Snowmobile Polaris Two Stroke (2007 year). Manual - part 16

3.7

MAINTENANCE

3

Piston Ring Installed Gap

Position the ring .50" (1.3 cm) from the top of the cylinder using
the piston to push it squarely into place. Measure installed gap
with a feeler gauge at both the top and bottom of the cylinder.

NOTE: A difference in end gap indicates cylinder
taper. The cylinder should be measured for
excessive taper and out of round. Replace rings if
the installed end gap exceeds the service limit.
Always check piston ring installed gap after re-
boring a cylinder or when installing new rings.

Piston rings are installed with marking or beveled side up see
diagram above.

Coolant Level

Coolant level in the coolant bottle must be maintained to prevent
overheating and serious engine damage. Check the coolant with
the engine temperature cold. The coolant level should be at the
FULL COLD level mark. If it is not add coolant to the FULL
COLD mark on the bottle. If you have coolant over the FULL
COLD level you may have air in the system and need to “bleed”
the air out of the system.

Recommended Coolant

Polaris snowmobiles use a premium 60/40 pre-mix antifreeze.
This premium antifreeze is mixed with deionized water for
better protection for aluminum cooling. This pre-mix is good for
temperatures down to -62°F (-52°C). Replace coolant every 2
years or if contaminated.

Cooling System Bleeding

1.

Allow the cooling system to cool completely.

2.

Check the coolant reservoir and make sure it is at the FULL
COLD mark.

3.

Place the snowmobile in its normal riding position and
apply the parking brake and run the engine at the specified
idle RPM until the thermostat opens up.

4.

Elevate the front of the machine slightly.

5.

Open the bleed screw (A) at the top of the water outlet
manifold.Only open slightly, do not remove the screw.

6.

Cycle the RPM from idle to 3000-4000 so that the coolant
can move around the system and push out the air from the
system.

7.

Tighten the bleed screw when coolant starts to come out of
the screw area.

8.

Turn off the machine and release the parking brake.

9.

Allow the system to cool completely and recheck the
coolant level.

NOTE:  It is important that the thermostat stays open
@ 120° F (50° C).When the thermostat opens it will
draw in cold coolant from the heat exchangers and
the cold coolant may close the thermostat again.

500 Fuji

500/600/700 Liberty

A

A

3.8

MAINTENANCE

Make sure the thermostat opens and stays open!
Cycle the RPM from idle to enough RPM (3500) to
get coolant to flow but not enough RPM to engage
the clutch. This allows air to bleed from the rear
crossover tube. It is important to get enough coolant
flow to purge the air from the front close-off cooler
and observe this air reaching the bottle.

NOTE: 

Once the thermostat is open tip the

snowmobile slightly on its right side and cycle the
RPM from idle to enough RPM (4000) to get coolant
to flow but not enough RPM to engage the clutch.
Then tilt the machine slightly on its left side so that
the coolant bottle is the highest point in the cooling
system and cycle the RPM from idle to enough RPM
(4000) to get coolant to flow but not enough RPM to
engage the clutch.

Bearing Fit

Any time crankshaft bearing failure occurs and the case is to be
reused, Polaris recommends checking the bearing fit into the
case halves using the following procedure.

With case halves cleaned, press a replacement bearing into each
of the main bearing journals to determine a basic amount of
press fit.

Do a comparison check of all journals by manually forcing the
bearing into the bearing seats noting if any are noticeably loose

or tight. Normal hand installation will be an indication of the
recommended interference fit. If the bearing falls out of the case
when the case is inverted, or if the crankcase bearing surface is
severely galled or damaged, the case should be replaced.

NOTE: Crankcase bearing interference fit is .001-
.002" (.026-.051mm).

Main Bearing

Clean crankshaft thoroughly and oil main and connecting rod
bearings with Polaris engine oil. Carefully check each main
bearing on the shaft.

Due to extremely close tolerances, the bearings must be
inspected visually, and by feel. Look for signs of discoloration,
scoring or galling. Turn the outer race of each bearing. The
bearings should turn smoothly and quietly. The inner race of
each bearing should fit tightly on the crankshaft. The outer race
should be firm with minimal side to side movement and no
detectable up and down movement. Replace any loose or rough
bearings.

Connecting Rod (Big End) Bearing

Specialized equipment and a sound knowledge of crankshaft
repair and straightening is required to perform crankshaft work
safely and correctly. Crankshaft repair should be performed by
trained Polaris service technicians in a properly equipped shop.

