41
Calibrating Main Jets/
Pilot Jets/Jet Needle E-
Clips (Internal)
Altitude, temperature, and the use of oxy-
genated gasoline affect the carburetion
needed for optimum engine performance.
The carburetor main jets must be
changed in conjunction with changes in
operating altitude, oxygenated gasoline
usage, and temperature. Also, the pilot
jets and jet needle E-clip positions may
have to be changed with changes in oper-
ating altitude. To change pilot jets and E-
clip positions, the carburetors must be
removed and disassembled (float cham-
ber, etc.). Arctic Cat highly recommends
that this service be done by an authorized
Arctic Cat Snowmobile dealer only.
NOTE: The following internal car-
buretor calibrations may be done by
the snowmobile owner if qualified to
do so. If the owner does not feel
qualified, take the snowmobile to an
authorized Arctic Cat Snowmobile
dealer for this service. This service
is at the discretion and expense of
the snowmobile owner.
As the ambient temperature rises or as
the snowmobile is operated at a higher
altitude, the main jets must be replaced
with leaner main jets. The original equip-
ment (production) main jets may need to
be changed (depending on the type of
gasoline you are using, your operating
altitude, and temperature). A Carburetor
Jet Chart decal is located on the belt
guard of the snowmobile. It should be
noted that when selecting the proper
main jets, it is better to be too rich rather
than too lean. To change carburetor main
jets, use the following procedure:
NOTE: Refer to Illustration 0745-
141 in this section for location of
components.
1. Loosen each carburetor flange
clamp and remove each carburetor
from the intake flange and boot.
2. Remove each drain screw and O-
ring from the carburetor float cham-
ber and drain the gas into a small
container or shop towels.
3. Using the main jet wrench (from the
tool kit), thread the main jet out of
each carburetor. Account for the baf-
fle ring. Install the new main jet and
the existing baffle ring. Tighten the
main jet securely.
4. Install each drain screw and O-ring;
then tighten securely.
5. Install and secure the carburetors.
Spark Plugs
NOTE: Always use the recom-
mended spark plugs in the engine.
See the appropriate specifications
sheet for correct spark plug gap.
Varying terrain conditions and operating
usage may require spark plugs of a differ-
ent heat range. For example, sustained
cross-country riding will usually require
colder heat-range spark plugs while trail
riding or other continual slow speed
operation will usually require hotter heat-
range spark plugs.
CAUTION
For information on altitude operation,
see Varying Altitude Operation sub-
section in this manual.
! WARNING
Whenever any maintenance is per-
formed on the fuel system, there
should be no welding, smoking, open
flames, etc., in the area.
CAUTION
Use only GENUINE Mikuni brass main
jets. Also, if using an oxygenated
gasoline (up to 10% ethanol), the car-
buretor main jet must be one size
larger than the main jet required for
regular unleaded gasoline.
CAUTION
A main jet which is too small will
cause severe engine damage. Engine
damage caused by lean jetting WILL
NOT BE covered by Arctic Cat Inc.
warranty policy.
