IO085
3. Piston skirt to cylinder clearance must be within
0.0006-0.0016".
4. If the piston/cylinder clearance exceeds the limit,
bore the cylinder and use an oversized piston or
replace both cylinder and piston.
Installing Piston Rings
1. Place the oil ring expander into the bottom groove of
the piston allowing the ends to contact each other.
2. Place one end of the thin oil ring between the top of
the oil ring expander and the ring groove; then wind
the ring around the piston until the ring is properly
seated into the ringland of the piston. Repeat this pro-
cedure for the lower thin oil ring.
3. Position the thin oil ring gaps 90° from the gap of the
oil ring expander and 180° from each other.
4. Install the middle and top compression ring with the
I.D. mark directed toward the dome of the piston.
NOTE: The top compression ring can be identified
by the chrome (silver) face of the ring.
Measuring Piston Pin Diameter
1. Measure the piston pin diameter at each end and in
the center. If measurement is less than minimum
specifications, the piston pin must be replaced.
2. Piston pin diameter must be within 0.6297-0.6299".
IO086
Measuring Piston Pin Bore Diameter
1. Insert an inside dial indicator into the piston-pin bore.
Take two measurements to ensure accuracy.
2. Piston pin bore must not exceed 0.433".
ATV-1069
CYLINDER/CYLINDER HEAD
NOTE: If the cylinder/cylinder head assembly can-
not be trued, they must be replaced.
Cleaning/Inspecting Cylinder Head
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 com-
bustion chamber or the sealing 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 covered
with #400 grit wet-or-dry sandpaper. Using light
pressure, move the cylinder head in a figure 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 assem-
bly by continuing to move the cylinder head in a fig-
ure eight motion until a uniform bright metallic finish
is attained.
Cleaning/Inspecting/Measuring
Cylinder Distortion
1. Wash the cylinder in parts-cleaning solvent.
CAUTION
Never allow the ends of the oil ring expanders to over-
lap. This allows a loss of oil control and incorrect ten-
sion of the ring.
CAUTION
Incorrect installation of the piston rings will result in
engine damage.
CAUTION
Water or parts-cleaning solvent must be used in con-
junction with the wet-or-dry sandpaper or damage to
the sealing surface may result.
