Crankshaft Index; Checking Crankshaft Index - Polaris IQ 2007 Service Manual

Engine and Cooling Systems
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 Index

Polaris crankshafts are pressed together. The connecting
rod journal center lines are indexed 180
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:
• 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, etc.)
• Excessive vibration of engine, back-firing, etc.
• Rough idle, poor top speed.

Checking Crankshaft Index

1. Remove the drive belt and drive clutch.
2. 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.
5.8
3.
4.
5.
6.
7.
8.
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.
9.
°
apart from each
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.
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.