Arctic Cat M 8000, Service Manual

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3
Engine Break-In
4000/8000
The Arctic Cat engine (when new or rebuilt) requires a
short break-in period before the engine is subjected 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.
6000
The Arctic Cat engine (when new or rebuilt) requires a
short break-in period before the engine is subjected to
heavy load conditions.
When the snowmobile is new (0 hours), an addition to
the increased fuel and oil ratio, the ECM will limit the
engine to 6500 RPM for the first 18 minutes of the
engine's run time. After the first 18 minutes, the rev limit
will be eliminated but a greater fuel and oil ratio will con-
tinue through the first two hours of engine run time.
Premixing fuel and oil during the break in period is not
required. With the oil delivery control strategy of the
electronic oil pump, the pump will automatically com-
pensate and deliver a richer fuel-to-oil ratio during the
engine break-in period.
Some customers may choose to pre-mix the first tank and
if this is the case, a pre-mix ratio of 100:1 is acceptable.
A pre-mix ratio of 100:1 combined with the richer
fuel/oil delivered from the electronic oil pump during
break-in may cause additional smoke at start up and idle.
During the break-in period, a maximum of 1/2 throttle
(with varying throttle positions) is recommended; how-
ever, brief full-throttle accelerations and variations in
driving speeds contribute to good engine break-in.
Drive Belt Break-In
Drive belts require a break-in period of 25 miles. Drive
the snowmobile for 25 miles at 3/4 throttle or less. By
revving the engine up and down (but not exceeding 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 opti-
mum 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 the Drive Train/Track/Brake
Systems section 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
recalibration of drive system components. Consult the
appropriate specification sheet on Cat Tracker Online.
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 char-
acteristics 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 engage-
ment speed.
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.
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.
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.
CAUTION
Running the engine with the drive belt removed could
result in serious engine damage and drive clutch failure.