel system
or carburetor,
check engine for leaks,
check position of flywheel on
crankshaft
53
8.2
Pawls
Removing
– Remove the fan cover with
rewind starter – see 8.2.
rin
t
Removing
Take the screws (arrows) out of
the fan cover.
ep
– Remove the fan cover.
1
fo
If clogged with dirt or pitch, the
entire starter mechanism, including
the rewind spring, must be removed
and disassembled – see 14.
rr
Wash all parts in STIHL cleaner
– see 14.
1
ot
2
Lubricate the rewind spring and
starter post with STIHL special
lubricant, see 14, before installing.
n
Installing
Use a screwdriver or pliers to
carefully remove the spring
clip (1) from the starter post.
er
sio
The hand guard is mounted to the
fan cover and fan housing with
the IS-M5x35 screw (1) and
bushing (2).
146RA092 VA
Carefully pull out the starter rope
several times and allow it to rewind
until its normal smooth action is
restored.
8.3
146RA091 VA
If the action of the starter rope
becomes very stiff and the rope
rewinds very slowly or not
completely, it can be assumed that
the starter mechanism is in order
but plugged with dirt. At very low
outside temperatures the lubricating
oil on the rewind spring may thicken
and cause the spring windings to
stick together. This has a
detrimental effect on the function of
the starter mechanism. In such a
case it is sufficient to apply a few
drops of paraffin (kerosine) to the
rewind spring.
Fan Cover
146RA011 VA
Rewind Starter
General
-n
8
8.1
On
lin
Reassemble all other parts in the
reverse sequence.
1
2
146RA093 VA
ev
– Tighten down the screws firmly
– see 3.5.
– Pull the pawls (1 and 2) out of the
rope rotor.
54
MS 270, MS 280
8.4
Rope Rotor
– Remove the fan cover with
rewind starter – see 8.2.
Installing
– Coat pegs of new pawls with
graphite grease – see 14.
Reassemble all other parts in the
reverse sequence.
Relieving tension of rewind
spring:
1
146RA094 VA
The rewind spring will not be under
tension if the starter rope is broken.
– Pull out the starter rope about
5 cm and hold the rope rotor
steady.
– Carefully pull the rope rotor off
the starter post.
ep
– While still holding the rope rotor
steady, take three full turns off the
rope rotor.
rin
t
Remove the washer (1) from the
starter post.
The rewind spring may pop out and
unwind if rope rotor is not removed
very carefully.
– Remove the starter rope from the
rotor.
– Remove the starter rotor
– see 8.5.
fo
rr
– Pull out the rope with the starter
grip and slowly release the rope
rotor.
ot
Reassemble in the reverse
sequence.
-n
– Install the starter rope – see 8.5.
lin
ev
er
sio
n
– Coat bore in rope rotor with
STIHL special lubricant – see 14.
Use a screwdriver or pliers to
carefully remove the spring
clip (1) from the starter post.
249RA141 VA
146RA092 VA
On
1
1
2
Fit the rotor on the starter post
so that the lug (1) on the rope
rotor slips behind the inner spring
loop (2).
– Tension the rewind spring
– see 8.5.2.
MS 270, MS 280
55
8.5
Starter Rope
Thread the end of the rope
through the hole in the side of the
rotor, pull it out.
rin
t
Starter grips without ElastoStart:
Thread one end of new rope
through the top of the starter grip
and tie a simple overhand knot.
146RA229 VA
146RA195 VA
– Remove the fan cover with
rewind starter – see 8.2.
ep
– Pull the rope with knot into the
starter grip.
rr
– For ElastoStart grips – see 8.5.1.
– Secure the rope with a simple
overhand knot.
sio
n
Unclip the segment (1) from the
upper retainer in the fan cover
and take it out of the lower
retainers.
Pull the rope back until the knot
locates in the recess (arrow) in
the rope rotor.
er
– If the starter rope is broken,
remove the remaining rope from
the rope rotor, fan cover and
starter grip.
146RA230 VA
-n
146RA090 VA
ot
fo
1
ev
– Tension the rewind spring
– see 8.5.2.
– Fit fan cover with rewind starter
– see 8.2.
146RA097 VA
On
lin
– If the starter rope is worn, relieve
tension of rewind spring, see 8.4,
pull the end of the rope out of the
rotor and undo the knot. Then pull
the worn rope out of the starter
grip, fan cover and rotor.
Thread the other end of the rope,
from outside, through the guide
bush in the fan housing.
56
MS 270, MS 280
8.5.1
ElastoStart
8.5.2
– Remove the fan cover with
rewind starter – see 8.2.
Tensioning
– Pull the grip and, if necessary, the
spring element off the starter
rope.
146RA098 VA
– Relieve tension of rewind spring
– see 8.4.
ep
rin
t
Make a loop in the starter rope.
Pry the cap (1) out of the starter
grip.
2
sio
n
Thread end of new starter rope
through the grip (1) and the
spring element (2) – if removed.
Grip the rope next to the rotor (in
area of arrow) and use it to turn
the rope rotor six times
clockwise.
er
Tie a simple overhand knot in the
end of the rope.
