Kohler KT19 series II User Manual

SECTION 7
DISASSEMBLY
the cylinder walls. As raw fuel seeps down the
cylinder walls, it washes the necessary lubricating
oils off the piston and cylinder walls so that the
piston rings make metal to metal contact with the
walls. Scoring of the cylinder walls can also be
caused by localized hot spots resulting from
blocked cooling fins or from inadequate or con·
taminated lubrication.
If the cylinder bore is badly scored, excessively
worn, tapered, or out of round more than .002"
resizing is necessary. Use an inside micrometer to
determine amount of wear (see "Specifications
And Tolerances," Section 1), then select the near·
est suitable oversize of either .003", .010", .020" or
.030". Resizing to one of these oversizes will allow
usage of the available oversize piston and ring
assemblies. Initially resize using a boring bar,
then use the following procedures for honing the
cylinder.
Honing
While most commercially available cylinder hones
can be used with either portable drills or drill
presses, the use of a low speed drill press is
preferred as it facilitates more accurate alignment
of the bore in relation to the crankshaft cross bore.
Honing is best accomplished at a drill speed of
about 250 RPM and 60 strokes per minute. After
installing coarse stones in hone, proceed as follows:
1. Lower hone into bore and after centering, adjust
so that stones are in contact with walls. Use of a
commercial cutting-cooling agent is recom·
mended.
2. With the lower edge of each stone positioned
even with the lowest edge of the bore, start drill
and honing process. Move hone up and down
while resizing to prevent formation of cutting
ridges. Check size frequently.
NOTE: Measure the piston diameter and resize
the bore to the piston to obtain the specified
running clearances. Keep in mind the tempera·
tures caused by honing may cause inaccurate
measurements. Make sure the barrel is cool
when measuring.
3. When bore is within .0025" of desired size,
remove coarse stones and replace with burnish-
ing stones. Continue with burnishing stones
until within .0005" of desired size then use finish
stones (220-280) and polish to final size. A cross-
hatch should be observed if honing is done
44
correctly.
The cross-hatch should intersect at
approximately 23-33° off the horizontal. Too flat
an angle could cause the rings to skip and wear
excessively, too high an angle will result in high
oil consumption (see Figure 7-7).
Figure 7-7. Cylinder Bore Cross-Hatch After Honing
4. After resizing, check the bore for roundness,
taper, and size. Use an inside micrometer, tele-
scoping gauge, or bore gauge to take measure-
ments. The measurements should be taken at
three locations in the cylinder-at the top, mid-
dle, and bottom. Two measurements should be
taken (perpendicular to each other) at each of
the three locations.
5. Carefully clean cylinder wall with soap and hot
water, then after drying thoroughly, apply light
coat of SAE 10 oil to prevent rust.
Valves- Inspection and Service
Carefully inspect valve mechanism parts. Check
valves and valve seat area or inserts for evidence
of deep pitting, cracks or distortion. Check clear-
ance of valve stems in guides. See Figure 7-8 for
valve details and specifications.
Hard starting, or loss of power accompanied by
high fuel consumption may be symptoms offaulty
valves. These symptoms could also be attributed to
worn rings, however, remove and check valves
first. After removal, clean valve head, face and
stem with power wire brush then carefully inspect
for defects such as warped valve head, excessive
corrosion or worn stem ends. Replace valves found
to be in bad condition. A normal valve and a valve
in bad condition are shown in the accompanying
illustrations, followed by explanations of other
common valve conditions.

Kohler KT19 series II Specifications

General

Brand	Kohler
Model	KT19 series II
Category	Engine
Language	English