51
4. Place a spring retainer over the valve springs; then
using the valve spring compressor, compress the
valve springs and install the valve keepers.
CC132D
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 top of the piston.
2. Inspect the piston for cracks in the piston pin, boss,
top, and skirt areas.
3. Inspect the piston for seizure marks or scuffing. If
piston is scored or galled, replace it with a new one.
4. Inspect the perimeter of each piston for signs of
“blowby” indicated by dark discoloration. “Blowby”
is caused by worn piston rings, excessive carbon in
ring grooves, 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 top of
the piston while rotating it out of the groove.
NOTE: When installing new rings, install as a
complete set only.
Cleaning/Inspecting Piston Ring
Grooves
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.
CC995
Measuring Piston Pin, Connecting
Rod Small End, and Piston-Pin Bore
1. Measure the piston pin outside diameter at each end
and in the center. If measurement does not meet
specifications, the piston pin must be replaced.
ATV-1070
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.
