Arctic Cat Sno Pro 120 2011, Service Manual

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2-90
REED VALVE ASSEMBLY
1. Inspect the reed valves, stoppers, and valve blocks
for cracks or any deterioration.
CM162
2. Wash the reed valves, stopper, and cage assembly in
parts-cleaning solvent and blow dry.
3. Inspect the reed stopper height. Using a caliper, mea-
sure the distance from the seat to the bottom outer tip
edge of the stopper. Measurement must not exceed
specifications. If measurement is not within specifi-
cations, either bend or replace the reed stopper.
CM163
4. Inspect the reed-to-seat clearance. Using a feeler
gauge, measure the clearance. Clearance must be less
than 0.008 in. If clearance is not within specifica-
tions, replace the reed valve.
5. To assemble, place the reed valves on the cage with
its clipped corner positioned to the lower right hand
corner of the cage. Place the reed stopper assembly
into position and secure with the screws tightened to
48 in.-lb.
CM164A
Measuring Critical
Components

NOTE: Critical engine specifications charts can be
found in Section 1 of this manual.
CYLINDER HEAD VOLUME
(Squish-Gap Method)
To check the squish gap, a micrometer and two heavy
pieces of solder will be needed.
1. Remove the spark plugs from the engine.
2. Simultaneously insert two pieces of solder down
through the spark plug hole and push them up against
the inner cylinder bore towards the MAG-side and
PTO-side of the cylinder.
3. Pull the recoil rope and crank the engine over several
times while the solder is being held firmly in place.
4. Remove both pieces of solder from the cylinder.
Using the micrometer, measure the very end of the
squeezed solder piece. Record the reading.

NOTE: If the solder hasn’t been squeezed by the
piston, a larger piece of solder must be used. Repeat
procedure.
5. Using the opposite end of the solder pieces, insert
them down through the spark plug hole towards the
PTO-side and MAG-side of the cylinder. Push on the
solder until they contact the inner cylinder bore.
6. Pull the recoil rope and crank the engine over several
times. Remove both pieces of solder from the cylin-
der and measure the opposite squeezed ends with a
micrometer. Record reading.

NOTE: Measure from PTO to MAG-side of the piston
to accurately measure the squish gap. Never measure
across piston, exhaust side to opposite side, as the
piston will rock and the reading won’t be accurate.
Readings may vary from side to side.

NOTE: Make sure the smaller reading is 0.059 in. or
less for the 800 cc or 0.058 in. or less for the 1000 cc.
CYLINDER TRUENESS
1. Measure each cylinder in the three locations from front
to back and side to side for a total of six readings.
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