Snowmobile Arctic Cat (2008 year). Manual - part 27

2-45

2

MD0289

14. Remove the four 6 mm nuts and eight 10 mm nuts

securing the cylinders to the crankcase.

„NOTE: Using a felt-tip marker, mark the cylinders
as to MAG-side and PTO-side for assembling.
Also, mark the pistons at this time.

MD0087

MD0086

15. Remove the cylinders making sure to support the

pistons so they are not damaged. Account for four

dowel pins.

MD0230

MD0096

16. Using an awl, remove the outside piston-pin cir-

clip and remove the piston pin using Piston Pin

Puller taking care not to drop the piston-pin bear-

ing washers into the crankcase.

MD0094

„NOTE: The open sides of the piston pin bearing
washers face inward.

! CAUTION

When removing a cylinder, make sure to support the
piston so it will not be damaged.

2-46

MD0251

MD0208

„NOTE: If the existing rings will not be replaced
with new rings, note the location and top side of
each ring for proper installation. When replacing
with new rings, replace as a complete set only.
When replacing rings note notches in ring ends
which correspond with locating pins in ring
grooves on intake side of the piston. This prevents
the rings from turning on the piston when assem-
bled.

MD0272

MD0271

17. Remove the two Allen-head cap screws securing

the oil-injection pump; then remove the pump.

Account for an O-ring.

MD0090

MD0092A

18. Remove the oil-injection pump driveshaft retainer.

Account for an O-ring.

MD0100A

2-47

2

19. Remove the oil-injection pump driveshaft.

Account for a thrust washer.

MD0101

20. Place the crankcase (with its bottom side up) on

two blocks of wood. Remove the 12 cap screws

securing the crankcase halves. Note the position of

the different-sized cap screws.

21. Separate the crankcase halves by installing two of

the cap screws in opposite corners leaving the heads

approximately 1/4 in. out. Using a plastic mallet,

tap on each cap screw until the crankcase halves

separate. Account for four dowel pins.

MD0283

MD0204

22. Remove the two cap screws; then remove the

crankshaft assembly from the upper crankcase half

making sure to hold both ends of the crankshaft to

keep the bearings and seals from falling off.

Account for bearings and a C-ring.

MD0246

Cleaning and Inspecting 

Engine

„NOTE: Whenever a part is worn excessively,
cracked, or damaged in any way, replacement is
necessary.

CYLINDER HEAD

1. Using a non-metallic carbon removal tool, remove

any carbon buildup from the combustion chambers

being careful not to nick, scrape, or damage the

combustion chambers or the sealing surfaces.

2. Inspect the spark-plug holes for any damaged

threads. Repair damaged threads using a heli-coil

insert.

3. Inspect the cylinder head for flatness using a

straightedge and a feeler gauge. Acceptable

warpage must not exceed 0.05 mm (0.002 in.).

„NOTE: If the warpage exceeds specification,
resurface the cylinder head using procedures
identified in step 4.

MD2491

! CAUTION

To prevent damage to the crankshaft, crankshaft
bearings, or seals, be sure to always lift the crank-
shaft from both ends.

2-48

4. Place the cylinder head on a Surface Plate covered

with #400 grit wet-or-dry sandpaper. Using light

pressure, move each cylinder head in a figure eight

motion. Inspect the sealing surface for any indica-

tion of high spots. A high spot can be noted by a

bright metallic finish. Correct any high spots

before assembly by continuing to move the cylin-

der head in a figure eight motion until a uniform

bright metallic finish is attained.

MD2492

CYLINDERS

1. Using a non-metallic carbon removal tool, remove

carbon buildup from the exhaust ports.

2. Wash the cylinders in parts-cleaning solvent.

3. Inspect the cylinders for pitting, scoring, scuffing,

and corrosion. If marks are found, repair the sur-

face with a Ball Hone and honing oil.

„NOTE: To produce the proper 45° crosshatch
pattern, maintain a low drill RPM. If honing oil is
not available, use a lightweight, petroleum-based
oil. Thoroughly clean the cylinders after honing
using detergent soap and hot water and dry with
compressed air; then immediately apply oil to the
cylinder bores. If a bore is severely damaged or
gouged, the cylinder will have to be replaced.

4. Place the head surface of each cylinder on the sur-

face plate covered with #400 grit wet-or-dry sand-

paper. Using light pressure, move each cylinder in

a figure eight motion. Inspect the surface for any

indication of high spots. A high spot can be noted

by a bright metallic finish. Correct any high spots

before assembly by continuing to move the cylin-

der in a figure eight motion until a uniform bright

metallic finish is attained.

PISTON ASSEMBLY

1. Using a non-metallic carbon removal tool, remove

the carbon buildup from the dome of each piston.

2. Take an old piston ring and snap it into two pieces;

then grind the end of the old ring to a 45° angle

and to a sharp edge. Using the sharpened ring as a

tool, clean carbon from the ring-grooves. Be sure

to position the ring with its tapered side up.

3. Inspect each piston for cracks in the piston pin and

skirt areas.

4. Inspect each piston for seizure marks or scuffing.

Repair with #400 grit wet-or-dry sandpaper and

water or honing oil.

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.

! 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 surface may result.

! CAUTION

Improper cleaning of the ring-grooves by the use of
the wrong type of ring-groove cleaner will result in
severe damage to the piston.