spark plugs replace YAMAHA VMAX 2015 Owners Manual

PERIODIC MAINTENANCE AND ADJUSTMENT
6-10
6
To install the panel
Place the panel in the original position,
and then install the bolt.
EAU46681
Checkin
g the spark plu gsThe spark plugs are important engine
components, which should be
checked periodically, preferably by a
Yamaha dealer. Since heat and depos-
its will cause any spark plug to slowly
erode, they should be removed and
checked in accordance with the peri-
odic maintenance and lubrication
chart. In addition, the condition of the
spark plugs can reveal the condition of
the engine.
The porcelain insulator around the
center electrode of each spark plug
should be a medium-to-light tan (the
ideal color when the vehicle is ridden
normally), and all spark plugs installed
in the engine should have the same
color. If any spark plug shows a dis-
tinctly different color, the engine could
be operating improperly. Do not at-
tempt to diagnose such problems
yourself. Instead, have a Yamaha deal-
er check the vehicle.
If a spark plug shows signs of elec-
trode erosion and excessive carbon or
other deposits, it should be replaced. Before installing a spark plug, the
spark plug gap should be measured
with a wire thickness gauge and re-
placed if out of specification.
Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the spark
plug threads.
1. Panel C
2. Bolt
1
2
Specified
spark plu g:
NGK/CR9EIA
DENSO/IU27D
1. Spark plug gap
Spark plu g g ap:
0.8–0.9 mm (0.031–0.035 in)
1
U2CEE0E0.book Page 10 Wednesday, August 27, 2014 11:11 AM

PERIODIC MAINTENANCE AND ADJUSTMENT
6-42
6
EAU63200
Troubleshootin g chartsStartin g prob lems or poor en gine performance
Check the fuel level in
the fuel tank.1. Fuel
There is enough fuel.
There is no fuel.
Check the battery.
Supply fuel.
The engine does not start.
Check the battery.
Operate the electric starter.4. Compression
There is compression.
There is no compression.
Have a Yamaha dealer check the vehicle. The engine does not start.
Have a Yamaha dealer check the vehicle.
Remove the spark plugs
and check the electrodes.3. Ignition
Wipe off with a dry cloth or replace the
spark plugs.
Have a Yamaha dealer check the vehicle.
The engine does not start.
Check the compression.
The engine does not start.
Check the ignition.
Operate the electric starter.2. Battery
The engine turns over
quickly.
The engine turns over
slowly.
The battery is good.Check the battery lead connections,
and have a Yamaha dealer charge
the battery if necessary.
DryWet
Operate the electric starter.
U2CEE0E0.book Page 42 Wednesday, August 27, 2014 11:11 AM