Arctic Cat 400 Service Manual page 330

2. Using a feeler gauge, measure each piston-ring
end gap. Acceptable ring end gap must be
within specifications.
Measuring Piston Pin (Outside
Diameter) and Piston-Pin Bore
1. Measure the piston pin outside diameter at each
end and in the center. If measurement is not
within specifications, the piston pin must be
replaced.
2. Insert an inside dial indicator into the piston-pin
bore. The diameter must not exceed specifica-
tions. Take two measurements to ensure accu-
racy.
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3-286
CC280D
ATV-1070
ATV-1069
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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. An F is stamped on the piston to indicate
front.
NOTE: Note the direction of the front (F) of the
piston (5) for correct ring end gap orientation.
2. Install compression ring #2 (C) so the "RN"
mark (D) is up; then install the top compression
ring #1 (A) so the "R" mark (B) is up (see illus-
tration).
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CC397D
ATV-1085C
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