Owner's Manual

21BR 340, BR 380
English / USA
Fine Tuning for Operation at High
Altitude or at Sea Level
A slight correction of the setting may be
necessary if engine power is not
satisfactory when operating at high
altitude or at sea level:
: Check standard setting.
: Warm up the engine.
: Turn the high speed screw (H)
slightly clockwise (leaner) – on
models with limiter caps (H = 1/4),
no further than stop.
If the setting is too lean, there is a
risk of engine damage due to
insufficient lubrication and
overheating.
Units with a catalytic converter* may
only be operated with unleaded
gasoline and STIHL two cycle engine
oil or equivalent quality two cycle engine
oils in a mix ratio of 50:1 (see chapter
“Fuel”).
The catalylic converter in the muffler
reduces noxious emissions in the
exhaust gas.
Correct adjustment of the carburetor (if
adjustable) and observance of the
specified mix ratio of gasoline and two
cycle engine oil are essential to
minimize harmful exhaust emissions
and ensure a long catalyst service life.
* see “Guide to Using this Manual”
Wrong fuel mix (too much engine oil in
the gasoline), a dirty air filter and
unfavorable running conditions (mostly
at part throttle etc.) affect the condition of
the spark plug. These factors cause
deposits to form on the insulator nose
which may result in trouble in operation.
Catalytic Converter* Checking the Spark Plug
000BA002 KN