146RA099 VA
1
380RA065 VA
-n
146RA198 VA
ot
fo
rr
3
1
ev
Pull the rope and spring element
into the grip and then fit the
cap (3).
2
146RA231 VA
1
On
lin
– Tension the rewind spring
– see 8.5.2.
– Fit fan cover with rewind starter
– see 8.2.
Pull starter rope and, if
necessary, the spring element (2)
out of the grip (1).
Undo the knot (arrow) in the
starter rope.
MS 270, MS 280
57
8.6
Starter Rope Guide Bush
When the starter rope is fully
extended, it must still be possible to
rotate the rope rotor at least another
half turn before maximum spring
tension is reached. If this is not the
case, pull the rope out, hold the
rope rotor steady and take off one
turn of the rope.
2 1
176RA187 VA
ot
fo
– Let go of the rope rotor and
slowly release the starter rope so
that it can rewind properly.
rin
t
– Hold the starter grip firmly to keep
the rope tensioned.
The rewind spring is correctly
tensioned when the starter grip sits
firmly in the rope guide bush without
drooping to one side. If this is not
the case, tension the spring by one
additional turn.
ep
Pull out the rope with the starter
grip and straighten it out.
– Remove the rope rotor – see 8.4.
rr
Hold the rope rotor steady.
135RA122 VA
146RA100 VA
Wear on the guide bush is
accelerated by the starter rope
being pulled sideways. The wall of
the guide bush eventually wears
through and the bush becomes
loose.
-n
Do not overtension the rewind
spring as this will cause it to
break.
Pull knot (1) out of recess (2) in
the rope rotor.
– Undo the knot.
Pull starter rope out of the rope
rotor and guide bush.
On
lin
ev
er
sio
n
– Fit the fan cover – see 8.2.
58
MS 270, MS 280
8.7
Replacing the Rewind
Spring
Troubleshooting chart – see 4.2.
1
The replacement spring comes
ready for installation and is secured
in a frame.
1
Important:
Wear a face shield and work gloves.
– Remove the rope rotor – see 8.4.
– Fit the thrust sleeve (1), tapered
end first, and the hex nut.
Tighten down the hex nut until the
bush is firmly seated.
The installing tool flares the lower
end of the rope bush.
Installing the rope bush
– Remove the installing tool.
rr
ep
– Use a suitable tool to pry the
damaged bush out of the fan
cover.
rin
t
If necessary, unclip segment (1)
from upper retainer in the fan
cover and take it out of the lower
retainers.
146RA102 VA
146RA090 VA
Removing
-n
138RA108 VA
ot
fo
– Place the new bush in its seat in
the fan cover.
sio
n
Use suitable pliers to grip the
outer spring loop and lift it up.
– Take the rewind spring out of the
fan cover.
lin
ev
er
– Remove any remaining pieces of
spring from the fan housing and
fan cover.
146RA101 VA
146RA097 VA
On
1
Insert the screw spindle (1) of the
installing tool 0000 890 2201
through the bush from inside the
fan cover.
Thread the starter rope through
the guide bush from outside and
fit it on the rope rotor – see 8.5.
– Install the rope rotor – see 8.4.
MS 270, MS 280
59
9
9.1
AV Handle System
Handlebar
138RA110 VA
146RA196 VA
– Remove the shroud – see 6.4.
The spring anchor loop must
engage the lug in the fan cover.
– Fit the spring housing in the fan
housing and press the spring
loop into the recess at the same
time.
Place suitable guides on the
recesses (arrows) and push the
spring into its seat in the fan
cover.
ot
– Tension the rewind spring
– see 8.5.2.
fo
– Install the rope rotor – see 8.4.
ep
– Position replacement spring with
frame in the fan cover.
rr
– Lubricate the spring with a few
drops of STIHL special lubricant
before installation – see 14.
rin
t
Fit the rewind spring in the
counterclockwise direction,
starting from outside and working
inwards.
Installing
Take out the screws (arrows).
1
Position the anchor loop about
25 mm from the edge of the
spring housing.
60
146RA105 VA
138RA109 VA
On
lin
ev
er
sio
n
-n
If the rewind spring has popped out,
refit it in the assembly tool
1116 893 4800 as follows:
146RA104 VA
Reassemble all other parts in the
reverse sequence.
Use screwdriver (1) to pry the clip
upwards.
MS 270, MS 280
9.2
Replacing Annular
Buffers
9.2.1
Crankcase
Removing
Annular rubber buffers and a spring
are installed between the tank
housing and crankcase to minimize
vibrations. Damaged annular
buffers must always be replaced.
146RA106 VA
– Remove the handlebar – see 9.1.
2
1
Fit an M6 screw (1) in the
bushing in the annular buffer (2).
ev
er
sio
n
Take out the screws (arrows).
146RA217 VA
-n
138RA207 VA
ot
fo
rr
ep
rin
t
Push the retainer through the
handlebar to the outside and
remove.
146RA218 VA
1
146RA107 VA
On
lin
1
Pry plug (1) out of the handlebar
to expose the annular buffer.
Use the screw to pull out the
bushing (1).
– Pry the annular buffer out of the
handlebar.
– Take the screw out of the
bushing.
