Stihl MS 391 Instruction Manual

MS 311, MS 391
English
54
EPA / CEPA
The Emission Compliance Period
referred to on the Emissions
Compliance Label indicates the number
of operating hours for which the engine
has been shown to meet Federal
emission requirements.
Category
Engine
STIHL single cylinder two-stroke engine
MS 311
MS 391
Ignition System
Electronic magneto ignition
Fuel System
All position diaphragm carburetor with
integral fuel pump
Chain Lubrication
Fully automatic, speed-controlled oil
pump with rotary piston. Additional
manual oil flow control
Weight
Cutting Attachments
Recommended cutting attachments
conforming with the 45 degree
computed kickback angle requirement
of Section 5.11 of
ANSI/OPEI B175.1-2012 when used on
this model chain saw (see the chapter
on "Safety Precautions and Working
Techniques"):
Rollomatic E guide bars
Actual cutting length will be less than
listed bar length.
Saw chain 3/8"
Specifications
A = 300 hours
B = 125 hours
C = 50 hours
Displacement: 3.60 cu.in
(59.0 cc)
Bore: 1.85 in (47 mm)
Stroke: 1.34 in (34 mm)
Engine power to
ISO 7293:
4.2 bhp (3.1 kW)
at 9,500 rpm
Idle speed: 2,800 rpm
Max. permissible
speed (with cutting
attachment): 13,000 rpm
Displacement: 3.90 cu.in
(64.1 cc)
Bore: 1.93 in (49 mm)
Stroke: 1.34 in (34 mm)
Engine power to
ISO 7293:
4.4 bhp (3.3 kW)
at 9,500 rpm
Idle speed: 2,800 rpm
Max. permissible
speed (with cutting
attachment): 13,000 rpm
Spark plug (resistor
type):
NGK BPMR 7 A,
Bosch WSR 6 F
Electrode gap: 0.02 in (0.5 mm)
Fuel tank capacity: 20.3 fl.oz (0.60 l)
Oil tank capacity: 11.8 fl.oz (0.350 l)
dry, without bar and chain
MS 311: 13.7 lbs (6.2 kg)
MS 391: 13.7 lbs (6.2 kg)
Reduced kickback STIHL guide bars
(with green label)
Bar lengths: 40, 45, 50 cm (16, 18,
20 in.)
Pitch: 3/8" (9.32 mm)
Groove width: 1.3 mm (0.050 in) or
1.6 mm (0.063 in.)
Sprocket nose: 10-tooth
Low kickback STIHL saw chain (with
green label)
Rapid Micro 3 (33 RM3) Type 3662
Rapid Super 3 (33 RS3) Type 3624
Pitch: 3/8" (9.32 mm)
Drive link gauge: 1.3 mm (0.050 in)

Stihl MS 391 Specifications

General

Motor type	2-stroke motor
Chain gauge	1.6 mm
Chain pitch	3/8 \
Automatic oiling	Yes
Oil tank capacity	0.35 L
Fuel tank capacity	0.6 L
Engine displacement	64.1 cm³
Engine power	4.4 hp
Power source	Gasoline

Weight and Dimensions

Weight	6200 g