Stihl MS 661 Instruction Manual

MS 661
English
33
If there is a noticeable loss of engine
power:
N Knock out the filter or blow it clear
with compressed air from the inside
outwards
If knocking-out or blowing-out does not
suffice, or in the case of stubborn dirt or
stuck filter fabric, the filter must be
subjected to a thorough cleaning.
Always replace a damaged filter.
Thorough filter cleaning
N Wash the filter in STIHL special-
purpose cleaner (special
accessory) or a clean, non-
flammable cleaning liquid (e.g.,
warm soapy water) – rinse the filter
from inside to out under a water jet
– do not use high-pressure cleaners
N Dry all filter parts – do not expose to
extreme heat
N Do not oil the filter
N Reinstall filter
Basic information
The carburettor comes from the factory
with a standard setting.
The carburettor has been adjusted for
optimum performance and fuel
efficiency in all operating states.
Standard setting
N Switching off the engine
N Check the air filter – clean or replace
it if necessary
N Turn the high speed adjusting
screw (H) counterclockwise as far
as possible (max. 3/4 turn)
N Turn the low speed adjusting
screw (L) clockwise as far as
possible – then turn it 1/4 turn
counterclockwise
Setting the idle speed
N Make standard setting
N Start engine and let it warm up
Engine stops when idling
N Turn the idle speed adjusting screw
(LA) clockwise until the saw chain
begins to run – then turn it back 1/4
turn.
Saw chain rotates at idle speed
N Turn the idle speed screw (LA)
counterclockwise until the chain
stops running – then turn another
1/4 turn in the same direction.
WARNING
If the saw chain continues to keep
rotating in idle even after adjustment,
have the chain saw checked by a
servicing dealer.
Speed erratic when idling; poor
acceleration (despite standard setting of
low speed adjusting screw)
The idle setting is too lean.
N Carefully turn the low speed
adjusting screw (L)
counterclockwise until the engine
runs smoothly and accelerates
properly.
Whenever the low speed adjusting
screw (L) has been adjusted, it is usually
also necessary to readjust the idle
speed adjusting screw (LA).
Cleaning the Air Filter Adjusting the Carburetor
H
L
LA
1166BA013 AM
H
L
LA
1166BA015 AM

Stihl MS 661 Specifications

General

Displacement	91.1 cc
Chain Pitch	3/8"
Engine Power	5.4 kW
Fuel Capacity	825 ml
Chain Oil Capacity	360 ml
Guide Bar Lengths	90 cm