Reassemble in the reverse
sequence.
MS 270, MS 280
61
9.2.2
Tank Housing
Removing
– Remove the chain sprocket
cover.
– Remove the cutting attachment –
wear work gloves to protect your
hands from injury.
146RA220 VA
146RA108 VA
1
1
Use the screw to pull out the
bushing (1).
rin
t
Use a screwdriver to pry the
annular buffer (1) out of its seat in
the crankcase.
ep
– Take the screw out of the
bushing.
fo
rr
1
Remove the chain catcher (1)
– see 5.2.
ev
Push home the annular buffer
until the groove (arrow) engages
over the housing rib.
Remove the bumper strip (2) and
pry the plugs (arrows) out of the
annular buffers.
er
– Coat inside and outside of
annular buffer with STIHL
installing fluid – see 14.
sio
n
Installing
2
2
3
146RA221 VA
1
146RA109 VA
-n
135RA126 VA
ot
2
Pull annular buffer (1) out of its
seat (3) in the tank housing and
the seat (2) in the crankcase.
– Repeat the procedure (fitting an
M6 in the bushing, pulling
bushing out with the screw and
then pulling out the annular
buffer) on the second annular
buffer in the tank housing.
lin
– Push the bushings, flat end first,
home as far as stop.
1
146RA219 VA
On
Reassemble all other parts in the
reverse sequence.
Fit an M6 screw (1) in the
bushing in the annular buffer (2).
62
MS 270, MS 280
9.3
Spring
1
3
3
146RA228 VA
2
146RA222 VA
– Remove the fan housing
– see 11.5.
Engage bearing plug with spring
in the teeth (arrow) in the fan
housing.
rin
t
Installing
– Coat inside and outside of
annular buffer with STIHL
installing fluid – see 14.
Note the different shapes of
annular buffers (1) and (2). Make
sure they are not switched during
installation.
fo
– Inspect fan housing, bearing plug
and spring for damage and
replace if necessary.
Reassemble in the reverse
sequence.
146RA227 VA
-n
– Remove the bearing plug from
the fan housing.
n
Apply a screwdriver to the coil
end and unscrew the spring (1)
together with the bearing
plug (2).
sio
Reassemble all other parts in the
reverse sequence.
ot
1
Press home the bushings (3), flat
end first, as far as stop.
rr
2
– Press home annular buffers in
crankcase and tank housing until
their grooves are properly seated
in the housings.
Do not use pointed or sharp-edged
tools for this job.
ep
Use pliers to unscrew the spring
from the bearing plug.
If the spring is too tight on the
bearing plug, proceed as follows:
146RA115 VA
On
lin
ev
er
– To ensure that the teeth on the
bearing plug are not damaged
during disassembly, unscrew the
bearing plug from the spring by
hand.
When installing the spring, make
sure the end of the spring coil
butts against the stop (arrow) on
the tank housing.
MS 270, MS 280
63
10
Master Control/
Handle System
10.1
Switch Shaft
– Remove the carburetor
– see 12.2.1.
Install in the reverse sequence.
146RA189 VA
1
rin
t
Inspect fan housing gasket (1)
and replace if necessary.
146RA089 VA
-n
sio
n
Remove the short circuit wire (1)
from the switch shaft (2).
ev
2
3
1
146RA183 VA
On
lin
Reassemble all other parts in the
reverse sequence.
1
er
Before fitting the screw (1) above
the spring, insert a 5 mm
diameter drift or punch in the hole
(arrow) to prevent the bearing
plug, with spring, slipping out of
the tank housing.
ot
146RA116 VA
fo
1
rr
2
ep
– Fit the fan housing and tighten
down the screws firmly
– see 3.5.
Pry the switch shaft (1) out of the
tank housing (2).
Carefully pull the switch shaft (1)
out of the pivot mount (3).
64
MS 270, MS 280
Pull the throttle rod out of the
throttle trigger sideways.
176RA216 VA
1
sio
n
Drive out the pin (3) with a 5 mm
drift.
Take out the throttle trigger (2)
with torsion spring (1).
3
2
146RA121 VA
146RA120 VA
-n
ot
fo
rr
3 21
rin
t
Push the two retainers (arrows)
on the underside of the hand
guard apart and remove the
handle molding upwards.
The torsion spring must be installed
so that it is under the interlock lever
and locates in its seat.
ep
– Remove the carburetor box cover
– see 6.4.
146RA119 VA
146RA117 VA
10.2
Throttle Trigger/Interlock Lever
10.2.1 Machines without QuickStop Super
Press down the interlock
lever (1).
Press the throttle trigger (2) up
and the switch shaft (3) to
"Choke" position.
er
Install in the reverse sequence.
146RA118 VA
On
lin
ev
1
– Move the switch shaft to the
normal operating position.
Pull out the interlock lever (1).
MS 270, MS 280
65
10.2.2 Machines with
QuickStop Super
Press down the end of the handle
molding until the retainers snap
into position in the handle
housing.
Push the two retainers (arrows)
on the underside of the hand
guard apart and remove the
handle molding upwards.
148RA100 VA
– Remove the carburetor box cover
– see 6.4.
