39
Installing Valves
1. Apply grease to the inside surface of the valve seals;
then place a lower spring seat and valve guide seal
over each valve guide.
2. Insert each valve into its original valve location.
3. Install the valve springs with the closest coils toward
the cylinder head.
ATV-1011A
4. Place a spring retainer over the valve springs; then
using the valve spring compressor, compress the
valve springs and install the valve cotters.
KM717A
PISTON ASSEMBLY
NOTE: Whenever a piston, rings, or pin 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.
3. Inspect the piston for seizure marks or scuffing.
Repair with #400 grit wet-or-dry sandpaper and
water or honing oil.
NOTE: If scuffing or seizure marks are too deep to
correct with the sandpaper, replace the piston.
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.
CC400D
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 Rings
1. Take an old piston ring and snap it into two pieces;
then grind the end of the old ring to a 45° angle and
to a sharp edge.
2. Using the sharpened ring as a tool, clean carbon from
the ring-grooves. Be sure to position the ring with its
tapered side up.
Measuring Piston-Ring End Gap
(Installed)
1. Place each piston ring in the wear portion of the cyl-
inder. Use the piston to position each ring squarely in
the cylinder.
2. Using a feeler gauge, measure each piston-ring end
gap. Acceptable ring end gap must not exceed speci-
fications.
KM452
CAUTION
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.
