Stihl MS 661 C-M User Manual

38 MS 661, MS 661 C-M
6.8 Piston Rings
– Remove the piston, b 6.7
– Remove the piston rings from the
piston.
: Use a piece of old piston ring to
scrape the grooves (arrows)
clean.
: Install the new piston rings in the
grooves so that the radii face
upward (arrows).
: Carefully fit the piston rings over
the piston so that the radii at the
ring gap meet at the fixing pins in
the piston grooves
– they might otherwise break.
– Install the piston, b 6.7
– Reassemble all other parts in the
reverse sequence.
1166RA095 TG
1166RA096 TG
6.9 Decompression Valve
– Remove the shroud, b 6.4
: Unscrew the decompression
valve (1).
: Check the sealing cone (arrow)
on the decompression valve for
damage.
– If the sealing cone does not close
completely or shows signs of
damage, install a new
decompression valve.
– Fit the decompression valve and
screw it home by hand.
– Tighten down the decompression
valve firmly.
– Reassemble all other parts in the
reverse sequence.
1166RA097 TG
1
5902RA164 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