Specifications - Stihl BT 121 Instruction Manual

Definitions
1 Starter Grip
The grip of the pull starter, for
starting the engine.
2 Carburetor Adjusting Screws
For tuning the carburetor.
3 Air Filter Cover
Covers and protects the air filter
element.
4 Fuel Filler Cap
For closing the fuel tank.
5 Muffler with Spark Arresting
Screen
Muffler reduces exhaust noises and
diverts exhaust gases away from
operator.
Spark arresting screen is designed
to reduce the risk of fire.
6 Slide Control
For starting throttle, run and stop.
Keeps the throttle partially open
during starting and switches off the
ignition to stop the engine.
7 Throttle Trigger Lockout
Must be depressed before the
throttle trigger can be activated.
8 Throttle Trigger
Controls the speed of the engine.
9 Spark Plug Boot
Connects the spark plug with the
ignition lead.
10 Screw Plug
Seals filler opening for gearbox
grease.
BT 121
11 Drilling Spindle
For attaching the chuck or adapter
to the power drill.
12 Fuel Pump
Provides additional fuel feed for a
cold start.
13 Choke Knob
Eases engine starting by enriching
mixture.
14 Auger Brake Activating Lever
Lever for engaging and disengaging
the auger brake.
15 Padding
Helps cushion thigh against handle
frame.

Specifications

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
A = 300 hours
B = 125 hours
C = 50 hours
Engine
STIHL single cylinder two-stroke engine
Displacement: 30.8 cm
Bore: 35 mm
Stroke: 32 mm
Engine power to 1.3 kW (1.8 HP)
ISO 7293: at 9,000 rpm
Idle speed: 2,800 rpm
Engine cut-off speed: 12,300 rpm
Ignition System
Electronic magneto ignition
(breakerless)
Spark plug (resistor Bosch WSR 6 F,
type): NGK BPMR 7 A
Electrode gap: 0.5 mm
English
3
23