POWERHEAD - 4-2190-817643R1 DECEMBER 1996
Cleaning and Inspection
Cylinder Block and Crankcase Cover
IMPORTANT: Crankcase cover and cylinder block are
matched, line-bored assembly should not be mis-
matched by using a different crankcase cover or cylin-
der block.
PE-51090
• Inspect cylinder block and crankcase cover for cracks
or fractures.
• Check gasket surfaces for nicks, deep grooves,
cracks and distortions that could cause compression
leakages.
• Check that all water passages in cylinder block are
not obstructed. Check locating pins in cylinder block
that they are tight.
• Check crankcase cover fuel/bleed passages that they
are not obstructed. Verify that check valves in crank-
case cover are not damaged.
• Thoroughly clean cylinder block and crankcase cover.
Verify that all sealant and old gaskets are removed
from matching surfaces. Clean all carbon deposits
from exhaust ports.
• Inspect spark plug holes for stripped or damaged
threads.
!
CAUTION
If crankcase cover and cylinder block is to be sub-
merged in a very strong cleaning solution, it will be
necessary to remove the crankcase cover/cylinder
block bleed system from cover/cylinder block to pre-
vent damage to hoses and check valves.
CYLINDER BORE SIZE
PISTON SIZE CYL. BLOCK
FINISH HONE
Standard Diameter 2.955 in.
75.057 mm
.015 Oversize 2.970 in.
75.438 mm
.030 Oversize 2.985 in.
75.819 mm
• Inspect cylinder bores for scoring (a transfer of alumi-
num from piston to cylinder wall). Cylinder wall scor-
ing usually can be “cleaned up” by honing or rebor-
ing.
!
CAUTION
When reboring cylinder block, remove hone frequent-
ly and check condition of cylinder walls. DO NOT hone
any more than absolutely necessary, as hone can re-
move cylinder wall material rapidly.
HONING PROCEDURE
Follow hone manufacture’s recommendations for use of
hone cleaning and lubrication during honing.
IMPORTANT: After honing, bores should be thorough-
ly cleaned with hot water and detergent. Scrub well
with stiff bristle brush and rinse with hot water. If any
abrasive material is allowed to remain in the cylinder
bore, it will cause a rapid wear of new piston rings and
cylinder bore. After cleaning, bores should be
swabbed several times with 2 cycle engine oil and a
clean cloth. Wipe excess oil with clean, dry cloth. Cyl-
inders should not be cleaned with kerosene or gaso-
line. Clean remainder of cylinder block.
• Hone all cylinder walls just enough to de-glaze.
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