Kohler Command PRO CS, Service Manual

Page: 113 / 162

10.1
Section 10
Internal Components
10
Section 10
Internal Components
This section covers the operation, inspection, and repair/reconditioning of major internal engine components. The
following components are not covered in this section, they are covered in their own sections:
Air Cleaner, Section 4
Carburetor & External Governor, Section 5
Retractable Starter, Section 7
Ignition, Charging, & Electric Starter, Section 8
Clean all parts thoroughly. Only clean parts can be accurately inspected and gauged for wear or damage. There
are many commercially available cleaners that will quickly remove grease, oil, and grime from engine parts.
When such a cleaner is used, follow the manufacturer’s instructions and safety precautions carefully.
Make sure all traces of the cleaner are removed before the engine is reassembled and placed into operation. Even
small amounts of these cleaners can quickly break down the lubricating properties of engine oil.
Refer to A Guide to Engine Rebuilding (TP-2150-A) for additional information. Measurement Guide (TP-2159-B)
and Engine Inspection Data Record (TP-2435) are also available; use these to record inspection results.
Automatic Compression Release (ACR)
These engines are equipped with an Automatic
Compression Release (ACR) mechanism. ACR lowers
compression at cranking speeds to make starting
easier.
Operation
The ACR mechanism consists of a spring-loaded arm
and sliding pin mounted to the camshaft. When the
engine is rotating at low cranking speeds (600 RPM or
less) the arm holds the pin so it protrudes above the
heel of the exhaust cam. This holds the exhaust valve
off of its seat during the first part of the compression
stroke.
After the engine speed increases above approximately
600 RPM, centrifugal force causes the spring-loaded
arm to move outward causing the pin to retract. When
in this position the pin has no effect on the exhaust
valve and the engine operates at full compression and
power.
When the engine is stopped, the spring returns the
lever and control pin assembly to the compression
release position, ready for the next start.
Figure 10-1. ACR Operation Details.
Pin
Return Spring
Pin
Decomp Weight
Engine at Start
Engine in
Operation