Husqvarna TC 250 2012 Specifications - Operation - Maintenance page 61

SPARK PLUG CHECK
Use:
- NGK CR9EI
spark plug (A);
the gap is:
- 0,8÷ 0,9 mm (0,031÷ 0,035 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 or poor performance at low speed.
- Remove the connector (1) from the coil (2).
- Loosen the two screws (3), remove coil (2) and retaining
bracket (4), and then remove the spark plug.
NOTE: during refitting, check that the gasket (5) is correctly
positioned; the reference lug (6) must correspond with the
retaining bracket (4) gap (7)
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.
A
0,8 ÷ 0,9 mm
0,031 ÷ 0,035 in.
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 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.
2
4
3
SPECIFICATIONS - OPERATION - MAINTENANCE
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 (1÷1,2 Kgm - 7.4÷8.9 ft/lb
Spark plugs which have cracked insulators or
corroded electrodes should be replaced.
1
5
).
6
7
EN - 19