1
Use a 4.5 mm drift to drive the
bushing (1) out of the interlock
lever (2) and then remove the
torsion spring (3).
rin
t
146RA117 VA
Fit the handle molding so that the
lugs engage the recesses.
2
148RA054 VA
-n
ot
fo
rr
ep
146RA122 VA
3
1
er
sio
n
To remove the switch lever (1), tilt
it back.
2
Ø
1
Use a 3 mm drift to drive the
needle roller (2) out of the
interlock lever (1). Remove the
interlock lever.
66
2
148RA055 VA
148RA099 VA
On
lin
ev
1
Disconnect brake cable (1) from
switch lever (2).
– Use a 3 mm drift to drive the
needle roller out of the switch
lever.
MS 270, MS 280
– Remove the switch lever.
– To remove the throttle trigger, first
remove the switch shaft
– see 10.1.
Chain Lubrication
Pickup Body/
Suction Hose
Impurities gradually clog the fine
pores of the filter with minute
particles of dirt. This prevents the oil
pump from supplying sufficient oil to
the bar and chain. In the event of
problems with the oil supply system,
first check the oil tank and the
pickup body. Clean the oil tank if
necessary.
146RA223 VA
11
11.1
1
Troubleshooting chart – see 4.3.
ep
rin
t
Disconnect the suction hose (1)
from the oil pump.
Removing
– Take the torsion spring off the
throttle trigger.
Collect chain oil in a clean container
or dispose of it properly at an
approved disposal site.
n
Use a 5 mm drift to drive out the
pin (3) and then remove the
throttle trigger (2) with torsion
spring (1).
er
– Remove the clutch – see 5.3.
When installing, make sure that
short arm of torsion spring locates in
the throttle trigger. The long arm
points toward the carburetor.
2
146RA224 VA
1
– Remove the chain catcher
– see 5.2.
146RA124 VA
On
lin
Pull the suction hose (1) with
pickup body out of the crankcase.
sio
Unscrew the oil filler cap (arrow)
and drain the oil tank.
ev
Install in the reverse sequence.
1
146RA197 VA
3
-n
148RA058 VA
1
ot
fo
rr
2
Pull the pickup body (1) off the
suction hose (2).
– Inspect the pickup body for
damage and dirt and replace if
necessary.
MS 270, MS 280
67
11.2
As a temporary measure, a dirty
pickup body may be washed in
STIHL cleaner – see 14.
Troubleshooting chart – see 4.3.
– Remove the chain sprocket cover
and cutting attachment.
– Examine suction hose for signs of
damage and replace if
necessary.
146RA226 VA
Wear work gloves to protect your
hands from injury.
1
– Remove the clutch drum/chain
sprocket – see 5.1.
rin
t
Use a blunt tool to push the
grommet (1) into position in the
crankcase. Make sure the
grommet is properly seated.
n
sio
rr
Take out the screw (1).
Remove the side plate (2).
– Engage the chain brake by
pushing the hand guard away
from the front handle.
On
lin
ev
Insert suction hose, pickup body
first, in the crankcase.
er
Coat grommet (1) on suction
hose with a little oil.
1
138RA004 VA
-n
146RA225 VA
Installing
– Push the pickup body into the
suction hose.
2
ot
fo
Reassemble all other parts in the
reverse sequence.
ep
Connect the suction hose to the
oil pump.
1
Delivery Hose
68
MS 270, MS 280
11.3
A vent valve is installed in the tank
wall to keep the internal pressure in
the oil tank equal to atmospheric
pressure.
1
1
Valve
146RA130 VA
146RA006 VA
Removing
2
– Unscrew the oil filler cap.
When installing, make sure the
hose is properly positioned (arrows)
and not kinked.
The hose (1) must be fitted
behind the brake band (2).
1
Collect chain oil in a clean container
or dispose of it properly at an
approved disposal site.
Pull the hose (2) off the oil
pump (3) and take it out of teh
crankcase.
Use a suitable tool to carefully
press the sleeve (1) into position.
176RA242 VA
146RA131 VA
n
– Carefully install the hose in the
crankcase, making sure the
sleeve does not drop out in the
process.
Use a 3 mm diameter drift to
carefully drive the valve out of the
housing from inside the tank.
Installing
ev
Install in the reverse sequence.
Fit the sleeve (1) in the hose.
sio
Carefully remove the sleeve (1)
from the hose.
er
3
-n
146RA129 VA
ot
fo
rr
1
– Drain the oil tank.
ep
Remove the cover (1).
rin
t
Take out the screws (arrows).
2
– Remove the inner side plate
– see 5.4.2.
On
lin
Reassemble all other parts in the
reverse sequence.
Use a 7 mm diameter drift to
carefully push home the valve
until it is about 1 mm below the
housing face ('a' in illustration).
Reassemble in the reverse
sequence.
MS 270, MS 280
69
11.4
Oil Pump
11.5
Check the suction hose and pickup
body before replacing the oil pump.
Fan Housing
– Drain the oil tank.
1 2
– Remove the flywheel – see 7.3.
– Remove the clutch – see 5.3.
Dispose oil and fluids properly.
