Snowmobile Arctic Cat (2009 year). Manual - part 13

MAINTENANCE

45

ADJUSTING 

CARBURETORS

The carburetors have been calibrated at

the factory for average riding condi-

tions; however, altitude, temperature,

and general wear may necessitate cer-

tain carburetor adjustments. 

Be sure

the correct carburetor main jets

for the operating temperature, alti-

tude, and type of gasoline are being

used (see Selecting Carburetor

Main Jets sub-section).

 Since carbu-

retor adjustments critically affect

engine performance, Arctic Cat recom-

mends that all changes in internal car-

buretor calibration and piston valve

synchronization be made by an autho-

rized Arctic Cat Snowmobile dealer;

however, four external adjustments can

be made on each carburetor. 

These are the choke cable travel, piston

valves, pilot air screws, and idle speed

screws.

 NOTE: Carburetor adjustments
and changing main jets 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 Arc-
tic Cat Snowmobile dealer for this
service. This service is at the dis-
cretion and expense of the snow-
mobile owner.

Adjusting Choke Cable

1. Be sure the ignition switch key is

in the OFF position and the brake

lever lock is set.

2. Loosen the jam nut securing each

choke cable adjuster. Rotate each

choke cable adjuster clockwise

until it bottoms against the brass

plunger cap.

0727-156

3. Slowly rotate one choke cable

adjuster counterclockwise while

checking the choke lever for free-

play. As soon as all free-play has

been removed from the end of the

lever, stop rotating the adjuster.

4. With free-play removed from the

lever, slowly rotate each choke

cable adjuster once again clock-

wise while checking the choke

cable lever for free-play. Adjust

until 3 mm (1/8 in.) free-play

between front bottom edge of lever

and housing is attained. Securely

tighten the adjuster jam nut.

732-848B

! CAUTION

After operating the snowmobile for
the initial 5-10 minutes, stop the
engine, allow the engine to cool
down, and check the coolant level.
Add coolant as necessary.

! CAUTION

Make sure to perform these adjust-
ment/synchronization procedures
on all carburetors.

46

MAINTENANCE

 NOTE: If a carburetor choke
cable is adjusted too tight, the
engine will only operate on one
cylinder at idle.

Synchronizing Piston 

Valves 

1. Remove the air-intake silencer

boots from the silencer to access

the intake bores.

2. Rotate the idle speed screws coun-

terclockwise until all spring ten-

sion is removed.

0727-156

3. Loosen the jam nut securing each

throttle cable swivel adapter; then

rotate each swivel adapter clock-

wise until each piston valve bot-

toms in the piston valve bore.

4. In turn on each carburetor, place a

finger lightly against the side of

the piston valve; then rotate the

carburetor swivel adapter counter-

clockwise until slight upward

movement of the valve is noted.

5. Check to make sure the valves

start to open at the exact same

moment by placing a thumb and

finger against the valves; then

lightly compress the throttle lever.

 NOTE: If an individual piston
valve starts to open before
another, rotate the swivel adapter
on the valve which is lifting first
clockwise, just enough to synchro-
nize the valves. Recheck by repeat-
ing steps 2-5.

6. With the piston valves synchro-

nized, tighten the swivel adapter

jam nuts securely. Slide the rubber

throttle cable caps down over the

swivel adapters.

 NOTE: There must be free-play
in the throttle lever on all models.

7. In turn on each carburetor, place a

finger against the piston valve.

Rotate the idle speed screw clock-

wise until it contacts the valve.

8. Compress the throttle lever to the

full-open position; then rotate each

idle speed screw clockwise 2 com-

plete turns. Release the throttle lever.

 NOTE: There must be 0.75-1.5
mm (0.030-0.060 in.) free-play
between the throttle lever and the
control housing.

9. At this point, there must be 0.75-

1.5 mm (0.030-0.060 in.) of cable

free-play gap in the throttle lever.

If there is no cable free-play in the

throttle lever, the throttle safety

switches will not function prop-

erly, and the engine will cut out in

the idle position.

0741-518

! WARNING

Be sure to tighten the swivel
adapter jam nuts securely. If a
swivel adapter jam nut is not tight-
ened, the adjuster can rotate out of
the carburetor cap causing the pis-
ton valve not to return to the full-
closed position.

