Dolmar Gasoline Chain Saws PS-421 - Manual (Page 38)

8
11 12
13
STOP
Replacing the spark plug
CAUTION:
Do not touch the spark plug or plug cap if the engine is
running (high voltage).
Switch off the engine before starting any maintenance work.
A hot engine can cause burns. Wear protective gloves!
The spark plug must be replaced in case of damage to the
insulator, electrode erosion (burn) or if the electrodes are very
dirty or oily.
Remove the filter cover (see „Cleaning the air filter“).
Pull the plug cap (8) off the spark plug. Use only the combination
wrench supplied with the saw to remove the spark plug.
Electrode gap
The electrode gap must be .020" (0.5 mm).
CAUTION: Use only the following spark plugs:
NGK CMR7A-5.
Checking the ignition spark
Insert combination tool between hood and cylinder as shown.
CAUTION! Do not insert the combination tool into the
spark plug hole! Make contact only with the cylinder (oth-
erwise you might damage the engine).
Using insulated pliers, press the unscrewed spark plug (9)
against the combination tool (away from the spark plug hole)
with the spark plug cap firmly on the plug.
Put combination switch (10) in the ON position.
Pull the starter cable hard.
If the function is correct, an ignition spark must be visible near
the electrodes.
Checking the muffler screws
Unscrew  screws (11) and remove the upper half of the muf-
fler (12).
Note: For saw models with catalytic converters (PS-5, PS-
421), remove the converter along with the upper muffler half.
The screws on the bottom muffler half (13) are now accessible,
and it is possible to check them for tightness. If they are loose,
tighten by hand (Caution: do not over-tighten).
STOP
8
.020”
(0,5 mm)
9
10