Content .. 10 11 12 13 ..

Snowmobile Arctic Cat (2006 year). Manual - part 12

MAINTENANCE

Adjusting Pilot Air Screw

1. While counting the rotations,

carefully rotate the pilot air

screw clockwise until lightly

seated.

2. Rotate the pilot air screw coun-

terclockwise the exact number

of rotations ± 1/4 turn from the

seated position for an initial set-

ting.

3. Install the air-intake silencer

boot taking care that the boot is

properly positioned and that the

boot is not “folded” in the air-

intake silencer causing a restric-

tion of air flow.

Adjusting Engine Idle Speed

1. With the snowmobile on a

shielded safety stand, start the

engine, release the parking

brake, and thoroughly warm up.

“Fine-tune” the idle speed

screw and the pilot air screw

until the engine idles smoothly

at the desired RPM (1500 RPM

is recommended).



NOTE: Make engine idle adjust-

ment only after the engine has
reached running temperature.



NOTE: If the engine does not

star t after the carburetor has
been adjusted, repeat steps 2-6 of
Adjusting Piston Valve sub-sec-
tion. If all cable slack is “taken
up,” the throttle/ignition monitor
switch will prevent the ignition
s y s t e m f ro m f i r i n g t h e sp a r k
plugs.

ADJUSTING CARBURETORS —
VM-STYLE (Twin)

The carburetors have been cali-

brated at the factory for average

riding conditions; however, alti-

tude, temperature, and general wear

may necessitate certain carburetor

adjustments. Be sure the correct

carburetor main jets for the oper-

ating temperature, altitude, and

type of gasoline are being used

(see Selecting Carburetor Main

Jet(s) section). Since carburetor

adjustments critically affect engine

performance, Arctic Cat recom-

mends that all changes in internal

carburetor calibration and piston

valve synchronization be made by

an authorized Arctic Cat Snowmo-

bile 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.

! CAUTION

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

! WARNING

DO NOT stand behind the snow-
m o b i l e o r n e a r t h e ro t a t i n g
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.

! WARNING

DO NOT operate the snowmo-
bile when any component in the
throttle system is damaged,
frayed, kinked, worn, or improp-
erly adjusted. If the snowmobile
is operated when the throttle
system is not functioning prop-
e r l y, p e r s o n a l i n j u r y c o u l d
result.

MAINTENANCE



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 expense is at the
discretion and expense of the
snowmobile 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.

R o t a t e e a c h c h o k e c a b l e

adjuster clockwise until it bot-

toms 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

clockwise 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



NOTE: If a carburetor choke

cable is adjusted too tight, the
engine will only operate on one
cylinder at idle.

Synchronizing Piston Valves



NOTE: On some models, the

air-intake silencer is a one-piece
unit, and the silencer boots can
be removed to access the intake
bores. Remove the boots; then
proceed to step 4.



NOTE: On some models, the

air-intake silencer includes a
cover/tool tray assembly and a
baffle/resonator, and the silencer
b o o t c a n n o t b e r e m o v e d t o
access the intake bores. Proceed
to step 1.

1. Open the air-intake silencer

cover; then remove the screws

securing the cover/tool tray

assembly to the silencer.

2. Close the cover; then tip the

cover/tool tray assembly for-

ward and out of its slots and

remove the assembly.

! CAUTION

Make sure to perform these
adjustment/synchronization
procedures on all carburetors.

MAINTENANCE

3. Using a large flat-blade screw-

driver, remove the baffle/reso-

nator tabs from the air-intake

silencer slots and remove the

baffle/resonator to access the

intake bores.



NOTE: The baffle/resonator can

b e r e m o v e d m o r e e a s i l y b y
removing the back tabs first.

4. Rotate the idle speed screws

counterclockwise until all

spring tension is removed.

0727-156

5. Loosen the jam nut securing

each throttle cable swivel

adapter; then rotate each swivel

adapter clockwise until each

piston valve bottoms in the pis-

ton valve bore.

6. In turn on each carburetor,

place a finger lightly against the

side of the piston valve; then

rotate the carburetor swivel

adapter counterclockwise until

slight upward movement of the

valve is noted.

7. 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

v a l v e s t a r t s t o o p e n b e f o r e
another, rotate the swivel adapter
on the valve which is lifting first
clockwise, just enough to syn-
chronize the valves. Recheck by
repeating steps 4-7.

8. With the piston valves synchro-

n i z e d , t i g h t e n t h e s w i v e l

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.

9. In turn on each carburetor,

place a finger against the piston

valve. Rotate the idle speed

screw clockwise until it con-

tacts the valve.

10. Compress the throttle lever to

the full-open position; then

rotate each idle speed screw

clockwise 2 complete 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.

11. 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

l e v e r, t h e t h r o t t l e s a f e t y

switches will not function prop-

erly, and the engine will cut out

in the idle position.

! WARNING

Be sure to tighten the swivel
adapter jam nuts securely. If a
swivel adapter jam nut is not
t i g h t e n e d , t h e a d j u s t e r c a n
rotate out of the carburetor cap
causing the piston valve not to
return to the full-closed posi-
tion.

MAINTENANCE

733-081C



NOTE: If cable free-play gap is

not correct, rotate each swivel
adapter an equal amount until
r e c o m m e n d e d f r e e - p l a y i s
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,

carefully rotate the pilot air

screws clockwise until lightly

seated.

2. Rotate the pilot air screws

counterclockwise the exact

number of rotations ± 1/4 turn

from the seated position as an

initial setting.

3. On some models, install the air-

intake silencer boots taking care

that the boots are properly posi-

tioned and that the boots are not

“folded” in the air-intake

silencer causing a restriction of

air flow.

4. On some models, install the

baffle/resonator and the cover/

tool tray assembly.

5. 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 throt-
tle pressure may be necessary to
keep the engine running. Allow
engine to warm up for 2-3 min-
utes.

6. 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: If a tachometer is being

used, engine idle RPM should be
approximately 1500.

! CAUTION

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

! WARNING

DO NOT stand behind the snow-
m o b i l e o r n e a r t h e ro t a t i n g
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.

Content .. 10 11 12 13 ..