2008 YAMAHA YFM50R ESP
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operating this ATV.
Never operate at speeds too fast for your skills
or the riding conditions. Always go at a speed
that is proper for the terrain, visibility, operating
conditions, and your experience.
Never attempt wheelies, jumps, or other stunts.
Always inspect your ATV each time you use it to
make sure it is in safe operating condition. Al-
ways follow the inspection and maintenance
procedures and schedules described in this
manual.
Always keep both hands on the handlebars and
both feet on the footrests of the ATV during op-
eration.
Always go slowly and be extra careful when op-
erating on unfamiliar terrain. Always be alert to
changing terrain conditions when operating the
ATV.
Never operate on excessively rough, slippery or
loose terrain until you have learned and prac-
ticed the skills necessary to control the ATV on
such terrain. Always be especially cautious on
these kinds of terrain.
Always follow proper procedures for turning as
described in this manual. Practice turning at low
speeds before attempting to turn at fasterspeeds and never turn at excessive speeds.
Never operate the ATV on hills too steep for the
ATV or for your abilities. Practice on smaller hills
before attempting larger hills.
Always follow proper procedures for climbing
hills as described in this manual. Check the ter-
rain carefully before you start up any hill. Never
climb hills with excessively slippery or loose sur-
faces. Shift your weight forward. Never open the
throttle suddenly or make sudden gear changes.
Never go over the top of a hill at high speed.
Always follow proper procedures for going down
hills and for braking on hills as described in this
manual. Check the terrain carefully before you
start down any hill. Shift your weight backward.
Never go down a hill at high speed. Avoid going
down a hill at an angle that would cause the ve-
hicle to lean sharply to one side. Go straight
down the hill where possible.
Always follow proper procedures for crossing
the side of a hill as described in this manual.
Avoid hills with excessively slippery or loose sur-
faces. Shift your weight to the uphill side of the
ATV. Never attempt to turn the ATV around on
any hill until you have mastered the turning tech-
nique described in this manual on level ground.
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mm (0.47 in) or the throttle cable could be dam-
aged.
EBU18391
Front brake lever
The front brake lever is located on the right handle-
bar. To apply the front brake, pull the brake lever
toward the handlebar grip.
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Rear brake lever
The rear brake lever is located on the left handle-
bar. To apply the rear brake, pull the brake lever to-
ward the handlebar grip.
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Parking brake
Use the parking brake before starting the engine or
parking the ATV, especially on a slope. Apply the
rear brake lever and push down the lock plate to
apply the parking brake. Squeeze the rear brake
lever to release the parking brake.
1. Front brake lever
1
1. Rear brake lever1
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of gasoline or higher octane grade.
CAUTION:
ECB00070
Use only unleaded gasoline. The use of leaded
gasoline will cause severe damage to internal
engine parts, such as the valves and piston
rings, as well as to the exhaust system.
WARNING
EWB00310
Do not overfill the fuel tank. Fuel expands
when it heats up. If the fuel tank is overfilled,
fuel could spill out due to heat from the en-
gine or the sun.
Be careful not to spill fuel, especially on the
engine or exhaust pipe which can cause a
fire and severe injury. Wipe up any spilled
fuel immediately.
Do not refuel right after the engine has been
running and is still very hot.
Be sure the fuel tank cap is closed securely.
EBU18820
Fuel cock
The fuel cock supplies fuel from the tank to the car-
buretor while also filtering it.The fuel cock lever positions are explained as fol-
lows and shown in the illustrations.
OFF
With the fuel cock lever in this position, fuel will not
flow. Always turn the fuel cock lever to this position
when the engine is not running.
1. Arrow mark positioned over “OFF”
RES
ONFUEL
OFF
1
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EBU19540
Fuel
Make sure that there is sufficient fuel in the tank.
(See page 4-8.)
WARNING
EWB00520
Do not overfill the fuel tank. Fuel expands
when it heats up. If the fuel tank is overfilled,
fuel could spill out due to heat from the en-
gine or the sun.
Be careful not to spill fuel, especially on the
engine or exhaust pipe which can cause a
fire and severe injury. Wipe up any spilled
fuel immediately.
Do not refuel right after the engine has been
running and is still very hot.
Be sure the fuel tank cap is closed securely.
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Engine oil
Make sure that the engine oil is at the specified lev-
el. Add oil as necessary. (See page 8-9.)
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Final gear oil
Make sure that the final gear oil is at the specified
level. Add oil as necessary. (See page 8-12.)
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Front and rear brakes
Brake levers
Check for correct free play in the brake levers. If
the free play is incorrect, adjust it. (See pages
8-21 and 8-23.)
