Cylinder / Piston Installation - Polaris ACE 900 2017 Service Manual

ENGINE / COOLING SYSTEM
4. Install the remaining circlip
(12:00 position) or bottom (6:00 position). Push the
piston pin in both directions to make sure the clips
are properly seated in the groove.

CYLINDER / PISTON INSTALLATION

CAUTION
Pistons must be installed into the cylinders with the
connecting rods attached.
DO NOT attempt to service the cylinder or pistons
without disassembling the crankcase. Although you can
remove the cylinder and pistons without disassembly,
you will not be able to reassemble the engine because
of the unique cylinder skirt and crankcase design.
NOTICE
If the pistons are being reused, reassemble in the same
cylinder bore and direction from which they were
removed (MAG / PTO).
New pistons are directional (intake vs. exhaust), but
can be placed in either cylinder.
1. Apply clean engine oil to each piston assembly
w
cylinder bore and bottom tapered portion of each
cylinder sleeve.
2. Verify that all ring end gaps
on each piston (see Chapter 3 – Piston Ring
Installation page 3.70.
3. Note the piston orientation mark (arrow) located on
top of the piston. Arrow should point toward the
exhaust side.
NOTICE
Orientation arrow is also located on the bottom side of
piston as an additional reference.
3.72
t
with gap at the top
q
,
e
are correctly located
4. Carefully compress the piston rings with your fingers
and install the piston / connecting rod assemblies
into the cylinder from the bottom side.
NOTICE
Use a slight front to back rocking motion until all rings
are captive in cylinder and past the cylinder sleeve
opening
5. Rotate the engine so the crankcase to cylinder
mounting surface is facing up.
6. Clean base gasket sealing surface on cylinder and
crankcase to remove all oil and grease.
NOTICE
Base gasket and surfaces must be DRY and oil free.
Use care upon assembly to keep oil away.
7. Reinstall dowel pins in crankcase if previously
removed.
8. Install a new cylinder base gasket.
9. Verify piston orientation (arrow pointing toward
exhaust) one last time prior to installation.
10. Carefully place the cylinder and pistons into the
upper crankcase.
9929422 R02 - 2017-2019 ACE 900 Service Manual
r
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