Arctic Cat Sno Pro 120 2011, Service Manual

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Engine Break-In
2-STROKE
The Arctic Cat 2-stroke engine (when new or rebuilt)
requires a short break-in period before the engine is sub-
jected to heavy load conditions. Arctic Cat requires that
the first tankful of fuel be premixed at a 100:1 ratio in all
oil-injection models.
During the break-in period, a maximum of 1/2 throttle is
recommended; however, brief full-throttle accelerations
and variations in driving speeds contribute to good
engine break-in.
4-STROKE
The Arctic Cat 4-stroke engine (when new or rebuilt)
requires a short break-in period before the engine is sub-
jected to heavy load conditions.
This engine does not require any pre-mixed fuel during
the break-in period.
To ensure trouble-free operation, careful adherence to the
following break-in guidelines will be beneficial.
* With occasional full-throttle operation.
To ensure proper engine break-in, Arctic Cat recom-
mends that the engine oil and filter be changed after 500
miles or after one month, whichever comes first. This
service is at the discretion and expense of the snowmo-
bile owner.
Drive Belt Break-In
Drive belts require a break-in period of approximately 25
miles. Drive the snowmobile for 25 miles at 3/4 throttle or
less. By revving the engine up and down (but not exceed-
ing 60 mph), the exposed cord on the side of a new belt
will be worn down. This will allow the drive belt to gain
its optimum flexibility and will extend drive belt life.

NOTE: Before starting the snowmobile in extremely
cold temperatures, the drive belt should be removed
and warmed up to room temperature. Once the drive
belt is at room temperature, install the drive belt (see
Drive Belt sub-section in Section 6 of this manual).
Genuine Parts
When replacement of parts is necessary, use only genuine
Arctic Cat parts. They are precision-made to ensure high
quality and correct fit.
High Altitude Operation
Operating a snowmobile at varying altitudes requires
changes in performance components. These changes
affect drive train components and carburetion compo-
nents.

NOTE: The 1100 cc turbo does not require calibra-
tion changes for varying altitudes.
High altitude information decal(s) are located beneath the
hood of the snowmobile on the Crossfire/M-Series and
on the belt guard on the remaining models.
The M-Series snowmobiles are initially set up at the fac-
tory for operation between 6000-9000 feet. Consult the
appropriate specifications for this information.
Following are basic high altitude theories for clutching,
engine, suspension, and track.
CLUTCHING
As altitude changes, engine horsepower changes with it.
As you go up in altitude, the engine loses horsepower.
Because of this, the constant velocity transmission
(CVT) system needs to be changed to compensate for the
horsepower loss.
At altitudes above 5000 ft, clutch engagement RPM is
normally higher than the standard setting due to the
horsepower loss at altitude as opposed to what would be
seen for horsepower at sea level. The engine will lose
peak horsepower but will also lose horsepower at
engagement speed. For this reason, higher engagement
speeds are usually needed at altitude in order to attain
acceptable acceleration. This higher engagement speed
can be attained several ways. Some of the methods will
affect other characteristics of CVT operation, so you
must be careful what you change. Drive clutch springs
are the most common way to increase engagement speed;
however, by simply changing the cam arms to a lighter
weight from the heavier sea level cam arm, you will gain
some engagement speed.
CAUTION
DO NOT exceed the one (1) tankful limitation of a 100:1
gas/oil break-in mixture. Continuous use of a gas/oil
mixture, unless consistently operating in extremely cold
conditions (-26°C/-15°F or colder), could cause spark
plug fouling and excessive carbon buildup.
CAUTION
DO NOT use premixed fuel in the snowmobile gas tank.
Engine damage will occur.
0-200 miles 1/2 Throttle (45 MPH-max)
200-400 miles 1/2-3/4 Throttle
400-600 miles 1/2-3/4 Throttle *
CAUTION
Never run the engine with the drive belt removed.
Excessive revving of the engine could result in serious
engine damage and drive clutch failure.
CAUTION
On the 570 cc, carefully follow the Carburetor Jet Chart
recommendations for proper carburetor calibration for
altitude, temperature, and gasoline being used.
Manual
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