Arctic Cat Sno Pro 120 User manual

FOREWORD
This Arctic Cat Service Manual contains service and maintenance information for the Model Year 2012 Arctic
Cat Snowmobiles (except the Sno Pro 120). The manual is designed to aid service personnel in service-oriented
applications.
This manual is divided into sections. The sections cover specific snowmobile components or systems and, in addition
to the standard service procedures, includes assembling, disassembling, and inspecting instructions. When using this
manual as a guide, the technician should use discretion as to how much disassembly is needed to correct any given con-
dition.
The service technician should become familiar with the operation and construction of the components or systems by
carefully studying the complete manual. This will assist the service technician in becoming more aware of and efficient
with servicing procedures. Such efficiency not only helps build consumer confidence but also saves time and labor.
All Arctic Cat publications and snowmobile decals display the words Warning, Caution, and Note to emphasize impor-
tant information. The symbol ! WARNING identifies personal safety-related information. Be sure to follow the
directive because it deals with the possibility of severe personal injury or even death. A CAUTION identifies
unsafe practices which may result in snowmobile-related damage. Follow the directive because it deals with the possi-
bility of damaging part or parts of the snowmobile. The symbol NOTE: identifies supplementary information worthy
of particular attention.
At the time of publication, all information, photographs, and illustrations were technically correct. Some photographs
and illustrations used in this manual are used for clarity purposes only and are not designed to depict actual conditions.
Because Arctic Cat Inc. constantly refines and improves its products, no retroactive obligation is incurred.
All materials and specifications are subject to change without notice.
Keep this manual accessible in the shop area for reference.
Product Service and Warranty Department
Arctic Cat Inc.
© 2011 Arctic Cat Inc. December 2011
®™ Trademarks of Arctic Cat Inc., Thief River Falls, MN

TM
SHARE OUR PASSION.
2012
2012
Snowmobile
Service Manual
Service Manual
TABLE OF
CONTENTS
Section
1. General Information/Specifications
2. Engine
3. Engine-Related Items
4. Fuel Systems
5. Electrical Systems
6. Drive Train/Track/Brake Systems
7. Rear Suspension
8. Steering and Body

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1
SECTION 1 — GENERAL INFORMATION/
SPECIFICATIONS
TABLE OF CONTENTS
General Specifications ......................................................1-2
Snowmobile Identification..................................................1-2
Recommended Gasoline and Oil ......................................1-2
Engine Break-In.................................................................1-2
Drive Belt Break-In ............................................................1-3
Genuine Parts ...................................................................1-3
Varying Altitude Operation.................................................1-3
Preparation For Storage ....................................................1-5
Preparation After Storage..................................................1-6
After Break-In Checkup/Checklist...........................................1-6
Engine Specifications ........................................................1-8
Crankshaft Runout/Repair Specifications (2-Stroke).........1-9
Arctic Power Valve (APV) System Specifications (800 cc) ...1-9
Carburetor Specifications (570 cc) ....................................1-9
Electrical Specifications...................................................1-10
Ignition Timing Specifications (2-Stroke).........................1-11
Drive System Specifications............................................1-12
Drive Clutch/Driven Pulley-Related Specifications ..........1-12
Drive System Components..............................................1-12
Drive Belt Dimensions .....................................................1-12
Gear Case Performance Calibrations..............................1-13
Chain Case Performance Calibrations ............................1-14
Suspension Specifications ..............................................1-15
Track Specifications.........................................................1-15
Torque Specifications ......................................................1-16
Torque Conversions.........................................................1-17

