Stihl 064 User manual

STIHL 064, 066 1
SERVICE MANUAL
064 and 066
Chain Saws
As the design concept of these two models is
almost identical, the descriptions and
servicing procedures generally apply to both.
Differences are described in detail.
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. Microfilmed
parts list are always more up to date than
printed lists.
A fault on the machine may have several
causes. Consult the "troubleshooting charts"
when tracing faults.
Refer to the "Technical Information Bulletins"
for engineering changes which have been
introduced since publication of this service
manual.
Service manuals and technical information
bulletins describing engineering changes are
intended exclusively for the use of STIHL
servicing dealers and staff and must not be
passed on to third parties.
Chain saw on assembly stand
Servicing and repairs are made
considerably easier if the saw is mounted
on assembly stand 5910 850 3100 or 5910
890 3100. This enables the saw to be
swivelled to the best position for the
ongoing repair and thus leaves both hands
free.
The saw is can be quickly secured to the
stand by means of the two bar mounting
studs and nuts.
The STIHL Special Tools manual lists all
special servicing tools currently available
from STIHL.
Always use original STIHL replacement
parts.
Original STIHL parts can be identified by
the STIHl part number, the logo
and the STIHL parts symbol. (
The symbol may appear alone on small
parts.
©
1992
A
n
d
reas
Stihl
.
W
a
ibli
ngen

STIHL 064, 066 2
CONTENTS
1. Specifications 3 4.6 Leakage Testing the 9. Electric Handle
Crankcase 41 Heating System 64
1.1 Engine 3 4.6.1 Preparations 41
1.2 Fuel System 4 4.6.2 Pressure Test 42 9.1 Troubleshooting 64
1.3 Ignition System 5 4.6.3 Vacuum Test 43 9.1.1 Troubleshooting Chart 65
1.4 Cutting Attachment 5 4.7 Replacing the Oil Seals 44 9.1.2 Test Connections and
1.5 Tightening Torques 7 Test Values 66
1.6 Special Accessories 8 9.2 Switch 67
1.6.1 For User 8 5. Ignition System 45 9.3 Heating Element in Rear
1.6.2 For Service 8 Handle 67
5.1 Repairing Component 9.4 Heating Element in
Parts 46 Front Handle 68
2. Troubleshooting 5.1.1 Spark Plug 46 9.5 Generator 69
Charts 9 5.1.2 Ignition Lead/Spark
Plug Terminal 48
2.1 Clutch, Chain Drive 5.1.3 Short Circuit Wire/ 10. Chain Lubrication 72
Chain Brake and Ground Wire 49
Chain Tensioner 9 5.1.4 Stop Contact 51 10.1 Pickup Body 72
2.2 Engine 10 5.1.5 Flywheel 52 10.2 Suction Hose 73
2.3 Ignition System 11 5.1.6 Ignition Module 53 10.3 Vent Valve 73
2.4 Rewind Starter 12 5.1.6.1 Ignition Timing 54 10.4 Removal and Installation
2.5 Chain Lubrication 13 5.1.6.2 Removing and of Oil Pump 73
2.6 Fuel System 14 Installing 54 10.5 Servicing the Oil Pump 75
5.1.7 LED (066 only) 55
3. Clutch, Chain Drive 11. Fuel System 76
Chain Brake and Chain 6. Rewind Starter 56
Tensioner 16 11.1 Air Filter 76
6.1 Routine Maintenance 56 11.2 Construction and
3.1 Clutch Drum/Chain 6.2 Rope Rotor/Pawls 56 Operation of Carburetor
Sprocket 16 6.3 Replacing the Starter with Compensator 77
3.2 Clutch 17 Rope 57 11.3 Leakage Testing the
3.3 Chain Brake 19 6.4 Replacing the Rewind Carburetor 78
3.3.1 Disassembly 19 Spring 57 11.4 Removal and Installation
3.3.2 Assembly 21 6.5 Tensioning Rewind of Carburetor 79
3.4 Chain Tensioner 23 Spring 58 11.5 Servicing the
3.5 Bar mounting studs 24 6.6 Replacing Starter Rope Carburetor 80
Guide Bush 59 11.6 Carburetor Adjustment
(Analog Ignition) 85
4. Engine 25 11.7 Carburetor Adjustment
7. AV Handle System 60 (Digital Ignition) 86
4.1 Removing and Refitting 11.8 Tank Vent 87
Exhaust Muffler 25 7.1 Repair 60 11.9 Fuel Filter and
4.2 Exposing the Cylinder 26 Fuel Hose 88
4.3 Cylinder and Piston 26 11.10 Tank Housing 89
4.3.1 Removal 26 8. Master Control 61 11.11 Carburetor Box 91
4.3.2 Installation 27
4.4 Piston Rings 31 8.1 Construction and
4.5 Crankcase 32 Function 61 12. Special Servicing
4.5.1 Removing the 8.2 Throttle Trigger/Inter- Tools and Aids 92
Crankshaft 32 lock Lever 62
4.5.2 Installing the 8.2 Switch Shaft 63 12.1 Special Servicing Tools 92
Crankshaft 35 12.2 Servicing Aids 93