146RA128 VA
– Remove the brake band
– see 5.4.2.
3
rin
t
Take out the screws (arrows).
Disconnect the delivery hose (2)
and suction hose (3).
ep
Remove the oil pump (1).
rr
Install in the reverse sequence.
Make sure the hoses are free from
kinks.
fo
1
1
Take out the fan housing
mounting screws (arrows).
Remove the fan housing (1).
lin
ev
er
sio
n
Pull worm (1) with drive spring off
the crankshaft.
146RA069 VA
-n
146RA127 VA
ot
– Lubricate worm with grease
before installation – see 14.
If necessary, remove the drive
spring from the worm.
146RA189 VA
176RA245 VA
On
1
Inspect fan housing gasket (1)
and replace if necessary.
Install in the reverse sequence.
70
MS 270, MS 280
12
12.1
Fuel System
Air Filter
Dirty air filters reduce engine power,
increase fuel consumption and
make starting more difficult.
1
Wash air filter thoroughly in STIHL
cleaner – see 14. Replace a
damaged air filter.
146RA116 VA
The air filter should be cleaned
when there is a noticeable loss of
engine power.
rin
t
– Fit the fan housing and tighten
down the screws firmly – see 3.5.
ep
Before fitting the screw (1) above
the spring, insert a 5 mm
diameter drift or punch in the hole
(arrow) to prevent the bearing
plug, with spring, slipping out of
the tank housing.
rr
2
146RA002 VA
-n
146RA133 VA
1
ot
fo
Reassemble all other parts in the
reverse sequence.
Unscrew the collar nuts (arrows).
Remove the carburetor box
cover (2).
Pull off the baffle in the direction
of the arrow.
lin
ev
er
sio
n
Release the twist lock (1).
– Remove all loose dirt from
around the filter.
Pull air filter (1) away to the rear.
MS 270, MS 280
146RA134 VA
1
146RA132 VA
On
1
Remove the filter base (1).
Install in the reverse sequence.
71
12.2
Carburetor
12.2.1 Removing and Installing
– Troubleshooting chart – see 4.5.
1
– Remove the filter base
– see 12.1.
146RA031 VA
146RA138 VA
– Open the tank cap to release
internal pressure.
– Close the tank cap.
2
Before fitting the carburetor,
check that the sleeve (1) and
washer (2) are in position.
rin
t
Fit the air filter and make sure it is
correctly seated (arrows).
146RA135 VA
-n
ot
fo
rr
ep
Reassemble in the reverse
sequence.
1
146RA136 VA
On
lin
ev
er
sio
n
Use a screwdriver to press the
throttle shaft down and
disconnect the throttle rod.
Pull the hose (1) off the
carburetor.
– Remove the carburetor.
72
MS 270, MS 280
12.2.2 Leakage Test
12.3
Servicing the Carburetor
12.3.1 Metering Diaphragm
In the case of problems with the
carburetor or fuel supply system,
also check and clean or replace the
tank vent – see 12.5.
3
– Remove the carburetor
– see 12.2.1.
2
1
– Remove the carburetor
– see 12.2.1.
ep
Close the vent screw (1) on the
rubber bulb (2) and pump air into
the carburetor until the pressure
gauge (3) shows a reading of
approx. 0.8 bar (8 kPa).
1
rr
2
– Connect the tester's pressure
hose 1106 850 2905 to the
nipple.
rin
t
– Remove the filter base
– see 12.1.
249RA012 VA
The carburetor can be tested for
leaks with the carburetor and
crankcase tester 1106 850 2905.
-n
143RA172 VA
1. The inlet needle is not sealing
(foreign matter in valve seat or
sealing cone of inlet needle is
damaged or inlet control lever
sticking). Remove to clean
– see 12.3.2.
n
Push the fuel line (1)
1110 141 8600 onto the
nipple (2) 0000 855 9200.
sio
2. Metering diaphragm damaged,
replace if necessary
– see 12.3.1.
1
146RA142 VA
ot
fo
If this pressure remains constant,
the carburetor is airtight. However, if
it drops, there are two possible
causes:
Take out the screws (arrows).
Remove the end cover (1).
ev
er
– After completing the test, open
the vent screw (1) and pull the
fuel line off the carburetor.
lin
– Push the fuel hose onto the
elbow connector.
Disconnect fuel hose (1) from the
carburetor.
Reassemble all other parts in the
reverse sequence.
146RA143 VA
– Install the carburetor
– see 12.2.1.
146RA136 VA
On
1
Remove the metering diaphragm
and gasket (arrow) from the
carburetor body or end cover.
– Push the fuel line with nipple onto
the carburetor’s elbow connector.
MS 270, MS 280
73
12.3.2 Inlet Needle
Place the gasket on the
carburetor body so that the tab
(arrow) points towards the
adjusting screws.
146RA147 VA
146RA145 VA
If the gasket and diaphragm are
stuck to the carburetor, remove
them very carefully.
rin
t
– Remove the metering diaphragm
– see 12.3.1.
Take out the screw (arrow).
ep
– Remove the inlet control lever
with spindle.
fo
rr
Note: There is a small spring under
the inlet control lever which may
pop out during disassembly.
