spark plugs replace YAMAHA MT-25 2016 Owners Manual

Periodic maintenance and adjustment
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6
EAU46862
TIPThe annual checks must be performed every year, except if a kilometer-based maintenance, or for the UK, a
mileage-based maintenance, is performed instead.
From 50000 km (30000 mi), repeat the maintenance intervals starting from 10000 km (6000 mi).
Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools, data and tech-
nical skills.
EAU46911
Periodic maintenance chart for the emission control systemNO. ITEM CHECK OR MAINTENANCE JOBODOMETER READING
ANNUAL
CHECK 1000 km
(600 mi)10000 km
(6000 mi)20000 km
(12000 mi)30000 km
(18000 mi)40000 km
(24000 mi)
1*Fuel line• Check fuel hoses for cracks or
damage.√√√√√
2*Spark plugs• Check condition.
• Clean and regap.√√
• Replace.√√
3*Va l ve s• Check valve clearance.
•Adjust.Every 40000 km (24000 mi)
4*Fuel injection sys-
tem• Adjust synchronization.√√√√√
5*Muffler and ex-
haust pipe• Check the screw clamp(s) for
looseness.√√√√√
6*Air induction sys-
tem• Check the air cut-off valve, reed
valve, and hose for damage.
• Replace any damaged parts if
necessary.√√√√√
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Periodic maintenance and adjustment
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6
EAU19643
Checking the spark plugsThe 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, if
necessary, adjusted to specification.
Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the spark
plug threads.
TIPIf a torque wrench is not available
when installing a spark plug, a good
estimate of the correct torque is 1/4…
1/2 turn past finger tight. However, the
spark plug should be tightened to the
specified torque as soon as possible.
Specified spark plug:
NGK/CR9E
1. Spark plug gap
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
Tightening torque:
Spark plug:
13 Nm (1.3 m·kgf, 9.4 ft·lbf)
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Periodic maintenance and adjustment
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6
EAU42505
Troubleshooting chartsStarting problems or poor engine 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.
Remove the spark plugs
and check the electrodes.3. Ignition
Wipe off with a dry cloth and correct the
spark plug gaps, or replace the spark plugs.
Have a Yamaha dealer check the vehicle.
Operate the electric starter.4. Compression
There is compression.
There is no compression.
The engine does not start.
Have a Yamaha dealer check the vehicle.Have a Yamaha dealer check the vehicle.
The engine does not start.
Check the compression.
Operate the electric starter.2. Battery
The engine turns over
quickly.
The engine turns over
slowly.
The engine does not start.
Check the ignition.
The battery is good.Check the battery lead connections,
and have a Yamaha dealer charge
the battery if necessary.
DryWet
Operate the electric starter.
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