Stihl MS 661 C-M User Manual

3MS 661, MS 661 C-M
1. Introduction and Safety Precautions
1.1 Introduction
This service manual contains
detailed descriptions of all the repair
and servicing procedures specific to
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.
A malfunction on the machine may
have several causes. To help locate
the problem, consult the chapter on
"Troubleshooting" and the
"STIHL Service Training System"
for all assemblies.
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 a
revised edition is issued.
The special tools mentioned in the
descriptions are listed in the chapter
on "Special Servicing Tools" in this
manual. Use the part numbers to
identify the tools in the
"Special Tools" manual. The
manual lists all special servicing
tools currently available from
STIHL.
Symbols are included in the text and
pictures for greater clarity.
The meanings are as follows:
In the descriptions:
: = Action to be taken that is
shown in the illustration
(above the text)
– = Action to be taken that is
not shown in the illustration
(above the text)
In the illustrations:
A Pointer (short arrow)
aDirection of movement
b 4.2 = Reference to another
chapter, i.e. chapter 4.2
in this example.
Service manuals and all technical
information bulletins are intended
exclusively for the use of properly
equipped repair shops. They must
not be passed to third parties.
Servicing and repairs are made
considerably easier if the machine
is mounted to assembly stand (3)
5910 890 3100. To do this, secure
the mounting plate (2)
5910 850 1651 to the assembly
stand with two screws (1) and
washers.
The above operation is not
necessary with the new assembly
stand 5910 890 3101 since the
mounting plate is already fitted.
1
2
3
1166RA444 TG
4
The screws must not project since
they may, depending on the
machine, damage housings when
the machine is clamped in position,
pack with washers (4) if necessary.
Preparations for servicing
The chain sprocket, saw chain and
guide bar must be removed to
mount the machine on the assembly
stand for servicing.
Engage the bar mounting studs in
the lower holes in the mounting
plate and secure the machine in
position with the M 8 nuts (arrows).
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.
1166RA001 TG

Stihl MS 661 C-M Specifications

General

Idle speed	- RPM
Motor type	2-stroke motor
Chain pitch	3/8 \
Blade length	800 mm
Product color	Black, Grey, Orange
Automatic oiling	Yes
Engine displacement	91.1 cm³
Power source	Gasoline
Sound power level	118 dB
Vibration emission	6.9 m/s²
Sound pressure level	105 dB

Weight and Dimensions

Weight	7400 g