Stihl MS 661 C-M User Manual

14 MS 661, MS 661 C-M
Condition Cause Remedy
Engine stops while idling Idle jet bores
or ports blocked
Clean the carburetor
Setting of low speed screw ( L) too
rich or too lean
Reset low speed screw (L)
correctly
Setting of idle speed screw LA
incorrect – throttle shutter
completely closed
Readjust idle speed screw
LA (clockwise)
Models with M-Tronic, carburetor
setting too rich or too lean
Check M-Tronic with STIHL MDG 1
and troubleshooting chart, b 8.7,
adjust or calibrate control unit,
b 8.1
(setting of idle speed screw must
not be changed)
Tank vent faulty Fit new tank vent
Leak in fuel hose between pickup
body and carburetor
Seal connections or install new fuel
hose
Engine will not idle, idle speed too
high
Setting of idle speed screw LA
incorrect – throttle shutter opened
too wide
Readjust idle speed screw
LA (counterclockwise)
Models with M-Tronic, idle speed
too high
Check M-Tronic with STIHL MDG 1
and troubleshooting chart, b 8.7,
adjust or calibrate control unit,
b 8.1
(setting of idle speed screw must
not be changed)
Oil seals / crankcase leaking Seal oil seals / crankcase, replace if
necessary
Throttle shutter does not close Install new carburetor

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