Snowmobile Arctic Cat 2-Stroke (2007 year). Manual - part 20

2-66

CM035

2. Drain the engine coolant (see Liquid Cooling Sys-

tem - Section 3).

3. Remove the cap screws and the lock nuts securing

the side-plate brace to the chassis; then remove the

brace.

„NOTE: The cap screws securing the steering
support to the chassis must be removed to remove
the side-plate brace.

CM004B

4. Remove the coolant hose and breather hose con-

nected to the cylinder head.

5. Remove the twelve 10 mm cap screws and two 8

mm cap screws (500 cc) securing the cylinder

head; then remove the cylinder head. Account for

the O-rings.

FC060

6. On the 600 cc, remove the APV’s from the cylin-

der.

FC056

7. Disconnect the two coolant hoses located beneath

the exhaust ports on the cylinders.

FC050A

„NOTE: At this point, remove all loose hardware to
avoid any falling down into the chassis.

8. Remove the residual coolant from the cylinder/

crankcase water jacket.

„NOTE: After draining the coolant, approximately
1.75 fluid oz of coolant will remain on both the
MAG-side and PTO-side. To remove the residual
coolant, use the following procedure.

a. Using Vacuum Pump (p/n 0644-131), or a suit-

able substitute, rig the pump to 3/16 in. outside

diameter hose.

FC058

b. In turn on each fitting of the crankcase, run the

vacuum pump to purge the cylinder/crankcase

water jacket of the residual coolant.

2-67

2

„NOTE: It is critical that all residual coolant is
totally removed from the cylinder/crankcase.

„NOTE: At this point, remove all loose hardware to
avoid any falling down into the chassis.

9. Remove the nuts (500 cc) or the cap screws and

nuts (600 cc) securing the cylinders to the crank-

case; then using a rubber hammer, gently tap the

cylinders and remove from the crankcase by lifting

them straight up off their studs. Account for gas-

ket(s) and any alignment pins.

FC061

„NOTE: If servicing the MAG-side only, the PTO-
side cylinder must be removed.

FC062

„NOTE: After the cylinders have been removed, it
is advisable to cover the crankcase to avoid com-
ponents falling into the crankcase.

10. Remove the PTO-side piston-pin circlip from the

PTO-side piston; then remove the PTO-side pis-

ton-pin circlip from the MAG-side piston.

11. Using Piston Pin Puller (p/n 0644-328) and

Medium Extractor Nut (p/n 0643-074), remove the

piston pins from both pistons.

FC064

„NOTE: The piston pins must be removed from the
PTO-side of the piston.

„NOTE: For proper assembly, keep all MAG-side
components and all PTO-side components sepa-
rated. Assemble them on their proper sides.

„NOTE: For servicing procedures, see Cleaning
and Inspecting Engine and Measuring Critical
Components in this sub-section.

INSTALLING TOP-SIDE 

COMPONENTS

„NOTE: Critical torque specifications are located
in the Assembly Schematics sub-section of this
section.

„NOTE: When installing the pistons, make sure to
install the MAG-side piston-pin circlips first with
the open ends directed either up or down.

1. Place the cylinders into position on the crankcase

accounting for gasket(s) and any alignment pins.

FC061

! CAUTION

Do not use the large extractor nut to remove the pin
or damage to the piston may occur.

2-68

FC062

2. 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

3. Apply oil to the connecting-rod small end bear-

ings; then install the small-end bearings. Install a

washer on each side of the connecting rod.

„NOTE: The shoulder side of the washer must
seat to the needle bearing.

CM172A

„NOTE: Prior to installing the pistons, make sure
to install the MAG-side piston pin circlips first.

4. Place each piston over the connecting rod so the

indicator dot on each piston will point toward the

intake/exhaust ports; then secure with an oiled pis-

ton pin.

„NOTE: The indicator dot (A) is found on the pis-
ton dome.

CM194A

5. Install the new circlips so the open end is directed

either up or down.

CM195A

6. Rotate each piston ring until the ring ends are

properly positioned on either side of the ring

keeper; then apply oil to the piston assemblies and

cylinder bores. Remove the rubber hoses from the

connecting rods.

7. In turn on each cylinder, place a piston holder (or

suitable substitute) beneath the piston skirt and

square the piston in respect to the crankcase; then

using a ring compressor or the fingers, compress

the rings and slide the cylinder over the piston.

Remove the piston holder and seat the cylinder

firmly onto the crankcase.

! CAUTION

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

! CAUTION

Make sure the circlips are firmly seated and the open
end is directed either up or down before continuing
with assembly.

! CAUTION

The cylinders should slide on easily. DO NOT force
the pistons into the cylinders.

2-69

2

8. Loosely secure the cylinders with existing hard-

ware. Do not tighten at this time.

„NOTE: The cylinders will be tightened at the
same time as the exhaust manifold is installed to
assure proper cylinder to exhaust manifold align-
ment.

9. Connect the two coolant hoses on the cylinders

beneath the exhaust ports.

FC050A

10. On the 600 cc, install the APV’s into the cylinder

and secure with existing hardware.

FC056

11. Place the cylinder head into position on the cylin-

ders making sure the O-rings are properly posi-

tioned; then in two steps, tighten the 8 mm cap

screws to specifications using the appropriate pat-

tern shown.

0738-204

„NOTE: On the 500 cc after tightening the 8 mm
cap screws, tighten the two remaining 6 mm cap
screws to specifications.

0738-205

12. Install the exhaust manifold. Tighten existing

hardware to specifications.

FC049

„NOTE: At this point, tighten the cylinders (from
step 8) to specifications.

! CAUTION

The long side of the exhaust valve must be facing
toward the cylinder head or severe engine damage
may occur.

500 cc

600 cc