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ENGINE
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9923412 - 2012 Sportsman 400/500 and EFI Tractor Service Manual
© Copyright 2011 Polaris Sales Inc.
5. Install the top ring (chrome faced) with the “R” mark
facing up and the end gap facing forward (toward the
exhaust).
6. Check to make sure the rings rotate freely in the
groove when compressed.
Piston Installation
1. Clean the gasket surfaces on the cylinder and
crankcase. Remove all traces of old gasket material.
2. Make sure the cylinder mounting bolt holes are clean
and free of debris.
3. Install a new circlip on one side of the piston with the
end gap facing up or down, and tang outward.
4. Apply clean engine oil to the piston rings, ring lands,
piston pin bore, piston pin, and piston skirt. Lubricate
the connecting rod (both ends), balancer drive gear,
and crankshaft main bearing area.
5. Install the piston on the connecting rod with the arrow
or : mark facing the magneto (RH) end of the
crankshaft. The piston pin should be a push fit in the
piston.
6. Install the other circlip with the gap facing up or down
and tang outward. (See Caution with Step 3 above).
Push the piston pin in both directions to make sure the
clips are properly seated in the groove.
Cylinder Installation
1. Place the dowel pins in the crankcase and install a
new cylinder base gasket.
2. Position the Piston Support Block (PN 2870390) (A)
beneath the piston skirt to support the piston during
cylinder installation.
3. Apply clean engine oil to the ring compressor and
install the compressor following manufacturer’s
instructions. CAUTION: Make sure the oil control ring
upper rail tab is positioned properly in the notch of the
piston. Verify all ring end gaps are correctly located.
Circlips become deformed during the removal
process. Do not re-use old circlips. Do not
compress the new clip more than necessary
upon installation to prevent loss of radial tension.
Severe engine damage may result if circlips are
re-used or deformed during installation.
Mark-up
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Second
Ring Profile
Mark-up
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