3-16
Table of Contents
(Servicing Components)
Piston Assembly.................................................... 3-16
Cylinder/Cylinder Head ......................................... 3-17
Centrifugal Clutch/Driven Pulley ........................... 3-20
Oil Pump ............................................................... 3-21
Piston Assembly
NOTE: Whenever a piston, rings, or pin is out of
tolerance, it 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 repair with the sand paper, replace the piston.
4. Inspect the perimeter of each piston for signs of
excessive “blowby.” Excessive “blowby” indi-
cates worn piston rings or an out-of-round cylin-
der.
REMOVING PISTON RINGS
1. Starting with the top ring, slide one end of the
ring out of the ring groove.
DSC02175
2. Remove each ring by working it in a circular
motion toward the dome of the piston.
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. Only use
parts-cleaning solvent to clean the third ring
groove (oil ring groove) of the piston.
MEASURING PISTON RING END
GAP
1. Place each piston ring in the wear portion of the
cylinder. 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 be
within specifications.
CC386D
MEASURING PISTON PIN (Outside
Diameter) AND PISTON PIN BORE
1. Measure the piston pin outside diameter at each
end and in the center. Minimum diameter must
be within specifications. If measurement is not
within specifications, the piston pin must be
replaced.
! CAUTION
Improper cleaning of the ring grooves by use of the
wrong type of ring-groove cleaner will result in
severe damage to the piston.
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