3.24PISTON
REMOVAL OVERVIEW
NOTE
Do not mix 2007 and later pistons with earlier style pistons.
New style pistons have tapered wrist pin boss. The wrist pin
portion of the connecting rod is also tapered.
See 3.15 TOP END OVERHAUL: DISASSEMBLY.
1. Remove breather assembly.
2. Remove rocker arm support plate.
3. Remove push rods and push rod covers. Do not remove
lifters or lifter covers.
4. Remove cylinder head.
5. Remove cylinder.
6. Remove piston.
DISASSEMBLY
Piston Rings
Wear safety glasses or goggles when removing or
installing compression rings. Compression rings can slip
from the pliers and could be propelled with enough force
to cause serious eye injury. (00469c)
1. See Figure 3-105. Carefully remove top (7) and second
(6) compression rings using the proper piston ring
expander (Snap-on PRS8).
2. Using your fingers, remove the oil rail expansion ring (5)
from the third ring groove. Remove top and bottom oil rails
(4).
3. Discard the piston rings.
1. Circlip
2. Piston pin
3. Piston
4. Oil rail
5. Expansion ring
6. Second compression ring
7. Top compression ring
Figure 3-105. Piston Assembly
CLEANING
1. To remove all carbon and combustion deposits, soak the
pistons in a special detergent that will not corrode alu-
minum. Maintain the temperature of the cleaning solution
well below 212° F (100° C).
NOTE
Do not sand blast or glass bead blast pistons. Bead blasting
rounds off ring lands and will result in oil contamination leading
to accelerated wear.
Compressed air can pierce the skin and flying debris from
compressed air could cause serious eye injury. Wear
safety glasses when working with compressed air. Never
use your hand to check for air leaks or to determine air
flow rates. (00061a)
2. Thoroughly rinse the pistons. Blow parts dry with moisture
free compressed air.
3. Clean the oil drain holes leading from the oil control ring
groove to the underside of the piston crown. Run a small
bristle brush through the passageways to ensure their
cleanliness, but be careful not to damage or enlarge the
holes. Do not use a wire brush.
3-76 2008 Dyna Service: Engine
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