engine YAMAHA YFM50R 2007 User Guide

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The lanyard should be held by putting your fingers
in the loop as shown.Should the ATV be separated from the parent by a
distance longer than the lanyard length, the lan-
yard will pull out the clip and stop the engine.
1. Engine stop switch
2. Clip
3. Lanyard
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2

1. Lanyard
1

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For further explanation of this switch and the lan-
yard, see “TEACHING YOUR CHILD TO OPER-
ATE THE ATV” in the “SAFETY INFORMATION”
section.
NOTE:


The engine cannot be started with the clip re-
moved.

When your child has developed sufficient skill to
no longer need you to follow with the lanyard,
the lanyard can be stowed under the seat of the
ATV. However, you must still closely supervise
your child at all times during ATV operation.
EBU18280
Throttle lever
Once the engine is running, movement of the throt-
tle lever will increase the engine speed.
Regulate the speed of the ATV by varying the
throttle position. Because the throttle is spring-
loaded, the ATV will decelerate, and the engine will
return to an idle any time the hand is removed from
the throttle lever.
Before starting the engine, check the throttle to be
sure it is operating smoothly. Make sure it returns
to the idle position as soon as the lever is released.
1. Lanyard
1

1. Throttle lever
1

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WARNING

EWB00250
Malfunction of the throttle could make it diffi-
cult to speed up or slow down when you need
to. This could cause an accident. Check the op-
eration of the throttle lever before you start the
engine. If the throttle does not work smoothly,
check for the cause. Correct the problem be-
fore riding the ATV or consult a Yamaha dealer.
EBU18361
Speed limiter
Your ATV was delivered with an adjustable speed
limiter. Yamaha recommends that all beginning
riders start off with the speed limiter adjusting
screw fully turned in to limit the amount of speed
available while they learn.
The speed limiter keeps the throttle from fully
opening, even when the throttle lever is pushed to
the maximum. The adjusting screw may be gradu-
ally turned out as the beginner becomes more fa-
miliar with operating the ATV.
1. Loosen the locknut.
2. To increase the maximum engine power avail-
able and the maximum speed of the ATV, turn
the adjusting screw in direction (a). To de-crease the maximum engine power available
and the maximum speed of the ATV, turn the
adjusting screw in direction (b).
3. Tighten the locknut.WARNING
EWB00230
Improper adjustment of the speed limiter and
throttle could cause throttle cable damage or
improper throttle operation. The child could
lose control, have an accident or be injured. Do
not turn the adjusting screw out more than 12
1. Locknut
2. Adjusting screw
3. No more than 12 mm (0.47 in)
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(b)
(a)

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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.
EBU18401
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.
EBU18460
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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WARNING

EWB00220

Always set the parking brake before starting
the engine. The ATV could start moving un-
expectedly if the parking brake is not ap-
plied. This could cause loss of control or a
collision.

Always be sure you have released the park-
ing brake before you begin to ride. The brake
could overheat if you ride the ATV without re-
leasing the parking brake. You could lose
braking performance which could cause an
accident. You could also wear out the brakes
prematurely.
EBU18630
Drive select lever
The drive select lever is located on the left side of
the engine. Use the drive select lever to shift the
transmission into drive or neutral.
EBU18720
Fuel tank cap
Remove the fuel tank cap by turning it counter-
clockwise.
1. Parking brake lock plate
1

1. Drive select lever
2. Drive position
3. Neutral position
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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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ON
With the fuel cock lever in this position, fuel flows
to the carburetor. Turn the fuel cock lever to this
position when starting the engine and riding.
RES
This indicates reserve. With the fuel cock lever in
this position, the fuel reserve is made available.
Turn the fuel cock lever to this position if you run
out of fuel while riding. When this occurs, refuel as
soon as possible and be sure to turn the fuel cock
lever back to “ON”!

EBU18860
Choke
The choke is used to start a cold engine.
Move the choke in direction (a) to turn on the
choke.
1. Arrow mark positioned over “ON”
ON
FUEL
RES
OFF
ON
1

1. Arrow mark positioned over “RES”
OFF
ONFUEL RES
RES
1

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Move the choke in direction (b) to turn off the
choke.
See the “Starting a cold engine” section on page
6-1 for proper operation.
EBU18870
Seat
To remove the seat
Pull the seat lock lever upward and pull up the seat
at the rear.
To install the seat
Insert the projection on the front of the seat into the
seat holder and push down on the seat at the rear.
NOTE:

Make sure that the seat is securely fitted.
1. Fully open “ON”
2. Half open (warming up position)
3. Closed “OFF”
4. Choke
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(b) (a)

1. Seat lock lever
1

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EBU19200
PRE-OPERATION CHECKS
EBU19220
Pre-operation check list
Before operating this ATV, be sure to check the items listed in the following table.
NOTE:

The maintenance of some items in the table has to be performed by a Yamaha dealer. Refer to the “Periodic
maintenance and lubrication chart” on page 8-3 to determine which service should be performed by a
Yamaha dealer.
ITEM ROUTINE PAGE
Fuel


Check fuel level in fuel tank, and add recommended fuel if neces-
sary.

Check fuel line for leakage. Correct if necessary.4-8, 5-3
Engine oil

Check oil level in engine, and add recommended oil to specified
level if necessary.

Check ATV for oil leakage. Correct if necessary.5-3, 8-8
Final gear oil

Check ATV for oil leakage. Correct if necessary. 5-3, 8-11
Front brake

Check operation, and correct if necessary.

Lubricate cable if necessary.

Check lever free play, and adjust if necessary.5-3, 8-19, 8-20
Rear brake

Check operation, and correct if necessary.

Lubricate cable if necessary.

Check lever free play, and adjust if necessary.5-3, 8-19, 8-22
Throttle lever

Make sure that operation is smooth. Lubricate cable and lever hous-
ing if necessary.

Check cable free play, and adjust if necessary.5-4, 8-18
Control cables

Make sure that operation is smooth. Lubricate if necessary. 8-23

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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.
EBU19560
Engine oil
Make sure that the engine oil is at the specified lev-
el. Add oil as necessary. (See page 8-8.)
EBU19590
Final gear oil
Make sure that the final gear oil is at the specified
level. Add oil as necessary. (See page 8-11.)
EBU19650
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
8-20 and 8-22.)

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 8-19.)
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.