Snowmobile Arctic Cat (2008 year). Manual - part 28

2-49

2

3. Inspect all threaded areas for damaged or stripped

threads.

4. Inspect the bearing areas for cracks or excessive

bearing movement. If evidence of excessive bear-

ing movement is noted, the crankcase must be

replaced.

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.

MD0200A

ADAPTER PLATES

1. Inspect for cracks, scoring, pitting, imperfections,

or warping.

2. Inspect the sealing surfaces for trueness by placing

each on the surface plate covered with #400 grit

wet-or-dry sandpaper. Using light pressure, move

both sides in a figure eight motion. Inspect the

sealing surface for any indication of high spots or

warping. Correct high spots by continuing to move

each side in a figure eight motion. Warped compo-

nents must be replaced.

„NOTE: In order to inspect adapter plate trueness,
it will be necessary to remove the studs.

A932

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.

! 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.

! CAUTION

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

2-50

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 OUTER 
CRANKSHAFT BEARINGS

„NOTE: Steps 1-2 are for removing the MAG-side
bearing.

1. Place the crankshaft in a suitable support; then

install Crankshaft Bearing Remover between the

journal and the MAG-side bearing.

2. Place the protective cap on the crankshaft end;

then remove the bearing from the end of the crank-

shaft. Account for any shim(s). Note the position

of the dowel pin hole.

AN068D

3. The PTO-side bearing may be removed simply by

sliding the bearing off the PTO end.

AN151A

4. Inspect the crankshaft bearing area for wear. If any

wear is noted on either end, replace the crankshaft

end.

INSTALLING OUTER
CRANKSHAFT BEARINGS

„NOTE: On certain models, steps 1-3 are for
installing the MAG-side bearing.

1. Wrap a thick towel around the crankshaft; then

secure the crankshaft vertically in a vise.

2. Heat the bearing either by placing the entire bear-

ing in a pan of oil on a hot plate or by squirting oil

into the bearing and using a propane torch to heat

the inner race of the bearing until a slight smoke is

noted coming from the bearing.

3. Place any shims removed during disassembly onto

the crankshaft; then slide the bearing 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.

4. Slide the PTO-side bearing onto the PTO end mak-

ing sure the dowel-pin hole will align with the hole

and pin in the crankcase.

AN151A

! CAUTION

DO NOT overheat the bearing.

2-51

2

REED VALVE ASSEMBLY

1. Inspect the reed valves, stoppers, and valve blocks

for cracks or any deterioration.

AQ046

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.

AJ156

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

three screws coated with red Loctite #271.

AQ047

Measuring Critical 

Components

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.

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 1.69 mm
(0.066 in.) or less.

2-52

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.

MD2493

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 0.085-0.115 mm (0.0035-

0.0045 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

piston to position each ring squarely in each cylin-

der.

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

end gap. Acceptable ring end gap must be within

0.030-0.050 mm (0.012-0.0196 in.).

MD2501

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 17.995-18.000 mm (0.7085-0.7087

in.). If any measurement varies by more than

0.02 mm (0.001 in.), the piston pin and bearing

must be replaced as a set.

AN056