STIHL 064, 066 3
1. SPECIFICATIONS
1.1 Engine 064 066
STIHL single-cylinder two-stroke
engine
Displacement: 85 cm³ (5.2 cu.in) 91.6 cm³ (5.6 cu.in)
Bore: 52 mm (2.05 in) 54 mm (2.12 in)
Stroke: 40 mm (1.6 in) 40 mm (1.6 in)
Compression ratio: 10.0 10.0
Power output: 4.8 kW (6.5 bhp) 5.0 kW (6.8 bhp)
at 9,500 rpm at 9,500 rpm
Max. torque: 5.45 Nm (4.0 Ib.ft) 5.6 Nm (4.1 Ib.ft)
at 6,500 rpm at 6,500 rpm
Cylinder bore: Highly wear-resistant electroplated coating
Max. permissible engine
speed with bar and
chain: 12,000 rpm
Cut-off speed: 13,500 rpm
Mean idle speed: 2,400 rpm 2,400 rpm
Crankshaft: Two-part, drop forged Two-part, drop forged
Crankshaft bearings: 2 deep groove ball bearings 2 deep groove ball bearings
Crankpin diameter: 16 mm (0.63 in) 16 mm (0.63 in)
Big-end bearing: Needle cage Needle cage
Piston pin dia.: 12 mm (0.47 in) 12 mm (0.47 in)
Small-end bearing: Needle cage Needle cage
Conrod length: 68 mm (2.67 in) 68 mm (2.67 in)
Rewind starter: Two-pawl system with automatic starter rope
rewind mechanism
Starter rope: 4.5 mm (0.18 in) dia., length 1000 mm (39.4 in)
Clutch: Centrifugal clutch Centrifugal clutch
without linings, without linings,
82 mm (3.2 in) dia. 82 mm (3.2 in) dia.
Clutch engages at: approx. 3,200 rpm approx. 3,200 rpm
Crankcase leakage test
at gauge pressure: 0.5 bar (7.25 psi) 0.5 bar (7.25 psi)
under vacuum: 0.5 bar (7.25 psi) 0.5 bar (7.25 psi)

STIHL 064, 066 4
1.2 Fuel System 064 066
Carburetor: All position diaphragm All position diaphragm
carburetor with integral carburetor with integral
fuel pump fuel pump
Basic setting
High speed screw H: Back off approx. 1 turn Back off approx. 1 turn
Low speed screw L: Back off approx. 1 turn Back off approx. 1 turn
(starting with screws (starting with screws
tight against their tight against their
seats) seats)
Carburetor leakage test
at gauge pressure: 0.4 bar (5.8 psi) 0.4 bar (5.8 psi)
Fuel tank capacity: 0.84 I (1.77 US pt) 0.84 I (1.77 US pt)
Fuel mixture: Regular brand-name gasoline and brand-name two-stroke
engine oil
Mix ratio: 50:1 50:1
with STIHL two-stroke engine oil with STIHL two-stroke engine oil
25:1 25:1
with other brand-name two-stroke, with other brand-name two-stroke,
air-cooled engine oils air-cooled engine oils
Compensator: Keeps pressures equal at clean
air side of filter and metering
diaphragm irrespective of how dirty
the filter is
Air filter: Standard (wire mesh) Standard (wire mesh)
element element
Special accessory: Special accessory:
Heavy duty (HD)-air filter Heavy duty (HD)-air filter

