Spark Arresting Screen* In Muffler; Checking The Spark Plug - Stihl HT 70 Instruction Manual

Erratic idling behavior
Idle setting too rich:
:
Turn low speed screw (L) clockwise
(about 1/4 turn) until the engine runs
and accelerates smoothly.
HT 70, HT 75
Spark Arresting Screen* in
Muffler
If the engine is low on power, check the
spark arresting screen in the muffler.
:
Lift spark arresting screen and pull it
out sideways.
:
Clean spark arresting screen if
necessary.
: If screen is damaged or coked up, fit
a new one.
:
Refit the spark arresting screen.
* see "Guide to Using this Manual"

Checking the Spark Plug

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.
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