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At low RPM, the exhaust valves are held
in the DOWN position by return springs.
This gives the engine a “"low port”"
exhaust design calibrated to provide
maximum low RPM power and improve
fuel economy at trail speeds.
At high RPM, the exhaust valves are
raised. This creates a “"high port”" exhaust
design calibrated to provide maximum
performance at high RPM.
22
NOTE: The RPM ranges will vary
from model to model.
NOTE: If the servomotor cycles
three times and then shuts down, the
exhaust
valve
adjusted
correctly.
valves may also be sticking.
NOTE: APV cleaning may be done
by the snowmobile owner if qualified
to do so. If the owner does not feel
739-152F
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.
Exhaust Controlled
Timing (ECT) System
(8000)
This system automatically adjusts the
ignition timing to provide maximum per-
formance through a variety of operating
conditions. The ECM receives input on
engine RPM (demand) and exhaust pipe
temperature
(engine
adjusts the ignition timing accordingly.
This system is not adjustable and is main-
739-152G
tenance free.
If a system fault is suspected, use an ohm-
meter to check continuity of the exhaust
pipe temperature sensor located in the
expansion chamber. A reading of either 0
ohm or infinity indicates a failed sensor.
NOTE: A disabled ECT system
WILL NOT cause engine damage;
however, a failed ECT system will
have slower throttle response and
may produce slightly less top-end
performance.
739-152H
cables
are
not
The
exhaust
condition)
and
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