STIHL 064, 066 5
1.3 Ignition System 064 066
Type: Electronic magneto Digital magneto
ignition (breakerless) ignition (breakerless)
with integral trigger with maximum speed
unit governor
Air gap: 0.2-0.3 mm (0.008-0.012 in) 0.2-0.3 mm (0.008-0.012 in)
Ignition timing: 2.6-3.4 mm 2.9-3.9 mm
(0.10-0.13 in) B.T.D.C. (0.11-0.15 in) B.T.D.C.
at 8,000 rpm at 8,000 rpm
Advance angle: 26°-30° B.T.D.C. 27.5°-32.5° B.T.D.C.
at 8,000 rpm at 8,000 rpm
Spark plug (suppressed): Bosch WSR 6 F or Bosch WSR 6 F or
NGK BPMR 7 A NGK BPMR 7 A
Electrode gap: 0.5 mm (0.020 in) 0.5 mm (0.020 in)
Spark plug thread: M14 x 1.25 M14 x 1.25
Length of thread: 9.5 mm (0.37 in) 9.5 mm (0,37 in)
Heat range: 200 200
LED: Aids carburetor adjustment
1.4 Cutting Attachment
Guide bars: STIHL Rollomatic S bars STIHL Rollomatic S bars
with sprocket nose. with sprocket nose.
STIHL Duromatic bars STIHL Duromatic bars
with stellite-tipped with stellite-tipped
nose. nose.
Both types with Both types with
corrosion-resistant corrosion-resistant
finish and induction finish and induction
hardened rails. hardened rails.
Bar lengths: Rollomatic: 40, 45, 50 Rollomatic: 40, 45, 50
63, 75 and 90 cm 63, 75 and 90 cm
(16, 18, 20, 25, 30 (16, 18, 20, 25, 30
and 35 in) and 35 in)
Duromatic: 40, 45, 50, Duromatic: 40, 45, 50,
63 and 75 cm 63 and 75 cm
(16, 18, 20, 25 and 30 in) (16, 18, 20, 25 and 30 in)

STIHL 064, 066 6
064 066
Oilomatic chain: 3/8" (9.32 mm) 3/8" (9.32 mm)
Rapid Micro and Super Rapid Micro and Super
(standard) (standard)
0.404" (10.26 mm) 0.404" (10.26 mm)
Rapid Micro and Rapid Super Rapid Micro and Rapid Super
(optional) (optional)
Chain sprocket: 8-tooth 3/8" rim or 8-tooth 3/8" rim or
spur sprocket spur sprocket
(alternatives) (alternatives)
7-tooth 0.404" spur 7-tooth 0.404" spur
or rim sprocket or rim sprocket
(optional) (optional)
Chain speed: 23.6 m/s (77.4 ft/s) 23.6 m/s (77.4 ft/s)
at 9,500 rpm at 9,500 rpm
(with 8-tooth 3/8" (with 8-tooth 3/8"
chain sprocket) chain sprocket)
Chain lubrication: Fully automatic, speed- Fully automatic, speed-
controlled reciprocating controlled reciprocating
oil pump, no feed at oil pump, no feed at
idle speed. Additional idle speed. Additional
manual oil flow control. manual oil flow control.
Oil feed rate,
adjustable: 11-21.5 cc/min 11-21.5 cc/min
(3/8-3/4 fl.oz/min) (3/8-3/4 fl.oz/min)
at 10,000 rpm at 10,000 rpm
Oil tank capacity: 0.35 l (0.74 US pt) 0.35 l (0.74 US pt)

