Cleaning And Adjusting Spark Plug - Yamaha 40V Owner's Manual

Maintenance
40VETO, 50HETO
EMU28954

Cleaning and adjusting spark plug

The spark plug is an important engine com-
ponent and is easy to inspect. The condition
of the spark plug can indicate something
about the condition of the engine. For exam-
ple, if the center electrode porcelain is very
white, this could indicate an intake air leak or
carburetion problem in that cylinder. Do not
attempt to diagnose any problems yourself.
Instead, take the outboard motor to a
Yamaha dealer. You should periodically re-
72
move and inspect the spark plug because
heat and deposits will cause the spark plug
to slowly break down and erode. If electrode
erosion becomes excessive, or if carbon and
other deposits are excessive, you should re-
place the spark plug with another of the cor-
rect type.
1. Remove the spark plug caps from the
spark plugs.
2. Remove the spark plug. If electrode ero-
sion becomes excessive, or if carbon
and other deposits are excessive, you
ZMU03414