Kohler Command PRO CS, Service Manual

Page: 114 / 162

10.2
Section 10
Internal Components
Benefits
As a result of the reduced compression at cranking
speeds, several important benefits are obtained:
1. Manual (retractable) starting is much easier.
Without ACR, manual starting would be virtually
impossible.
2. Electric start models can use a smaller starter and
battery that are more practical for the application.
3. ACR eliminates the need for a spark retard/
advance mechanism. A spark retard/advance
mechanism would be required on engines
without ACR to prevent the kickback that would
occur during starting. ACR eliminates this
kickback making manual starting safer.
4. 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.
5. Engines with ACR start much faster in cold
weather than engines without ACR.
6. Engines with ACR can be started with spark
plugs that are worn or fouled. Engines without
ACR are more difficult to start with those same
spark plugs.
Camshaft & Tappets
Inspection and Service
Inspect the gear teeth of the camshaft. If the teeth are
badly worn, chipped, or some are missing,
replacement of the camshaft will be necessary. If
unusual wear or damage is evident on either lobe or
the mating tappet, the camshaft and both tappets must
be replaced. Check the condition and operation of the
ACR mechanism. See Figure 10-2.
Figure 10-2. Camshaft and Tappet Inspection
Points.
Measure the cam lobe profile, A and B , as shown
using an outside micrometer and compare with
specifications listed.
Inspect
Inspect
Intake Exhaust
CS4, CS6 26.9 ± 0.05 mm 26.68 ± 0.05 mm
(1.06 ± 0.002 in.) (1.05 ± 0.002 in.)
CS8.5, CS10, 32.55 ± 0.05 mm 32.55 ± 0.05 mm
CS12 (1.28 ± 0.002 in.) (1.28 ± 0.002 in.)
Figure 10-3. Cam Lobe Checking ‘‘A’’.
Cam Lobe Dimension–A
A