Tool Kit; Spark Plug Inspection - Yamaha VK540EG Owner's Manual

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TOOL KIT

The owner's tool kit has the tools which are sufficient for
most periodic maintenance and minor repair. A torque
wrench is also necessary to properly tighten nuts and bolts.
1 Tool kit
846-006
NOTE:
If you do not have a torque wrench available during a
service operation requiring one, take your machine to a
Yamaha dealer to check the torque settings and adjust
them if necessary.
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SPARK PLUG INSPECTION

The spark plug is an important engine component and is
easy to inspect. The condition of the spark plug can
indicate something of the condition of the engine. Check
the coloration on the white porcelain insulator around the
center electrode. The ideal coloration at this point is a
medium to a light tan color for a machine that is being
ridden normally. If a spark plug shows a distinctly different
color, there could be something wrong with the engine. For
example, a very white center electrode porcelain color
could indicate an intake track air leak or carburetion
problem for that cylinder. Do not attempt to diagnose such
problems yourself. Instead, take the machine to your
Yamaha dealer. You should periodically remove and in-
spect the spark plug because heat and deposits will cause
any spark plug to slowly break down and erode. Consult
your dealer before changing to a different type of spark
plug.
Standard spark plug:
BR9ES (NGK)
Spark plugs are produced in several different thread
lengths. The thread length (reach) is the distance from the
spark plug gasket seat to the end of the threaded portion.
If the reach is too long, overheating and engine damage
may result. If the reach is too short, spark plug fouling and
poor performance may result. Also, if too short, carbon will
form on the exposed threads resulting in combustion
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