Snowmobile Arctic Cat (2008 year). Manual - part 18

 

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Snowmobile Arctic Cat (2008 year). Manual - part 18

 

 

2-9

2

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 between the

journal and the MAG-end 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: For installing purposes, note the offset
position of the dowel pin hole.

CM045A

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).

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.

2-10

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.

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 within
2.27-2.95 mm (0.089-0.116 in.).

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

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

(clearance) must be within 0.066-0.086 mm

(0.0026-0.0034 in.).

! CAUTION

DO NOT overheat the bearing.

2-11

2

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

0.15-0.35 mm (0.006-0.014 in.).

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 17.945-18.000 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

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 (0.9056-0.9059 in.).

CRANKSHAFT RUNOUT

0742-727

1. Using the V Blocks, support the crankshaft on the

surface plate.

2-12

„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.

1. Install the C-ring and the five bearing retaining

pins into the lower crankcase half.

2. Lubricate the inner lips of the crankshaft oil seals

with grease; then slide the seals onto the crank-

shaft making sure the spring side of each seal faces

the center of the crankshaft.

AC087

3. Apply oil to the crankshaft bearings; then install

the dowel pins, C-ring, and crankshaft into the

lower crankcase half. Be sure the alignment hole

in each bearing is positioned over its respective

bearing retaining pin in the crankcase; then seat

the crankshaft.

MS986A

„NOTE: Make sure the crankshaft center seal is
properly positioned in the groove of the lower
crankcase half.

„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.

4. Apply a thin coat of Three Bond Sealant to the

lower crankcase sealing surface.

! CAUTION

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

 

 

 

 

 

 

 

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