Arctic Cat 400 Service Manual page 146

Measuring Piston Skirt/
Cylinder Clearance
1. Measure the cylinder front to back in six places.
2. Measure the corresponding piston diameter at a
point 15 mm (0.6 in.) above the piston skirt at a
right angle to the piston-pin bore. Subtract this
measurement from the measurement in step 1.
The difference (clearance) must be within speci-
fications.
Installing Piston Rings
1. Install ring expander (4) in the bottom groove of
the piston; then install the thin oil rings (3) over
the expander making sure the expander ends do
not overlap. Stagger the end gaps of the upper
and lower thin oil rings according to the illustra-
tion.
NOTE: Note the direction of the exhaust side of
the piston (5) for correct ring end gap orientation.
2. Install the compression rings (1 and 2) so the let-
ter on the top surface of each ring faces the
dome of the piston. Rotate the rings until the
ring end gaps are on directly opposite sides of
the piston according to the illustration.
NOTE: The chrome (silver) ring should be
installed in the top position.
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ATV-1085B
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! CAUTION
Incorrect installation of the piston rings will result
in engine damage.
CYLINDER/CYLINDER HEAD
ASSEMBLY
NOTE: If the cylinder/cylinder head assembly
cannot be trued, they must be replaced.
Cleaning/Inspecting Cylinder Head
! CAUTION
The cylinder head studs must be removed for this
procedure.
1. Using a non-metallic carbon removal tool,
remove any carbon buildup from the combus-
tion chamber being careful not to nick, scrape,
or damage the combustion chamber or the seal-
ing surface.
2. Inspect the spark plug hole for any damaged
threads. Repair damaged threads using a
"heli-coil" insert.
3. Place the cylinder head on the surface plate cov-
ered with #400 grit wet-or-dry sandpaper. Using
light pressure, move the cylinder head in a fig-
ure eight motion. Inspect the sealing surface for
any indication of high spots. A high spot can be
noted by a bright metallic finish. Correct any
high spots before assembly by continuing to
move the cylinder head in a figure eight motion
until a uniform bright metallic finish is attained.
! CAUTION
Water or parts-cleaning solvent must be used in
conjunction with the wet-or-dry sandpaper or dam-
age to the sealing surface may result.
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