STIHL 064, 066 7
1.5 Tightening Torques
Fastener Thread size For component Torque Remarks
Nm (Ibf.ft)
Spline screw IS-M5x20 Crankcase 9.0 (6.6)
Spline screw IS-M5x20 Cylinder 12.0 (8.8)
Spline screw IS-M6x20 Cylinder 15.0 (11.8) 4)
Spline screw IS-M5x12 Muffler to cylinder 10.0 (7.5) 1)2)
Spline screw IS-M6x20 Muffler to cylinder 15.0 (11.0) 4)
Spline screw IS-M5x6 Muffler upper casing (top) 11.0 (8.1) 1)2)
Spline screw IS-M5x12 Muffler upper casing (bottom) 8.0 (5.9) 1)2)
Spline screw IS-M5x20 Ignition module 9.0 (6.6) 1)2)
Nut M8x1 Crankshaft (flywheel) 33.0 (24.3)
Flange locknut VM 5 Carburetor 3.5 (2.6)
Spline screw IS-M4x16 Shroud 3.0 (2.2) 1)2)
M12x1 L Clutch carrier 50.0 (37.0)
M14x1.25 Spark plug 25.0 (18.5)
Spline screw IS-6x19 Annular buffer (top) 3.5 (2.6)
Spline screw IS-6x19 Annular buffer (bottom) 7.0 (5.2)
Spline screw IS-5.8x19 Front handle 7.0 (5.2) 2)3)
Self-tapping screw B3.9x19 Handle molding 1.0 (0.75)
Spline screw IS-M5x12 Annular buffer plate 9.0 (6.6) 1)
Spline screw IS-M5x16 Chain catcher 7.0 (5.2)
Spline screw IS-M5x12 Spiked bumper (top) 7.0 (5.2)
Spline screw IS-M5x16 Chain catcher pin
to spiked bumper 6.0 (4.4)
Spline screw IS-M5x12 Rubber buffer to crankcase 3.5 (2.6)
Locknut M5 Spiked bumper to sprocket cover 8.0 (5.9)
Pan head screw BM3x8 Guard in sprocket cover 1.0 (0.75)
Pan head screw M3.5x12 Generator (heating) 2.0 (1.5)
Pan head screw M4x12 Cover (chain tensioner) 3.5 (2.6)
Spline screw IS-M4x12 Oil pump 3.0 (2.2)
Spline screw IS-M4x12 Cover (chain brake) 2.0 (1.5)
Spline screw IS-M5x18 Fan housing 3.5 (2.6)
Spline screw IS-M5x12 Starter post in fan housing 6.0 (4.4)
Starter post M8 Fan housing 6.0 (4.4)
Screw assy. IS-M5x30 Hand guard (left) 7.0 (5.2) 1)
Pan head screw M4x8 Inner side plate 3.0 (2.2)
Collar stud M8 Guide bar mounting 15.0 (11.0) 1)
Remarks:
1) Screw must be secured with adhesive 0786 111 1101 (Loctite 242).
2) Washer must be fitted under screw head. On front handle, fit washer under heads of side screws only.
3) Screw must be secured with adhesive 0786 111 1117 (Loctite 648).
4) Model 066 only.
Note: Screws secured with adhesive are easier to release if the adhesive is heated first with a hot air blower
(hair dryer). Exercise caution on polymer components.

STIHL 064, 066 8
1.6 Special Accessories 064 / 066
1.6.1 For User
STIHL repair kit 064 1122 900 5000
Intake air preheating kit 1122 007 1027
7-tooth 0.404" rim
sprocket kit 1122 007 1002
8-tooth 3/8" spur
sprocket 1122 640 2000
7-tooth 0.404" spur
sprocket 1122 640 2001
Valve (fuel tank vent) 1110 353 1600
0.404" (10.26 mm) Oilomatic
chains
Spiked bumpers for thick bark
1.6.2 For Service
Carburetor parts kit 064 1122 007 1060
Gasket set 064/066 1122 007 1051

STIHL 064, 066 9
2. TROUBLESHOOTING
CHARTS
2.1 Clutch,
Chain Drive,
Chain Brake and
Chain Tensioner
Condition
Saw chain turns at
idle speed
Cause
Engine idle speed too high
Spring hook(s) broken
Remedy
Readjust at idle speed
adjustment screw
(counterclockwise)
Fit new spring(s)
Loud noises Springs stretched or fatigued
Needle cage damaged
Clutch shoe retainer
broken
Clutch shoes and carrier
worn
Replace all clutch springs
Fit new needle cage
Fit new retainer
Fit new clutch
Chain sprocket wears
rapidly
Chain wears rapidly
Chain not properly
tensioned
Chain not properly
tensioned
Poor chain lubrication
rectify problem
Worn chain sprocket
Tension chain as specified
Tension chain as specified
Check chain lubrication and
Fit new sprocket
Chain does not stop
immediately when chain brake
is activated
Brake spring broken
Brake band stretched or
broken
Fit new brake spring
Fit new brake band

