Kohler K9J Service Manual page 106

Measuring Piston-to-Bore Clearance
Before installing the piston into the cylinder bore, it
is necessary that the clearance be accurately
checked. This step is often overlooked, and if the
clearances are not within specifications, generally
engine failure will result.
NOTE: Do not use a feeler gauge to measure pis-
ton-to-bore clearance, it will yield inaccurate
measurements. Use a micrometer.
The following procedures should be used to accu-
rately measure the piston-to-bore clearance:
1 . Use a micrometer and measure the diameter
of the piston as shown in Figure 11-4.
0
/
Style A
Style A-Measure piston diameter (01) perpendicular
to piston pin just below the oil ring groove.
1/2"
'><?');
i
KXXX><Io
~
01--'---+-l{f \\1-+---01
Style C
\.1
t
lll
1/2"
01
i
1..---01
Style 0
Styles C and 0-Measure piston diameter (01)
perpendicular to piston pin at 1/2" above the
bottom of the skirt.
Figure 11-4. Measuring Piston Diameter.
2. Use an inside micrometer, telescoping gauge,
or bore gauge and measure the cylinder bore.
Take the measurement approximately 2-1 /2"
below the top of the bore and perpendicular to
the piston pin.
3. Piston-to-bore clearance is the difference be-
tween the bore and the piston diameter (step
2 minus step 1) . For style A pistons only,
clearance should be: .0035"/.006" for K91,
.007"/.010" for K161-K341. For piston styles C
and D, clearance should be: .0034" 1.0051" for
K181, .0045"
1.0062"
for K301, .0050"
1.0067"
for K321 , and . 0030"
I.
0050" for K341 .
VALVES
Inspection and Service
Carefully inspect valve mechanism parts. Inspect
valve springs and related hardware for excessive
wear or distortion. Valve spring free height should
be at approximately the dimension given in the
chart below. Check valves and valve seat area or
inserts for evidence of deep pitting, cracks or dis-
tortion. Check clearance of valve stems in guides.
See Figure 11-5 for valve details and specifica-
tions.
11.3
m