WARNING

When performing the following checks and 
adjustments, stay clear of all moving parts to avoid
serious personal injury. Never remove the pressure 
cap when the engine is warm or hot. If the pressure 
cap is to be removed, the engine must be cool. 
Severe personal injury could result from stream or hot 
liquid.

= In. / mm. 

Bearing Interference Fit: .001-.002" (.026-.051mm)

3.9

MAINTENANCE

3

Measure connecting rod big end side clearance with a feeler
gauge. 500/600/700 Liberty™ engines should have a clearance
of .011 - .030" (.28 -.75mm) and be equal on all rods within .002"
(.05mm).

Rotate the connecting rod on the crankshaft and feel for any
rough spots. Check radial end play in rod by supporting rod
against one thrust washer and alternately applying up and down
pressure. Replace bearing, pin, and thrust washers if side
clearance is excessive or if there is any up and down movement
detectable in the big end bearing.

Wrist Pin Bearing

1.

Clean the end of the connecting rod and inspect inner bore
with a magnifying glass. Look for any surface
irregularities including pitting, wear, or dents.

2.

Run you fingernail around the inside of the rod and check
for rough spots, galling, or wear.

3.

Oil and install needle bearing and pin in connecting rod.

4.

Rotate pin slowly and check for rough spots or any
resistance to movement.

5.

Slide pin back and forth through bearing while rotating and
check for rough spots.

6.

With pin and bearing centered in rod, twist ends back and
forth in all directions to check for excessive axial play.

7.

Pull up and down evenly on both ends of pin to check for
radial play.

8.

Replace pin and bearing if there is any resistance to rotation
or excessive axial or radial movement. If play or roughness
is evident with a new pin and bearing, replace the
connecting rod.

Crankshaft Indexing

Polaris uses crankshafts that are pressed together. The
connecting rod journal center lines are indexed 180° apart from
each other.

It is sometimes necessary to check multi-cylinder crankshafts to
verify that one cylinder has not been forced out of position
relative to the other cylinder. Some causes for a “out of index”
crankshaft include but are not limited to the following:

• Hydrolock from water or fuel

• Impact to drive clutch from object or accident

• Abrupt piston or other mechanical failure

• Engine lock-up due to drive belt failure

Checking Crankshaft Index

1.

Remove the drive belt. See “Drive Belt Removal” on
page 6.10.

2.

Remove the drive clutch. See “Drive Clutch Removal” on
page 6.15.

3.

Securely fasten a large degree wheel on the flywheel or
PTO end of the crankshaft. Make sure that it is mounted
concentrically with the crankshaft center line. 

4.

With a section of wire (wire coat hanger), anchor it to a
convenient spot. Bend one end at the outer perimeter of the
degree wheel as shown below.

5.

Install a dial indicator into the magneto end cylinder spark
plug hole. The ignition timing is referenced by the magneto
end.

6.

Locate TDC as accurately as possible by finding the center
of the point where there is no piston movement note the
“Zero” the dial indicator at this point.

= In. / mm. 

500/600/700 Liberty Engine Connecting Rod (Big 

End) Side Clearance: .011-.030" (.28-.75mm)

NEEDLE BEARING

CAUTION

Disconnect the battery ground cable and ALL spark
plug high tension leads. Ground high tension leads to
the engine. Disconnect lanyard (if equipped) and/or
press the engine stop switch before proceeding with
the following procedure.

3.10

MAINTENANCE

7.

Continue to rotate the crankshaft in the normal direction of rotation until the dial indicator reads .100" (2.54mm) after top dead
center (ATDC).

8.

Bend the pointer or move the degree wheel until the pointer aligns with a 180° mark on the degree wheel.

9.

With the pointer aligned, make sure the degree wheel and pointer are secured and will not move out of position. Re-check
accuracy of this location a few times. The pointer should align with the 180° mark when the dial indicator reads .100” (2.54mm)
ATDC.

NOTE:  Do not move the crankshaft, degree wheel or pointer after the initial setting on the MAG end cylinder -
simply read the wheel and dial indicator.

10. Remove the dial indicator and install in PTO cylinder. Repeat finding TDC. Note the degree wheel indication when the dial

indicator reads .100" ATDC. It should be 180° (+/-2°) from the MAG cylinder mark.

Symptoms of an out of index crankshaft can include but are not limited to the following:

• Difficulty calibrating carburetor (repetitive plug fouling on one cylinder with no other cause)

• Unexplained piston failure on one cylinder (i.e. severe detonation, broken ring lands, piston holing)

• Excessive vibration of engine, back firing, etc.

• Rough idle, poor top speed.