STIHL 064, 066 10
Always check and, if necessary, repair the following parts before looking for faults on the engine:
- Air filter
- Fuel system
- Carburetor
- Ignition system
Condition Cause Remedy
Engine does not start Oil seals in crankcase Replace oil seals
easily, stalls at leaking
idle speed, but
operates normally Manifold leaking Seal or replace manifold
at full throttle
Cylinder base gasket Replace gasket
leaking
Crankcase damaged (cracks) Replace crankcase
Engine does not Secondary air seepage Mount manifold correctly or
deliver full power through poorly mounted replace
or runs erratically or faulty manifold
Piston rings leaking Fit new piston rings
or broken
Muffler carbonized Clean muffler (inlet and
exhaust), replace spark
arrestor screen (if fitted)
Engine overheating Insufficient cylinder Thoroughly clean all cooling
cooling. Air inlets in air openings
fan housing blocked or
cooling fins on cylinder
very dirty
Intake air preheating Remove intake air preheating
being used at too high components; close rotary
an outside temperature shutter
2.2 Engine

STIHL 064, 066 11
2.3 Ignition System
Warning: 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!
Ignition system in order.
Look for fault in fuel system and
carburetor.
yes
Replace ignition module. Does engine now run after
positive spark test?
Fit new flywheel.
Is spark test positive?
Use ohmmeter to check ignition lead
for break. If break is detected, replace
ignition lead.
Does spark test now produce sparkover?
Does flywheel appear to be
in good condition?
Fit new spark plug.Is air gap correct?
Correct the air gap (0.2 - 0.3 mm).
Is spark test positive?
Insert screwdriver in place of spark plug in spark
plug terminal and hold about 4 mm (1/8") away from
ground. Sparkover?
Replace faulty ignition lead of short circuit wire.
Repair contact spring or switch shaft.
Faulty insulation on ignition lead
or short circuit wire?
Is connector sleeve touching
short circuit contact?
Clean spark plug and reset electrode gap.
Does spark test produce powerful spark?
Press terminal firmly onto spark plug
and fit spring if necessary.
Spark plug terminal firmly seated on spark plug?
Remove spark plug.
Is it in good condition?
no
no
no
no
no
yes
no
no yes
yes no
no
no
no
yes
yes

STIHL 064, 066 12
2.4 Rewind Starter
Condition Cause Remedy
Starter rope broken Rope pulled out too Fit new starter rope
vigorously as far as stop
or over edge - i.e. not
vertically
Normal wear Fit new starter rope
Rewind spring broken Spring overtensioned - no Fit new rewind spring
reserve when rope is
fully extended
Heavily soiled or Fit new rewind spring
corroded
Starter rope can be Guide pegs on pawls or Fit new pawls
pulled out almost pawls themselves are
without resistance worn
(crankshaft does not
turn) Spring clip fatigued Fit new spring clip
Starter rope is Starter mechanism is Thoroughly clean complete
difficult to pull very dirty (dusty starter mechanism
and rewinds very conditions)
slowly
Lubricating oil on rewind Apply a few drops of kerosine
spring becomes viscous at (paraffin) to spring, then
very low outside pull rope carefully several
temperatures (spring times until normal action is
windings stick together) restored

