Arctic Cat 2015 400 Service Manual page 42

 NOTE: The valve seals must be replaced.
3. Remove the valve springs; then invert the cylinder
head and remove the valves.
Measuring Valve Guide (Bore)
1. Insert a snap gauge 1/2 way down into each valve
guide bore; then remove the gauge and measure it
with a micrometer.
2. Acceptable inside diameter range must be within
specifications.
3. If a valve guide is out of tolerance, the cylinder head
must be replaced.
Servicing Valves/Valve Guides/Valve
Seats
If valves, valve guides, or valve seats require servicing or
replacement, Arctic Cat recommends that the compo-
nents be taken to a qualified machine shop for servicing.
CAUTION
If valves are discolored or pitted or if the seating sur-
face is worn, the valve must be replaced. Do not attempt
to grind the valves or severe engine damage may occur.
Installing Valves
1. Apply grease to the inside surface of the valve seals;
then place a lower spring seat and valve guide seal
over each valve guide.
2. Insert each valve into its original valve location.
3. Install the valve springs with the painted end of the
spring facing away from the cylinder head.
40
 NOTE: If the paint is not visible, install the ends of
the springs with the closest wound coils toward the
head.
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4. Place a spring retainer over the valve springs; then
using the valve spring compressor, compress the
valve springs and install the valve keepers.
PISTON ASSEMBLY
 NOTE: Whenever a piston, rings, or pin are out of
tolerance, they must be replaced.
Inspecting Piston
1. Inspect the piston for cracks in the piston pin, boss,
top, and skirt areas.
2. Inspect the piston for seizure marks or scuffing. If
piston is scored or galled, replace it with a new one.
3. Inspect the perimeter of each piston for signs of
"blowby" indicated by dark discoloration. "Blowby"
is caused by worn piston rings, excessive carbon in
ring grooves, or an out-of-round cylinder.
Removing Piston Rings
1. Starting with the top ring, slide one end of the ring
out of the ring-groove.
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ATV-1011A
CC994