Cleaning/Inspecting Piston; Removing Piston Rings; Cleaning/Inspecting Piston Ring Grooves - Arctic Cat Sno Pro 120 Service Manual

B. Find the Present Shim Size (three-digit-number)
at the top-side horizontal column of the table.
C. Match the clearance in the vertical column with
the present shim size to obtain the recommended
replacement shim.
 NOTE: At this point, complete steps 33-40 of
Assembling in this sub-section before proceeding to
step 5.
5. Rotate the engine until the camshaft lobe of the valve
being measured is directly away from the tappet.
6. With the engine at top-dead-center, measure the
valve/tappet clearance of the cylinder that is on the
compression stroke; then rotate the engine another
360° and measure the clearances of the other cylin-
der.
 NOTE: When measuring valve/tappet clearance on
the exhaust valves, rotate the engine until the decom-
pression pin of the valve/tappet is activated; then
using a screwdriver, carefully tap the decompression
arm until the decompression pin releases the tappet.
7. After verifying proper valve/tappet clearance, install
the timing inspection plug to the magneto case and
tighten to 22 ft-lb.
 NOTE: At this time, remove the items used to close
off the intake ports of the cylinder head.
PISTON ASSEMBLY
 NOTE: Whenever a piston, rings, or pins are out of
tolerance, they must be replaced.

Cleaning/Inspecting Piston

1. Using a non-metallic carbon removal tool, remove
any carbon buildup from the dome of the piston.
2. Inspect the piston for cracks in the piston pin, dome,
and skirt areas.
ZJ105 3. Inspect the piston for seizure marks or scuffing.
 NOTE: If seizure marks or scuffing is detected, the
piston must be replaced.
4. Inspect the perimeter of each piston for signs of
excessive "blowby." Excessive "blowby" indicates
worn piston rings 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.
2. Remove each ring by working it toward the dome of
the piston while rotating it out of the groove.
 NOTE: If the existing rings will not be replaced with
new ones, note the location of each ring for proper
installation. When installing new rings, install as a
complete set only.
Cleaning/Inspecting Piston Ring
IO051A
Grooves
Using a ring groove cleaning tool, clean carbon from the
ring grooves. Be sure to position the ring with the letter
side up.
Improper cleaning of the ring grooves by the use of the
wrong type of ring groove cleaner will result in severe
damage to the piston.
CAUTION
IO052B
2
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