Husqvarna TC 250 2011, Specifications - Operation - Maintenance

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SPARK PLUG CHECK
Use NGK CR9EB spark plug (2); the gap is 0.027÷0.031 in.
A wider gap may cause difficulties in starting engine and in
overloading coil.
A gap that is too narrow may cause difficulties when accelera-
ting, when idling the engine or when performing at low
speeds.
Clean the dirt away from the base of the spark plug before re-
moving it from the cylinder after removing the cap (1).
It is very useful to examine the state of the spark plug just after it
has been removed from the engine since the deposits on the plug
and the colour of the insulator provide useful indications.
Correct heat rating:
The tip of the insulator should be dry and the colour should be
light brown or grey.
High heat rating:
In this case, the insulator tip is dry and covered with dark de-
posits.
Low heat rating:
In this case, the spark plug is overheated and insulator tip is
vitreous, white or grey in colour.
CAUTION*: Select a spark plug with a colder
or hotter heat range carefully and cautiou -
sly. A spark plug with too hot a heat range
may lead to preignition and possible engine
damage. A spark plug with too cold a heat
range may foul as the result of too much car -
bon buildup.
Before refitting the plug, thoroughly clean the
electrodes and the insulator using a brass-metal
brush.
Apply a little graphite grease to the spark plug
thread; fit and screw the spark plug by hand then
tighten to the torque of 10÷12 Nm- 7.4÷8.9 ft/
lb. Loosen the spark plug then tighten it again
to the torque of 10÷12 Nm- 7.4÷8.9 ft/lb.
Spark plugs which have cracked insulators or
corroded electrodes should be replaced.