Boss BA440 PISTON Product Manual page 17

Now hone the cylinder to break the glaze and remove
the buildup at the top of the cylinders. Measure the
inside diameter of the cylinder for roundness and
excessive wear. The bore should be 2.625" (0.0025"
tolerance). If the bore is oversized, the cylinder must
be replaced. Next, with a ring expander, remove the
compression and oil rings. After the old rings have
been removed, with the ring expander, install the new
ring kit. Make certain that the oil ring is on the bottom
and the beveled edge of the compression ring is
toward the top of the piston. Now position the
cylinder base gasket on the crankcase, using a few
drops of oil to hold it in position. Install the cylinder
block spacer and gasket on the crankcase. Next you
will rotate the rings so that the gaps of the three rings
are 120 degrees apart. Lightly lubricate the inside of
the cylinder and rotate the crankshaft so that a piston
is at the top of the stroke. Compress the rings with a
ring compressor and slide the cylinder over the piston.
Repeat this step for the other piston.
Now slide the cylinder down until it mates with the
crankcase. Start all cylinder mounting bolts until they
are snug, then torque the bolts to 180 in-lbs in the
sequence shown below. Do not torque the full 180
in-lbs all at once, but in 25 - 50 in-lbs increments.
Maintenance
Position the gaskets and valve plate on top of the
cylinder. Then position the head on the cylinder and
turn bolts finger tight. After tightening with hands,
torque the studs/nuts to 240 in-lbs in 25 - 50 in-lb
increments in the sequence shown below.
Now reconnect the 3/4" discharge hose and discharge
jumper hose. Next, install the compressor and connect
the wiring and test the machine.
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