Snowmobile Arctic Cat 2-Stroke (2007 year). Manual - part 10

2-26

AN135

„NOTE: If scuffing or seizure marks are too deep
to correct with the sandpaper, it will be necessary
to replace the piston.

5. Inspect the perimeter of each piston for signs of

excessive “blowby.” Excessive “blowby” indicates

worn piston rings or an out-of-round cylinder.

CRANKCASE

1. Wash the crankcase halves in parts-cleaning sol-

vent.

„NOTE: Before washing the crankcase halves,
make sure the four bearing dowel pins have been
removed and accounted for.

2. Inspect the crankcase halves for scoring, pitting,

scuffing, or any imperfections in the casting.

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, repair by peening the bear-

ing area in a pinking (sawtooth) pattern.

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.

A519

INTAKE MANIFOLD INSULATORS 

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.

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.

! 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.

2-27

2

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 OUTER 
CRANKSHAFT BEARINGS

1. Place the crankshaft in a suitable support; then

install Crankshaft Bearing Remover (p/n 0144-

302) between the journal and the MAG-end bear-

ing.

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. Install the crankshaft bearing remover between the

journal and PTO-end bearing; then remove the

bearing from the end of the crankshaft. Account

for any shim(s). Note the position of the dowel pin

hole.

AC100

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

wear is noted on either end, replace the crankshaft

end.

INSTALLING OUTER
CRANKSHAFT BEARINGS

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.

! CAUTION

DO NOT overheat the bearing.

2-28

Measuring Critical 

Components

„NOTE: Critical engine specifications charts can
be found at the beginning of this section.

CYLINDER HEAD VOLUME 
(Squish-Gap Method)

To check the squish gap, a micrometer and a heavy

piece of solder will be needed.

1. Remove the spark plugs from the engine.

2. Insert the solder piece down through the spark

plug hole and push it up against the inner cylinder

bore towards the MAG-side of the engine.

3. Pull the recoil rope and crank the engine over sev-

eral times while the solder is being held firmly in

place.

4. Remove the 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 piece, insert it

down through the spark plug hole towards the

PTO-side of the engine. Push on the solder until it

contacts the inner cylinder bore.

6. Pull the recoil rope and crank the engine over sev-

eral times. Remove the solder from the cylinder

and measure the squeezed end with a micrometer.

Record reading and refer to the chart.

„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. Make sure the

smaller reading is within the specifications listed.

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.

MD2496

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

between the highest and lowest reading. Maxi-

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

specifications.

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 (0.394 in.) above the piston skirt at a

right angle to the piston-pin bore. Subtract this

measurement from the measurement in step 1. The

difference (clearance) must be within specifica-

tions.

AC091

2-29

2

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

specifications.

MD2497

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 specifications. 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

specifications. 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 specifi-

cations.

CRANKSHAFT RUNOUT

1. Using the V Blocks (p/n 0644-022), 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 F (PTO-end) from the

crankshaft end. Zero the indicator and rotate the

crankshaft slowly. Note the amount of crankshaft

runout (total indicator reading).

„NOTE: For runout location point specifications,
see Crankshaft Runout Specifications chart on
page 19 of this section.

3. Position the indicator contact point against the

crankshaft location point D (MAG-end) from the

crankshaft end. Zero the indicator and rotate the

crankshaft slowly. Note the amount of crankshaft

runout (total indicator reading).