Husqvarna TC 250 2009 Manual De Uso página 90

MUM1-250_310_450_510_2009_GB
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 accelerat-
ing, 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.
2
24
18-11-2008 11:10 Pagina 24
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 deposits.
Low heat rating:
In this case, the spark plug is overheated and insulator tip is vitre-
ous, white or grey in colour.
CAUTION*: Select a spark plug with a colder or
hotter heat range carefully and cautiously. A
spark plug with too hot a heat range may
lead to preignition and possible engine dam-
age. A spark plug with too cold a heat range
may foul as the result of too much carbon
buildup.
1
Before refitting the plug, thoroughly clean the
electrodes and the insulator using a brass-met-
al 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.