Servicing Components - Arctic Cat ZR 120 Service Manual

 NOTE: If the seals or bearings of the crankshaft need
to be replaced, see Crankshaft Bearings in Servicing
Components.

Servicing Components

Thoroughly clean all non-electrical components in parts-
cleaning solvent; then remove any carbon buildup from
the cylinder head, piston dome, valves, and valve seats.
Visually inspect all engine components for wear or damage.
CYLINDER HEAD/VALVE ASSEMBLY
 NOTE: Remove the valves by pressing down on the
spring retainer and removing the valve keeper. Account
for valve springs, spring retainers, and valve keepers.
Keep all valves and related components as a set.
When servicing valves and cylinder head assembly,
inspect valve seats, head warpage, valve stems, valve
faces, and valve stem ends for pits, burn marks, or other
signs of abnormal wear. Never reuse the intake valve
seal. Always replace the seal.
 NOTE: Discard any valve that fails the listed inspec-
tions. Do not grind the valves. If a valve or cylinder
head is damaged, it must be replaced.
Measuring Cylinder Head Distortion
1. Using a non-metallic carbon removal tool, remove
any carbon buildup from the combustion chamber
being careful not to nick, scrape, or damage the
combustion chamber or the sealing surfaces.
2. Inspect the spark-plug hole for any damaged
threads. Repair damaged threads using a heli-coil
insert.
3. Inspect the cylinder head for flatness using a
straightedge and a feeler gauge. Acceptable distor-
tion must not exceed 0.004".
Measuring Valve Stem Runout
1. Support each valve stem end with V Blocks; then
check the valve stem runout using a dial indicator.
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2. Maximum runout must not exceed 0.0004" for
both valves.
Measuring Valve Face Width
1. Using a micrometer, measure the width of the
valve face.
2. Acceptable valve face width must be at least
0.030".
Measuring Valve Face Runout
1. Mount a dial indicator on a surface plate; then
place the valve stem on a set of V blocks.
2. Position the dial indicator contact point on the out-
side edge of the valve face; then zero the indicator.
IO087
3. Rotate the valve in the V blocks.
4. Maximum runout must not exceed 0.0012".
ATV-1082
ATV-1004
ATV1082A