Cam Gears; Crankshaft And Crank Gear; Crankcase; Honing - Kohler Courage SV470-600 Service Manual

Section 9
Inspection and Reconditioning
Benefits
Reducing the compression at cranking speeds results
in several important benefits.
1. The starter and battery can be smaller, more
practical for the applications in which these
engines are used.
2. ACR eliminates ''kickback'' during starting, so a
spark retard/advance mechanism is no longer
required.
3. The choke control setting is less critical with ACR.
In the event of flooding, excess fuel is blown out
the opened exhaust valve and does not hamper
starting.
4. Engines with ACR start much faster in cold
weather.
5. Engines with ACR can be started with spark plugs
that are worn or fouled. Engines without ACR
would be less likely to start with the same plugs.

Cam Gears

Inspection and Service
Inspect the gear teeth and cam lobes of the intake and
exhaust cam gears. If the lobes exhibit excessive
wear, or the teeth are worn, chipped or broken,
replacement of the cam gear(s) will be necessary.

Crankshaft and Crank Gear

Inspection and Service
Inspect the teeth of the crank gear. If the teeth are
badly worn, chipped, or some are missing,
replacement of the crank gear will be necessary.
Remove the gear by pulling it off the key and
crankshaft.
Inspect the crankshaft bearing journal surfaces for
wear, scoring, grooving, etc. If they show signs of
damage or are out of running clearance specifications,
the crankshaft must be replaced.
Inspect the crankshaft keyways. If worn or chipped,
replacement of the crankshaft will be necessary.
Inspect the crankpin for wear, score marks or
aluminum transfer. Slight score marks can be cleaned
with crocus cloth soaked in oil. If wear limits are
exceeded (see Section 1), it will be necessary to
replace the crankshaft.
9.2
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Crankcase

Inspection and Service
Check all gasket surfaces to make sure they are free
of gasket fragments and deep scratches or nicks.
Check the cylinder wall for scoring. In severe cases,
unburned fuel can wash the necessary lubricating oil
off the piston and cylinder wall. The piston rings make
metal to metal contact with the wall, causing scuffing
and scoring. Scoring of the cylinder wall can also be
caused by localized hot spots from blocked cooling
fins or from inadequate or contaminated lubrication.
If the cylinder bore is scored, worn, tapered, or out-of-
round, resizing may be possible. Use an inside
micrometer or telescoping gauge to determine the
amount of wear (refer to Section 1). If wear exceeds
the published limits, a 0.08 mm (0.003 in.) oversize
piston is available. If the cylinder will not clean up at
0.08 mm (0.003 in.) oversize, a short block or
replacement engine will need to be considered.

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 counter 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 the hone into the bore and, after centering,
adjust it so that the stones are in contact with the
cylinder wall. Use of a commercial cutting-cooling
agent is recommended.
2. With the lower edge of each stone positioned
even with the lowest edge of the bore, start the
drill and honing process. Move the hone up and
down while resizing to prevent the formation of
cutting ridges. Check the size frequently. Make
sure the bore is cool when measuring.
Not For Resale