Snowmobile Arctic Cat (2008 year). Manual - part 29

2-53

2

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

18.002-18.010 mm (0.7087-0.7090 in.). 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

23.003-23.011 mm (0.9056-0.9059 in.).

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 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).

FC046

4. Position the indicator contact point against the

crankshaft at location point C (center). Zero the

indicator and rotate the crankshaft slowly. Note

the amount of crankshaft runout (total indicator

reading).

5. If runout exceeds 0.05 mm (0.002 in.) at any of the

checkpoints, the crankshaft must be either

straightened or replaced.

Assembling Engine

„NOTE: The use of new gaskets and seals is rec-
ommended when assembling the engine.

„NOTE: Before the engine is assembled, clean the
threads of the cap screws and the threaded areas
of the engine where Loctite will be used.

„NOTE: When the use of a lubricant is indicated,
use Arctic Cat 50:1 Injection Oil.

2-54

 1. Place the upper crankcase half (with its bottom

side up) on two blocks of wood.

2. Lightly grease the inner lips of the crankshaft

seals; then slide them onto the crankshaft.

3. Apply oil to the crankshaft bearings; then install

the crankshaft into the upper crankcase half. Be

sure the alignment hole in each bearing is posi-

tioned over its respective dowel pin in the crank-

case; then seat the crankshaft.

„NOTE: To check the bearing for proper position,
place the point of a sharp tool into the dimple
found in the bearing race. Strike the tool with the
palm of the hand in either direction. If the bearing
moves, it isn’t positioned correctly and must be
rotated until it drops onto the dowel pin. 

„NOTE: Make sure the crankshaft center C-ring
(integral with the center seal) is properly posi-
tioned in the groove of the upper crankcase half.

4. Install the four crankcase dowel pins.

5. Evenly apply a thin coat of Three Bond Sealant to the

entire bottom half crankcase sealing surface. 

„NOTE: Use only Three Bond Sealant to seal the
crankcase halves.

 MD0203

6. Install crankcase lower half. Install eight 8 mm

and four 6 mm cap screws. Tighten in three steps

the 8 mm cap screws to 17 ft-lb and the 6 mm cap

screws to 8 ft-lb using the pattern shown.

737-027A

MD0212

„NOTE: Check the reed valve on each cylinder for
cracking or fraying around the edges. Make sure
they are closing completely.

„NOTE: To inspect a reed valve assembly, remove
the two Phillips-head screws securing the reed
valve and reed valve stopper to the block; then
remove the reed valve and stopper.

MD0088

„NOTE: Apply blue Loctite #243 on the Phillips-
head screws when assembling.

„NOTE: Make sure the angled corner on the reed
valve align with the angled corner on the reed
valve stopper.

! CAUTION

To prevent damage to the crankshaft, crankshaft
bearings, or seals, make sure to always lift the
crankshaft from both ends.

! CAUTION

If the bearings are not properly seated during
assembly, the crankcase halves will not seal tightly
and severe engine damage will result.

2-55

2

MD0213

7.  Install the piston rings on each piston so the letter

on the top (inclined surface) of each ring faces the

dome of the piston.

726-306A

„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.

MD0208

MD0272

MD0271

8. Lubricate the piston pin bearings and install them

into the connecting rods. 

9.  Install a piston pin bearing washer on each side of

the bearings with the open sides facing the bear-

ings.

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

! CAUTION

Do not over-tighten the Phillips-head screws when
installing the reed valves and reed valve stoppers.

! CAUTION

Incorrect installation of the piston rings will result in
engine damage.

2-56

MD0251

10. Place pistons over the connecting rods with the

arrow (or indicator dot) pointing toward the

exhaust port; then secure with an oiled piston pin.

Install piston pin circlips with the open ends up or

down.

MD0293

MD0248

11. Place the cylinder base gasket into position on the

crankcase making sure the gasket is properly ori-

ented so the dowel pins will fit through the holes

easily.

„NOTE: Be sure to spray a thin coat of Copper
Coat Gasket Sealant onto the gasket if it is being
reused.

12. Rotate each piston ring until the ring ends are

properly positioned with the pins in the ring

grooves; then apply oil to the piston assemblies

and cylinder bores. Using a ring compressor or the

fingers, compress the rings and slide the cylinder

over the piston. Seat the cylinder firmly onto the

crankcase. 

„NOTE: The cylinders should slide on easily. DO
NOT force them on.

MD0229

13. Secure each cylinder by installing the four 6 mm

and eight 10 mm nuts. Tighten the 10 mm nuts to

36 ft-lb and the 6 mm nuts to 8 ft-lb.

MD0086

MD0087

14. Install a new cylinder head gasket and the cylinder

head; then install the eight cap screws and two

nuts with washers. Tighten in three steps to 18 ft-

lb using the pattern shown.

! CAUTION

Make sure the circlips are firmly seated in their
grooves and the open ends are pointed up or down
before continuing with assembly.