3-14
2. Install the compression rings (1 and 2) so the letter
on the top surface of each ring faces the dome of
the piston. Rotate the rings until the ring end gaps
are on directly opposite sides of the piston accord-
ing to the illustration.
726-306A
CYLINDER ASSEMBLY
NOTE: If the cylinder cannot be trued, it must be
replaced.
Cleaning/Inspecting Cylinder
1. Wash the cylinder in parts-cleaning solvent.
2. Inspect the cylinder for pitting, scoring, scuffing,
warpage, and corrosion. If marks are found, repair
the surface using a cylinder hone (see Honing Cyl-
inder in this sub-section).
3. Place the cylinder on the surface plate covered
with #400 grit wet-or-dry sandpaper. Using light
pressure, move the cylinder in a figure eight
motion. Inspect the sealing surface for any indica-
tion of high spots. A high spot can be noted by a
bright metallic finish. Correct any high spots
before assembly by continuing to move the cylin-
der in a figure eight motion until a uniform bright
metallic finish is attained.
Inspecting Cam Chain Guide
1. Inspect cam chain guide for cuts, tears, breaks, or
chips.
2. If the chain guide is damaged, it must be replaced.
Honing Cylinder
1. Using a slide gauge and a dial indicator or a snap
gauge, measure the cylinder bore diameter in three
locations from top to bottom and again from top to
bottom at 90° from the first measurements for a
total of six measurements. The trueness
(out-of-roundness) is the difference between the
highest and lowest reading. Maximum trueness
(out-of-roundness) must not exceed specifications.
CC127D
2. Wash the cylinder in parts-cleaning solvent.
3. Inspect the cylinder for pitting, scoring, scuffing,
and corrosion. If marks are found, repair the sur-
face using a #320 grit ball hone.
NOTE: To produce the proper 60° cross-hatch
pattern, use a low RPM drill (600 RPM) at the rate
of 30 strokes per minute. If honing oil is not avail-
able, use a lightweight petroleum-based oil. Thor-
oughly clean cylinder after honing using soap and
hot water. Dry with compressed air; then immedi-
ately apply oil to the cylinder bore. If the bore is
severely damaged or gouged, replace the cylinder.
CC390D
4. If any measurement exceeds the limit, replace the
cylinder.
! 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.
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Содержание ATV 250 Utility 2009
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