Kohler COMMAND CV17-745 Service Manual page 163

Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Excessive Combustion Temperatures: The white
deposits seen here indicate very high combustion
temperatures, usually due to a lean fuel mixture.
Gum: Gum deposits usually result from using stale
gasoline. Gum is a prevalent cause of valve sticking.
The cure is to ream the valve guides and clean or
replace the valves, depending on their condition.
Stem Corrosion: Moisture in fuel or from condensation
are the most common causes of valve stem corrosion.
Condensation occurs from improper preservation during
storage and when engine is repeatedly stopped before
it has a chance to reach normal operating
temperatures. Replace corroded valves.
Overheating: An exhaust valve subject to overheating
will have a dark discoloration in the area above the valve
guide. Worn guides and faulty valve springs may cause
this condition. Also check for clogged air intake, and
blocked fins when this condition is noted.
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Inspection and Reconditioning
Section 10
10
10.7