3.5
MAINTENANCE
3
INSPECTONS
Cylinder Head Inspection
Inspect each piston dome area of the cylinder head for warping
by placing a straight edge across the dome area.
With a feeler gauge measure any gap under the straight edge.
Replace cylinder head if measurement exceeds the service limit
of .003" (.08mm).
NOTE: Cylinder head warp service limit is:
.003"(.08mm).
Cylinder Measurement
Inspect each cylinder for wear, scratches, or damage. If no
damage is evident, measure the cylinder for taper and out of
round with a telescoping gauge or a dial bore gauge. Measure the
bore .50" from the top of the cylinder; in line with the piston pin
and 90° to the pin to determine if the bore is out of round. Repeat
the measurements at the middle of the cylinder and the bottom
of the cylinder to determine taper or out of round at the bottom.
Use the chart below and record all measurements.
Cylinder Honing
The cylinder bore must be de-glazed whenever new piston rings
are installed. A light honing with fine stones removes only a
very small amount of material. A proper crosshatch pattern is
important to provide a surface that will hold oil, and allow the
rings to seat properly. If the crosshatch is too steep, oil retention
will be reduced. A crosshatch angle which is too shallow will
cause ring vibration, poor sealing, and overheating of the rings
due to blow-by and reduced contact with the cylinder wall.
Service life of the pistons and rings will be greatly reduced.
NOTE: A Nikasil cylinder can be lightly honed with a
soft stone hone but an not be oversized.
Cylinder Measurement Worksheet
TOP
Tx Ty
MIDDLE
Mx My
BOTTOM
Bx By
Out of round = Tx - Ty and By - Bx
Taper limit = Ty - By and Tx - Bx
Cylinder taper limit is .002"(.051mm) Max
Cylinder out of round limit is
.002"(.051mm)
Cylinder Measurement Worksheet
EXAMPLE OF A CROSS HATCH PATTERN
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