3.
Clean base of boring bar before
bar
is set up.
Deposits under boring bar will cause it to tilt and the
cylinder will be distorted after boring.
4.
Make an initial rough cut, followed by a finish cut.
Then hone cylinder bore to the specified oversize.
Honing Cylinders (Using Precision
Hones)
Refer
to
hone manufacturer's recommended grit site to
produce specified surface finish of
20
to
40
RMS.
Too
rough of a finish will wear out the rings and too smooth
of a finish can retard piston ring seating:
1. Position block solidly for either vertical
or
horizontal
honing. Use either a drill press or heavy-duty drill
which operates at approximately
250
to
450
rpm.
2.
Follow hone manufacturer's instructions for the use
of oil or lubricant on stones. Do not use lubricants
with a dry hone.
3.
Insert hone in bore and adjust stones to fit snugly to
the narrowest section. When adjusted correctly, the
hone should not shake or chatter in cylinder bore,
but will drag freely up and down when hone is not
running.
4.
Connect drill
to
hone and start drill. Feel out bore for
high spots, which cause an increased drag on
stones. Move hone up and down in bore with short
overlapping strokes about
40
times per minute.
Usually bottom of cylinder must be worked out first
because it is smaller.
As
cylinder takes
a
uniform
through cylinder bore.
diameter, move hone up and down all the way
5.
Check diameter of the cylinder regularly during
honing.
A
dial bore gauge is the easiest method but
a telescoping gauge can be used. Check size at
six
places in bore: measure twice at top, middle and
bottom at 90-degree angles.
6.
Crosshatch formed by the stones should form an
included angle of
23
degrees. This can be achieved
by moving the rotating hone
(250
to
450
rpm) up and
down in cylinder bore about
40
times per minute.
7.
Clean cylinder bores thoroughly with soap, water
and clean rags.
A
clean white rag should not
become soiled on wall after cleaning is complete.
Do not use a solvent
or
gasoline since they wash oil
from the walls but leave the metal particles.
8. Dry crankcase and coat
it
with oil.
Deglazing Cylinder Bores
Deglaze the cylinder bores
if
there are no scuff marks
and
no
wear or out of round beyond specifications
before installing new rings. Deglazing gives a fine finish.
but does not enlarge cylinder diameter,
so
the original
pistons with new rings may still be used.
The reason for deglazing a cylinder is to provide cavities
to hold oil during piston ring break-in.
1.
Wipe cylinder bores with a clean cloth which has
been dipped in clean, light engine oil.
2.
Use a brush type deglazing tool with coated bristle
tips to produce a crosshatch pattern in the cylinder
bore.
3.
Use a slow speed drill to drive the deglazing tool.
Move deglazing tool up and down in cylinder (10 to
12 complete strokes) rapidly enough
to
obtain a
crosshatch pattern (Figure 18).
PRODUCECROSSHATCHSCRATCHES
AVOID
THIS
FINISH
FOR
FAST
RING SEATING
FIGURE
18.
CROSSHATCHING
Improper cylinder cleaning will
result in engine damage.
Do
not
use gasoline, solvents, or commercial cleaners to
clean cylinder bores.
4.
Clean cylinder bore thoroughly with soap, water
and clean rags. Continue cleaning until a clean
white rag shows no discoloring when wiped through
cylinder bore.
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