MAINTENANCE

47

 NOTE: If cable free-play gap is
not correct, rotate each swivel
adapter an equal amount until rec-
ommended free-play is achieved.
Each piston valve must be resting
against the tip of its idle speed
screw.

 NOTE: If throttle cable free-play
is incorrect, the carburetor safety
switches will be activated prema-
turely and the engine will not start.

Fine-Tuning Pilot Air 

Screws and Idle Speed 

Screws

1. While counting the rotations, care-

fully rotate the pilot air screws

clockwise until lightly seated.

2. Rotate the pilot air screws counter-

clockwise the exact number of

rotations ± 1/4 turn from the seated

position as an initial setting.

3. Install the air-intake silencer boots

taking care that the boots are prop-

erly positioned and that the boots

are not “folded” in the air-intake

silencer causing a restriction of air

flow.

4. With the snowmobile on a

shielded safety stand, start the

engine, release the brake lever

lock, and thoroughly warm up.

 NOTE: Make engine idle adjust-
ment only after the engine has
reached running temperature.
Since the idle speed screws have
not been fine-tuned, slight throttle
pressure may be necessary to
keep the engine running. Allow
engine to warm up for 2-3 minutes.

5. After the engine has been thor-

oughly warmed up, fine-tune the

pilot air screws (equally) and the

idle speed screws (equally) until

the engine runs smoothly.

 NOTE: Engine idle RPM should
be approximately 1500.

6. Test the throttle control lever by

compressing and releasing it sev-

eral times. The lever must return to

the idle position quickly and com-

pletely.

! CAUTION

Do not force a pilot air screw when
rotating it clockwise; damage to
the pilot air screw needle tip will
result.

! WARNING

DO NOT stand behind the snowmo-
bile or near the rotating track.
NEVER run the track at high speed
when the track is suspended.

! WARNING

If a tachometer is not available,
care must be taken not to adjust
engine idle speed too high.

! CAUTION

It is important that the pilot air
screws are adjusted equally and
that the idle speed screws are
adjusted equally.

! WARNING

DO NOT operate the snowmobile
when any component in the throt-
tle system is damaged, frayed,
kinked, worn, or improperly
adjusted. If the snowmobile is
operated when the throttle system
is not functioning properly, per-
sonal injury could result.

48

MAINTENANCE

SELECTING 

CARBURETOR MAIN 

JETS

Altitude, temperature, and the use of

oxygenated gasoline affect the carbure-

tion needed for optimum engine perfor-

mance. The carburetor main jets must

be changed in conjunction with changes

in operating altitude, oxygenated gaso-

line usage, and temperature. As the

ambient temperature rises or as the

snowmobile is operated at a higher alti-

tude, the main jets must be replaced

with leaner main jets. The original

equipment (production) main jets may

need to be changed (depending on the

type of gasoline you are using, your

operating altitude, and temperature). A

Main Jet Chart decal is located beneath

the hood 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: Carburetor main jets may
be changed 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.

1. Loosen each carburetor flange

clamp and remove each carburetor

from the intake flange and boot.

2. Remove each drain plug and O-

ring from the carburetor float

chamber 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 baffle ring/washer. Install the

new main jet and the existing baf-

fle ring/washer. Tighten the main

jet securely.

0728-054

4. Install each drain plug and O-ring;

then tighten securely.

5. Install and secure the carburetors.

SPARK PLUGS

(1100 cc Models)

 NOTE: If spark plugs must be
replaced, take the snowmobile to
an authorized Arctic Cat Snowmo-
bile dealer for inspection and ser-
vice. This service is at the
discretion and expense of the
snowmobile owner.

! CAUTION

Use only GENUINE Mikuni brass
main jets. Also, if using an oxygen-
ated gasoline (up to 10% ethanol
or up to 15% MTBE), the carburetor
main jet must be one size larger
than the main jet required for regu-
lar unleaded gasoline.

! CAUTION

A main jet which is too small will
cause severe engine damage.
Engine damage caused by lean jet-
ting WILL NOT BE covered by Arc-
tic Cat warranty policy.

! WARNING

Whenever any maintenance is per-
formed on the fuel system, there
should be no welding, smoking,
open flames, etc., in the area.