Stihl TS 420 - 7.2 Leak testing; 7.2.1 Preparatory steps; 7.2.2 Vacuum test

TS 410, TS 420
English
32
Correcting the carburetor setting for use
at high altitudes
The setting may have to be marginally
corrected if engine performance is
unsatisfactory at high altitudes:
N Make standard setting
N Let the engine warm up
N Turn the high speed adjusting
screw(H) slightly clockwise (leaner)
– max. up to the stop
NOTICE
After descending from a high altitude,
restore the carburetor setting to the
standard setting.
If you make the setting too lean it will
increase the risk of engine damage
through lack of lubrication and
overheating.
In some countries, the mufflers are fitted
with a spark arresting screen.
N If engine performance deteriorates,
check the spark arresting screen in
the muffler.
WARNING
Wait until engine has cooled completely
before performing the following
operations.
N Undo screw(1)
N Pull the spark arresting screen(2)
upward out of the muffler
N Clean the soiled spark arresting
screen
N If the screen is damaged or heavily
carbonized, fit a new one
N Refit the spark arresting screen in
reverse order of steps
N If the engine is down on power,
difficult to start or runs poorly at idle
speed, first check the spark plug.
N Fit a new spark plug after about 100
operating hours – or sooner if the
electrodes are badly eroded. Install
only suppressed spark plugs of the
type approved by STIHL – see
"Specifications".
Removing the spark plug
N Switch off the engine – move stop
switch to STOPor0
N Unscrew screw(1) and remove
cap(2) – screw(1) is secured in the
cap(2) to prevent loss
N Remove the spark plug boot (3).
N Unscrew the spark plug (4).
Spark Arresting Screen in
Muffler
2
370BA031 KN
1
Spark Plug
1307BA030 KN
1
2
4
1307BA031 KN
3