Install in the reverse sequence.
146RA146 VA
n
sio
The gasket and metering
diaphragm are held in position by
integrally cast pegs.
ev
The diaphragm, inlet and outlet
valves are subjected to continuous
alternating stresses and the
material eventually shows signs of
fatigue, i.e. the diaphragm distorts
and swells and has to be replaced.
Fit the metering diaphragm (1) on
the carburetor body so that the
perforated plate faces the inlet
control lever and the tab (arrow)
points towards the adjusting
screws.
er
Carefully separate the diaphragm
and gasket.
1
-n
176RA272 VA
ot
– Take out the inlet needle.
lin
– Fit the end cover.
Reassemble all other parts in the
reverse sequence.
146RA149 VA
On
– Insert the screws and tighten
them down firmly – see 3.5.
If there is an annular indentation
on the sealing cone of the inlet
needle, it will be necessary to
replace the inlet needle because
it will no longer seal properly.
74
MS 270, MS 280
12.3.3 Fixed Jet
Install in the reverse sequence.
The upper edge of the inlet control
lever must be flush with the top of
the carburetor body.
1
– Install the metering diaphragm
– see 12.3.1.
146RA150 VA
Reassemble all other parts in the
reverse sequence.
rin
t
– Remove the metering diaphragm
– see 12.3.1.
ep
Use a suitable screwdriver to
unscrew the fixed jet (1).
rr
4
fo
3
-n
146RA148 VA
2
Reassemble in the reverse
sequence.
ot
1
Take care not to damage the fixed
jet with the screwdriver when
removing and installing.
n
Fit the inlet needle (1).
sio
Fit spring (2) in bore.
ev
– Engage clevis in annular groove
on head of the inlet needle.
er
Insert spindle (3) in the inlet
control lever (4).
lin
– Press the inlet control lever down
and secure it with the screw.
On
Make sure the helical spring locates
on the control lever’s nipple.
– Check that inlet control lever
moves freely.
MS 270, MS 280
75
12.3.4 Pump Diaphragm
The diaphragm, inlet and outlet
valves are subjected to continuous
alternating stresses and the
material eventually shows signs of
fatigue, i.e. the diaphragm distorts
and swells and has to be replaced.
146RA144 VA
146RA139 VA
1
1
Place the diaphragm and gasket
on the carburetor body so that
their tabs (arrow) point towards
the elbow connector (1).
rin
t
Take out the screw (arrow).
Remove the end cover (1).
ep
– Fit the end cover on the
carburetor body.
The pump diaphragm, gasket and
end cover are held in position by
pegs on the end cover.
fo
rr
1
1 2
146RA141 VA
Reassemble all other parts in the
reverse sequence.
n
Inspect the fuel strainer (1) for
contamination and damage. If
necessary, use a needle to
remove it from the carburetor
body and clean or replace.
sio
Carefully remove the gasket (1)
and pump diaphragm (2) from the
end cover or carburetor body.
-n
146RA140 VA
ot
– Fit screw and tighten down firmly
– see 3.5.
176RA268 VA
On
lin
ev
er
Install in the reverse sequence.
Carefully separate the diaphragm
and gasket.
– Inspect diaphragm for damage
and wear, install a new gasket.
76
MS 270, MS 280
12.3.5 Accelerator Pump
– Remove the carburetor
– see 12.2.1.
1
– Set the throttle shaft to the full
throttle position.
Carefully pull the throttle shutter
out of the shaft.
Remove ball (1), pump piston (2)
with sealing ring (3) and
spring (4) from the carburetor
body.
rin
t
146RA153 VA
4
146RA155 VA
2
3
146RA154 VA
-n
146RA151 VA
Use a suitable pointed tool to
remove the sealing plug.
1
ot
fo
rr
ep
– Inspect parts for damage and
wear and replace if necessary.
sio
n
Remove the snap ring (1) from
the throttle shaft.
Wear safety glasses while
installing the accelerator pump/
throttle shaft to protect your eyes
from injury if parts suddenly pop out
of the carburetor body.
Note correct installed sequence of
the individual parts of the
accelerator pump: First fit the
spring (4), then the pump piston (2),
with the ball seat (arrow) facing you,
and the ball (1).
Use a suitable tool to press the
ball (1) down and fit the throttle
shaft.
ev
er
Hold accelerator pump bore closed
with one finger so that the parts of
the accelerator pump do not pop out
of the carburetor when the throttle
shaft is removed.
Wear safety glasses.
Install in the reverse sequence.
On
1
146RA152 VA
lin
– Pull the throttle shaft out of the
carburetor body.
Take the screw (1) out of the
throttle shutter.
MS 270, MS 280
77
Fit the throttle shutter (1) in the
shaft.
146RA160 VA
1
1
Check that the center of the notch in
the throttle shutter is in line with the
hole (arrow) in the carburetor body.
rin
t
Check correct installed position
of the spring (1).
146RA159 VA
146RA157 VA
1
ep
Tighten the screw (1) moderately.
rr
– Center the throttle shutter so that
it moves freely.
fo
– Tighten down the screw (1)
firmly.