STIHL 064, 066 13
2.5 Chain Lubrication
Important: In the event of trouble with the chain lubrication system, always investigate the other possible sources of faults before
disassembling the oil pump.
Condition Cause Remedy
Chain receives Oil tank empty Fill up with oil
no oil
Oil hose has come off Reconnect hose to pump or
stub on oil pump or fit it in crankcase recess, or
out of crankcase recess, install a new hose.
or hose is damaged*
Sealing ring in crankcase Remove oil pump, fit new
recess is faulty** sealing ring and reinstall
oil pump
Oil inlet hole in guide Clean oil inlet hole
bar is blocked
Intake hose or pickup Wash intake hose and pickup
body (strainer) clogged body (strainer) in white
or intake hose ruptured spirit and blow out with
compressed air; replace if
necessary
Valve in oil tank blocked Clean or replace valve
Teeth on pump piston Fit new pump piston and/or new
and/or worm worn worm
Machine losing Oil hose has come off Reconnect hose to pump or
chain oil stub on oil pump or fit it in crankcase recess, or
out of crankcase recess, install a new hose.
or hose is damaged*
Cylinder bore in pump Fit new pump housing
housing worn
Oil pump delivers Control screw and/or Fit new control screw and/or
too little oil control edge on pump new pump piston
piston worn
Bore in pump housing Fit new pump housing
worn
* Older machines
** New machines

STIHL 064, 066 14
2.6 Fuel System
Condition Cause Remedy
Carburetor floods; Inlet needle not sealing. Foreign Remove and clean or replace
engine stalls matter in valve seat or cone inlet needle, clean fuel
damaged. tank, pickup body and fuel
line if necessary
Inlet control lever Free off inlet control lever
sticking on spindle
Helical spring not located on Remove inlet control lever
nipple of inlet control lever and refit correctly
Perforated disc on diaphragm Fit new metering diaphragm
is deformed and presses constantly
against inlet control lever
Inlet control lever is too high Set inlet control lever flush with
(relative to design position) top of metering chamber face
Poor acceleration Idle jet "too lean" Back off low speed adjusting
screw slightly
(see carburetor adjustment)
Main jet "too lean" Back off high speed adjusting
screw slightly
(see carburetor adjustment)
Inlet control lever is too low Set inlet control lever flush with
(relative to design position) top of metering chamber face
Inlet needle sticking Remove inlet needle, clean
to valve seat and refit
Connecting bore to Clean bore
atmosphere blocked
Diaphragm gasket leaking Fit new diaphragm gasket
Metering diaphragm Fit new metering diaphragm
damaged or shrunk
Engine will not idle, Throttle valve opened too far Reset idle speed adjusting
idle speed too high by idle speed adjusting screw screw correctly

STIHL 064, 066 15
Condition Cause Remedy
Engine stalls at Idle jet bores or Clean jet bores and blow out
idle speed channels blocked with compressed air
Idle jet "too rich" Screw in low speed adjusting
screw slightly
(see carburetor adjustment)
Setting of idle speed adjusting Set idle speed adjusting screw
screw incorrect - throttle shutter correctly
completely closed
Small plastic plate in Clean or renew valve jet
valve jet does not close
Engine speed drops Air filter plugged Clean air filter
quickly under load
- low power Tank vent faulty Clean tank vent or replace if
necessary
Leak in fuel line between Seal or renew connections and
tank and fuel pump fuel line
Pump diaphragm damaged Fit new pump diaphragm
or fatigued
Main jet bores or Clean bores and channels
channels blocked
Fuel pickup body dirty Clean pickup body, fit new
filter
Fuel strainers dirty Clean fuel strainers

STIHL 064, 066 16
3. CLUTCH, CHAIN DRIVE,
CHAIN BRAKE AND CHAIN
TENSIONER
3.1 Clutch Drum/Chain
Sprocket Top:
Removing needle cage
Bottom:
Top: Assembly sequence of chain drive
1 = Saw chain 1 = Spur sprocket (with clutch drum)
2 = Guide bar Top: 2 = Needle cage
3 = Sprocket cover Removing E-clip 3 = Washer
4 = E-clip
Bottom: Bottom: 5 = Clutch drum (for rim sprocket)
Disen
g
a
g
in
g
chain brake Removin
g
clutch drum or chain s
p
rocket 6 = Rim s
p
rocket
- Unscrew sprocket cover nuts and remove
sprocket cover.
- Remove saw chain and guide bar.
- Disengage the chain brake by pulling the
hand guard toward the front handle.
- Pry the E-clip off the crankshaft.
- Remove the washer from the clutch drum
or chain sprocket.
- Pull off the rim sprocket with clutch drum
or the spur spocket.
- Take the needle cage out of the clutch
drum or chain sprocket.
Reassemble in the reverse sequence.
Caution: Rim sprocket must be fitted
with chip ejector cavities facing
outward.
Note: Clean stub of crankshaft. Replace
the needle cage or wash it in clean white
spirit and lubricate with STIHL
multipurpose grease, see 12.2.
Rotate the clutch drum or spur sprocket,
apply slight pressure at the same time, until
the oil pump drive spring engages the slot
on the outside diameter of the drum.

