Arctic Cat ZR 900 Series 2006 Operator's Manual page 53

Removing/Installing Spark
Plugs (2-Stroke Models)
1. Remove the spark plug caps
from the plugs.
2. Using a spark plug wrench,
remove the plugs.
3. Install the plugs and finger-
tighten.
4. Tighten the spark plugs to 2.5-
2.8 kg-m (18-20 ft-lb); then
install the spark plug caps.
Removing/Installing Spark
Plugs (660 cc Models)
1. Remove the spark plug/coil
cover.
2. Remove the cap screws secur-
ing the spark plug coils to the
engine; then remove the coils.
3. Using a spark plug wrench,
remove the plugs.
4. Install the plugs and finger-
tighten.
5. Tighten the spark plugs to 2.1
kg-m (15 ft-lb); then install the
spark plug coils and secure
them with cap screws.
6. Install the spark plug/coil cover.
Checking Spark Plugs
(2-Stroke Models)
To see if the spark plugs being used
are of the proper heat range (after
the snowmobile has been operated
under normal driving conditions),
remove the spark plugs and exam-
ine the condition of the center elec-
trode insulator of each spark plug.
52
A. TAN or LIGHT BROWN
insulator indicates correct
spark plugs (heat range).
B. LIGHT GRAY or WHITE
insulator indicates over-
heating of the engine. This
condition is caused by a too
lean condition or incorrect
spark plugs (heat range too
hot).
C. BLACK insulator indicates
fuel in the combustion
chamber is not burning
completely. This condition
is caused by a too rich
condition, too much oil, or
incorrect spark plugs (heat
range too cold).

NOTE: If the center electrode
insulators are light gray, white, or
black and if the carburetor adjust-
ments (on carbureted models),
oil-injection pump synchroniza-
tion, and ignition timing are cor-
rect, different heat-range spark
plugs may be necessary. Autho-
rized Arctic Cat Snowmobile deal-
ers have detailed spark plug
information. Consult a dealer
before changing spark plugs, as
incorrect heat-range spark plugs
could cause poor engine perfor-
mance or engine damage.
MAINTENANCE
AO352A