146RA161 VA
n
Check that the stamped digits face
you.
sio
Use a suitable tool to carefully
install a new sealing plug (arrow)
in the accelerator pump’s bore.
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146RA151 VA
ot
– Check freedom of movement
again.
146RA158 VA
On
a
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The two marks (see arrows) must
be parallel to the throttle shaft.
Press home sealing plug so that it
is recessed 1 mm (dimension 'a')
in the accelerator pump’s bore.
78
MS 270, MS 280
12.4
Adjusting
Adjustments for operation at
high altitude or sea level
Chain runs while engine is idling
– Turn the idle speed screw (LA)
counterclockwise until the chain
stops running. Then turn the
screw about another full turn in
the same direction.
– Idle setting too lean. Turn the low
speed screw (L) counterclockwise, but 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).
– Open the high speed screw (H)
counterclockwise as far as stop.
ot
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Make the following adjustments:
– Turn high speed screw (H)
clockwise (leaner) no further than
stop.
ep
– With this carburetor it is only
possible to correct the settings of
the high speed screw (H) and low
speed screw (L) within fine limits.
At high altitude
rr
Do not remove the limiter cap to
carry out the standard setting.
– Check standard setting.
– Warm up the engine.
Erratic idling behavior, poor
acceleration
although low speed screw is set one
quarter turn open.
Standard setting
A minor correction may be
necessary if engine power is not
satisfactory when operating at high
altitude or at sea level.
rin
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146RA162 VA
– Set the low speed screw (L) so it
is one quarter turn open.
– Turn high speed screw (H)
counterclockwise (richer) no
further than stop.
If the setting is made too lean there
is a risk of engine damage as a
result of insufficient lubrication and
overheating.
-n
– Close the low speed screw (L)
clockwise as far as stop, then
open it one quarter turn counterclockwise.
At sea level
Engine stops while idling
er
– Set the low speed screw (L) so it
is one quarter turn open.
sio
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Adjusting engine idle speed
On
lin
ev
– Turn the idle speed screw (LA)
clockwise until the saw chain
begins to move. Then turn it back
one full turn.
MS 270, MS 280
79
Adjusting engine idle speed
rin
t
Insert puller 5910 890 4500 in
center of limiter caps, apply slight
pressure and screw home
counterclockwise until the limiter
caps come out of the carburetor
body.
– Check the air filter and clean or
replace as necessary.
– Check chain tension.
ep
After removing the limiter cap it is
necessary to carry out the standard
setting.
146RA166 VA
The limiter caps need be removed
from the adjusting screws only if it is
necessary to replace the high speed
screw (H) or low speed screw (L),
clean the carburetor or carry out the
standard setting.
Perform the two following
operations:
146RA163 VA
12.4.1 Standard Setting
rr
– Warm up the engine.
fo
1
2
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n
sio
On MS 270, make the following
adjustment:
– Open the high speed screw (H)
(1) 1 1/8 turns.
ev
Turn the right-hand limiter cap (2)
of low speed screw (L) clockwise
as far as stop. Turn the limiter cap
back one quarter turn until its lugs
are in line with the carburetor
openings.
– Screw down both adjusting
screws until they are against their
seats.
er
Turn the left-hand limiter cap (1)
of high speed screw (H) counterclockwise as far as stop until the
limiter cap lugs are in line with the
carburetor openings.
lin
– Open the low speed screw (L) (2)
1 1/4 turns.
On MS 280, make the following
adjustment:
On
146RA167 VA
ot
2
146RA167 VA
1
Adjust idle speed with a tachometer.
Adjust specified engine speeds
within tolerance of +/- 200 rpm.
1. Adjust engine speed with idle
speed screw (LA) to 3,300 rpm.
2. Turn low speed screw (L)
clockwise or counterclockwise
to obtain maximum engine
speed.
If this speed is higher than
3,700 rpm, abort the procedure and
start again with step 1.
3. Use the idle speed screw (LA)
to set engine speed again to
3,300 rpm.
4. Set the engine speed to
2,800 rpm with the low speed
screw (L).
5. Set engine’s maximum speed
to 13,500 rpm with the high
speed screw (H).
– Open the high speed screw (H)
(1) 1 1/4 turns.
– Open the low speed screw (L)
(2) 1 1/4 turns.
80
MS 270, MS 280
12.5
In the event of trouble with the
carburetor or the fuel supply
system, always check and clean the
tank vent.
Check function by performing
vacuum test on the tank via the fuel
hose.
1
146RA190 VA
Limiter caps that have been
removed once are damaged and
must not be re-used.
Correct operation of the carburetor
is only possible if atmospheric
pressure and internal fuel tank
pressure are equal at all times. This
is ensured by the tank vent.
Equalization of pressure in the
fuel tank takes place via the tank
vent valve (1). There must be no
build-up of vacuum during the
test. In the event of a malfunction,
use a screwdriver to remove the
vent valve (1) and install a new
valve with a new sealing ring.
rin
t
6. Install new limiter caps, noting
that the stop lugs on the limiter
caps must line up with the
openings in the carburetor.
Tank Vent
– Reassemble in the reverse
sequence.
fo
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ep
– Remove the filter base
– see 12.1.
