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Snowmobile Polaris 600 RUSH (2010 year). Instruction - part 15

3.10

Engine/Cooling/Exhaust

9923311 - 2010-2012 PRO-RIDE RUSH/Switchback/RMK Service Manual

Reed Valve Inspection

Loosen the hose clamps.

Remove the throttle body from the intake boots.

Remove the intake boot fasteners.

Remove the intake assembly.

Separate the intake boot from the reed cages.

Separate the reed stuffer(s) from the reed cage and
inspect the reeds before they are removed from the
reed cage.

NOTE: Measure the air gap between the fiber reed and the
reed block. The air gap should not exceed .015" (.38mm). If
clearance is excessive DO NOT attempt to reverse the reeds
to reduce the air gap. Always replace them if damaged or
worn. Check each fiber reed for white stress marks or
missing material.

Inspect the leading edges of each reed pedal. If edges
are chipped, or excessively worn, replace the reed
assembly.

Bearing Fit

Any time crankshaft bearing failure occurs and the case is
reused, check the bearing fit into the case halves using the
following procedure.

With case halves cleaned, reinstall the main bearings with
a piece of Plastigage between the bearing race and
crankcase.

Install and torque the crankcase fasteners to
specification. Take the crankcase apart, and then
measure the Plastigage. Compare Plastigage width to
interference fit specification.

The air gap should not exceed.015” (0.30mm)

INSPECT EACH PEDAL EDGE FOR DAMAGE

= In. / mm.

.061mm)

Bearing Interference Fit:



.0014" - .0024" (0.035-0.061mm)

3.11

Engine/Cooling/Exhaust

9923311 - 2010-2012 PRO-RIDE RUSH/Switchback/RMK Service Manual

Crankshaft Runout Inspection

Support the crankshaft in a set of “V” blocks as shown.

Use a dial indicator to measure the runout at the
following locations:

• PTO end = First taper after bearing flat.

• MAG end = 1/2" from bearing flat.

Runout deflection cannot exceed .0025" (.07mm).

If the runout deflection exceeds the maximum
specification, crankshaft trueing may correct the
deflection.

Main Bearing

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

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 Lower Bearing

Measure connecting rod big end side clearance with a
feeler gauge on both sides of the connecting rod. The side
clearance on either side of the connecting rod cannot
exceed the connecting rod side clearance specification.
The difference between the two clearance measurements
cannot exceed the maximum clearance differential
specification.

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.

= In. / mm.

Connecting Rod Side Clearance:



.0114"-.0295" (0.289-0.749mm)



Maximum Clearance Differential



.002" (0.051mm)

3.12

Engine/Cooling/Exhaust

9923311 - 2010-2012 PRO-RIDE RUSH/Switchback/RMK Service Manual

Piston Needle Bearing

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.

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

Oil and install needle bearing and pin in connecting
rod.

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

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

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

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

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.

3.13

Engine/Cooling/Exhaust

9923311 - 2010-2012 PRO-RIDE RUSH/Switchback/RMK Service Manual

Crankshaft Index

Polaris crankshafts 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

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

• Unexplained piston failure on one cylinder (i.e.

severe detonation, broken ring lands, etc.)

• Excessive vibration of engine, back-firing, etc.

• Rough idle, poor top speed.

Checking Crankshaft Index

Remove the drive belt and drive clutch.

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.

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.

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

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.

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

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

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.

Remove the dial indicator and install in PTO cylinder.
Repeat finding TDC process. Note the degree wheel
indication when the dial indicator reads .100" ATDC.
It should be 180° (+/-2°) from the MAG cylinder mark.

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