STIHL 064, 066 17
3.2 Clutch
Top:
1 = Spark plug terminal
2 = Spark plug Top: Top:
Locking strip 0000 893 5902 Clutch
Bottom:
Shroud mounting screws (third screw Bottom: Bottom:
hidden in this view) Locking strip in position Assembly hook 5910 890 2800
To remove and disassemble the clutch:
Troubleshooting chart - see 2.1.
- Remove outer half of air filter - see 11.1.
- Pull terminal off the spark plug and
unscrew the spark plug.
- Take out shroud mounting screws and
remove the shroud.
- Push the locking strip into the spark
plug hole so that "TOP" or "OBEN" is
facing upward.
Important: To avoid the risk of piston
damage, use only the specified locking
strip.
- Remove the clutch drum or chain
sprocket, see 3.1.
- Unscrew clutch from stub of
crankshaft.
Caution: Clutch has left-hand thread.
Unscrew it clockwise.

STIHL 064, 066 18
Top: Top:
Removing a clutch spring Fitting retainer on clutch shoe
Bottom: Bottom:
Cover washer Component parts of clutch Pushing clutch shoe onto carrier
Note: A new clutch with cover washer, a
modified carrier and different clutch shoe
retainers has been installed from
machine number X 22 377 760.
Important: Always fit identical
replacement parts.
- Remove cover washer, if fitted, from
stub of crankshaft.
-To reassemble and install the
clutch:
- Push the retainers onto the
clutch shoes.
- Fit the clutch shoes over the
arms of the clutch carrier so that
the series number, e.g. 1122a, is
on the same side as the carrier's
hexagon.
- Clamp the clutch, e.g. one clutch
shoe, in a vise.
- Use assembly hook to remove all
the clutch springs.
- Pull the clutch shoes off the
carrier.
- Pull the retainers off the clutch
shoes.
- Clean all parts and stub of crank-
shaft in white spirit. Replace any
damaged or worn parts.

STIHL 064, 066 19
- Attach one end of each spring to
the clutch shoes by hand.
- Use the assembly hook to attach
the other ends of the springs and
press them firmly into the clutch
shoes with one finger.
- Fit a cover washer on necked
crankshaft stubs. Do not fit a
cover on crankshaft stubs without
a neck.
3.3 Chain Brake
3.3.1 Disassembly
Top: Top: Top:
Attaching clutch springs Crankshaft stub without neck Inner side plate mounting screw
Bottom: Bottom: Bottom:
Crankshaft stub with neck Ti
g
htenin
g
the clutch Cover mountin
g
screws
- Screw clutch onto crankshaft and
tighten down to a torque of 50
Nm (37 Ibf.ft).
- Install clutch drum with rim
sprocket (or spur sprocket)
- see 3.1.
- Remove locking strip from
cylinder. Install spark plug and
tighten - down to a torque of 25
Nm (18.5 Ibf.ft).
- Fit outer half of air filter.
- Remove the clutch drum with rim
sprocket (or spur sprocket)
- see 3.1
- Remove mounting screw from
inner side plate and lift side plate
away.
- Remove mounting screws from
cover and take out the cover.

STIHL 064, 066 20
Top: Top: Top:
Detaching brake spring Hand guard mounting screw E-clip on cam lever pivot pin
Bottom: Bottom: Bottom:
Removing brake band E-clip on bell crank Detaching spring from pivot pin
- Carefully pry the brake spring off
the anchor pin.
- Pry the brake band out of its seat
in the crankcase and detach it
from the bell crank.
- Remove the E-clip from the cam lever
pivot pin.
- Detach spring from cam lever.
- Pull the cam lever off the pivot pin.
- Remove the spring.
- Take out the hand guard mounting screw.
- Remove E-clip from bell crank pivot pin.
- Pull hand guard with bell crank off the
pivot pins.