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146RA136 VA
ot
1
2
1
146RA168 VA
On
lin
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– Disconnect the fuel hose (1) from
the carburetor.
Connect vacuum pump (1)
0000 850 3501 to fuel hose (2)
and subject fuel tank to vacuum.
MS 270, MS 280
81
Pickup Body
12.7
The diaphragm pump draws fuel out
of the tank and into the carburetor
via the fuel hose. Any impurities
mixed with the fuel are retained by
the pickup body (filter). The fine
pores of the filter eventually become
clogged with minute particles of dirt.
This restricts the passage of fuel
and results in fuel starvation.
Fuel Hose
– Remove the carburetor
– see 12.2.1.
– Pull off the pickup body
– see 12.6.
1
146RA172 VA
12.6
2
rin
t
Pickup body
ep
Use hook (2) 5910 893 8800 to
pull the pickup body (1) out of the
fuel tank.
fo
rr
Do not stretch the fuel hose too
much during this operation.
sio
n
Use a screwdriver to pry the
flange of the fuel suction hose out
of the fuel tank.
er
Pull the suction hose (1) with
pickup body out of the tank.
ev
Install in the reverse sequence.
Coat the hose flange (2) with a
little oil to simplify installation.
The straight side of the hose
flange must locate against the
marking (arrow) on the housing.
lin
Remove the filler cap (1) and
drain the tank.
146RA173 VA
On
– Pour a small amount of clean
gasoline into the tank. Close the
tank and shake the saw
vigorously.
– Open the tank again and drain it.
Dispose of fuel properly.
2
146RA174 VA
-n
176RA296 VA
In the event of trouble with the fuel
supply system, always check the
fuel tank and the pickup body first.
Clean the fuel tank if necessary.
Cleaning the fuel tank
1
ot
1
Reassemble all other parts in the
reverse sequence.
Pull the pickup body off the fuel
hose.
– Fit a new pickup body.
Install in the reverse sequence.
82
MS 270, MS 280
13
Special Servicing Tools
Part Name
Part No.
Application
Rem.
1
2
3
4
5
Locking strip
Sealing plate
Wooden assembly block
Socket, DIN 3124, 13 mm
Clamping bar
0000 893 5903
0000 855 8106
1108 893 4800
5910 893 5608
5910 890 2000
6
7
Assembly stand
Carburetor and crankcase tester
5910 890 3100
1106 850 2905
8
Vacuum pump
0000 850 3501
9
10
11
12
13
14
– Nipple
– Fuel line
Test flange
Press sleeve
Assembly drift
Installing tool 10
0000 855 9200
1110 141 8600
1119 850 4201
1108 893 2405
1108 893 4700
5910 890 2210
15
16
17
18
19
20
21
Assembly sleeve
Ignition system tester, ZAT 4
Ignition system tester, ZAT 3
Puller
Stud puller, M8
Installing tool
Setting gauge
1118 893 4602
5910 850 4503
5910 850 4520
4133 893 0800
5910 893 0501
0000 890 2201
1111 890 6400
22
23
24
Hook
Assembly tube
Torque wrench
5910 893 8800
1117 890 0900
5910 890 0301
25
Torque wrench
Blocking the crankshaft
Sealing exhaust port for leakage test
Fitting piston
Flywheel nut
For mounting chainsaw to
assembly stand
Holds chainsaw for repairs
Testing engine and carburetor
for leaks
Testing crankcase for leaks,
testing tank vent
Testing carburetor for leaks
Testing carburetor for leaks
Leakage test
Installing oil seal (starter side)
Removing and fitting piston pin
Installing hookless snap rings
in piston
Installing oil seal (clutch side)
Checking ignition
Checking ignition
Releasing flywheel
Removing guide bar mounting studs
Flaring starter rope guide bush
Setting air gap between ignition module
and flywhee
Removing pickup body
Attaching/detaching brake spring
0.5 – 18 Nm (0.4 – 13.5 lbf.ft)
Alternative:
Torque wrench 5910 890 0302 with
optical/acoustic signal
6 – 80 Nm (4.4 – 60 lbf.ft)
Alternative:
Torque wrench 5910 890 0312 with
optical/acoustic signal
5910 890 0311
On
lin
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No.
MS 270, MS 280
83
14
Servicing Aids
No.
Part Name
Part No.
Application
1
Lubricating grease (225g tube)
0781 120 1111
2
STIHL special lubricant
0781 417 1315
3
4
5
6
7
Dirko sealant (100g tube)
STIHL cleaner
Graphite grease
Molykote grease
Medium-strength threadlocking
adhesive (Loctite 243)
High-strength threadlocking
adhesive (Loctite 270)
0783 830 2000
Oil seals, oil pump drive, chain sprocket bearing,
sliding and bearing points of throttle trigger,
switch lever, brake lever and interlock lever
Bearing bore in rope rotor, rewind spring in fan
housing
Crankcase, oil seals (outside)
Crankshaft stubs
Pegs on pawls
Sliding and bearing points of brake band
rin
t
0786 111 1109
On
lin
ev
er
sio
n
-n
ot
fo
rr
ep
8
0786 110 0101
84
MS 270, MS 280