Snowmobile Arctic Cat (2008 year). Manual - part 58

2-170

5. Inspect the bearing dowel pins for wear.

6. Inspect the sealing surfaces of the crankcase

halves for trueness by placing each crankcase half

on the surface plate covered with #400 grit wet-or-

dry sandpaper. Using light pressure, move each

half in a figure eight motion. Inspect the sealing

surfaces for any indication of high spots. A high

spot can be noted by a bright metallic finish. Cor-

rect any high spots by continuing to move the half

in a figure eight motion until a uniform bright

metallic finish is attained.

„NOTE: Care must be taken not to remove an
excessive amount of aluminum, or the crankcase
will have to be replaced. If excessive aluminum is
removed, too much pre-load will be exerted on the
crankshaft bearings when assembled.

CM160

CRANKSHAFT

„NOTE: If any servicing of the connecting rods,
center bearings, or oil-injection pump drive gear is
necessary, Arctic Cat recommends that the crank-
shaft be taken to a qualified machine shop for that
service.

1. Wash the crankshaft with bearings in parts-clean-

ing solvent.

2. Inspect the bearings for wear, scoring, scuffing,

damage, or discoloration. Rotate the bearings.

Bearings must rotate freely and must not bind or

feel rough. If any abnormal condition is noted,

replace the bearing.

FC039

3. Inspect the connecting-rod bearings by rotating

them. The bearings must rotate freely and must not

bind or feel rough. If a connecting-rod bearing

must be replaced, the connecting rod and crank pin

must also be replaced.

FC040

4. Inspect the oil-injection pump drive gear for any

signs of worn or chipped teeth. If either condition

exists, replace the gear.

„NOTE: Lubricate bearings thoroughly prior to
assembly.

REMOVING/INSTALLING OUTER 
CRANKSHAFT BEARINGS

„NOTE: The end bearings are not pressed onto
the crankshaft. The bearings can be removed sim-
ply by sliding them off the crankshaft.

CM161

! CAUTION

Water or parts-cleaning solvent must be used in
conjunction with the wet-or-dry sandpaper or dam-
age to the sealing surface may result.

2-171

2

Inspect the crankshaft bearing area for wear. If any

wear is noted on either end, replace the crankshaft end.

„NOTE: Install the bearings by sliding each bear-
ing onto the crankshaft making sure the dowel-pin
hole in the outer race is properly positioned and
will align with its hole and pin in the crankcase.

CM161

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,

measure the distance from the seat to the bottom

outer tip edge of the stopper. Measurement must

not exceed specifications. If measurement is not

within specifications, 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 0.20 mm (0.008 in.). If clearance is not

within specifications, 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 stop-

per assembly into position and secure with the

screws coated with red Loctite #271.

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 sev-

eral times while the solder is being held firmly in

place.

2-172

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 sev-

eral times. Remove both pieces of solder from the

cylinder and measure the opposite squeezed ends

with a micrometer. Record reading.

„NOTE: Measure from PTO to MAG-side of the pis-
ton to accurately measure the squish gap. Never
measure across piston, exhaust to carburetor
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 1.5 mm
(0.059 in.) or less for the 800 cc or 1.49 mm (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 read-

ings.

FC044

2. The trueness (out-of-roundness) is the difference

between the highest and lowest reading. Maxi-

mum trueness (out-of-roundness) must not exceed

0.1 mm (0.004 in.).

0725-586

PISTON SKIRT/CYLINDER 
CLEARANCE

1. Measure each cylinder front to back about 2.5 cm

(1 in.) from the bottom of each cylinder.

2. Measure the corresponding piston skirt diameter at a

point 1 cm above the piston skirt at a right angle to

the piston-pin bore. Subtract this measurement from

the measurement in step 1. The difference (clear-

ance) must be within 0.075-0.105 mm (0.0029-

0.0041 in.).

AC091

PISTON-RING END GAP

1. Place each piston ring in the wear portion above the

exhaust port of its respective cylinder. Use the pis-

ton to position each ring squarely in each cylinder.

2. Using a feeler gauge, measure each piston-ring

end gap. Acceptable ring end gap must be within

0.30-0.50 mm (0.012-0.0196 in.).

2-173

2

FC045

PISTON PIN AND PISTON-PIN 
BORE

1. Measure the piston pin diameter at each end and in

the center. Acceptable piston pin measurement

must be within 21.995-22.000 mm (0.8659-0.8661

in.) for the 800 cc or 23.995-24.000 mm (0.9447-

0.9449 in.) for the 1000 cc. If any measurement

varies by more than 0.02 mm (0.001 in.), the pis-

ton pin and bearing must be replaced as a set.

AN056

2. Insert a snap gauge into each piston-pin bore; then

remove the gauge and measure it with a microme-

ter. The diameter measurement must be within

22.002-22.010 mm (0.8662-0.8665 in.) for the 800

cc or 24.002-24.010 mm (0.9450-0.9453 in.) for

the 1000 cc. Take two measurements to ensure

accuracy.

AC092

CONNECTING-ROD SMALL END 
BORE

1. Insert a snap gauge into each connecting-rod small

end bore; then remove the gauge and measure it

with a micrometer.

AN061

2. The diameter measurement must be within 27.003-

27.011 mm (1.0631-1.0634 in.) for the 800 cc or

29.003-29.011 mm (1.1410-1.1420 in.) for the

1000 cc.

CRANKSHAFT RUNOUT

0742-727

1. Using the V Blocks, support the crankshaft on the

surface plate.

„NOTE: The V blocks should support the crank-
shaft on the outer bearings.

2. Mount a dial indicator and base on the surface

plate. Position the indicator contact point against

the crankshaft location point A (PTO-end) from

the crankshaft end. Zero the indicator and rotate

the crankshaft slowly. Note the amount of crank-

shaft runout (total indicator reading).

„NOTE: For runout location point specifications,
see Crankshaft Runout Specifications chart in
Section 1 of this manual.

3. Position the indicator contact point against the

crankshaft location point B (MAG-end) from the

crankshaft end. Zero the indicator and rotate the

crankshaft slowly. Note the amount of crankshaft

runout (total indicator reading).