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General Specifications
NOTE: General specifications for each 2012 Arctic
Cat Snowmobile can be accessed from the Arctic Cat
Cat Tracker Dealer Communication System online.
Snowmobile
Identification
The Arctic Cat Snowmobile has two important identifica-
tion numbers. The Vehicle Identification Number (VIN) is
stamped into the tunnel near the right-side footrest or on top
of the tunnel behind the seat. The decal also displays perti-
nent production information. The Engine Serial Number
(ESN) is stamped into the crankcase of the engine.
These numbers are required to complete warranty claims
properly. No warranty will be allowed by Arctic Cat Inc.
if the engine serial number or VIN is removed or muti-
lated in any way.
Recommended Gasoline
and Oil
RECOMMENDED GASOLINE (500/
570/1100 cc Non-Turbo)
The recommended gasoline to use in these snowmobiles
is 87 octane regular unleaded. In many areas, oxygenates
are added to the gasoline. Oxygenated gasolines contain-
ing up to 10% ethanol are acceptable gasolines; however,
on the 570 cc models whenever using oxygenated gaso-
lines, the carburetor main jet must be one size larger than
the main jet required for regular unleaded gasoline. For
example, if a 220 main jet is recommended for regular
unleaded gasoline, a 230 main jet must be installed if
using an oxygenated gasoline.
When using ethanol blended gasoline, adding a gasoline
antifreeze is not necessary since ethanol will prevent the
accumulation of moisture in the fuel system.
NOTE: On the 500 cc models for optimum perfor-
mance, do not exceed the recommended 87 octane
gasoline. Using a higher octane gasoline will not
increase overall performance.
RECOMMENDED GASOLINE
(800/1100 cc Turbo)
The recommended gasoline to use in these snowmobiles
is 91 octane (minimum).
NOTE: If a situation arises wherein 91 octane gaso-
line is not available, 87 octane gasoline can be substi-
tuted; however, do not prolong the usage of 87 octane
gasoline as it will cause poor engine performance.
In many areas, oxygenates are added to the gasoline.
Oxygenated gasolines containing up to 10% ethanol are
acceptable gasolines. Do not use gasolines containing
methanol.
RECOMMENDED OIL (2-Stroke)
The recommended oil to use in the oil-injection system is
Arctic Cat Formula 50 Injection Oil for 500/570 cc models
or either Arctic Cat APV Synthetic 2-Cycle Oil or Formula
SS Semi-Synthetic Oil for 800 cc models. These oils are
specially formulated to be used either as an injection oil or
as a pre-mix oil (for break-in) and meets all of the lubrica-
tion requirements of the Arctic Cat snowmobile engine.
RECOMMENDED OIL (4-Stroke)
The recommended oil to use is Synthetic 0W-40 Oil in all
temperatures and conditions.
OILCHARTJ
After the engine break-in period, the engine oil should be
changed every 2500-3000 miles (non-turbo) or 1500-
2000 miles (turbo) and before prolonged storage.
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.
CAUTION
Do not use white gas or gasolines containing methanol.
Only Arctic Cat approved gasoline additives should be
used.
CAUTION
Any oil used in place of the recommended oil may
cause serious damage.
CAUTION
Any oil used in place of the recommended oil could
cause serious engine damage.
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 could cause spark plug fouling and excessive
carbon buildup.

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1
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 recommends
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 snowmobile 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.
Varying Altitude
Operation
Operating a snowmobile at varying altitudes requires recal-
ibration of carburetor and/or drive system components.
The altitude information decal is located beneath the hood
of the snowmobile on the belt guard on the 500/570/1100
cc non-turbo models. Consult the appropriate specification
sheet on Cat Tracker Online for the F/M/XF models.
Following are basic altitude theories for clutching,
engine, suspension, and track.
CLUTCHING
On a normally-aspirated engine as altitude changes,
engine horsepower changes with it. As you go up in alti-
tude, the engine loses horsepower. Because of this, the
continuously variable transmission (CVT) system needs
to be calibrated to compensate for the horsepower loss.
At altitudes above 5000 ft, the engine loses peak horse-
power but will also lose horsepower at engagement speed.
For this reason, calibrating the drive system is usually
needed in order to attain acceptable performance. Changing
drive clutch engagement speed can be done 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.
Other more complicated methods exist such as engage-
ment notches and changing the position of the cam arm
center of gravity in relation to the roller. This is called
“tucking the weight” and can be used, but, like the
engagement notch, it can hurt belt life.
The driven clutch will also play a part in CVT tuning for
high altitude operation. A steeper helix (torque bracket)
angle in the driven clutch will mean a quicker up-shift. A
shallower angle will mean a slower up-shift. If the up-shift
is too quick, due to a very steep helix, RPM will be pulled
down under the peak operating RPM of the engine (where
the horsepower is) and performance will suffer. The engine
may even bog. If you have a helix that is too shallow, the
engine may over-rev or have poor acceleration. Usually,
angles shallower than the sea level calibrations work best.
The driven spring will also affect driven clutch tuning.
Tighten the spring, and RPM will increase. Loosen the
spring, and RPM will decrease. The spring should be used
to fine-tune and complement the helix selection.
Carburetor calibration changes for high altitude operation will
have an effect on the CVT system and how it operates. Under-
standing the basics of CVT operation is important in order to
make the correct high altitude CVT calibration changes.
ENGINE
A normally aspirated engine will generate more horsepower
at sea level than it does at higher altitudes. The reason is that
the higher you go, less oxygen is available for the engine to
use during its combustion process. Less oxygen means it
needs less fuel to obtain the correct air/fuel ratio to operate
properly. This is why the fuel ratio has to be recalibrated.
High altitude engines operate as though they have a lower
compression ratio. This, along with less oxygen and less
fuel, means that the engine generates less horsepower.
The carbureted models will also have lower pressure applied
to the float chamber because of pressure changes in the atmo-
sphere between high altitude and sea level. All of these char-
acteristics will become more evident the higher the altitude.
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
Running the engine with the drive belt removed 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.