Check operation of the levers. They should
move smoothly and there should be a firm feel-
ing when the brake is applied. If not, have the
ATV checked by a Yamaha dealer.
Brake operation
Test the brakes at slow speed after starting out to
make sure they are working properly. If the brakes
do not provide proper braking performance, check
the brakes for wear. (See page 8-20.)
WARNING
EWB00570
Always check the brakes at the start of every
ride. Do not ride the ATV if you find any prob-
lem with the brakes or you could lose braking
ability, which could lead to an accident. If a
problem cannot be corrected by the adjust-
ment procedures provided in this manual, have
the ATV checked by a Yamaha dealer.
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crank the engine more than 10 seconds on each
attempt.
7. If the engine is started with the choke in posi-
tion (1), the choke should be returned to posi-
tion (2) to warm up the engine. If the engine is
started with the choke in position (2), keep the
choke in this position to warm up the engine.
CAUTION:
ECB00160
For maximum engine life, always warm the en-
gine up before starting off. Never accelerate
hard when the engine is cold!
8. Continue warming up the engine until it idles
smoothly, then return the choke to position (3)
before riding.
NOTE:
The engine is warm when it responds normally to
the throttle with the choke turned off.
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Starting a warm engine
Follow the same procedure as for starting a cold
engine, with the exception that the choke is not re-
quired when the engine is warm. Instead, start the
engine with the throttle slightly open.
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Shifting
This ATV has an automatic, centrifugal clutch.
To shift into the drive position, release the throttle
lever and apply the parking brake.
To shift into neutral, stop the ATV by releasing the
throttle lever and applying the brakes smoothly
and evenly.
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To start out and accelerate
1. Release the throttle lever.
CAUTION:
ECB00210
Always close the throttle before shifting the
transmission into drive, otherwise damage to
the engine and drive train may result.
2. Apply the parking brake. (See page 6-5.)
3. Shift the transmission into drive.
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When riding in an area where you might not easily
be seen, such as desert terrain, mount a caution
flag on the ATV. DO NOT use the flag pole bracket
as a trailer hitch.
WARNING
EWB01550
Always mount a caution flag on the ATV to
make you more visible when operating in areas
where you might not be seen by other vehicles.
Watch carefully for other vehicles.
Do not ride in areas posted “no trespassing”.
Do not ride on private property without getting per-
mission.
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Checking the spark plug
The spark plug is an important engine component,
which is easy to check. Since heat and deposits
will cause any spark plug to slowly erode, the spark
plug should be removed and checked in accor-
dance with the periodic maintenance and lubrica-
tion chart. In addition, the condition of the spark
plug can reveal the condition of the engine.
To remove the spark plug
1. Remove the spark plug cap.
2. Remove the spark plug as shown, with thespark plug wrench included in the owner’s tool
kit.
To check the spark plug
1. Check that the porcelain insulator around the
center electrode of the spark plug is a medi-
um-to-light tan (the ideal color when the ATV
is ridden normally).NOTE:
If the spark plug shows a distinctly different color,
the engine could be operating improperly. Do not
attempt to diagnose such problems yourself. In-
stead, have a Yamaha dealer check the ATV.
1. Spark plug cap
1
1. Spark plug wrench
1
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touching exhaust components.
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Adjusting the carburetor
The carburetor should be checked and, if neces-
sary, adjusted at the intervals specified in the peri-
odic maintenance and lubrication chart. The
carburetor is an important part of the engine and
requires very sophisticated adjustment. Therefore,
most carburetor adjustments should be left to a
Yamaha dealer, who has the necessary profes-
sional knowledge and experience. The adjustment
described in the following section, however, may
be performed by the owner as part of routine main-
tenance.
CAUTION:
ECB00480
The carburetor has been set and extensively
tested at the Yamaha factory. Changing these
settings without sufficient technical knowl-
edge may result in poor performance of or
damage to the engine.
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Adjusting the engine idling speed
The engine idling speed must be checked and, ifnecessary, adjusted as follows at the intervals
specified in the periodic maintenance and lubrica-
tion chart.
NOTE:
A diagnostic tachometer is needed to make this
adjustment.
1. Start the engine and warm it up.
NOTE:
The engine is warm when it quickly responds to the
throttle.
2. Attach the tachometer to the spark plug lead.
3. Check the engine idling speed and, if neces-
sary, adjust it to specification by turning the
throttle stop screw at the carburetor. To in-
crease the engine idling speed, turn the throt-
tle stop screw in direction (a), and to decrease
it, turn the screw in direction (b).