Arctic Cat Sno Pro 120 2011, Service Manual

Page: 266 / 535

5
5-5
2. To determine which switch needs adjusting, discon-
nect both carburetor safety switches from the main
wiring harness connector.
3. Connect a digital ohmmeter to one carburetor safety
switch connector; then compress the throttle lever
while observing the meter reading and measure the
gap between the throttle lever and control housing at
the moment the meter reading changes from open to
closed. Repeat this step for the other carburetor
safety switch.

NOTE: The correct throttle lever/control housing
gap is a range of 0.375-0.500 in. the moment the
meter reading changes from open to closed. A switch
that changes from open to closed before the other
one is the switch that must be raised to attain safety
switch synchronization.
742-349A
4. If an adjustment is necessary, loosen the switch
bracket screws, move the switch up, tighten the
screws, and then reset using step 3.

NOTE: After completion of any adjustments, throttle
lever “side pressure” should not cause an ignition
miss at idle. Carburetor switches set too low or an
excessively tight throttle cable makes the shutdown
system very sensitive to throttle lever “side pres-
sure” near idle. To test carburetor safety switch syn-
chronization, follow steps 5-9.
5. Reconnect the carburetor safety switch connectors.
Place the rear of the snowmobile on a shielded safety
stand; then start the engine and allow it to warm up
for 3-4 minutes.
6. Hold both the top and bottom of the throttle lever pin
so that depression of the throttle lever does not move
the lever pin in its control slot.
0728-916
7. Slowly depress the throttle lever to increase engine
RPM.

NOTE: Engine RPM must be allowed to increase
slowly.
8. Observe the tachometer and the drive clutch to deter-
mine the moment the carburetor safety switches shut
down the ignition. Since retaining the throttle lever
pin prevents the switch in the throttle control housing
from closing, the carburetor safety switches should
shut down the ignition at or slightly after clutch
engagement.
9. Repeat steps 6-8 several times. If ignition shutdown
always occurs at or slightly after clutch engagement,
the carburetor safety switches are synchronized.
10. To complete the procedure, repeat step 1.

NOTE: After completion of any adjustments, throttle
lever “side pressure” should not cause an ignition
miss at idle. Carburetor safety switches set too low or
an excessively tight throttle cable makes the shut-
down system very sensitive to throttle lever “side
pressure” near idle.
Throttle Position Sensor
(2-Stroke EFI Models)

NOTE: Engines equipped with throttle position sen-
sor have a protective feature called “fail-safe” igni-
tion timing preventing engine damage should the
TPS fail. If the TPS does fail, the engine may run nor-
mally at low RPM but will run poorly at high RPM
allowing the operator to get the snowmobile to safety
with no engine damage. The engine will continue to
operate this way until the TPS is adjusted or
replaced.

NOTE: Ignition timing specifications are located on
the Electrical Specifications Chart in Section 1 of this
manual.
Manual
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