Snowmobile Arctic Cat 2-Stroke (2007 year). Manual - part 22

2-74

„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.

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

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

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.

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 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

2-75

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

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).

FC046

4. Position the indicator contact point against the

crankshaft at location point E (center). Zero the

indicator and rotate the crankshaft slowly. Note

the amount of crankshaft runout (total indicator

reading).

5. If runout exceeds specifications 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: When the use of a lubricant is indicated,
use Arctic Cat Synthetic APV 2-Cycle Oil.

1. Apply a thin coat of grease to the inner seal lips of

the water pump seal.

2. Using the seal driver, position the inner water

pump shaft seal onto the seal driver and gently tap

the seal down into position.

„NOTE: Grease must be applied to the lips of the
inner seal before installation.

MS986A

2-76

„NOTE: The seal must be installed with its spring
side towards the crankshaft.

3. Install the snap ring securing the inner seal in the

crankcase.

MS415

4. Using the seal driver, carefully install the outer

water pump seal. Gently tap the seal down into

position until it seats itself against its flange.

MS988

5. Apply a thin coat of grease to the sealing surface

of the oil-injection pump/water pump driveshaft;

then place the Oil Seal Protector Tool (p/n 0644-

219) at the end of the shaft. Twist the driveshaft

clockwise as it is pushed through the oil and water

pump seals; then remove the tool. 

FS191

6. Position the shim on the oil-injection pump end of

the driveshaft.

CM044

7. Position the upper crankcase half upside-down on

two wooden blocks; then install the C-ring, the

four bearing retaining pins, and the two crankcase

dowel pins.

8. Place the PTO-side crankshaft bearing into posi-

tion making sure the bearing retaining pin hole is

positioned inward.

„NOTE: The bearing retaining pin hole is the hole
that does not go entirely through the bearing case.

CM043A

9. Lubricate the inner lips of the crankshaft oil seals

with grease; then slide the seals (and rubber spacer

on the 600 cc) onto the crankshaft making sure the

spring side of each seal faces the center of the

crankshaft.

! CAUTION

Be very careful not to damage the seals when
installing the oil pump driveshaft. Be certain to use
the seal protector tool. Twist the driveshaft clock-
wise as it enters the seal area and while it is being
pushed through the seals.

2-77

2

„NOTE: There is a MAG-side seal and a PTO-side
seal.

10. 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.

CM045A

„ 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.

11. Position the two center seal rings with their end

gaps 180° apart (up on one and down on the

other); then apply a thin coat of High-Temp Seal-

ant (p/n 0636-069) to the entire bottom half of the

crankcase sealing surface.

CM036A

FC071

„NOTE: Use only Arctic Cat High-Temp Sealant (p/
n 0636-069) to seal the crankcase halves.

12. Assemble the crankcase halves making sure that the

crankshaft gear and oil-injection pump driveshaft

gears mesh. Rotate the crankshaft one full turn to

align the crankshaft gear and pump driveshaft.

13. Install the crankcase cap screws (coated with blue

Loctite #243) securing the crankcase halves. 

14. Tighten the three 6 mm cap screws to specifica-

tions and the ten 10 mm cap screws to specifica-

tions using the appropriate pattern shown.

0738-201

738-202A

„NOTE: On the 500 cc, secure the connecting rods
with rubber bands. On the 600 cc, secure the con-
necting rods with rubber hoses.

15. Install the oil-injection pump retainer O-ring and

retainer.

! CAUTION

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

500 cc

600 cc